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Dr. Vincenzo Vaiano

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Department of Industrial Engineering, University Salerno, Via Giovanni Paolo 2 132, I-84084 Fisciano, Salerno, Italy

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Department of Chemistry and Biology "A.Zambelli", University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano, SA, Italy

Catalysis for Sustainable Chemistry and Energy

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closed (31 July 2022)

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closed (31 October 2022)

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Topic Information

Dear Colleagues,

This Topic Issue entitled “Catalysis for Sustainable Chemistry and Energy” is related to the design and/or the development of catalysts able to minimize the adverse environmental impact, such as greenhouse gas emissions, and avoid, simultaneously, the use and the generation of by-products having toxic and hazardous properties. Such aims can be achieved by means of tuning the chemical structure and composition of catalytic materials, also at an atomic and/or molecular scale, in a manner to enhance not only the reactants conversion but also the selectivity towards the desired products. Papers and Review papers dealing with all types of both homogeneous and heterogeneous catalysis, including organocatalysis, photocatalysis, electrocatalysis, environmental catalysis, biocatalysis/enzymes and nanostructured catalysis to promote selective conversions, fall within the scope of this Topic Issue. Novel reactor or photoreactor configurations, such as catalytic reactors that combine the reaction and separation steps, or design and/or development of (photo)reactors for process intensification, such as microreactors membrane-based reactors and reactors using structured catalysts, are also within the scope of the Topic Issue and they are welcomed.

Prof. Dr. Vincenzo Vaiano
Dr. Olga Sacco
Topic Editors

Keywords

nanostructured catalysts
photocatalysts
electrocatalysts
environmental catalysts
biocatalysts
organocatalysts
selective conversions
catalytic processes for CO₂ mitigation
microreactors
membrane-based reactors
process intensification

Participating Journals

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Catalysts catalysts	3.9	6.3	2011	14.3 Days	CHF 2700
Chemistry chemistry	2.1	2.5	2019	19.1 Days	CHF 1800
Energies energies	3.2	5.5	2008	16.1 Days	CHF 2600
Nanomaterials nanomaterials	5.3	7.4	2010	13.6 Days	CHF 2900
Sustainability sustainability	3.9	5.8	2009	18.8 Days	CHF 2400

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Catalysis for Sustainable Chemistry and Energy, 2nd Volume (2 articles)

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16 pages, 4062 KiB

Open AccessArticle

Metal-Doped Mesoporous MnO₂-CeO₂ Catalysts for Low-Temperature Pre-Oxidation of NO to NO₂ in Fast SCR Process

by Chun-Nan Kuo, Cheng-Shiuan Li, Yu-Lun Lai and Shao-I Yen

Catalysts 2023, 13(4), 694; https://doi.org/10.3390/catal13040694 - 03 Apr 2023

Viewed by 1246

Selective catalytic reduction (SCR) is an effective system for treating nitrogen oxides (NO_x; mainly NO), and fast SCR requires the equimolar reactants of NO and NO₂. This study focused on catalysts for oxidizing 50% of NO to NO₂ [...] Read more.

Selective catalytic reduction (SCR) is an effective system for treating nitrogen oxides (NO_x; mainly NO), and fast SCR requires the equimolar reactants of NO and NO₂. This study focused on catalysts for oxidizing 50% of NO to NO₂. A series of catalysts composed of a variety of components, such as mesoporous mMnO₂-nCeO₂ as carrier catalysts (m:n = 9:1 and 7:3) and transition metals (e.g., Fe, Co, Ni, Cu, and Cr), were synthesized and characterized using N₂ adsorption, in situ XRD, TEM, and XPS. All samples had a mesoporous structure with pore size around 8 nm. XPS results demonstrated that addition of cerium ion increased the surface area and provided oxygen vacancy due to the formation of Ce³⁺ within the structure. NO oxidation activity was tested using a feed (205~300 ppm NO and 6% O₂) that simulated typical flue gas conditions. Doped mesoporous mMnO₂–nCeO₂ has higher NO oxidation activity than pristine mMnO₂–nCeO₂. The doped mMnO₂-nCeO₂ catalyzed 50% of NO to NO₂ at between 140 and 200 °C resulting in an equivalent amount of NO and NO₂. Among the transition metals, Cu, Ni, Co, Fe, and Cr have the highest to lowest oxidation activity, respectively. The precatalytic oxidation of NO can potentially be combined with the current SCR system without changes to existing equipment and can be applied to the exhaust gas treatment for de-NO_x. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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4 pages, 178 KiB

Open AccessEditorial

Advances in Hydrogen and Syngas Generation

by Vladislav Sadykov

Energies 2023, 16(7), 3127; https://doi.org/10.3390/en16073127 - 29 Mar 2023

Viewed by 988

To solve problems related to global warming, environmental pollution, and green energy fields, a lot of research is now devoted to the catalysis of biofuels and biogas transformation into syngas and hydrogen [...] Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

22 pages, 2950 KiB

Open AccessReview

Nanostructured Electrocatalysts for Advanced Applications in Fuel Cells

by Lukman Ahmed Omeiza, Abdalla M. Abdalla, Bo Wei, Anitha Dhanasekaran, Yathavan Subramanian, Shammya Afroze, Md Sumon Reza, Saifullah Abu Bakar and Abul Kalam Azad

Energies 2023, 16(4), 1876; https://doi.org/10.3390/en16041876 - 14 Feb 2023

Cited by 17 | Viewed by 2631

Nanostructured materials have gained much attention in recent engineering and material- science research due to their unique structural makeup, which stands them out from their bulk counterparts. Their novel properties of tiny-size structural elements (molecules or crystallites, clusters) of nanoscale dimensions (1 to [...] Read more.

Nanostructured materials have gained much attention in recent engineering and material- science research due to their unique structural makeup, which stands them out from their bulk counterparts. Their novel properties of tiny-size structural elements (molecules or crystallites, clusters) of nanoscale dimensions (1 to 100 nm) make them a perfect material for energy applications. The recent keen interest in nanostructured materials research by academia and industrial experts arises from the unique variable characteristics of increased electrical and thermal conductivity. This occurs as nanostructured materials undergo a transient process from infinite-extended solid to a particle of ascertainable numbers of atoms. The commercial and energy sectors are very interested in developing and expanding simple synthetic pathways for nanostructured-electrocatalysts materials to aid in optimizing the number of active regions. Over the decades, various techniques have been put forward to design and synthesize nanostructured-electrocatalysts materials for electrochemical generation of energy and storage applications. As a result, the design of fuel cells, supercapacitors, and energy-storage devices has advanced significantly. This review provides a comprehensive outlook of various synthesis techniques and highlight the challenges of nanostructured- electrocatalysts materials application in fuel cells. Several synthesis methods are discussed and summarized for enhanced nanomaterial preparation and high product attainment with the sol-gel synthesis method being emphasized. The design methodology for an effective nanostructured electrocatalysts with high efficiency for fuel cells was also discussed. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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13 pages, 2928 KiB

Open AccessArticle

Catalytic Activity of Ni Based Materials Prepared by Different Methods for Hydrogen Production via the Water Gas Shift Reaction

by Opas Tojira and Pannipa Tepamatr

Catalysts 2023, 13(1), 176; https://doi.org/10.3390/catal13010176 - 12 Jan 2023

Cited by 5 | Viewed by 1513

Water gas shift reactions (WGS) were evaluated over Ni/CeO₂ and Ni/CeSmO catalysts for hydrogen production. The effects of catalyst preparation method and Sm loading were investigated. The Ni/ceria and Ni/CeSmO catalysts were synthesized by combustion, sol gel and sol gel-combustion method. After [...] Read more.

Water gas shift reactions (WGS) were evaluated over Ni/CeO₂ and Ni/CeSmO catalysts for hydrogen production. The effects of catalyst preparation method and Sm loading were investigated. The Ni/ceria and Ni/CeSmO catalysts were synthesized by combustion, sol gel and sol gel-combustion method. After WGS tests, the catalysts were determined the carbon deposition by thermogravimetric analysis. The thermogravimetric analysis and temperature programmed NH₃ desorption showed that addition of Sm promoter made higher the weak acid sites and lower the amount of carbon deposition than the unpromoted catalyst due to it being easily removed. CO chemisorption result indicated that Ni/Ce5%SmO catalyst prepared by combustion method has the highest Ni metal dispersion and metallic surface area compared to the other catalysts. The enhancement of WGS activity of this catalyst is due to more surface active sites being exposed to reactants. Furthermore, H₂-temperature programmed reduction analysis confirmed an easiest reduction of this catalyst. This behavior accelerates the redox process at the ceria surface and enhances the oxygen vacancy concentration. The catalytic activity measurements exhibited that the optimum Sm loading was 5% wt. and the best catalyst preparation was the combustion method. The high surface area and small crystallite size of the 5%Ni/Ce5%SmO (combustion) catalyst resulted in sufficient dispersion, which closely related to the WGS activity of the catalyst. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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22 pages, 5880 KiB

Open AccessFeature PaperArticle

Catalytic Hydrodeoxygenation of Vanillin, a Bio-Oil Model Compound over Renewable Ni/Biochar Catalyst

by Ismaila Mudi, Abarasi Hart, Andrew Ingram and Joseph Wood

Catalysts 2023, 13(1), 171; https://doi.org/10.3390/catal13010171 - 11 Jan 2023

Cited by 4 | Viewed by 2258

This study aims to examine the hydrodeoxygenation (HDO) of vanillin, an oxygenated phenolic compound present in bio-oil, into creosol. Biochar residue generated when wood is slowly pyrolyzed is utilized as a catalyst support. To improve biochar’s physicochemical properties, H₂SO₄ (sulfuric [...] Read more.

This study aims to examine the hydrodeoxygenation (HDO) of vanillin, an oxygenated phenolic compound present in bio-oil, into creosol. Biochar residue generated when wood is slowly pyrolyzed is utilized as a catalyst support. To improve biochar’s physicochemical properties, H₂SO₄ (sulfuric acid) and KOH (potassium hydroxide) are used as chemical activators. By means of a wet impregnation method with nickel salt, an Ni/biochar catalyst was prepared and utilized in the HDO of vanillin using a 100 mL Parr reactor, catalyst loading 0.4–0.8 g, temperature 100 °C to 150 °C, hydrogen (H₂) pressures of 30 to 50 bar, and a stirring rate of 1000 rpm. The prepared catalysts were characterized with the nitrogen-sorption isotherm technique, carbon dioxide temperature-programmed desorption (CO₂-TPD), scanning electron microscopy (SEM) coupled with energy dispersed X-ray analysis (EDX), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). Based on chemical treatment, Ni/biochar (KOH) pore sizes were found to be dominated by mesopores, with a surface area increase of 64.7% and a volume increase of 65.3%, while Ni/biochar (H₂SO₄) was mostly microporous and mesoporous, with an area increase of 372.3% and a volume increase of 256.8% in comparison to Ni/biochar (74.84 m²g⁻¹ and 0.095 cm³g⁻¹). Vanillin conversion of up to 97% with 91.17% selectivity to p-creosol was obtained over Ni/biochar catalyst; in addition to being highly selective and active for p-creosol, a plausible fuel, the catalyst was stable after four cycles. Chemical treatments of the biochar support resulted in improved physicochemical properties, leading to improved catalytic performance in terms of vanillin conversion and p-creosol yield in the order Ni/biochar (H₂SO₄) > Ni/biochar (KOH) > Ni/biochar. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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18 pages, 3755 KiB

Open AccessArticle

Ultrasound-Assisted Synthesis of a N-TiO₂/Fe₃O₄@ZnO Complex and Its Catalytic Application for Desulfurization

by Payal Dalvi, Ananya Dey and Parag R. Gogate

Sustainability 2022, 14(23), 16201; https://doi.org/10.3390/su142316201 - 05 Dec 2022

Cited by 1 | Viewed by 1446

Ultrasound (US)-assisted synthesis of a N-doped TiO₂ catalyst supported on magnetically separable Fe₃O₄@ZnO particles and its subsequent application for catalytic desulfurization were performed in the present work. The catalyst was also synthesized conventionally to compare the role of [...] Read more.

Ultrasound (US)-assisted synthesis of a N-doped TiO₂ catalyst supported on magnetically separable Fe₃O₄@ZnO particles and its subsequent application for catalytic desulfurization were performed in the present work. The catalyst was also synthesized conventionally to compare the role of acoustic cavitation (US horn working at 20 kHz frequency) in improving the catalyst characteristics. The effects of different ultrasonic (US) power (80 W to 120 W) and duration (15 min to 75 min) were studied to elucidate the best operating conditions for obtaining the minimum particle size of the catalyst. Under optimal conditions of 80 W power and 30 min of time, a minimum particle size of 31.22 μm was obtained. The particle size for the conventionally synthesized catalyst was 806.4 µm, confirming that the particles were agglomerated in the absence of ultrasound. The synthesized catalyst was used for the desulfurization of thiophene to assess the performance of the catalyst, along with a comparative study between the conventionally synthesized catalyst and that obtained using the US-assisted approach. It was evident that the performance of the catalyst synthesized sonochemically was superior, as US enhanced the activity of the catalyst by reducing the particle size and achieving homogeneity. The desulfurization achieved using the sonochemically synthesized catalyst was 47% in 100 min at a 2 g/L catalyst dose and a 3 mL/L H₂O₂ dose. The desulfurization was only 25% using the conventionally synthesized catalysts under the same operating conditions. Overall, the present work demonstrates the advantages of US in improving the catalyst characteristics, as well as the successful application of catalyst in desulfurization. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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13 pages, 16579 KiB

Open AccessArticle

Microwave Assisted Esterification of Aryl/Alkyl Acids Catalyzed by N-Fluorobenzenesulfonimide

by Bojan Božić, Jelena Lađarević, Miloš Petković, Dušan Mijin and Stojan Stavber

Catalysts 2022, 12(11), 1413; https://doi.org/10.3390/catal12111413 - 11 Nov 2022

Viewed by 1484

The susceptibility of the carbonyl group towards nucleophilic attack affords the construction of various organic compounds. Thus, investigations of carbonyl activation applying greener methodologies are highly important. In the present work, among the investigated N-halo compounds, N-fluorobenzenesulfonimide (NFSi) has been found [...] Read more.

The susceptibility of the carbonyl group towards nucleophilic attack affords the construction of various organic compounds. Thus, investigations of carbonyl activation applying greener methodologies are highly important. In the present work, among the investigated N-halo compounds, N-fluorobenzenesulfonimide (NFSi) has been found as an efficient and selective catalyst in the reaction of direct esterification of aryl and alkyl carboxylic acids supported by microwave (MW) irradiation. The comprehensive esterification of different benzoic acids and mono-, di- and tri-carboxy alkyl derivatives was performed, whereby significant reaction time reductions were achieved. The presented method used NFSi as an easily manipulatable, non-metal, water- and air-tolerant catalyst, allowing simple synthetic and isolation procedures and energy saving, compared to conventional methodologies. Importantly, in contrast to esterification under thermal conditions, where N-halo compounds behave as pre-catalysts, in the MW-supported protocol, a distinct reaction mechanism has been proposed that assumes NFSi as a sustainable catalyst. Moreover, a scale-up of the industrially important derivative was performed. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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10 pages, 2597 KiB

Open AccessArticle

Hierarchical Co–Pi Clusters/Fe₂O₃ Nanorods/FTO Micropillars 3D Branched Photoanode for High-Performance Photoelectrochemical Water Splitting

by Nakhyun Kim, Sucheol Ju, Jisung Ha, Hojung Choi, Hansang Sung and Heon Lee

Nanomaterials 2022, 12(20), 3664; https://doi.org/10.3390/nano12203664 - 18 Oct 2022

Cited by 1 | Viewed by 1369

In this study, an efficient hierarchical Co–Pi cluster/Fe₂O₃ nanorod/fluorine-doped tin oxide (FTO) micropillar three-dimensional (3D) branched photoanode was designed for enhanced photoelectrochemical performance. A periodic array of FTO micropillars, which acts as a highly conductive “host” framework for uniform light [...] Read more.

In this study, an efficient hierarchical Co–Pi cluster/Fe₂O₃ nanorod/fluorine-doped tin oxide (FTO) micropillar three-dimensional (3D) branched photoanode was designed for enhanced photoelectrochemical performance. A periodic array of FTO micropillars, which acts as a highly conductive “host” framework for uniform light scattering and provides an extremely enlarged active area, was fabricated by direct printing and mist-chemical vapor deposition (CVD). Fe₂O₃ nanorods that act as light absorber “guest” materials and Co–Pi clusters that give rise to random light scattering were synthesized via a hydrothermal reaction and photoassisted electrodeposition, respectively. The hierarchical 3D branched photoanode exhibited enhanced light absorption efficiency because of multiple light scattering, which was a combination of uniform light scattering from the periodic FTO micropillars and random light scattering from the Fe₂O₃ nanorods. Additionally, the large surface area of the 3D FTO micropillar, together with the surface area provided by the one-dimensional Fe₂O₃ nanorods, contributed to a remarkable increase in the specific area of the photoanode. Because of these enhancements and further improvements facilitated by decoration with a Co–Pi catalyst that enhanced water oxidation, the 3D branched Fe₂O₃ photoanode achieved a photocurrent density of 1.51 mA cm⁻² at 1.23 V_RHE, which was 5.2 times higher than that generated by the non-decorated flat Fe₂O₃ photoanode. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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24 pages, 4452 KiB

Open AccessReview

Production of Minor Ginsenoside CK from Major Ginsenosides by Biotransformation and Its Advances in Targeted Delivery to Tumor Tissues Using Nanoformulations

by Mohanapriya Murugesan, Ramya Mathiyalagan, Vinothini Boopathi, Byoung Man Kong, Sung-Keun Choi, Chang-Soon Lee, Deok Chun Yang, Se Chan Kang and Thavasyappan Thambi

Nanomaterials 2022, 12(19), 3427; https://doi.org/10.3390/nano12193427 - 30 Sep 2022

Cited by 16 | Viewed by 2844

For over 2000 years, ginseng (roots of Panax ginseng C.A. Meyer) has been used as a traditional herbal medicine. Ginsenosides are bioactive compounds present in ginseng responsible for the pharmacological effects and curing various acute diseases as well as chronic diseases including cardiovascular [...] Read more.

For over 2000 years, ginseng (roots of Panax ginseng C.A. Meyer) has been used as a traditional herbal medicine. Ginsenosides are bioactive compounds present in ginseng responsible for the pharmacological effects and curing various acute diseases as well as chronic diseases including cardiovascular disease, cancer and diabetes. Structurally, ginsenosides consist of a hydrophobic aglycone moiety fused with one to four hydrophilic glycoside moieties. Based on the position of sugar units and their abundance, ginsenosides are classified into major and minor ginsenosides. Despite the great potential of ginsenosides, major ginsenosides are poorly absorbed in the blood circulation, resulting in poor bioavailability. Interestingly, owing to their small molecular weight, minor ginsenosides exhibit good permeability across cell membranes and bioavailability. However, extremely small quantities of minor ginsenosides extracted from ginseng plants cannot fulfill the requirement of scientific and clinical studies. Therefore, the production of minor ginsenosides in mass production is a topic of interest. In addition, their poor solubility and lack of targetability to tumor tissues limits their application in cancer therapy. In this review, various methods used for the transformation of major ginsenosides to minor ginsenoside compound K (CK) are summarized. For the production of CK, various transformation methods apply to major ginsenosides. The challenges present in these transformations and future research directions for producing bulk quantities of minor ginsenosides are discussed. Furthermore, attention is also paid to the utilization of nanoformulation technology to improve the bioavailability of minor ginsenoside CK. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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12 pages, 2342 KiB

Open AccessArticle

Single-Phase θ-Fe₃C Derived from Prussian Blue and Its Catalytic Application in Fischer-Tropsch Synthesis

by Wei Zhang, Caiping Ma, Xingwu Liu, Yong Yang, Yongwang Li and Xiaodong Wen

Catalysts 2022, 12(10), 1140; https://doi.org/10.3390/catal12101140 - 29 Sep 2022

Cited by 3 | Viewed by 1647

Elucidation of the intrinsic catalytic principle of iron carbides remains a substantial challenge in iron-catalyzed Fischer-Tropsch synthesis (FTS), due to possible interference from other Fe-containing species. Here, we propose a facile approach to synthesize single-phase θ-Fe₃C via the pyrolysis of a [...] Read more.

Elucidation of the intrinsic catalytic principle of iron carbides remains a substantial challenge in iron-catalyzed Fischer-Tropsch synthesis (FTS), due to possible interference from other Fe-containing species. Here, we propose a facile approach to synthesize single-phase θ-Fe₃C via the pyrolysis of a molecularly defined Fe-C complex (Fe₄[Fe(CN)₆]₃), thus affording close examination of its catalytic behavior during FTS. The crystal structure of prepared θ-Fe₃C is unambiguously verified by combined XRD and MES measurement, demonstrating its single-phase nature. Strikingly, single-phase θ-Fe₃C exhibited excellent selectivity to light olefins (77.8%) in the C₂-C₄ hydrocarbons with less than 10% CO₂ formation in typical FTS conditions. This strategy further succeeds with promotion of Mn, evident for its wide-ranging compatibility for the promising industrial development of catalysts. This work offers a facile approach for oriented preparation of single-phase θ-Fe₃C and provides an in-depth understanding of its intrinsic catalytic performance in FTS. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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42 pages, 6071 KiB

Open AccessReview

A Review on the Different Aspects and Challenges of the Dry Reforming of Methane (DRM) Reaction

by Aseel G. S. Hussien and Kyriaki Polychronopoulou

Nanomaterials 2022, 12(19), 3400; https://doi.org/10.3390/nano12193400 - 28 Sep 2022

Cited by 27 | Viewed by 4595

The dry reforming of methane (DRM) reaction is among the most popular catalytic reactions for the production of syngas (H₂/CO) with a H₂:CO ratio favorable for the Fischer–Tropsch reaction; this makes the DRM reaction important from an industrial perspective, [...] Read more.

The dry reforming of methane (DRM) reaction is among the most popular catalytic reactions for the production of syngas (H₂/CO) with a H₂:CO ratio favorable for the Fischer–Tropsch reaction; this makes the DRM reaction important from an industrial perspective, as unlimited possibilities for production of valuable products are presented by the FT process. At the same time, simultaneously tackling two major contributors to the greenhouse effect (CH₄ and CO₂) is an additional contribution of the DRM reaction. The main players in the DRM arena—Ni-supported catalysts—suffer from both coking and sintering, while the activation of the two reactants (CO₂ and CH₄) through different approaches merits further exploration, opening new pathways for innovation. In this review, different families of materials are explored and discussed, ranging from metal-supported catalysts, to layered materials, to organic frameworks. DRM catalyst design criteria—such as support basicity and surface area, bimetallic active sites and promoters, and metal–support interaction—are all discussed. To evaluate the reactivity of the surface and understand the energetics of the process, density-functional theory calculations are used as a unique tool. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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23 pages, 6670 KiB

Open AccessReview

Non-Noble Metal Catalysts in Cathodic Oxygen Reduction Reaction of Proton Exchange Membrane Fuel Cells: Recent Advances

by Zhuo Hao, Yangyang Ma, Yisong Chen, Pei Fu and Pengyu Wang

Nanomaterials 2022, 12(19), 3331; https://doi.org/10.3390/nano12193331 - 24 Sep 2022

Cited by 9 | Viewed by 3029

The oxygen reduction reaction (ORR) is one of the crucial energy conversion reactions in proton exchange membrane fuel cells (PEMFCs). Low price and remarkable catalyst performance are very important for the cathode ORR of PEMFCs. Among the various explored ORR catalysts, non-noble metals [...] Read more.

The oxygen reduction reaction (ORR) is one of the crucial energy conversion reactions in proton exchange membrane fuel cells (PEMFCs). Low price and remarkable catalyst performance are very important for the cathode ORR of PEMFCs. Among the various explored ORR catalysts, non-noble metals (transition metal: Fe, Co, Mn, etc.) and N co-doped C (M–N–C) ORR catalysts have drawn increasing attention due to the abundance of these resources and their low price. In this paper, the recent advances of single-atom catalysts (SACs) and double-atom catalysts (DACs) in the cathode ORR of PEMFCs is reviewed systematically, with emphasis on the synthesis methods and ORR performance of the catalysts. Finally, challenges and prospects are provided for further advancing non-noble metal catalysts in PEMFCs. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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10 pages, 4593 KiB

Open AccessArticle

Se-Doped Ni₅P₄ Nanocatalysts for High-Efficiency Hydrogen Evolution Reaction

by Cuihua An, Yuchen Wang, Penggang Jiao, Shuai Wu, Lingxiao Gao, Chunyou Zhu, Junsheng Li and Ning Hu

Catalysts 2022, 12(9), 1055; https://doi.org/10.3390/catal12091055 - 16 Sep 2022

Cited by 3 | Viewed by 1689

Increasing energy consumption and environmental pollution problems have forced people to turn their attention to the development and utilization of hydrogen energy, which requires that hydrogen energy can be efficiently prepared. However, the sluggish kinetics of hydrogen evolution reaction (HER) requires higher overpotential. [...] Read more.

Increasing energy consumption and environmental pollution problems have forced people to turn their attention to the development and utilization of hydrogen energy, which requires that hydrogen energy can be efficiently prepared. However, the sluggish kinetics of hydrogen evolution reaction (HER) requires higher overpotential. It is urgent to design and fabricate catalysts to drive the procedure and decrease the overpotential of HER. It is well known that platinum catalysts are the best for HER, but their high cost limits their wide application. Transition metals such as Fe, Co, Mo and Ni are abundant, and transition metal phosphides are considered as promising HER catalysts. Nevertheless, catalysts in powder form are very easily soluble in the electrolyte, which leads to inferior cycling stability. In this work, Ni₅P₄ anchored on Ni foam was doped with Se powder. After SEM characterization, the Ni₅P₄-Se was anchored on Ni foam, which circumvents the use of the conductive additives and binder. The Ni₅P₄-Se formed a porous nanosheet structure with enhanced electron transfer capability. The prepared Ni₅P₄-Se exhibited high electrochemical performances. At 10 mA cm⁻², the overpotential was only 128 mV and the Tafel slope is 163.14 mV dec⁻¹. Additionally, the overpotential was stabilized at 128 mV for 30 h, suggesting its excellent cycling stability. The results show that Se doping can make the two phases achieve a good synergistic effect, which makes the Ni₅P₄-Se catalyst display excellent HER catalytic activity and stability. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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19 pages, 4321 KiB

Open AccessArticle

Synthesis, Characterization, and Solar Photo-Activation of Chitosan-Modified Nickel Magnetite Bio-Composite for Degradation of Recalcitrant Organic Pollutants in Water

by Asmat Ara, Rozina Khattak, Muhammad Sufaid Khan, Bushra Begum, Sanaullah Khan and Changseok Han

Catalysts 2022, 12(9), 983; https://doi.org/10.3390/catal12090983 - 31 Aug 2022

Cited by 9 | Viewed by 1728

Photocatalysis is a promising process for decomposing harmful organic pollutants in water. In this study, solar/photocatalytic degradation of two model azo dyes, i.e., methylene blue (MB) and methyl red (MR), in water usinga nanostructured chitosan-modified nickel magnetite (CS-NM) bio-composite was investigated. The CS-NM [...] Read more.

Photocatalysis is a promising process for decomposing harmful organic pollutants in water. In this study, solar/photocatalytic degradation of two model azo dyes, i.e., methylene blue (MB) and methyl red (MR), in water usinga nanostructured chitosan-modified nickel magnetite (CS-NM) bio-composite was investigated. The CS-NM bio-composite was synthesized through a co-precipitation method and characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), thermogravimetry (TGA), and UV-Vis spectroscopy. FTIR analysis showed the uniform incorporation and conjugation of nickel magnetite (NM) into the chitosan (CS) polymer matrix. SEM showed that the average particle size was 0.5 μm. The TGA results revealed the good thermal stability of the prepared bio-composite at 300 °C. The point of zero charge was calculated as 7.5. The effect of water quality and process parameters, such as concentration of dyes, catalyst dose, solution pH, and temperatures, was investigated, for application purposes. The solar/CS-NM photocatalysis resulted in 99 and 96% degradation of individual MB and MR (C₀ = 50 ppm), respectively, in 90 min. The degradation of MB and MR by solar/CS-NM photocatalysis followed pseudo-first-order kinetics, with observed rate constants (k) of 0.077 and 0.072 min⁻¹, respectively. The CS-NM photocatalyst showed high recyclability, represented by only a 4–6% loss in the photocatalytic efficiency, after four cycles. The results showed that solar/CS-NM photocatalysis is an efficient technique for degrading recalcitrant organic pollutants, such as azo dyes, in water environments. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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16 pages, 5256 KiB

Open AccessReview

Recent Advances in Ferroelectric Materials-Based Photoelectrochemical Reaction

by Limin Yu, Lijing Wang, Yanmeng Dou, Yongya Zhang, Pan Li, Jieqiong Li and Wei Wei

Nanomaterials 2022, 12(17), 3026; https://doi.org/10.3390/nano12173026 - 31 Aug 2022

Cited by 5 | Viewed by 2537

Inorganic perovskite ferroelectric-based nanomaterials as sustainable new energy materials, due to their intrinsic ferroelectricity and environmental compatibility, are intended to play a crucial role in photoelectrochemical field as major functional materials. Because of versatile physical properties and excellent optoelectronic properties, ferroelectric-based nanomaterials attract [...] Read more.

Inorganic perovskite ferroelectric-based nanomaterials as sustainable new energy materials, due to their intrinsic ferroelectricity and environmental compatibility, are intended to play a crucial role in photoelectrochemical field as major functional materials. Because of versatile physical properties and excellent optoelectronic properties, ferroelectric-based nanomaterials attract much attention in the field of photocatalysis, photoelectrochemical water splitting and photovoltaic. The aim of this review is to cover the recent advances by stating the different kinds of ferroelectrics separately in the photoelectrochemical field as well as discussing how ferroelectric polarization will impact functioning of photo-induced carrier separation and transportation in the interface of the compounded semiconductors. In addition, the future prospects of ferroelectric-based nanomaterials are also discussed. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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12 pages, 3092 KiB

Open AccessArticle

Heterostructured Co₂P Nanocomposite Embedded in a N, P Co-Doped Carbon Layer as a High Performance Electrocatalyst for Overall Water Splitting

by Ji Chen, Shuwen Zhao, Yifan Zhao, Weijie Zhou, Ruijie Dai, Xuan Zhao, Zhengang Chen, Hua Zhang and Anran Chen

Catalysts 2022, 12(9), 957; https://doi.org/10.3390/catal12090957 - 28 Aug 2022

Cited by 2 | Viewed by 1975

Hydrogen is the mainstream future energy source because of its high energy density and environmentally-friendly properties. In this study, Fe-Co₂P/NPC materials were prepared by the wet chemical synthesis method, in which Fe-Co₂P nanowires were wrapped by the N, P [...] Read more.

Hydrogen is the mainstream future energy source because of its high energy density and environmentally-friendly properties. In this study, Fe-Co₂P/NPC materials were prepared by the wet chemical synthesis method, in which Fe-Co₂P nanowires were wrapped by the N, P co-doped carbon layers (NPC) under aging and phosphorylation strategies. When Fe-Co₂P/NPC/NF was subjected to hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), the overpotential was only 73 mV and 217 mV to reach the current density of 10 mA cm⁻², respectively. When the cathode and anode were both Fe-Co₂P/NPC/NF, a current density of 10 mA cm⁻² was achieved with only 1.56 V. This work provides a new idea for the design and preparation of non-precious metal-based transition metal phosphide catalysts. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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14 pages, 3301 KiB

Open AccessArticle

Size-Dependent Strong Metal–Support Interactions of Rutile TiO₂-Supported Ni Catalysts for Hydrodeoxygenation of m-Cresol

by Beilei Cui, Hua Wang, Qingfeng Ge and Xinli Zhu

Catalysts 2022, 12(9), 955; https://doi.org/10.3390/catal12090955 - 28 Aug 2022

Cited by 5 | Viewed by 1921

A series of rutile TiO₂-supported Ni catalysts with varying Ni sizes were prepared and reduced at 650 °C to explore the effect of Ni size on the strong metal–support interactions (SMSI) and its consequences on the hydrodeoxygenation (HDO) of m-cresol at [...] Read more.

A series of rutile TiO₂-supported Ni catalysts with varying Ni sizes were prepared and reduced at 650 °C to explore the effect of Ni size on the strong metal–support interactions (SMSI) and its consequences on the hydrodeoxygenation (HDO) of m-cresol at 350 °C and atmospheric pressure. When the Ni size increases from 4 to 29.1 nm, the SMSI becomes stronger, e.g., the thickness of the TiO_x overlayer and the coverage extent of TiO_x on the Ni particle surface increase. Direct deoxygenation to toluene is the dominant pathway on Ni/TiO₂ catalysts with varying Ni loadings, with almost no CH₄ being formed. These results indicate that the TiO_x overlayer significantly alters the property of Ni. That is, the C-C hydrogenolysis activity on bare Ni is completely inhibited due to SMSI, while the deoxygenation activity is improved at the Ni-TiO_x interfacial perimeter sites. Meanwhile, the turnover frequency of HDO on small Ni particles of 4 nm is > 2 times higher than that on large Ni particles of 29.1 nm, indicating that the small Ni particle with moderate SMSI appears to be optimal for the direct deoxygenation of m-cresol to toluene. The results suggest HDO activity may be enhanced by tuning the metal particle size and SMSI degree. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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13 pages, 3922 KiB

Open AccessArticle

Bioethanol Conversion into Propylene over Various Zeolite Catalysts: Reaction Optimization and Catalyst Deactivation

by Wei Xia, Chao Ma, Yaxin Huang, Shuangshuang Li, Xue Wang, Kun Chen and Dong Liu

Nanomaterials 2022, 12(16), 2746; https://doi.org/10.3390/nano12162746 - 10 Aug 2022

Cited by 4 | Viewed by 1858

Catalytic conversions of bioethanol to propylene were investigated over different zeolite catalysts. H-ZSM-5 (SiO₂/Al₂O₃ = 80) was found to be the most effective for propylene production. Furthermore, H-ZSM-5 (SiO₂/Al₂O₃ = 80) was investigated [...] Read more.

Catalytic conversions of bioethanol to propylene were investigated over different zeolite catalysts. H-ZSM-5 (SiO₂/Al₂O₃ = 80) was found to be the most effective for propylene production. Furthermore, H-ZSM-5 (SiO₂/Al₂O₃ = 80) was investigated under different variables of catalytic reaction (calcination temperature, feed composition, reaction temperature, and time on stream) for the conversion of ethanol to propylene. The H-ZSM-5(80) catalysts calcined at 600 °C showed the highest propylene yield. The moderate acidic site on ZSM-5 is required for the production of propylene. The activity on ZSM-5 is independent of the ethanol feed composition. H-ZSM-5 catalyst deactivation was observed, owing to dealumination. The highest propylene yield was 23.4% obtained over HZSM-5(80). Propylene, butene, and ≥C5 olefins were formed by parallel reaction from ethylene. Olefins were converted to each paraffin by sequential hydrogenation reaction. HZSM-5(80) catalyst is a promising catalyst not only for ethanol but also for the conversion of bioethanol to light olefins. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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52 pages, 7318 KiB

Open AccessReview

Mineral-Supported Photocatalysts: A Review of Materials, Mechanisms and Environmental Applications

by Xue Li, Ulla Simon, Maged F. Bekheet and Aleksander Gurlo

Energies 2022, 15(15), 5607; https://doi.org/10.3390/en15155607 - 02 Aug 2022

Cited by 13 | Viewed by 2478

Although they are of significant importance for environmental applications, the industrialization of photocatalytic techniques still faces many difficulties, and the most urgent concern is cost control. Natural minerals possess abundant chemical inertia and cost-efficiency, which is suitable for hybridizing with various effective photocatalysts. [...] Read more.

Although they are of significant importance for environmental applications, the industrialization of photocatalytic techniques still faces many difficulties, and the most urgent concern is cost control. Natural minerals possess abundant chemical inertia and cost-efficiency, which is suitable for hybridizing with various effective photocatalysts. The use of natural minerals in photocatalytic systems can not only significantly decrease the pure photocatalyst dosage but can also produce a favorable synergistic effect between photocatalyst and mineral substrate. This review article discusses the current progress regarding the use of various mineral classes in photocatalytic applications. Owing to their unique structures, large surface area, and negatively charged surface, silicate minerals could enhance the adsorption capacity, reduce particle aggregation, and promote photogenerated electron-hole pair separation for hybrid photocatalysts. Moreover, controlling the morphology and structure properties of these materials could have a great influence on their light-harvesting ability and photocatalytic activity. Composed of silica and alumina or magnesia, some silicate minerals possess unique orderly organized porous or layered structures, which are proper templates to modify the photocatalyst framework. The non-silicate minerals (referred to carbonate and carbon-based minerals, sulfate, and sulfide minerals and other special minerals) can function not only as catalyst supports but also as photocatalysts after special modification due to their unique chemical formula and impurities. The dye-sensitized minerals, as another natural mineral application in photocatalysis, are proved to be superior photocatalysts for hydrogen evolution and wastewater treatment. This work aims to provide a complete research overview of the mineral-supported photocatalysts and summarizes the common synergistic effects between different mineral substrates and photocatalysts as well as to inspire more possibilities for natural mineral application in photocatalysis. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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26 pages, 5988 KiB

Open AccessReview

Recent Advances Regarding Precious Metal-Based Electrocatalysts for Acidic Water Splitting

by Yuanting Peng, Yucong Liao, Donghao Ye, Zihan Meng, Rui Wang, Shengqiu Zhao, Tian Tian and Haolin Tang

Nanomaterials 2022, 12(15), 2618; https://doi.org/10.3390/nano12152618 - 29 Jul 2022

Cited by 9 | Viewed by 2741

Electrochemical water splitting has wide applicability in preparing high-density green energy. The Proton exchange membrane (PEM) water electrolysis system is a promising technique for the generation of hydrogen due to its high electrolytic efficiency, safety and reliability, compactness, and quick response to renewable [...] Read more.

Electrochemical water splitting has wide applicability in preparing high-density green energy. The Proton exchange membrane (PEM) water electrolysis system is a promising technique for the generation of hydrogen due to its high electrolytic efficiency, safety and reliability, compactness, and quick response to renewable energy sources. However, the instability of catalysts for electrochemical water splitting under operating conditions limits their practical applications. Until now, only precious metal-based materials have met the requirements for rigorous long-term stability and high catalytic activity under acid conditions. In this review, the recent progress made in this regard is presented and analyzed to clarify the role of precious metals in the promotion of the electrolytic decomposition of water. Reducing precious metal loading, enhancing catalytic activity, and improving catalytic lifetime are crucial directions for developing a new generation of PEM water electrolysis catalysts. A summary of the synthesis of high-performance catalysts based on precious metals and an analysis of the factors affecting catalytic performance were derived from a recent investigation. Finally, we present the remaining challenges and future perspectives as guidelines for practical use. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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39 pages, 7841 KiB

Open AccessReview

A Review on Deactivation and Regeneration of Catalysts for Dimethyl Ether Synthesis

by Joanna Sobczak, Izabela Wysocka, Stanisław Murgrabia and Andrzej Rogala

Energies 2022, 15(15), 5420; https://doi.org/10.3390/en15155420 - 27 Jul 2022

Cited by 11 | Viewed by 2490

The deactivation of catalysts and their regeneration are two very important challenges that need to be addressed for many industrial processes. The most quoted reasons for the deterioration of dimethyl ether synthesis (DME) concern the sintering and the hydrothermal leaching of copper particles, [...] Read more.

The deactivation of catalysts and their regeneration are two very important challenges that need to be addressed for many industrial processes. The most quoted reasons for the deterioration of dimethyl ether synthesis (DME) concern the sintering and the hydrothermal leaching of copper particles, their migration to acid sites, the partial formation of copper and zinc hydroxycarbonates, the formation of carbon deposits, and surface contamination with undesirable compounds present in syngas. This review summarises recent findings in the field of DME catalyst deactivation and regeneration. The most-used catalysts, their modifications, along with a comparison of the basic parameters, deactivation approaches, and regeneration methods are presented. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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23 pages, 7079 KiB

Open AccessFeature PaperArticle

The Effect of Different Pretreatment of Chicken Manure for Electricity Generation in Membrane-Less Microbial Fuel Cell

by Nurhazirah Mohd Azmi, Muhammad Najib Ikmal Mohd Sabri, Husnul Azan Tajarudin, Noor Fazliani Shoparwe, Muaz Mohd Zaini Makhtar, Hafiza Shukor, Mahboob Alam, Masoom Raza Siddiqui and Mohd Rafatullah

Catalysts 2022, 12(8), 810; https://doi.org/10.3390/catal12080810 - 24 Jul 2022

Cited by 4 | Viewed by 1815

The need for energy resources is growing all the time, which means that more fossil fuels are needed to provide them. People prefer to consume chicken as a source of protein, and this creates an abundance of waste. Thus, microbial fuel cells represent [...] Read more.

The need for energy resources is growing all the time, which means that more fossil fuels are needed to provide them. People prefer to consume chicken as a source of protein, and this creates an abundance of waste. Thus, microbial fuel cells represent a new technological approach with the potential to generate electricity through the action of electrogenic bacteria toward chicken manure, while reducing the abundance of chicken manure. This study investigated the effect of different pretreatment (thermal, alkaline, and sonication pretreatment) of chicken manure to improve the performance of a membrane-less microbial fuel cell (ML-MFC). Statistical response surface methodology (RSM) through a central composite design (CCD) under a quadratic model was conducted for optimization of the ML-MFC performance focusing on the COD removal efficiency (R² = 0.8917), biomass (R² = 0.9101), and power density response (R² = 0.8794). The study demonstrated that the highest COD removal (80.68%), biomass (7.8539 mg/L), and power density (220 mW/m²) were obtained when the pretreatment conditions were 140 °C, 20 kHz, and pH 10. The polarization curve of the best condition of ML-MFC was plotted to classify the behavior of the ML-MFC. The kinetic growth of Bacillus subtillis (BS) showed that, in treated chicken manure, the specific growth rate µ = 0.20 h⁻¹ and doubling time Td = 3.43 h, whereas, in untreated chicken manure, µ = 0.11 h⁻¹ and Td = 6.08. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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15 pages, 3999 KiB

Open AccessArticle

Decorating of Ag and CuO on ZnO Nanowires by Plasma Electrolyte Oxidation Method for Enhanced Photocatalytic Efficiency

by Phung Thi Thu, Vu Duy Thinh, Vu Dinh Lam, Ta Ngoc Bach, Le Thi Hong Phong, Do Hoang Tung, Do Hung Manh, Nguyen Van Khien, Trinh Xuan Anh and Ngo Thi Hong Le

Catalysts 2022, 12(7), 801; https://doi.org/10.3390/catal12070801 - 21 Jul 2022

Cited by 10 | Viewed by 2017

In this work, photocatalytic performance is divulged in the ternary CuO-Ag-ZnO nanowire synthesized via a two-step approach. The decoration of Ag and CuO nanostructures onto the surface of ZnO nanowires was simply carried out by using the plasma electrolytic oxidation method in a [...] Read more.

In this work, photocatalytic performance is divulged in the ternary CuO-Ag-ZnO nanowire synthesized via a two-step approach. The decoration of Ag and CuO nanostructures onto the surface of ZnO nanowires was simply carried out by using the plasma electrolytic oxidation method in a short time. The structure, size, morphology, and optical properties of as-prepared samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, and spectrophotometry measurements. The diameters of Ag nanoparticles and ZnO nanoflowers are in the range of 5–20 nm and 20–60 nm, respectively. Within the first 15 min, methyl orange was decolorized 96.3 and 82.8% in the CuO-Ag-ZnO and Ag-ZnO, respectively, and there is only about 46.7% of that decomposed in pure ZnO. The CuO-Ag-ZnO shows a higher rate constant k = 0.2007 min⁻¹ and a lower half-life time t = 6.1 min compared to Ag-ZnO and bare ZnO nanowires. The photo-reusability of the ternary nanostructures was estimated to be much outweighed compared to ZnO nanowires. Interestingly, the synergic incorporation between noble metal–semiconductor or semiconductor–semiconductor in the interfaces of Ag-CuO, Ag-ZnO, and CuO-ZnO expands the visible light absorption range and eliminates the photogenerated electron–hole recombination, resulting in a superior visible-light-driven photocatalyst. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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13 pages, 3395 KiB

Open AccessArticle

Antifouling Systems Based on Copper and Silver Nanoparticles Supported on Silica, Titania, and Silica/Titania Mixed Oxides

by Carla Calabrese, Valeria La Parola, Simone Cappello, Annamaria Visco, Cristina Scolaro and Leonarda Francesca Liotta

Nanomaterials 2022, 12(14), 2371; https://doi.org/10.3390/nano12142371 - 11 Jul 2022

Cited by 4 | Viewed by 1751

Silica, titania, and mixed silica–titania powders have been used as supports for loading 5 wt% Cu, 5 wt% Ag, and 2.5 wt% Cu-2.5 wt% Ag with the aim of providing a series of nanomaterials with antifouling properties. All the solids were easily prepared [...] Read more.

Silica, titania, and mixed silica–titania powders have been used as supports for loading 5 wt% Cu, 5 wt% Ag, and 2.5 wt% Cu-2.5 wt% Ag with the aim of providing a series of nanomaterials with antifouling properties. All the solids were easily prepared by the wetness-impregnation method from commercially available chemical precursors. The resulting materials were characterized by several techniques such as X-ray diffraction analysis, X-ray photoelectron spectroscopy, N₂ physisorption, and temperature-programmed reduction measurements. Four selected Cu and Ag SiO₂- and TiO₂-supported powders were tested as fillers for the preparation of marine antifouling coatings and complex viscosity measurements. Titania-based coatings showed better adhesion than silica-based coatings and the commercial topcoat. The addition of fillers enhances the resin viscosity, suggesting better workability of titania-based coatings than silica-based ones. The ecotoxicological performance of the powders was evaluated by Microtox luminescence tests, using the marine luminescent bacterium Vibrio fisheri. Further investigations of the microbiological activity of such materials were carried out focusing on the bacterial growth of Pseudoalteromonas sp., Alteromonas sp., and Pseudomonas sp. through measurements of optical density at 600 nm (OD_600nm). Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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22 pages, 4455 KiB

Open AccessArticle

Quality or Quantity? How Structural Parameters Affect Catalytic Activity of Iron Oxides for CO Oxidation

by Steffen Schlicher, Nils Prinz, Julius Bürger, Andreas Omlor, Christian Singer, Mirijam Zobel, Roland Schoch, Jörg K. N. Lindner, Volker Schünemann, Sven Kureti and Matthias Bauer

Catalysts 2022, 12(6), 675; https://doi.org/10.3390/catal12060675 - 20 Jun 2022

Cited by 4 | Viewed by 2228

The replacement of noble metal catalysts by abundant iron as an active compound in CO oxidation is of ecologic and economic interest. However, improvement of their catalytic performance to the same level as state-of-the-art noble metal catalysts requires an in depth understanding of [...] Read more.

The replacement of noble metal catalysts by abundant iron as an active compound in CO oxidation is of ecologic and economic interest. However, improvement of their catalytic performance to the same level as state-of-the-art noble metal catalysts requires an in depth understanding of their working principle on an atomic level. As a contribution to this aim, a series of iron oxide catalysts with varying Fe loadings from 1 to 20 wt% immobilized on a γ-Al₂O₃ support is presented here, and a multidimensional structure–activity correlation is established. The CO oxidation activity is correlated to structural details obtained by various spectroscopic, diffraction, and microscopic methods, such as PXRD, PDF analysis, DRUVS, Mössbauer spectroscopy, STEM-EDX, and XAS. Low Fe loadings lead to less agglomerated but high percentual amounts of isolated, tetrahedrally coordinated iron oxide species, while the absolute amount of isolated species reaches its maximum at high Fe loadings. Consequently, the highest CO oxidation activity in terms of turnover frequencies can be correlated to small, finely dispersed iron oxide species with a large amount of tetrahedrally oxygen coordinated iron sites, while the overall amount of isolated iron oxide species correlates with a lower light-off temperature. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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15 pages, 3739 KiB

Open AccessArticle

Highly Active Palladium-Decorated Reduced Graphene Oxides for Heterogeneous Catalysis and Electrocatalysis: Hydrogen Production from Formaldehyde and Electrochemical Formaldehyde Detection

by Xiaogang Liu, Wenjie Chen and Xin Zhang

Nanomaterials 2022, 12(11), 1890; https://doi.org/10.3390/nano12111890 - 31 May 2022

Cited by 7 | Viewed by 1955

The exploitation of highly efficient and stable hydrogen generation from chemical storage of formaldehyde (FA) is of great significance to the sustainable development of the future. Moreover, developing an accurate, rapid, reliable, and cost-effective catalyst for electrochemical detection of FA in solution is [...] Read more.

The exploitation of highly efficient and stable hydrogen generation from chemical storage of formaldehyde (FA) is of great significance to the sustainable development of the future. Moreover, developing an accurate, rapid, reliable, and cost-effective catalyst for electrochemical detection of FA in solution is appealing. Herein, we report rational construction of Pd nanoparticles decorated reduced graphene oxides (Pd/rGO) nanohybrids not only as robust catalysts to produce hydrogen from alkaline FA solution and but also electrocatalysts for electrochemical detection of FA. By optimizing the reaction parameters including FA concentration, NaOH concentration and reaction temperature, Pd/rGO with Pd loading of 0.5 wt% could exhibit a high hydrogen production rate of 272 mL g⁻¹min⁻¹ at room temperature of 25 °C, which is 3.2 times that of conventional Pd NPs. In addition, as-prepared Pd/rGO nanohybrids modified glassy carbon (GC) electrodes are used as FA-detected electrochemical sensors. A sensitive oxidation peak with a current density of 8.38 mA/cm² was observed at 0.12 V (vs. Ag/AgCl) in 0.5 M NaOH containing 10 mM FA over Pd/rGO catalysts with Pd loading of 0.5 wt%. The results showed the prepared Pd/rGO nanocatalyst not only exhibited efficient and stable hydrogen production from alkaline FA solution but also had good electrocatalytic properties with respect to formaldehyde electrooxidation as a result of the synergistic effect of Pd NPs and rGO nanosheets. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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10 pages, 2375 KiB

Open AccessCommunication

Co-Based Nanosheets with Transitional Metal Doping for Oxygen Evolution Reaction

by Chunhua Xiong and Chao Cai

Nanomaterials 2022, 12(11), 1788; https://doi.org/10.3390/nano12111788 - 24 May 2022

Viewed by 1422

Activated two-dimension (2D) materials are used in various applications as high-performance catalysts. Breaking the long-range order of the basal plane of 2D materials can highly promote catalytic activity by supplying more active sites. Here we developed a method to synthesize ultrathin MCoO_x [...] Read more.

Activated two-dimension (2D) materials are used in various applications as high-performance catalysts. Breaking the long-range order of the basal plane of 2D materials can highly promote catalytic activity by supplying more active sites. Here we developed a method to synthesize ultrathin MCoO_x (M = V, Mn, Fe, Ni, Cu, Zn) amorphous nanosheets (ANSs). These Co-based ANSs show high oxygen evolution reaction (OER) activity in alkaline solution due to the broken long-range order and the presence of abundant low bonded O on the basal plane. The stable Fe₁Co₁O_x ANSs also show an overpotential of ca. 240 mV of achieving 10 mA/cm² in OER, better than most reported transition metal-based electrocatalysts. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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18 pages, 7549 KiB

Open AccessFeature PaperArticle

Mechanism Insight into Catalytic Performance of Ni₁₂P₅ over Ni₂P toward the Catalytic Deoxygenation of Butyric Acid

by Shuai Fu, Dan Li, Tinghao Liu, Lijuan Liu, Huaqing Yang and Changwei Hu

Catalysts 2022, 12(5), 569; https://doi.org/10.3390/catal12050569 - 21 May 2022

Cited by 1 | Viewed by 1709

The Ni/P ratio of nickel phosphide has an important effect on the catalytic performance toward the deoxygenation of fatty acids to biofuel. The Ni₁₂P₅ cluster is preferred to model Ni₁₂P₅ catalyst with butyric acid as the reactant [...] Read more.

The Ni/P ratio of nickel phosphide has an important effect on the catalytic performance toward the deoxygenation of fatty acids to biofuel. The Ni₁₂P₅ cluster is preferred to model Ni₁₂P₅ catalyst with butyric acid as the reactant model of palmitic acid. The catalytic deoxygenation mechanism of butyric acid over Ni₁₂P₅ cluster has been theoretically investigated at GGA-PBE/DSPP, DNP level in dodecane solution. From butyric acid, the hydrodehydration is predominated to form n-butanal. Then, from n-butanal, low temperature benefits the hydroreduction to form butanol and then hydrodehydration to produce n-butane, whereas high temperature favors the direct decarbonylation to yield propane. n-Butane originates from n-butanol through hydrodehydration and not from n-butylene. Propane comes from n-butanal through decarbonylation and not from propanol and/or propylene. Additionally, CO stems from n-butanal through decarbonylation, whereas CO₂ is ruled out from butyric acid through decarboxylation. Compared with Ni₁₂P₆ cluster, Ni₁₂P₅ cluster exhibits higher catalytic activity for the formation of butanal, n-butanol, and n-butane, while it displays lower catalytic activity toward the direct decarbonylation and dehydration to yield propylene. These results can be attributed to less negative charges of Ni-sites over Ni₁₂P₅ cluster, compared with Ni₁₂P₆ cluster. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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12 pages, 5617 KiB

Open AccessArticle

Plasma-Wind-Assisted In₂S₃ Preparation with an Amorphous Surface Structure for Enhanced Photocatalytic Hydrogen Production

by Shaohui Guo, Hui Luo, Xiaochuan Duan, Bingqing Wei and Xianming Zhang

Nanomaterials 2022, 12(10), 1761; https://doi.org/10.3390/nano12101761 - 21 May 2022

Cited by 3 | Viewed by 1888

Photocatalytic production from water is considered an effective solution to fossil fuel-related environmental concerns, and photocatalyst surface science holds a significant interest in balancing photocatalysts’ stability and activity. We propose a plasma-wind method to tune the surface properties of a photocatalyst with an [...] Read more.

Photocatalytic production from water is considered an effective solution to fossil fuel-related environmental concerns, and photocatalyst surface science holds a significant interest in balancing photocatalysts’ stability and activity. We propose a plasma-wind method to tune the surface properties of a photocatalyst with an amorphous structure. Theoretical calculation shows that the amorphous surface structure can cause an unsaturated coordination environment to adjust the electron distribution, forming more adsorption sites. Thus, the photocatalyst with a crystal–amorphous (C–A) interface can strengthen light absorption, harvest photo-induced electrons, and enrich the active sites, which help improve hydrogen yield. As a proof of concept, with indium sulfide (In₂S₃) nanosheets used as the catalyst, an impressive hydrogen production rate up to 457.35 μmol cm⁻² h⁻¹ has been achieved. Moreover, after plasma-assisted treatment, In₂S₃ with a C–A interface can produce hydrogen from water under natural outdoor conditions. Following a six-hour test, the rate of photocatalytic hydrogen evolution is found to be 400.50 μmol cm⁻² g⁻¹, which demonstrates that a catalyst prepared through plasma treatment is both effective and highly practical. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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19 pages, 4069 KiB

Open AccessArticle

Coke-Resistant Ni/CeZrO₂ Catalysts for Dry Reforming of Methane to Produce Hydrogen-Rich Syngas

by Intan Clarissa Sophiana, Ferry Iskandar, Hary Devianto, Norikazu Nishiyama and Yogi Wibisono Budhi

Nanomaterials 2022, 12(9), 1556; https://doi.org/10.3390/nano12091556 - 04 May 2022

Cited by 13 | Viewed by 2476

Dry reforming of methane was studied over high-ratio zirconia in ceria-zirconia-mixed oxide-supported Ni catalysts. The catalyst was synthesized using co-precipitation and impregnation methods. The effects of the catalyst support and Ni composition on the physicochemical characteristics and performance of the catalysts were investigated. [...] Read more.

Dry reforming of methane was studied over high-ratio zirconia in ceria-zirconia-mixed oxide-supported Ni catalysts. The catalyst was synthesized using co-precipitation and impregnation methods. The effects of the catalyst support and Ni composition on the physicochemical characteristics and performance of the catalysts were investigated. Characterization of the physicochemical properties was conducted using X-ray diffraction (XRD), N₂-physisorption, H₂-TPR, and CO₂-TPD. The results of the activity and stability evaluations of the synthesized catalysts over a period of 240 min at a temperature of 700 °C, atmospheric pressure, and WHSV of 60,000 mL g⁻¹ h⁻¹ showed that the 10%Ni/CeZrO₂ catalyst exhibited the highest catalytic performance, with conversions of CH₄ and CO₂ up to 74% and 55%, respectively, being reached. The H₂/CO ratio in the product was 1.4, which is higher than the stoichiometric ratio of 1, indicating a higher formation of H₂. The spent catalysts showed minimal carbon deposition based on the thermo-gravimetry analysis, which was <0.01 gC/gcat, so carbon deposition could be neglected. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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20 pages, 5261 KiB

Open AccessArticle

Tetrabutyl Ammonium Salts of Keggin-Type Vanadium-Substituted Phosphomolybdates and Phosphotungstates for Selective Aerobic Catalytic Oxidation of Benzyl Alcohol

by Juan Díaz, Luis R. Pizzio, Gina Pecchi, Cristian H. Campos, Laura Azócar, Rodrigo Briones, Romina Romero, Adolfo Henríquez, Eric M. Gaigneaux and David Contreras

Catalysts 2022, 12(5), 507; https://doi.org/10.3390/catal12050507 - 30 Apr 2022

Cited by 11 | Viewed by 2225

A series of tetrabutyl ammonium (TBA) salts of V-included Keggin-type polyoxoanions with W (TBA₄PW₁₁V₁O₄₀ and TBA₅PW₁₀V₂O₄₀) and Mo (TBA₄PMo₁₁V₁O₄₀ and TBA [...] Read more.

A series of tetrabutyl ammonium (TBA) salts of V-included Keggin-type polyoxoanions with W (TBA₄PW₁₁V₁O₄₀ and TBA₅PW₁₀V₂O₄₀) and Mo (TBA₄PMo₁₁V₁O₄₀ and TBA₅PMo₁₀V₂O₄₀) as addenda atoms were prepared using a hydrothermal method. These synthesized materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-Vis diffuse reflectance (DRS UV-Vis), thermogravimetric analysis (TGA), CHN elemental analysis (EA), inductively coupled plasma spectrometry (ICP-MS), and N₂ physisorption techniques to assess their physicochemical/textural properties and correlate them with their catalytic performances. According to FT-IR and DRS UV-Vis, (PV_XW(Mo)_12−XO₄₀)^(3+X)− anions are the main species present in the TBA salts. Additionally, CHN-EA and ICP-MS revealed that the desired stoichiometry was obtained. Their catalytic activities in the liquid-phase aerobic oxidation of benzyl alcohol to benzaldehyde were studied at 5 bar of O₂ at 170 °C. Independently of the addenda atom nature, the catalytic activity increased with the number of V in the Keggin anion structure. For both series of catalysts, TBA salts of polyoxometalates with the highest V-substitution degree (TBA₅PMo₁₀V₂O₄₀ and TBA₅PW₁₀V₂O₄₀) showed higher activity. The maximum benzyl alcohol conversions obtained were 93% and 97% using (TBA)₅PMo₁₀V₂O₄₀ and (TBA)₅PW₁₀V₂O₄₀ as catalysts, respectively. In all the cases, the selectivity toward benzaldehyde was higher than 99%. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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16 pages, 2997 KiB

Open AccessArticle

A Promising Catalyst for the Dehydrogenation of Perhydro-Dibenzyltoluene: Pt/Al₂O₃ Prepared by Supercritical CO₂ Deposition

by Phillimon Modisha, Rudaviro Garidzirai, Hande Güneş, Selmi Erim Bozbag, Sarshad Rommel, Erdal Uzunlar, Mark Aindow, Can Erkey and Dmitri Bessarabov

Catalysts 2022, 12(5), 489; https://doi.org/10.3390/catal12050489 - 28 Apr 2022

Cited by 7 | Viewed by 3019

Pt/Al₂O₃ catalysts prepared via supercritical deposition (SCD), with supercritical CO₂, wet impregnation (WI) methods and a selected benchmark catalyst, were evaluated for the dehydrogenation of perhydro-dibenzyltoluene (H18-DBT) at 300 °C in a batch reactor. After ten dehydrogenation runs, [...] Read more.

Pt/Al₂O₃ catalysts prepared via supercritical deposition (SCD), with supercritical CO₂, wet impregnation (WI) methods and a selected benchmark catalyst, were evaluated for the dehydrogenation of perhydro-dibenzyltoluene (H18-DBT) at 300 °C in a batch reactor. After ten dehydrogenation runs, the average performance of the catalyst prepared using SCD was the highest compared to the benchmark and WI-prepared catalysts. The pre-treatment of the catalysts with the product (dibenzyltoluene) indicated that the deactivation observed is mainly due to the adsorbed H0-DBT blocking the active sites for the reactant (H18-DBT). Furthermore, the SCD method afforded a catalyst with a higher dispersion of smaller sized Pt particles, thus improving catalytic performance towards the dehydrogenation of H18-DBT. The particle diameters of the SCD- and WI-prepared catalysts varied in the ranges of 0.6–2.2 nm and 0.8–3.4 nm and had average particle sizes of 1.1 nm and 1.7 nm, respectively. Energy dispersive X-ray spectroscopy analysis of the catalysts after ten dehydrogenation runs revealed the presence of carbon. In this study, improved catalyst performance led to the production of more liquid-based by-products and carbon material compared to catalysts with low catalytic performance. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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10 pages, 1347 KiB

Open AccessArticle

Carbon Nanotubes Modified by BiMo Metal Oxides for Oxidative Dehydrogenation of 1-Butene to 1,3-Butadiene without Steam

by Jiao Wu, Yu Liang, Gui Li and Chao Wan

Chemistry 2022, 4(2), 370-379; https://doi.org/10.3390/chemistry4020027 - 27 Apr 2022

Cited by 2 | Viewed by 1798

Oxidative dehydrogenation (ODH) reaction has emerged as a promising route for converting 1-butene to value-added 1,3-butadiene (BD). However, the low BD selectivity of the current catalysts (≤40%) and high steam input are now the challenge of this process. Here, we demonstrate the fabrication [...] Read more.

Oxidative dehydrogenation (ODH) reaction has emerged as a promising route for converting 1-butene to value-added 1,3-butadiene (BD). However, the low BD selectivity of the current catalysts (≤40%) and high steam input are now the challenge of this process. Here, we demonstrate the fabrication BiMo oxides immobilized on carbon nanotubes (BiMo/CNTs), employing the sol–gel method, as a novel catalyst for the ODH of 1-butene without steam in a fixed-bed reactor. The catalytic performances of BiMo/CNTs with different compositions in the absence of steam were investigated. When BiMo/CNTs at a molar ratio of 0.018 were employed in the ODH of 1-butene under reaction conditions of 440 °C, 1-butene/oxygen = 1/0.8, and no steam, the optimal BD yield was achieved as high as 52.2%. Under this reaction condition, the catalyst maintains good stability without steam after 10 h of reaction. This work not only promotes the application of carbon materials in oxidative dehydrogenation reaction, but also accelerates the production of 1,3-butadiene in a more economical way. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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15 pages, 3702 KiB

Open AccessArticle

Comparative Study of Pd–Ni Bimetallic Catalysts Supported on UiO-66 and UiO-66-NH₂ in Selective 1,3-Butadiene Hydrogenation

by Lili Liu, Lei Yu, Xiaojing Zhou, Chunling Xin, Songyuan Sun, Zhidong Liu, Jinyu Zhang, Ying Liu and Xishi Tai

Nanomaterials 2022, 12(9), 1484; https://doi.org/10.3390/nano12091484 - 27 Apr 2022

Cited by 3 | Viewed by 1992

Selective hydrogenation of 1,3-butadiene (BD) is regarded as the most promising route for removing BD from butene streams. Bimetallic Pd–Ni catalysts with changed Pd/Ni molar ratios and monometallic Pd catalysts were synthesized using two differently structured metal-organic framework supports: UiO-66 and UiO-66-NH₂ [...] Read more.

Selective hydrogenation of 1,3-butadiene (BD) is regarded as the most promising route for removing BD from butene streams. Bimetallic Pd–Ni catalysts with changed Pd/Ni molar ratios and monometallic Pd catalysts were synthesized using two differently structured metal-organic framework supports: UiO-66 and UiO-66-NH₂. The effects of the structure of support and the molar ratio of Pd/Ni on the catalytic property of selective BD hydrogenation were studied. The Pd–Ni bimetallic supported catalysts, PdNi/UiO-66 (1:1) and PdNi/UiO-66-NH₂ (1:1), exhibited fine catalytic property at low temperature. Compared with UiO-66, UiO-66-NH₂ with a certain number of alkaline sites could reduce the catalytic activity for the BD hydrogenation reaction. However, the alkaline environment of UiO-66-NH₂ is helpful to improve the butene selectivity. PdNi/UiO-66-NH₂ (1:1) catalyst presented better stability than PdNi/UiO-66 (1:1) under the reaction conditions, caused by the strong interaction between the –NH₂ groups of UiO-66-NH₂ and PdNi NPs. Moreover, the PdNi/UiO-66-NH₂ (1:1) catalyst presented good reproducibility in the hydrogenation of BD. These findings afford a beneficial guidance for the design and preparation of efficient catalysts for selective BD hydrogenation. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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27 pages, 118440 KiB

Open AccessArticle

Synthesis, Characterization, and Catalytic Activity of Nickel Sulfided Catalysts for the Dehydrogenation of Propane: Effect of Sulfiding Agent and Sulfidation Temperature

by Tayyibah Tahier, Ebrahim Mohiuddin, Alicia Botes, Madelaine Frazenburg, Subelia Botha and Masikana M. Mdleleni

Catalysts 2022, 12(5), 483; https://doi.org/10.3390/catal12050483 - 25 Apr 2022

Cited by 1 | Viewed by 2021

The effect of sulfiding agent and sulfidation temperature on nickel catalysts supported on MgAl₂O₄ were investigated for propane dehydrogenation. The catalysts were prepared by reduction of NiO/MgAl₂O₄, followed by sulfidation using (NH₄)₂SO [...] Read more.

The effect of sulfiding agent and sulfidation temperature on nickel catalysts supported on MgAl₂O₄ were investigated for propane dehydrogenation. The catalysts were prepared by reduction of NiO/MgAl₂O₄, followed by sulfidation using (NH₄)₂SO₄ (S1), (NH₄)₂S (S2), and DMSO (S3) as sulfiding agents. The catalysts were sulfided at 200 °C, 400 °C, and 550 °C to form Ni/MgAl₂O₄-Sx-y, where x and y represent the sulfiding agent and sulfidation temperature, respectively. Physiochemical properties of the catalysts were characterized by XRD, BET, SEM, TEM, and TGA to investigate the type of nickel-sulfur species, surface area, morphology, particle size, and stability of the catalysts. Structural and textural properties revealed that the anion present on the sulfiding agent as well as the sulfidation temperature affect both the type and the strength of the Ni-S species. For the S1 catalysts, the SO₄²⁻ ion interacted with the support to form MgSO₄, while the S²⁻ ion on the S2 and S3 catalysts was responsible for the formation of the Ni₃S₂ phase. The sulfidation temperature contributed to the %S present on each catalyst. Although the catalysts sulfided by S3 contained the least %S, Ni/MgAl₂O₄-S3-550 displayed the best catalytic performance as a result of the higher particle dispersion and stronger Ni-S interaction compared to S1 and S2 catalysts. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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10 pages, 2426 KiB

Open AccessArticle

Catalytic Conversion of High Fructose Corn Syrup to Methyl Lactate with CoO@silicalite-1

by Yuxi Jiang, Xilei Lyu, Hao Chen, Xiwen Wei, Zihao Zhang and Xiuyang Lu

Catalysts 2022, 12(4), 442; https://doi.org/10.3390/catal12040442 - 14 Apr 2022

Cited by 2 | Viewed by 1898

Methyl lactate (MLA), a versatile biomass platform, was typically produced from the catalytic conversion of high-priced fructose. High fructose corn syrup (HFCS) is a mixture of glucose, fructose, water, etc., which is viewed as an economical substitute for fructose to produce MLA due [...] Read more.

Methyl lactate (MLA), a versatile biomass platform, was typically produced from the catalytic conversion of high-priced fructose. High fructose corn syrup (HFCS) is a mixture of glucose, fructose, water, etc., which is viewed as an economical substitute for fructose to produce MLA due to the much lower cost of separation and drying processes. However, the transformation of HFCS to MLA is still a challenge due to its complex components and the presence of water. In this work, the catalytic conversion of HFCS to MLA over CoO@silicalite-1 catalyst synthesized via a straightforward post citric acid treatment approach was reported. The maximum MLA yield reached 43.8% at 180 °C for 18 h after optimizing the reaction conditions and Co loading. Interestingly, adding extra 3% water could further increase the MLA yield, implying that our CoO@silicalite-1 catalyst is also capable for upgrading wet HFCS. As a result, the costly drying process of wet HFCS can be avoided. Moreover, the activity of CoO@silicalite-1 catalyst can be regenerated for at least four cycles via facile calcination in air. This study, therefore, will provide a new opportunity to not only solve the HFCS-overproduction issues but also produce value-added MLA. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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12 pages, 1976 KiB

Open AccessArticle

Protonated Chiral 1,2-Diamine Organocatalysts for N-Selective Nitroso Aldol Reaction

by Jae Ho Shim, Ji Yeon Lee, Hyeon Soo Kim and Deok-Chan Ha

Catalysts 2022, 12(4), 435; https://doi.org/10.3390/catal12040435 - 13 Apr 2022

Cited by 1 | Viewed by 2280

The introduction of nitrogen to carbonyl groups is considered both challenging and highly desirable by those who work in the field of organic synthesis. In this study, a diphenylethylenediamine-derived catalyst demonstrating N-selectivity was designed using a quantum calculation for the nitroso aldol [...] Read more.

The introduction of nitrogen to carbonyl groups is considered both challenging and highly desirable by those who work in the field of organic synthesis. In this study, a diphenylethylenediamine-derived catalyst demonstrating N-selectivity was designed using a quantum calculation for the nitroso aldol reaction. The reductive monoalkylation of (R,R)-(+)-1,2-diphenylethylenediamine afforded an organic chiral diamine catalyst in high yield. The expected reaction mechanism for the nitroso aldol reaction was determined, and the product and solvent conditions were optimized through quantum calculations. The calculation results revealed that the enantioselectivity is determined by the hydrogen bond between the alkyl substituent of the chiral diamine and the oxygen of the aromatic aldehyde on the ammonium moiety. The reaction was found to proceed optimally in the presence of 5 mol % catalyst at −10 °C in brine. Using these conditions, an eco-friendly nitroso aldol reaction was performed in which the organic catalyst and cyclohexanone formed enamine. Nitrosobenzene, activated by hydrogen bonding with an ammonium catalyst, was used to minimize the steric hindrance between the catalyst and the reactant, resulting in high enantioselectivity. A nitroso aldol product with high N-selectivity and enantioselectivity (98% ee) was obtained in 95% yield. The catalyst developed in this study provides a less expensive and more environmentally friendly alternative for the nitroso aldol reaction. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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12 pages, 1928 KiB

Open AccessArticle

Hybrid Catalysts from Copper Biosorbing Bacterial Strains and Their Recycling for Catalytic Application in the Asymmetric Addition Reaction of B₂(pin)₂ on α,β-Unsaturated Chalcones

by Raffaella Gandolfi, Giorgio Facchetti, Lucia Cavalca, Stefania Mazzini, Milena Colombo, Giulia Coffetti, Gigliola Borgonovo, Leonardo Scaglioni, Sarah Zecchin and Isabella Rimoldi

Catalysts 2022, 12(4), 433; https://doi.org/10.3390/catal12040433 - 11 Apr 2022

Cited by 4 | Viewed by 1918

The recycling of heavy metal contaminants from wastewater as a source of valuable products perfectly fits with the principles of a Circular Economy system in view of restoring pollutants back into the system endowed with new social and economic benefits. Heavy metals are [...] Read more.

The recycling of heavy metal contaminants from wastewater as a source of valuable products perfectly fits with the principles of a Circular Economy system in view of restoring pollutants back into the system endowed with new social and economic benefits. Heavy metals are often present in such a low concentration that it makes the removal efficiency difficult to realize through the conventional physicochemical methods with high selectivity. Biosorption, conversely, by EPSs (extracellular polymeric substances) produced by several bacterial cells’ strains, is gaining a great deal of attention as an economic, efficient and sustainable depolluting process of wastewater from metal cations such as copper. Metal coordination to EPS components was thus deeply investigated by ¹H NMR titration experiments. The 1,10–Phenanthroline–copper complex was exploited for quantifying the ability of different strains to sequester copper by a practical UV-Vis spectrophotometric method. The obtained data distinguished Serratia plymuthica strain SC5II as the bacterial strain displaying copper-adsorbing properties higher than any other, with Stenotrophomonas sp. strain 13a resulting in the worst one. Different analytical techniques, i.e., Dynamic Light Scattering (DLS), FT-IR analysis and SEM spectroscopy were thus employed to rationalize these results. Finally, the obtained copper chelates were successfully employed as hybrid catalysts in the asymmetric boron addition to α,β-unsaturated chalcones for the synthesis of valuable pharmaceutical intermediates, thus placing waste management in a new circular perspective. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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19 pages, 3123 KiB

Open AccessArticle

Thermal and Catalytic Pyrolysis of Urban Plastic Waste: Modified Mordenite and ZSM-5 Zeolites

by Taihana Parente Paula, Maria de Fatima Vieira Marques, Mônica Regina da Costa Marques, Michelle Souza Oliveira and Sergio Neves Monteiro

Chemistry 2022, 4(2), 297-315; https://doi.org/10.3390/chemistry4020023 - 08 Apr 2022

Cited by 10 | Viewed by 2791

Zeolites have been successfully applied as catalysts in the pyrolysis of plastics to obtain valuable lower molecular weight hydrocarbon compounds. In the present work, mordenite was directly synthesized and chemically modified from commercial mordenite to increase pore volume. For the first time, the [...] Read more.

Zeolites have been successfully applied as catalysts in the pyrolysis of plastics to obtain valuable lower molecular weight hydrocarbon compounds. In the present work, mordenite was directly synthesized and chemically modified from commercial mordenite to increase pore volume. For the first time, the performance of these mordenites was compared with that of an alkali-treated ZSM-5 as catalysts for assisting the pyrolysis of simulated urban plastic waste. The investigated zeolites were: (i) as-supplied synthetic ZSM-5 (ZSM-5/AS); (ii) 0.2 M NaOH treated ZSM-5 (ZSM-5/02); (iii) as-supplied mordenite (MOR/AS); (iv) 0.2 M NaOH treated mordenite (MOR/02); and (v) synthetic lab-developed mordenite (MOR/SD). The modified and synthesized zeolites were individually applied as catalysts in the 700 °C pyrolyzes of combined polyethylene, polypropylene, and polystyrene wastes in a mixture simulating most plastics found in Rio de Janeiro (Brazil) city garbage composition. X-ray diffraction revealed crystallite sizes of all zeolites in a nanometric range from 17 to 43 nm. Textural analysis disclosed the alkali-treated ZSM-5/02 with a superior external surface area, 153 m²/g, and mesopore volume equal to 0.253 cm³/g. Lower values were obtained by MOR/02 (39 m²/g and 0.072 cm³/g). The pyrolysis of the plastic mixture with ZSM-5/02 presented a lower initial degradation temperature, 387 °C, followed by MOR/02, with 417 °C. The ZSM-5/02 catalyst obtained the highest conversion in the pyrolysis of the plastic mixture, totaling 49.2%. However, pyrolysis assisted by the MOR/02 catalyst showed the largest fraction (81.5%) of light hydrocarbons. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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21 pages, 2740 KiB

Open AccessEditor’s ChoiceArticle

Development of a Bifunctional Ti-Based Gas Diffusion Electrode for ORR and OER by One- and Two-Step Pt-Ir Electrodeposition

by Maximilian Cieluch, Pit Yannick Podleschny, Norbert Kazamer, Florian Josef Wirkert, Ulrich Wilhelm Rost and Michael Brodmann

Nanomaterials 2022, 12(7), 1233; https://doi.org/10.3390/nano12071233 - 06 Apr 2022

Cited by 5 | Viewed by 3097

The present paper presents one- and two-step approaches for electrochemical Pt and Ir deposition on a porous Ti-substrate to obtain a bifunctional oxygen electrode. Surface pre-treatment of the fiber-based Ti-substrate with oxalic acid provides an alternative to plasma treatment for partially stripping TiO [...] Read more.

The present paper presents one- and two-step approaches for electrochemical Pt and Ir deposition on a porous Ti-substrate to obtain a bifunctional oxygen electrode. Surface pre-treatment of the fiber-based Ti-substrate with oxalic acid provides an alternative to plasma treatment for partially stripping TiO₂ from the electrode surface and roughening the topography. Electrochemical catalyst deposition performed directly onto the pretreated Ti-substrates bypasses unnecessary preparation and processing of catalyst support structures. A single Pt constant potential deposition (CPD), directly followed by pulsed electrodeposition (PED), created nanosized noble agglomerates. Subsequently, Ir was deposited via PED onto the Pt sub-structure to obtain a successively deposited PtIr catalyst layer. For the co-deposition of PtIr, a binary PtIr-alloy electrolyte was used applying PED. Micrographically, areal micro- and nano-scaled Pt sub-structure were observed, supplemented by homogenously distributed, nanosized Ir agglomerates for the successive PtIr deposition. In contrast, the PtIr co-deposition led to spherical, nanosized PtIr agglomerates. The electrochemical ORR and OER activity showed increased hydrogen desorption peaks for the Pt-deposited substrate, as well as broadening and flattening of the hydrogen desorption peaks for PtIr deposited substrates. The anodic kinetic parameters for the prepared electrodes were found to be higher than those of a polished Ir-disc. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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15 pages, 4697 KiB

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Thermocatalytic Hydrogenation of CO₂ to Methanol Using Cu-ZnO Bimetallic Catalysts Supported on Metal–Organic Frameworks

by Zama G. Duma, Xoliswa Dyosiba, John Moma, Henrietta W. Langmi, Benoit Louis, Ksenia Parkhomenko and Nicholas M. Musyoka

Catalysts 2022, 12(4), 401; https://doi.org/10.3390/catal12040401 - 05 Apr 2022

Cited by 8 | Viewed by 4323

The thermocatalytic hydrogenation of carbon dioxide (CO₂) to methanol is considered as a potential route for green hydrogen storage as well as a mean for utilizing captured CO₂, owing to the many established applications of methanol. Copper–zinc bimetallic catalysts [...] Read more.

The thermocatalytic hydrogenation of carbon dioxide (CO₂) to methanol is considered as a potential route for green hydrogen storage as well as a mean for utilizing captured CO₂, owing to the many established applications of methanol. Copper–zinc bimetallic catalysts supported on a zirconium-based UiO-66 metal–organic framework (MOF) were prepared via slurry phase impregnation and benchmarked against the promoted, co-precipitated, conventional ternary CuO/ZnO/Al₂O₃ (CZA) catalyst for the thermocatalytic hydrogenation of CO₂ to methanol. A decrease in crystallinity and specific surface area of the UiO-66 support was observed using X-ray diffraction and N₂-sorption isotherms, whereas hydrogen-temperature-programmed reduction and X-ray photoelectron spectroscopy revealed the presence of copper active sites after impregnation and thermal activation. Other characterisation techniques such as scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis were employed to assess the physicochemical properties of the resulting catalysts. The UiO-66 (Zr) MOF-supported catalyst exhibited a good CO₂ conversion of 27 and 16% selectivity towards methanol, whereas the magnesium-promoted CZA catalyst had a CO₂ conversion of 31% and methanol selectivity of 24%. The prepared catalysts performed similarly to a CZA commercial catalyst which exhibited a CO₂ conversion and methanol selectivity of 30 and 15%. The study demonstrates the prospective use of Cu-Zn bimetallic catalysts supported on MOFs for direct CO₂ hydrogenation to produce green methanol. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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14 pages, 10171 KiB

Open AccessArticle

Morphologically Controllable Hierarchical ZnO Microspheres Catalyst and Its Photocatalytic Activity

by Xiaoqian Ai, Shun Yan and Ligang Ma

Nanomaterials 2022, 12(7), 1124; https://doi.org/10.3390/nano12071124 - 29 Mar 2022

Cited by 8 | Viewed by 1569

The degradation of pollutants in wastewater using abundant resources and renewable energy sources, such as light, is attractive from an environmental perspective. ZnO is a well-known photocatalytic material. Therefore, in this study, a hierarchical ZnO microsphere precursor was prepared using a hydrothermal method. [...] Read more.

The degradation of pollutants in wastewater using abundant resources and renewable energy sources, such as light, is attractive from an environmental perspective. ZnO is a well-known photocatalytic material. Therefore, in this study, a hierarchical ZnO microsphere precursor was prepared using a hydrothermal method. The precursor was subsequently annealed at different temperatures, which enabled the production of a ZnO catalyst having a controllable morphology. Specifically, as the annealing temperature increased, the precursor crystallized into hexagonal wurtzite and the crystallinity also increased. The catalysts were tested for their photocatalytic activity for the degradation of dye molecules (methylene blue and rhodamine B), and the catalyst sample annealed at 400 °C showed the best photocatalytic activity. The origin of this activity was studied using electron paramagnetic resonance spectroscopy and transient photocurrent measurements, and the structure of the optimal catalyst was invested using electron microscopy measurements, which revealed that it was formed of two-dimensional nanosheets having smooth surfaces, forming a 2D cellular network. Thus, we have presented a promising photocatalyst for the mineralization of organic contaminants in wastewater. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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17 pages, 3043 KiB

Open AccessArticle

Photovoltaic Properties of ZnO Films Co-Doped with Mn and La to Enhance Solar Cell Efficiency

by Muhammad Amjad, Muhammad Iftikhar Khan, Norah Alwadai, Muhammad Irfan, Ikram-ul-Haq, Hind Albalawi, Aljawhara H. Almuqrin, Maha M. Almoneef and Munawar Iqbal

Nanomaterials 2022, 12(7), 1057; https://doi.org/10.3390/nano12071057 - 24 Mar 2022

Cited by 20 | Viewed by 2483

In the present investigation, ZnO films co-doped with Mn and La were synthesized by the sol–gel technique. XRD analysis revealed that ZnO had a hexagonal structure. Mixed hexagonal and cubic phases appeared in ZnO containing Mn (1%) and La (1.5%). The grain size, [...] Read more.

In the present investigation, ZnO films co-doped with Mn and La were synthesized by the sol–gel technique. XRD analysis revealed that ZnO had a hexagonal structure. Mixed hexagonal and cubic phases appeared in ZnO containing Mn (1%) and La (1.5%). The grain size, d-spacing, unit cell, lattice parameters, atomic packing fraction, volume, strain, crystallinity, and bond length of co-doped ZnO films were determined as a function of doped ion contents. Through UV analysis, it was found that pristine ZnO had E_g = 3.5 eV, and it decreased when increasing the doping concentration, reaching the minimum value for the sample with 1% Mn and 1% La. The optical parameters of the films, such as absorption, transmittance, dielectric constants, and refractive index, were also analyzed. DSSCs were fabricated using the prepared ZnO films. For pure ZnO film, the values were: efficiency = 0.69%, current density = 2.5 mAcm⁻², and open-circuit voltage = 0.56 V. When ZnO was co-doped with Mn and La, the efficiency increased significantly. DSSCs with a ZnO photoanode co-doped with 1% Mn and 1% La exhibited maximum values of J_sc = 4.28 mAcm⁻², V_oc = 0.6 V, and efficiency = 1.89%, which is 174% better than pristine ZnO-based DSSCs. This material is good for the electrode of perovskite solar cells. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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8 pages, 1733 KiB

Open AccessArticle

Deposition of Size-Selected Gold Nanoclusters onto Strontium Titanate Crystals for Water Splitting under Visible Light

by Chuhang Zhang

Catalysts 2022, 12(4), 367; https://doi.org/10.3390/catal12040367 - 23 Mar 2022

Cited by 1 | Viewed by 1561

Using a modulated pulse power magnetron sputtering (MPP-MSP) coupled with a quadrupole mass spectrometer (Q-MS), intensive size-selected gold nanoclusters (Au_n) ranging from n = 5 to 40 in size are synthesized and soft landed onto a strontium titanate (STO) crystal surface [...] Read more.

Using a modulated pulse power magnetron sputtering (MPP-MSP) coupled with a quadrupole mass spectrometer (Q-MS), intensive size-selected gold nanoclusters (Au_n) ranging from n = 5 to 40 in size are synthesized and soft landed onto a strontium titanate (STO) crystal surface as a co-catalyst for photocatalytic water splitting. The photocatalytic reactivity of the Au_n/STO is investigated by measuring the photocurrent density of the sample under visible light radiation. It is found that the Au_n co-catalysts enable the visible light response of the Au_n/STO photocatalyst. The photocurrent density is sensitively dependent on the size of the Au_n on the STO, and Au₁₆ exhibits its maximum photocurrent under visible light. The underlying physics of the size-specific photocurrent are explained in terms of the size-dependent electron affinity of Au_n. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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10 pages, 4392 KiB

Open AccessArticle

CoFeS₂@CoS₂ Nanocubes Entangled with CNT for Efficient Bifunctional Performance for Oxygen Evolution and Oxygen Reduction Reactions

by Jaeeun Jeon, Kyoung Ryeol Park, Kang Min Kim, Daehyeon Ko, HyukSu Han, Nuri Oh, Sunghwan Yeo, Chisung Ahn and Sungwook Mhin

Nanomaterials 2022, 12(6), 983; https://doi.org/10.3390/nano12060983 - 16 Mar 2022

Cited by 9 | Viewed by 2572

Exploring bifunctional electrocatalysts to lower the activation energy barriers for sluggish electrochemical reactions for both the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are of great importance in achieving lower energy consumption and higher conversion efficiency for future energy conversion and [...] Read more.

Exploring bifunctional electrocatalysts to lower the activation energy barriers for sluggish electrochemical reactions for both the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are of great importance in achieving lower energy consumption and higher conversion efficiency for future energy conversion and storage system. Despite the excellent performance of precious metal-based electrocatalysts for OER and ORR, their high cost and scarcity hamper their large-scale industrial application. As alternatives to precious metal-based electrocatalysts, the development of earth-abundant and efficient catalysts with excellent electrocatalytic performance in both the OER and the ORR is urgently required. Herein, we report a core–shell CoFeS₂@CoS₂ heterostructure entangled with carbon nanotubes as an efficient bifunctional electrocatalyst for both the OER and the ORR. The CoFeS₂@CoS₂ nanocubes entangled with carbon nanotubes show superior electrochemical performance for both the OER and the ORR: a potential of 1.5 V (vs. RHE) at a current density of 10 mA cm⁻² for the OER in alkaline medium and an onset potential of 0.976 V for the ORR. This work suggests a processing methodology for the development of the core–shell heterostructures with enhanced bifunctional performance for both the OER and the ORR. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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16 pages, 21446 KiB

Open AccessReview

Formic Acid Dehydrogenation Using Noble-Metal Nanoheterogeneous Catalysts: Towards Sustainable Hydrogen-Based Energy

by Abbas Al-Nayili, Hasan Sh. Majdi, Talib M. Albayati and Noori M. Cata Saady

Catalysts 2022, 12(3), 324; https://doi.org/10.3390/catal12030324 - 11 Mar 2022

Cited by 53 | Viewed by 5299

The need for sustainable energy sources is now more urgent than ever, and hydrogen is significant in the future of energy. However, several obstacles remain in the way of widespread hydrogen use, most of which are related to transport and storage. Dilute formic [...] Read more.

The need for sustainable energy sources is now more urgent than ever, and hydrogen is significant in the future of energy. However, several obstacles remain in the way of widespread hydrogen use, most of which are related to transport and storage. Dilute formic acid (FA) is recognized asa a safe fuel for low-temperature fuel cells. This review examines FA as a potential hydrogen storage molecule that can be dehydrogenated to yield highly pure hydrogen (H₂) and carbon dioxide (CO₂) with very little carbon monoxide (CO) gas produced via nanoheterogeneous catalysts. It also present the use of Au and Pd as nanoheterogeneous catalysts for formic acid liquid phase decomposition, focusing on the influence of noble metals in monometallic, bimetallic, and trimetallic compositions on the catalytic dehydrogenation of FA under mild temperatures (20–50 °C). The review shows that FA production from CO₂ without a base by direct catalytic carbon dioxide hydrogenation is far more sustainable than existing techniques. Finally, using FA as an energy carrier to selectively release hydrogen for fuel cell power generation appears to be a potential technique. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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10 pages, 1674 KiB

Open AccessArticle

Synthesis of Novel Magnetic Carbon Microtube-Based Solid Acid and Its Catalytic Activities for Biodiesel Synthesis

by Huijun Jiang, Xiaoqiu Dong and Jianxin Shou

Catalysts 2022, 12(3), 305; https://doi.org/10.3390/catal12030305 - 08 Mar 2022

Cited by 2 | Viewed by 1693

Novel magnetic carbon microtube-based solid acid was synthesized via the carbonization of FeCl₃-doped willow catkin and benzenediazoniumsulfonate acid-based sulfonation. The biomass willow catkin provided the special microtube structure and the high surface area of 215 m²/g for the novel [...] Read more.

Novel magnetic carbon microtube-based solid acid was synthesized via the carbonization of FeCl₃-doped willow catkin and benzenediazoniumsulfonate acid-based sulfonation. The biomass willow catkin provided the special microtube structure and the high surface area of 215 m²/g for the novel solid acid. The microtube structure was well conserved during the mild carbonization (400 °C) and sulfonation process. The large number of acidic sites (2.3 mmol/g) on the microtube surface was quite accessible to reactants. Its magnetic properties offered a simple separation process. The novel solid acid showed very high activity for biodiesel synthesis, using cooking oils as raw material, which gave a total yield of 99% and free fatty acid conversion of 98.7% under mild conditions (70 °C). The facile synthetic process, high activity, high stability, and high recovery simplicity were the main properties of the novel magnetic solid acid, which is one of the best choices for biodiesel synthesis. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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35 pages, 5671 KiB

Open AccessReview

Operando Photo-Electrochemical Catalysts Synchrotron Studies

by Mikhail A. Soldatov, Pavel V. Medvedev, Victor Roldugin, Ivan N. Novomlinskiy, Ilia Pankin, Hui Su, Qinghua Liu and Alexander V. Soldatov

Nanomaterials 2022, 12(5), 839; https://doi.org/10.3390/nano12050839 - 02 Mar 2022

Cited by 3 | Viewed by 3464

The attempts to develop efficient methods of solar energy conversion into chemical fuel are ongoing amid climate changes associated with global warming. Photo-electrocatalytic (PEC) water splitting and CO₂ reduction reactions show high potential to tackle this challenge. However, the development of economically [...] Read more.

The attempts to develop efficient methods of solar energy conversion into chemical fuel are ongoing amid climate changes associated with global warming. Photo-electrocatalytic (PEC) water splitting and CO₂ reduction reactions show high potential to tackle this challenge. However, the development of economically feasible solutions of PEC solar energy conversion requires novel efficient and stable earth-abundant nanostructured materials. The latter are hardly available without detailed understanding of the local atomic and electronic structure dynamics and mechanisms of the processes occurring during chemical reactions on the catalyst–electrolyte interface. This review considers recent efforts to study photo-electrocatalytic reactions using in situ and operando synchrotron spectroscopies. Particular attention is paid to the operando reaction mechanisms, which were established using X-ray Absorption (XAS) and X-ray Photoelectron (XPS) Spectroscopies. Operando cells that are needed to perform such experiments on synchrotron are covered. Classical and modern theoretical approaches to extract structural information from X-ray Absorption Near-Edge Structure (XANES) spectra are discussed. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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14 pages, 11165 KiB

Open AccessArticle

Optimization and Kinetic Studies on Biodiesel Conversion from Chlorella vulgaris Microalgae Using Pyrrolidinium-Based Ionic Liquids as a Catalyst

by Noorhafizah Hasanudin, Noraini Abd Ghani, Asyraf Hanim Ab Rahim, Ninna Sakina Azman, Nurhusna Aisyah Rosdi and Asiah Nusaibah Masri

Catalysts 2022, 12(3), 277; https://doi.org/10.3390/catal12030277 - 01 Mar 2022

Cited by 3 | Viewed by 2302

This study describes the potential conversion of dried microalgae. Chlorella vulgaris (C. vulgaris) into fatty acid methyl ester (FAME) using the direct transesterification (DT) method and using ionic liquids (ILs) as a catalyst. In this work, the performance of monocationic IL, [...] Read more.

This study describes the potential conversion of dried microalgae. Chlorella vulgaris (C. vulgaris) into fatty acid methyl ester (FAME) using the direct transesterification (DT) method and using ionic liquids (ILs) as a catalyst. In this work, the performance of monocationic IL, namely 1-butyl-1-methylpyrrolidinium bromide (IL 1), and dicationic IL, namely 1,4-bis(1-methylpyrrolidinium-1-yl) butane dibromide (IL 2), as catalysts was compared for DT of C. vulgaris under microwave irradiation. The results revealed that IL 2 showed a better performance in catalyzing the DT reaction by producing 87.9 mg/g% of FAME, while the use of IL 1 led to 74.3 mg/g% of FAME under optimum conditions. The kinetic study for direct transesterification of C. vulgaris showed that the reaction followed a first order kinetic reaction where the activation energies were calculated to be 22.2499 kJ mol⁻¹ and 22.0413 kJ mol⁻¹ for IL 1 and IL 2, respectively. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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13 pages, 5501 KiB

Open AccessArticle

Green Synthesis of Flowerball-like MoS₂/VC Nanocomposite and Its Efficient Catalytic Performance for Oxygen Reduction Either in Alkaline or Acid Media

by Xiaofeng Zhang, Yayun Ke, Ting Wang, Jiannan Cai, Qiufeng Huang and Shen Lin

Catalysts 2022, 12(3), 259; https://doi.org/10.3390/catal12030259 - 25 Feb 2022

Cited by 1 | Viewed by 2302

Opening up electrocatalysts for oxygen reduction reaction (ORR) is essential for practical application in fuel cells and metal-air batteries; however, how to make the catalysts with both good performance and low cost is difficult. Recently, research on the ORR of molybdenum disulfide-based catalysts [...] Read more.

Opening up electrocatalysts for oxygen reduction reaction (ORR) is essential for practical application in fuel cells and metal-air batteries; however, how to make the catalysts with both good performance and low cost is difficult. Recently, research on the ORR of molybdenum disulfide-based catalysts in alkaline electrolytes has been on the rise. However, the development of MoS₂ catalyst for acidic ORR is still in its infancy. Herein, without using reductant and morphology control reagent, we firstly obtained flowerball-like MoS₂/Vulcan XC-72R (VC) nanocomposites via hydrothermal method. The designed composite exhibits a nearly 4e⁻ ORR process with 0.78 and 0.92 V onset potentials in 0.1 M KOH and HClO₄, respectively. Furthermore, the flowerball-like composite shows utmost electrochemical stability judging by 87 and 80% current retention for about 5.5 h either in alkaline or acid media, long term durability for continuous 10,000 cycles, and stronger resistance to methanol than the commercial Pt/C catalyst. The abundant Mo edges as catalytic active centers of flowerball-like structure, high electron conductivity, and enhanced mass transport in either alkaline or acidic electrolyte are favorable for catalytic performance. The prepared catalyst provides great potential for the substitution of noble metal based catalysts in fuel cells and metal-air batteries. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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10 pages, 3857 KiB

Open AccessFeature PaperArticle

High Oxygen Reduction Activity of Pt-Ni Alloy Catalyst for Proton Exchange Membrane Fuel Cells

by Jun Gu, Guang-Meng Zhang, Rui Yao, Tao Yu, Meng-Fei Han and Run-Sheng Huang

Catalysts 2022, 12(3), 250; https://doi.org/10.3390/catal12030250 - 22 Feb 2022

Cited by 6 | Viewed by 2465

In order to fill the research gap of high metal loading of high performance PtNi alloy catalysts, a PtNi/C alloy nano-catalyst with metal loading more than 50 wt.% and core-shell like structure was prepared by ethylene glycol reduction, high temperature annealing, and acid [...] Read more.

In order to fill the research gap of high metal loading of high performance PtNi alloy catalysts, a PtNi/C alloy nano-catalyst with metal loading more than 50 wt.% and core-shell like structure was prepared by ethylene glycol reduction, high temperature annealing, and acid pickling. The electrochemical test results showed that the prepared PtNi alloy catalyst had excellent electrochemical activity: the electrochemical surface area (ECSA) was 63.8 m²·g_Pt⁻¹, and the mass activity (MA) was 0.574 A·mg_Pt⁻¹, which is 2.73 times greater than those of the Pt/C JM (Johnson Matthey) catalyst. The durability of the PtNi/C catalyst was further investigated. After 30 K cycles of accelerated durability test, the ECSA and MA of the PtNi/C alloy catalyst decreased by 10.2% and 31.2%, respectively. The PtNi/C alloy catalyst prepared in this study has excellent catalytic activity and overcomes the problem of insufficient durability of traditional alloy catalysts and has the potential for large-scale commercial application. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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12 pages, 2819 KiB

Open AccessArticle

Immobilization of Lipases on Modified Silica Clay for Bio-Diesel Production: The Effect of Surface Hydrophobicity on Performance

by Youdan Duan, Ting Zou, Sijin Wu and Haiming Cheng

Catalysts 2022, 12(2), 242; https://doi.org/10.3390/catal12020242 - 21 Feb 2022

Cited by 5 | Viewed by 1520

The hydrophobicity of a support plays a critical role in the catalytic efficiency of immobilized lipases. 3-aminopropyltriethoxysilane (APTES)-modified silica clay (A-SC) was coupled with silane coupling agents of different alkyl chains (methyl triethoxysilane, vinyl triethoxysilane, octyl triethoxysilane, and dodecyl triethoxysilane) to prepare a [...] Read more.

The hydrophobicity of a support plays a critical role in the catalytic efficiency of immobilized lipases. 3-aminopropyltriethoxysilane (APTES)-modified silica clay (A-SC) was coupled with silane coupling agents of different alkyl chains (methyl triethoxysilane, vinyl triethoxysilane, octyl triethoxysilane, and dodecyl triethoxysilane) to prepare a series of hydrophobic support for lipase immobilization. The lipases were immobilized onto the support by conducting glutaraldehyde cross-linking processes. The results showed that the activity of the immobilized biocatalyst increased with hydrophobicity. The hydrolytic activity of Lip-Glu-C₁₂-SC (contact angle 119.8°) can reach 5900 U/g, which was about three times that of Lip-Glu-A-SC (contact angle 46.5°). The immobilized lipase was applied as a biocatalyst for biodiesel production. The results showed that the catalytic yield of biodiesel with highly hydrophobic Lip-Glu-C₁₂-SC could be as high as 96%, which is about 30% higher than that of Lip-Glu-A-SC. After being recycled five times, the immobilized lipase still maintained good catalytic activity and stability. This study provides a good strategy to improve the efficiency of immobilized lipases, showing great potential for future industrial application on biodiesel production. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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14 pages, 3050 KiB

Open AccessArticle

Highly Efficient Hierarchical Porous Carbon Supported Pd-Based Catalysts for Additive-Free Dehydrogenation of Formic Acid

by Xinyi Miao, Fengwu Tian, Miaomiao Bai, Yujia Zhang, Wei Wang, Zuoping Zhao, Xianzhao Shao and Xiaohui Ji

Catalysts 2022, 12(2), 240; https://doi.org/10.3390/catal12020240 - 20 Feb 2022

Cited by 7 | Viewed by 2240

Formic acid (FA) is one of the most prospective hydrogen carriers for renewable energy transformation. In this context, the addition of extra-amine is always required for promoting the reactivity of FA, which is still a key challenge. Herein, we report a simple but [...] Read more.

Formic acid (FA) is one of the most prospective hydrogen carriers for renewable energy transformation. In this context, the addition of extra-amine is always required for promoting the reactivity of FA, which is still a key challenge. Herein, we report a simple but effective strategy to synthesize Pd nanoparticles, supported on NH₂-functionalized, phosphorous-doped glucose-based porous carbon (NH₂-P-GC). The introduction of NH₂- groups on the support acts as an immobilized amine-additive for FA dehydrogenation, while phosphorus not only serves as an electronic promoter to keep Pd in the electronic deficient state for FA dehydrogenation, but also as an enlarger of the aperture size of the carbon. As a result, the Pd/NH₂-P-GC has exceptional catalytic activity, 100% H₂ selectivity, CO generation that is undetectable, and good reusability for hydrogen production from FA. In the additive-free dehydrogenation of aqueous FA solution, the initial turnover frequency (TOF) can reach 5126 h⁻¹ at room temperature, which is substantially higher than the best heterogeneous catalyst so far recorded. Overall, the system’s high activity, selectivity, stability, and simplicity in producing CO-free H₂/CO₂ gas from FA, without the need for any additive, makes it attractive for practical deployment. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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24 pages, 2146 KiB

Open AccessReview

Production of Jet Biofuels by Catalytic Hydroprocessing of Esters and Fatty Acids: A Review

by Rodolpho R. C. Monteiro, Isabela A. dos Santos, Maria R. A. Arcanjo, Célio L. Cavalcante, Jr., Francisco M. T. de Luna, Roberto Fernandez-Lafuente and Rodrigo S. Vieira

Catalysts 2022, 12(2), 237; https://doi.org/10.3390/catal12020237 - 20 Feb 2022

Cited by 19 | Viewed by 8365

The transition from fossil to bio-based fuels is a requisite for reducing CO₂ emissions in the aviation sector. Jet biofuels are alternative aviation fuels with similar chemical composition and performance of fossil jet fuels. In this context, the Hydroprocessing of Esters and [...] Read more.

The transition from fossil to bio-based fuels is a requisite for reducing CO₂ emissions in the aviation sector. Jet biofuels are alternative aviation fuels with similar chemical composition and performance of fossil jet fuels. In this context, the Hydroprocessing of Esters and Fatty Acids (HEFA) presents the most consolidated pathway for producing jet biofuels. The process for converting esters and/or fatty acids into hydrocarbons may involve hydrodeoxygenation, hydrocracking and hydroisomerization, depending on the chemical composition of the selected feedstock and the desired fuel properties. Furthermore, the HEFA process is usually performed under high H₂ pressures and temperatures, with reactions mediated by a heterogeneous catalyst. In this framework, supported noble metals have been preferably employed in the HEFA process; however, some efforts were reported to utilize non-noble metals, achieving a similar performance of noble metals. Besides the metallic site, the acidic site of the catalyst is crucial for product selectivity. Bifunctional catalysts have been employed for the complete process of jet biofuel production with standardized properties, with a special remark for using zeolites as support. The proper design of heterogeneous catalysts may also reduce the consumption of hydrogen. Finally, the potential of enzymes as catalysts for intermediate products of the HEFA pathway is highlighted. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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17 pages, 2371 KiB

Open AccessArticle

Investigating the Optimization Design of Internal Flow Fields Using a Selective Catalytic Reduction Device and Computational Fluid Dynamics

by Bin Hu, Cong Chen, Shouxi Jiang, Xiaosong Liu and Qianjin Dai

Energies 2022, 15(4), 1451; https://doi.org/10.3390/en15041451 - 16 Feb 2022

Cited by 6 | Viewed by 2046

Selective catalytic reduction (SCR) and denitrification are the best technologies for nitrogen oxides (NO_x) control in coal-fired power plants, and their denitration efficiency and ammonia escape rate are closely related to their internal flow characteristics. By adding a deflector to the [...] Read more.

Selective catalytic reduction (SCR) and denitrification are the best technologies for nitrogen oxides (NO_x) control in coal-fired power plants, and their denitration efficiency and ammonia escape rate are closely related to their internal flow characteristics. By adding a deflector to the SCR device, the flow field in the curve can be effectively improved, and the stable and efficient operation of the SCR device can be realized. Based on the numerical simulation method, the SCR system of a coking coal-fired boiler in a steel plant was simulated using k-ε (the turbulence model), and three design schemes of deflectors were proposed and numerically simulated simultaneously. After optimization, the ammonia injection grid’s downstream velocity variance coefficient C_V was 6.69, the catalyst upper cross-section velocity variance coefficient was 11.84, the cross-sectional temperature average was 499 K, the maximum temperature deviation was 9 °C, the maximum-to-minimum temperature interval span was 15 °C, the cross-sectional NH₃/NOx molar ratio average value was 0.8122, the coefficient of variance was 4.67, and the pressure loss was 1855 Pa. The findings of this work will help improve the denitration efficiency and provide an important reference for the actual transformation design. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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14 pages, 28849 KiB

Open AccessArticle

Facile Synthesis of Sillén-Aurivillius Layered Oxide Bi₇Fe₂Ti₂O₁₇Cl with Efficient Photocatalytic Performance for Degradation of Tetracycline

by Yan Gu, Fang Yu, Jikun Chen and Qinfang Zhang

Catalysts 2022, 12(2), 221; https://doi.org/10.3390/catal12020221 - 15 Feb 2022

Cited by 7 | Viewed by 2260

The development of an efficient and environment-friendly photocatalyst for antibiotics degradation is of great significance and still remains a major challenge. Herein, a novel Sillén-Aurivillius layered oxide Bi₇Fe₂Ti₂O₁₇Cl is successfully synthesized via a one-step flux [...] Read more.

The development of an efficient and environment-friendly photocatalyst for antibiotics degradation is of great significance and still remains a major challenge. Herein, a novel Sillén-Aurivillius layered oxide Bi₇Fe₂Ti₂O₁₇Cl is successfully synthesized via a one-step flux route (noted as F-BFTOC) and solid-state reaction (noted as S-BFTOC). The as-prepared F-BFTOC manifests the enhanced visible-light photocatalytic performance towards tetracycline (TC) degradation compared with Bi₄NbO₈Cl and its degradation efficiency reaches 90% within 90 min. Additionally, the proposed degradation pathway and photocatalytic mechanism are systematically investigated by liquid chromatography tandem-mass spectrometry (HPLC-MS), active species trapping test, electron spin resonance (ESR) and first-principles calculations. The superior degradation of antibiotics is primarily derived from the photo-generated h⁺, and radical ·O₂⁻ as the dominant active species. More importantly, the F-BFTOC exhibits excellent cycle stability and TC is ultimately transformed into non-toxic open-loop products. Simultaneously, Rhodamine B (RhB) as a typical organic pollutant is further employed to evaluate the photocatalytic activity of F-BFTOC, and 98% of the degradation efficiency is achieved. BFTOC as a multifunctional photocatalyst for pollutant degradation offers a new insight for Sillén-Aurivillius photocatalytic in the field of water purification. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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25 pages, 33737 KiB

Open AccessArticle

Evaluation of Au/ZrO₂ Catalysts Prepared via Postsynthesis Methods in CO₂ Hydrogenation to Methanol

by Tatiparthi Vikram Sagar, Janez Zavašnik, Matjaž Finšgar, Nataša Novak Tušar and Albin Pintar

Catalysts 2022, 12(2), 218; https://doi.org/10.3390/catal12020218 - 14 Feb 2022

Cited by 13 | Viewed by 3450

Au nanoparticles supported on ZrO₂ enhance its surface acidic/basic properties to produce a high yield of methanol via the hydrogenation of CO₂. Amorphous ZrO₂-supported 0.5–1 wt.% Au catalysts were synthesized by two methods, namely deposition precipitation (DP) and [...] Read more.

Au nanoparticles supported on ZrO₂ enhance its surface acidic/basic properties to produce a high yield of methanol via the hydrogenation of CO₂. Amorphous ZrO₂-supported 0.5–1 wt.% Au catalysts were synthesized by two methods, namely deposition precipitation (DP) and impregnation (IMP), characterized by a variety of techniques, and evaluated in the process of CO₂ hydrogenation to methanol. The DP-method catalysts were highly advantageous over the IMP-method catalyst. The DP method delivered samples with a large surface area, along with the control of the Au particle size. The strength and number of acidic and basic sites was enhanced on the catalyst surface. These surface changes attributed to the DP method greatly improved the catalytic activity when compared to the IMP method. The variations in the surface sites due to different preparation methods exhibited a huge impact on the formation of important intermediates (formate, dioxymethylene and methoxy) and their rapid hydrogenation to methanol via the formate route, as revealed by means of in situ DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) analysis. Finally, the rate of formation of methanol was enhanced by the increased synergy between the metal and the support. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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11 pages, 6147 KiB

Open AccessArticle

Skeletal Nickel Catalyst for the Methanation Reaction Developed by Laser-Engineered Net-Shaping Technology

by Kuo Yan, Zaiwen Lin, Xu Li, Meng Chen, Xiaolong Wang, Yuren Wang, Jun Wang and Heng Jiang

Catalysts 2022, 12(2), 208; https://doi.org/10.3390/catal12020208 - 10 Feb 2022

Viewed by 2331

Here, we report a skeletal nickel catalyst prepared by cumulative processing. The Ni, Al, and CoCrMo multi-component alloys were printed by a dual-powder laser-engineered net-shaping system, and alloy samples with different components were obtained through high-throughput design. After leaching in 5 mol/L NaOH [...] Read more.

Here, we report a skeletal nickel catalyst prepared by cumulative processing. The Ni, Al, and CoCrMo multi-component alloys were printed by a dual-powder laser-engineered net-shaping system, and alloy samples with different components were obtained through high-throughput design. After leaching in 5 mol/L NaOH at 40 °C for 2 h, the specific surface area of the catalyst increased with increasing Al content. Increasing the leaching temperature and prolonging the leaching time also effectively increased the specific surface area of the catalyst. After leaching at 80 °C for 12 h, the specific surface area was 42.36 m²/g. After cleaning and hydrogen-reduction treatment at 400 °C, the catalyst showed high catalytic activity. The highest conversion rate of CO reached 89.56%, and the selectivity of CH₄ remained above 98% for a long time. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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8 pages, 1825 KiB

Open AccessArticle

Ru@Carbon Nanotube Composite Microsponge: Fabrication in Supercritical CO₂ for Hydrogenation of p-Chloronitrobenzene

by Xianghong Ge, Hui Liu, Xingxing Ding, Yanyan Liu, Xingsheng Li, Xianli Wu and Baojun Li

Nanomaterials 2022, 12(3), 539; https://doi.org/10.3390/nano12030539 - 04 Feb 2022

Cited by 1 | Viewed by 1564

Novel heterogeneous catalysts are needed to selectively anchor metal nanoparticles (NPs) into the internal space of carbon nanotubes (CNTs). Here, supercritical CO₂ (SC-CO₂) was used to fabricate the Ru@CNT composite microsponge via impregnation. Under SC-CO₂ conditions, the highly dispersive [...] Read more.

Novel heterogeneous catalysts are needed to selectively anchor metal nanoparticles (NPs) into the internal space of carbon nanotubes (CNTs). Here, supercritical CO₂ (SC-CO₂) was used to fabricate the Ru@CNT composite microsponge via impregnation. Under SC-CO₂ conditions, the highly dispersive Ru NPs, with a uniform diameter of 3 nm, were anchored exclusively into the internal space of CNTs. The CNTs are assembled into a microsponge composite. The supercritical temperature for catalyst preparation, catalytic hydrogenation temperature, and time all have a significant impact on the catalytic activity of Ru@CNTs. The best catalytic activity was obtained at 100 °C and 8.0 MPa: this gave excellent selectivity in the hydrogenation of p-chloronitrobenzene at 100 °C. This assembly strategy assisted by SC-CO₂ will be promising for the fabrication of advanced carbon composite powder materials. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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12 pages, 2852 KiB

Open AccessArticle

Organocatalysis for the Asymmetric Michael Addition of Aldehydes and α,β-Unsaturated Nitroalkenes

by Jae Ho Shim, Seok Hyun Cheun, Hyeon Soo Kim and Deok-Chan Ha

Catalysts 2022, 12(2), 121; https://doi.org/10.3390/catal12020121 - 20 Jan 2022

Cited by 2 | Viewed by 2641

Michael addition is an important reaction because it can be used to synthesize a wide range of natural products or complex compounds that exhibit biological activities. In this study, a mirror image of an aldehyde and α,β-unsaturated nitroalkene were reacted in the presence [...] Read more.

Michael addition is an important reaction because it can be used to synthesize a wide range of natural products or complex compounds that exhibit biological activities. In this study, a mirror image of an aldehyde and α,β-unsaturated nitroalkene were reacted in the presence of (R,R)-1,2-diphenylethylenediamine (DPEN). Herein, thiourea was introduced as an organic catalyst, and a selective Michael addition reaction was carried out. The primary amine moiety of DPEN reacts with aldehydes to form enamines, which is activated by the hydrogen bond formation between the nitro groups of α,β-unsaturated nitroalkenes and thiourea. Our aim was to obtain an asymmetric Michael product by adding 1,4-enamine to an alkene to form a new carbon–carbon bond. As a result, the primary amine of the chiral diamine was converted to an enamine. The reaction proceeded with a relatively high degree of enantioselectivity, which was achieved using double activation via hydrogen bonding of the nitro group and thiourea. Michael products with a high degree of enantioselectivity (97–99% synee) and diastereoselectivity (syn/anti = 9/1) were obtained in yields ranging from 94–99% depending on the aldehydes. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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14 pages, 2207 KiB

Open AccessArticle

Graded Preparation and Industrial Applications of Large-Ball Polyolefin Catalyst Carriers

by Xinfeng Lv, Yuhao Du, Shanjun Du and Lan Xiang

Catalysts 2022, 12(2), 117; https://doi.org/10.3390/catal12020117 - 19 Jan 2022

Cited by 4 | Viewed by 1593

In the process of preparing polyolefin catalyst carrier, the particle size is often unqualified because of the adhesion of smaller particles to each other and the crushing effect of mechanical vibration. To improve the output of target products, reduce loss, and improve yield, [...] Read more.

In the process of preparing polyolefin catalyst carrier, the particle size is often unqualified because of the adhesion of smaller particles to each other and the crushing effect of mechanical vibration. To improve the output of target products, reduce loss, and improve yield, a high-precision and high-efficiency carrier particle classification process was developed according to the embedded principle. The hydraulic hydrocyclone equipment designed in this work could eliminate short-circuit flow and achieve good integration of the internal flow field, thereby enhancing the separation accuracy and high separation efficiency. The process was successfully applied to the industry with smooth operation. The large-ball polyolefin catalyst carrier prepared by grading showed a small distribution coefficient, high yield, and excellent polymerization performance, and the average particle size of the graded large ball catalyst support was 65–75 μm with the SPAN < 0.7, which could meet the needs of DQC700 series catalyst products. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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11 pages, 24512 KiB

Open AccessArticle

Nickel-Based Selenides with a Fractal Structure as an Excellent Bifunctional Electrocatalyst for Water Splitting

by Jingxuan He, Ting Qian, Chao Cai, Xia Xiang, Sean Li and Xiaotao Zu

Nanomaterials 2022, 12(2), 281; https://doi.org/10.3390/nano12020281 - 17 Jan 2022

Cited by 28 | Viewed by 2685

Nickel-based selenides are believed to be promising non-precious metal electrocatalysts, and have been widely used for both oxygen evolution reactions (OER) and hydrogen evolution reactions (HER). Here, we control the aging time to prepare Ni_xSe_y with different fractal structures as [...] Read more.

Nickel-based selenides are believed to be promising non-precious metal electrocatalysts, and have been widely used for both oxygen evolution reactions (OER) and hydrogen evolution reactions (HER). Here, we control the aging time to prepare Ni_xSe_y with different fractal structures as a bifunctional catalyst. An obtained sample with an aging time of 80 min shows outstanding electrocatalytic performance for hydrogen evolution reactions (HER) with an overpotential of 225 mV (η@10 mA/cm²) and for oxygen evolution reactions (OER) with an overpotential of 309 mV (η@50 mA/cm²). Moreover, to further improve catalytic activity, we doped Fe in Ni_xSe_y to obtain the ternary nickel-based selenide, Fe_0.2Ni_0.8Se (FNSs). The HER activity of FNS increased two-fold at 10 mA/cm², and the overpotential of OER decreased to 255 mV at 50 mA/cm². The synthetic strategy and research results of this work have a certain reference value for other low-cost and high-efficiency transition metal catalysts for electrocatalytic water splitting. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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11 pages, 6132 KiB

Open AccessArticle

Surfactant-Free Monodispersed Pd Nanoparticles Template for Core-Shell Pd@PdPt Nanoparticles as Electrocatalyst towards Methanol Oxidation Reaction (MOR)

by Fulin Zheng, Tsz-Lung Kwong and Ka-Fu Yung

Nanomaterials 2022, 12(2), 260; https://doi.org/10.3390/nano12020260 - 14 Jan 2022

Cited by 8 | Viewed by 2027

An eco-friendly two-step synthetic method for synthesizing Pd@PdPt/CNTs nanoparticles was introduced and studied for the methanol oxidation reaction. The Pd@PdPt alloy core-shell structure was synthesized by preparing a surfactant-free monodispersed Pd/CNTs precursor through the hydrolysis of tetrachloropalladate (II) ion ([PdCl₄]²⁻ [...] Read more.

An eco-friendly two-step synthetic method for synthesizing Pd@PdPt/CNTs nanoparticles was introduced and studied for the methanol oxidation reaction. The Pd@PdPt alloy core-shell structure was synthesized by preparing a surfactant-free monodispersed Pd/CNTs precursor through the hydrolysis of tetrachloropalladate (II) ion ([PdCl₄]²⁻) in the presence of carbon nanotubes (CNTs) and the subsequent hydrogen reduction and followed by a galvanic replacement reaction. This method opens up an eco-friendly, practical, and straightforward route for synthesizing monometallic or bimetallic nanoparticles with a clean surfactant-free electrocatalytic surface. It is quite promising for large-scale preparation. The Pd@PdPt/CNTs electrocatalyst demonstrated a high specific mass activity for methanol oxidation (400.2 mAmg_Pt⁻¹) and excellent stability towards direct methanol oxidation compared to its monometallic counterparts. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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15 pages, 9827 KiB

Open AccessArticle

Hypercrosslinked Ionic Polymers with High Ionic Content for Efficient Conversion of Carbon Dioxide into Cyclic Carbonates

by Xu Liao, Baoyou Pei, Ruixun Ma, Lingzheng Kong, Xilin Gao, Jiao He, Xiaoyan Luo and Jinqing Lin

Catalysts 2022, 12(1), 62; https://doi.org/10.3390/catal12010062 - 06 Jan 2022

Cited by 11 | Viewed by 2643

The effective conversion of carbon dioxide (CO₂) into cyclic carbonates requires porous materials with high ionic content and large specific surface area. Herein, we developed a new systematic post-synthetic modification strategy for synthesizing imidazolium-based hypercrosslinked ionic polymers (HIPs) with high ionic [...] Read more.

The effective conversion of carbon dioxide (CO₂) into cyclic carbonates requires porous materials with high ionic content and large specific surface area. Herein, we developed a new systematic post-synthetic modification strategy for synthesizing imidazolium-based hypercrosslinked ionic polymers (HIPs) with high ionic content (up to 2.1 mmol g⁻¹) and large specific surface area (385 m² g⁻¹) from porous hypercrosslinked polymers (HCPs) through addition reaction and quaternization. The obtained HIPs were efficient in CO₂ capture and conversion. Under the synergistic effect of high ionic content, large specific surface area, and plentiful micro/mesoporosity, the metal-free catalyst [HCP-CH₂-Im][Cl]-1 exhibited quantitative selectivities, high catalytic yields, and good substrate compatibility for the conversion of CO₂ into cyclic carbonates at atmospheric pressure (0.1 MPa) in a shorter reaction time in the absence of cocatalysts, solvents, and additives. High catalytic yields (styrene oxide, 120 °C, 8 h, 94% yield; 100 °C, 20 h, 93% yield) can be achieved by appropriately extending the reaction times at low temperature, and the reaction times are shorter than other porous materials under the same conditions. This work provides a new strategy for synthesizing an efficient metal-free heterogeneous catalyst with high ionic content and a large specific surface area from HCPs for the conversion of CO₂ into cyclic carbonates. It also demonstrates that the ionic content and specific surface area must be coordinated to obtain high catalytic activity for CO₂ cycloaddition reaction. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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19 pages, 6450 KiB

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Pentamethylcyclopentadienyl Molybdenum(V) Complexes Derived from Iodoanilines: Synthesis, Structure, and ROP of ε-Caprolactone

by Tian Xing, Mark R. J. Elsegood, Sophie H. Dale and Carl Redshaw

Catalysts 2021, 11(12), 1554; https://doi.org/10.3390/catal11121554 - 20 Dec 2021

Cited by 2 | Viewed by 2342

The reaction of [Mo(η-C₅Me₅)Cl₄] with the ortho-, meta-, or para-iodo-functionalized anilines 2-IC₆H₄NH₂, 3-IC₆H₄NH₂, 4-IC₆H₄NH₂ yields imido or [...] Read more.

The reaction of [Mo(η-C₅Me₅)Cl₄] with the ortho-, meta-, or para-iodo-functionalized anilines 2-IC₆H₄NH₂, 3-IC₆H₄NH₂, 4-IC₆H₄NH₂ yields imido or amine products of the type [Mo(η-C₅Me₅)Cl₂(IC₆H₄N)] (2-I, 1, 3-I, 3, 4-I, 5) or [Mo(η-C₅Me₅)Cl₄(IC₆H₄NH₂)] (3-I, 2, 4-I, 4), respectively, depending on the reaction stoichiometry/conditions; we were unable to isolate an amine complex of the 2-I derivative. The reaction of [Mo(η-C₅Me₅)Cl₄] with one equivalent of 2-I,4-FC₆H₃NH₂ in the presence of Et₃N afforded [Mo(η-C₅Me₅)Cl₂(2-I,4-FC₆H₃N)]·MeCN (6·MeCN), which, upon exposure to air, afforded the Mo(VI) imido complex [Mo(η-C₅Me₅)Cl₃(2-I,4-FC₆H₃N)] (7). For comparative studies, the structure of the aniline (C₆H₅NH₂)-derived complex [Mo(η-C₅Me₅)Cl₂(2-C₆H₃N)] (8) has also been prepared. The molecular structures of 1–8 have been determined and reveal packing in the form of zig-zag chains or ladders. The complexes catalyze, in the presence of benzyl alcohol under N₂, the ring-opening polymerization (ROP) of ε-caprolactone affording relatively low molecular weight products. The MALDI-ToF spectra indicate that a number of polymer series bearing a variety of end groups are formed. Conducting the ROPs as melts or under air results in the isolation of higher molecular weight products, again bearing a variety of end groups. Kinetic studies reveal the aniline-derived imido complex 8 performs best, whilst a meta-iodo substituent and a Mo(V) centre are also found to be beneficial. The structures of the side products 2-IC₆H₄NH₃Cl and 3-IC₆H₄NH₃Cl are also reported. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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20 pages, 4565 KiB

Open AccessArticle

Synergistic Effect of Neighboring Fe and Cu Cation Sites Boosts Fe_nCu_m-BEA Activity for the Continuous Direct Oxidation of Methane to Methanol

by Yan Li, Ning Liu, Chengna Dai, Ruinian Xu, Gangqiang Yu, Ning Wang, Jie Zhang and Biaohua Chen

Catalysts 2021, 11(12), 1444; https://doi.org/10.3390/catal11121444 - 27 Nov 2021

Cited by 7 | Viewed by 2262

Direct oxidation of methane to methanol (DMTM), constituting a major challenge for C₁ chemistry, has aroused significant interest. The present work reports the synergistic effect of neighboring [Fe]--[Cu] cations, which can significantly boost the CH₃OH productivity (100.9 and 41.9 → [...] Read more.

Direct oxidation of methane to methanol (DMTM), constituting a major challenge for C₁ chemistry, has aroused significant interest. The present work reports the synergistic effect of neighboring [Fe]--[Cu] cations, which can significantly boost the CH₃OH productivity (100.9 and 41.9 → 259.1 μmol∙g⁻¹_cat∙h⁻¹) and selectivity (0.28 and 17.6% → 71.7%) of the best performing Fe_0.6%Cu_0.68%-BEA (relative to monomeric Fe_1.28%- and Cu_1.28%-BEA) during the continuous H₂O-mediated N₂O DMTM. The combined experimental (in situ FTIR, D₂O isotopic tracer technique) and theoretical (DFT, ab initio molecular dynamics (AIMD)) studies reveal deeper mechanistic insights that the synergistic effect of [Fe]--[Cu] can not only significantly favor active O production (ΔG = 0.18 eV), but also efficiently motivate the reaction following a H₂O proton-transfer route (ΔG = 0.07 eV), eventually strikingly promoting CH₃OH productivity/selectivity. Generally, the proposed strategy by employing the synergistic effect of bimetallic cations to modify DMTM activity would substantially favor other highly efficient catalyst designs. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Enantioselective Organocatalyzed Michael Addition of Aldehydes to Maleimides in Aqueous Medi
Authors: Jae Ho Shim 1,*, Cheun Seok Hyun 2, Hyeon Soo Kim 1, and Deok-Chan Ha 2
Affiliation: 1. Department of Anatomy, Korea University College of Medicine, 126-1, Anam-dong 5-ga, Seongbuk-gu, Seoul, Republic of Korea; shimjh3000@korea.ac.kr, anatomykim@korea.ac.kr 2. Department of Chemistry, Korea University College of Science, Anam-ro, Seongb
Abstract: Thiourea was introduced into (R,R)-1,2-diphenylethylenediamine (DPEN) as an organocatalyst to obtain aldehydes and maleimides. Enantioselective Michael addition reaction was carried out as an eco-friendly method using water as the solvent. As a result of the reaction between isobutyraldehyde and maleimide, a yield of 97% or more and enantioselectivity of 99% were obtained using low catalyst loading (0.01 mol%). The solvent effect can be explained by theoretical calculations that indicate the participation of a transition state in which the CF3 substituent of the catalyst is hydrogen bond activated by the surrounding water molecules. This discovery enabled the use of a low catalyst loading in the organic reactions of chiral substances for pharmaceutical applications in the industry. In addition, a method for optimizing the organocatalysts was proposed and the organic reaction mechanisms were determined through quantum calculations.

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Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Catalysts catalysts	3.9	6.3	2011	14.3 Days	CHF 2700
Chemistry chemistry	2.1	2.5	2019	19.1 Days	CHF 1800
Energies energies	3.2	5.5	2008	16.1 Days	CHF 2600
Nanomaterials nanomaterials	5.3	7.4	2010	13.6 Days	CHF 2900
Sustainability sustainability	3.9	5.8	2009	18.8 Days	CHF 2400

Submit your Abstract

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Catalysts catalysts	3.9	6.3	2011	14.3 Days	CHF 2700
Chemistry chemistry	2.1	2.5	2019	19.1 Days	CHF 1800
Energies energies	3.2	5.5	2008	16.1 Days	CHF 2600
Nanomaterials nanomaterials	5.3	7.4	2010	13.6 Days	CHF 2900
Sustainability sustainability	3.9	5.8	2009	18.8 Days	CHF 2400

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