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Catalysts, Volume 13, Issue 6 (June 2023) – 112 articles

Cover Story (view full-size image): The development of general strategies for the electrochemical enantiocontrol of a transformation still presents considerable challenges; in particular, relatively few contributions of highly enantioselective catalytic electrochemical reactions have been reported to date. In this review article, the most recent examples of asymmetric electrochemical catalysis are discussed. The article is organised by the three types of enantioselective catalysis: metal-based catalysis, organocatalysis, and biocatalysis. In each section, the most significant and recent advances are presented and discussed. View this paper
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11 pages, 2536 KiB  
Communication
Long-Term Hydrogen Production from a Methanol–Water Solution Catalyzed by an Iridium Complex
by Shohichi Furukawa, Kaito Kubota, Han Wang, Haotong Gong, Shumpei Kajita and Ken-ichi Fujita
Catalysts 2023, 13(6), 1027; https://doi.org/10.3390/catal13061027 - 20 Jun 2023
Cited by 1 | Viewed by 1219
Abstract
Long-term hydrogen production from a methanol–water solution was achieved by developing a new reaction system employing a homogeneous iridium catalyst bearing a bipyridonate-type functional ligand. By optimizing the methanol:water ratio of the reaction solution, the efficiency of hydrogen production was greatly improved in [...] Read more.
Long-term hydrogen production from a methanol–water solution was achieved by developing a new reaction system employing a homogeneous iridium catalyst bearing a bipyridonate-type functional ligand. By optimizing the methanol:water ratio of the reaction solution, the efficiency of hydrogen production was greatly improved in relation to that reported in our previous studies. Additionally, the effect of the scale of reaction was investigated. It was found that a small-scale reaction led to a longer lifetime of the iridium catalyst, accomplishing long-term continuous hydrogen production at a constant rate for over 500 h. Furthermore, procedures for catalyst reuse were studied. After hydrogen production for 400 h, all volatiles in the reaction system were removed under vacuum. This simple procedure is highly effective for the reactivation and reuse of the catalyst. Finally, hydrogen production (13.7 L, 562 mmol) from methanol (12.3 mL, 303 mmol) and water (5.46 mL, 303 mmol), in a continuous reaction for 800 h, was achieved. Full article
(This article belongs to the Special Issue Advances in Reforming Catalysts for Hydrogen Production)
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15 pages, 3696 KiB  
Article
A DFT Study of the Copolymerization of Methyl Vinyl Sulfone and Ethylene Catalyzed by Phosphine–Sulfonate and α-Diimine Palladium Complexes
by Ling Zhu, Shuang Li, Xiaohui Kang, Wenzhen Zhang and Yi Luo
Catalysts 2023, 13(6), 1026; https://doi.org/10.3390/catal13061026 - 20 Jun 2023
Viewed by 997
Abstract
Density functional theory (DFT) calculations were comparatively carried out to reveal the origins of different catalytic performances from phosphine–benzene sulfonate (A, [{P^O}PdMe(L)] (P^O = Κ2-P,O-Ar2PC6H4SO3 with Ar = 2-MeOC6H4 [...] Read more.
Density functional theory (DFT) calculations were comparatively carried out to reveal the origins of different catalytic performances from phosphine–benzene sulfonate (A, [{P^O}PdMe(L)] (P^O = Κ2-P,O-Ar2PC6H4SO3 with Ar = 2-MeOC6H4)) and α-diimine (B, [{N^N}PdMe(Cl)] (N^N = (ArN=C(Me)-C(Me)=NAr) with Ar = 2,6-iPr2C6H3)) palladium complexes toward the copolymerization of ethylene and methyl vinyl sulfone (MVS). Having achieved agreement between theory and experiment, it was found that the favorable 2,1-selective insertion of MVS into phosphine–sulfonate palladium complex A was due to there being less structural deformations in the catalyst and monomer. Both the MVS and ethylene insertions were calculated, and the former was found to be more favorable for chain initiation and chain propagation. In the case of α-diimine palladium system B, the resulting product of the first MVS insertion was quite stable, and the stronger O-backbiting interaction hampered the insertion of the incoming ethylene molecule. These computational results are expected to provide some hints for the design of transition metal copolymerization catalysts. Full article
(This article belongs to the Special Issue Metal-Organic Catalyst for High Performance Materials)
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23 pages, 23164 KiB  
Review
An Overview of Catalytic Carbonylative Double Cyclization Reactions
by Bartolo Gabriele, Raffaella Mancuso, Nicola Della Ca’, Lucia Veltri and Ida Ziccarelli
Catalysts 2023, 13(6), 1025; https://doi.org/10.3390/catal13061025 - 20 Jun 2023
Cited by 6 | Viewed by 1163
Abstract
This short review is aimed at giving an overview of catalytic carbonylative double cyclization reactions, which are processes in which suitable organic substrates and carbon monoxide are sequentially activated by a promoting a catalyst to form two new cycles with the concomitant incorporation [...] Read more.
This short review is aimed at giving an overview of catalytic carbonylative double cyclization reactions, which are processes in which suitable organic substrates and carbon monoxide are sequentially activated by a promoting a catalyst to form two new cycles with the concomitant incorporation of carbon monoxide as a carbonyl function in the final product. Paradigmatic examples of this powerful synthetic methodology, which allows the one-step synthesis of complex molecular architectures from simple building blocks using the simplest and readily available C-1 unit (CO), are illustrated and discussed. The review is divided into five sections: (1) Introduction, (2) Functionalized Olefinic Substrates, (3) Functionalized Acetylenic Substrates, (4) Functionalized Halides, (5) Conclusions and Future Perspectives. Full article
(This article belongs to the Special Issue Exclusive Review Papers in Catalysis in Organic and Polymer Chemistry)
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15 pages, 3691 KiB  
Article
Stable Sulfonic MCM-41 Catalyst for Furfural Production from Renewable Resources in a Biphasic System
by Yasnina Olivares, Carla Herrera, Juan Seguel, Catherine Sepúlveda, Carolina Parra and Gina Pecchi
Catalysts 2023, 13(6), 1024; https://doi.org/10.3390/catal13061024 - 20 Jun 2023
Cited by 1 | Viewed by 1225
Abstract
An MCM-41-SO3H catalyst with 14 wt% S was successfully synthesized to be used in furfural production from xylose and hemicellulose in a biphasic n-butanol/water system. The precursor MCM-41 and the acid-functionalized MCM-41-SO3H catalyst were characterized by XRD, FTIR, TEM, [...] Read more.
An MCM-41-SO3H catalyst with 14 wt% S was successfully synthesized to be used in furfural production from xylose and hemicellulose in a biphasic n-butanol/water system. The precursor MCM-41 and the acid-functionalized MCM-41-SO3H catalyst were characterized by XRD, FTIR, TEM, N2 physisorption, ICP-MS, TPD-NH3, and XPS. The characterization results indicated that the sulfonic process partially decreased the ordered mesoporous structure and increased the acid strength of the initial MCM-41. The catalytic performance of the xylose conversion was evaluated in a batch-type reactor using different biphasic ecological and renewable n-butanol/water ratios (1:1, 1.5:1, 2:1, and 2.5:1) as dissolvent at 170 °C. The effect of the dissolvent mixture was clearly seen from the larger initial reaction rate and TOF values for the 1.5:1 ratio. This catalytic behavior indicated that a proper proportion of n-butanol/water dissolvent mixture enhanced the solubility of the substrate in the n-butanol-rich mixture and prevented the deactivation of acidic sulfonated surface groups. To achieve transformation of lignocellulosic raw material to value-added products, the MCM-41-SO3H catalyst was also used for the production of furfural. The recycling evaluation tests indicated that for the recovered catalyst submitted to a sulfonation process, the yield of furfural was closer to the fresh catalyst. Full article
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13 pages, 2845 KiB  
Article
Photocatalytic Removal of Water Emerging Pollutants in an Optimized Packed Bed Photoreactor Using Solar Light
by M. E. Borges, H. de Paz Carmona, M. Gutiérrez and P. Esparza
Catalysts 2023, 13(6), 1023; https://doi.org/10.3390/catal13061023 - 20 Jun 2023
Cited by 5 | Viewed by 2311
Abstract
Photocatalysis is an advanced oxidation process that is an environmentally friendly option and one of the most critical technologies in green chemistry today. This work studied the upscaling of photocatalysis as a suitable process for wastewater treatment to remove emerging pollutants. For this [...] Read more.
Photocatalysis is an advanced oxidation process that is an environmentally friendly option and one of the most critical technologies in green chemistry today. This work studied the upscaling of photocatalysis as a suitable process for wastewater treatment to remove emerging pollutants. For this purpose, unsupported and supported TiO2 photocatalysts were tested in the photodegradation of ciprofloxacin as a model molecule of an emerging wastewater component, using visible, UV radiation, and solar light. The suitability of TiO2 as a photocatalyst to decompose ciprofloxacin was confirmed in batch photoreactor under Visible and UV radiation, with degradation rates up to 90% after 30 min of irradiation and low adsorption values. TiO2 as a photocatalyst coated in glass support material at the packed bed photoreactor showed good photoactivity for emergent contaminants degradation (95%) under solar radiation. It has been possible to verify that the photocatalytic reactor system constitutes a viable process for eliminating emerging contaminants through environmentally sustainable treatments. Our results corroborate the possibility of degrading emerging contaminants by solar radiation using a packed bed photoreactor, providing a more effective option from a practical and economical point of view for wastewater effluent treatments. Full article
(This article belongs to the Special Issue Photocatalytical Technology in Europe: State-of-the-Art)
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26 pages, 11108 KiB  
Review
The Asymmetric Petasis Borono-Mannich Reaction: Insights on the Last 15 Years
by Carolina Marques and Pedro Brandão
Catalysts 2023, 13(6), 1022; https://doi.org/10.3390/catal13061022 - 19 Jun 2023
Cited by 1 | Viewed by 1762
Abstract
The Petasis borono-Mannich reaction, commonly described as the Petasis reaction, was one of the latest famous multicomponent reactions described in the literature. Currently celebrating its 30th anniversary since it was first reported by Petasis and Akritopoulou in 1993, this reaction has emerged as [...] Read more.
The Petasis borono-Mannich reaction, commonly described as the Petasis reaction, was one of the latest famous multicomponent reactions described in the literature. Currently celebrating its 30th anniversary since it was first reported by Petasis and Akritopoulou in 1993, this reaction has emerged as a powerful tool for the synthesis of biologically relevant molecules (such as substituted amines or amino acids), among others. This three-component catalyst-free reaction (the classic model), involving the coupling of an aldehyde, an amine, and a boronic acid, enables the synthesis of polysubstituted amine-containing molecules. Several accounts regarding the catalyst-free version using different carbonyl, amine, and boron-type components have been reported thus far. In contrast, the asymmetric version is still in its infancy since it was first reported in 2007. In this work, we aim to review the asymmetric versions of the Petasis reaction reported over the last 15 years, considering the chiral pool approach (asymmetric induction by one reaction component) and the use of catalysts (organocatalysts, transition-metal catalysts, and others) to access enantiomeric and diastereomeric pure amino-derivatives. Insights regarding the catalyzed Petasis reaction and consequent sustainable synthesis will be highlighted. Full article
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14 pages, 3385 KiB  
Article
Fe-N-C Catalyst Derived from MOFs with Enhanced Catalytic Performance for Selective Oxidation of Emerging Contaminants
by Cheng Zeng, Yan Wang, Jinquan Wan and Zhicheng Yan
Catalysts 2023, 13(6), 1021; https://doi.org/10.3390/catal13061021 - 19 Jun 2023
Cited by 1 | Viewed by 1087
Abstract
Fe-N-C/peroxymonosulfate (PMS) systems have demonstrated selective oxidation of pollutants, but the underlying mechanism and reasons for variability remain unclear. In this work, we synthesized a highly active Fe-N-C catalyst derived from MOFs using a pyrolysis protection strategy. We assessed its catalytic activity by [...] Read more.
Fe-N-C/peroxymonosulfate (PMS) systems have demonstrated selective oxidation of pollutants, but the underlying mechanism and reasons for variability remain unclear. In this work, we synthesized a highly active Fe-N-C catalyst derived from MOFs using a pyrolysis protection strategy. We assessed its catalytic activity by employing PMS as an activator for pollutant degradation. The presence of Fe-Nx sites favored the catalytic performance of FeMIL-N-C, exhibiting 23 times higher activity compared to N-C. Moreover, we investigated the degradation performance and mechanism of the FeMIL-N-C/PMS system through both experimental and theoretical analyses, focusing on pollutants with diverse electronic structures, namely bisphenol A (BPA) and atrazine (ATZ)N-C. Our findings revealed that the degradation of ATZ primarily follows the free radical pathway, whereas BPA degradation is dominated by electron transfer pathways. Specifically, pollutants with a low LUMO- HOMO energy gap (BPA) can be degraded via the FeMIL-N-C/PMS system through the electron transfer pathway. Conversely, pollutants with a high LUMO-HOMO energy gap (ATZ) exhibit limited electron donation and predominantly undergo degradation through the free radical pathway. This work introduces novel insights into the mechanisms underlying the selective oxidation of pollutants, facilitating a deeper understanding of effective pollutant removal strategies. Full article
(This article belongs to the Special Issue Advanced Catalytic Technology for Environmental Pollution Control)
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14 pages, 4655 KiB  
Article
Electrolessly Deposited Carbon-Supported CuNiSn Electrocatalysts for the Electrochemical Reduction of CO2
by Wasu Chaitree, Atikom Hongmeuan, Piriya Pinthong and Joongjai Panpranot
Catalysts 2023, 13(6), 1020; https://doi.org/10.3390/catal13061020 - 19 Jun 2023
Viewed by 1224
Abstract
Aiming at developing low-cost, high-performance catalysts for the electrochemical reduction of CO2 (CO2-ERR) to valuable multicarbon (C2–C3) chemicals to alleviate global warming, trimetallic alloy electrocatalysts containing Cu, Ni, and Sn supported on a Pd-activated carbon fabric [...] Read more.
Aiming at developing low-cost, high-performance catalysts for the electrochemical reduction of CO2 (CO2-ERR) to valuable multicarbon (C2–C3) chemicals to alleviate global warming, trimetallic alloy electrocatalysts containing Cu, Ni, and Sn supported on a Pd-activated carbon fabric substrate (CS) were prepared via an electroless deposition method. The as-deposited CuNiSn/CS electrocatalysts were employed in CO2-ERR in an H-cell type reactor at an applied potential of −1.6 V vs. Ag/AgCl. The effect of the electroless deposition time (15, 30, and 45 min) was investigated, finding no significant structural differences according to the X-ray diffraction patterns. The evaluation of the reaction performance via linear sweep voltammetry revealed that CO2 was more effectively reduced to adsorbed species on the catalytic surface sites of the electrocatalyst prepared with a 30 min deposition time. The analysis of the gas and liquid products via gas chromatography and nuclear magnetic resonance, respectively, revealed that the Faradaic efficiency and H2 production over CuNiSn/CS was lower than those over related bimetallic and monometallic electrocatalysts, indicating the inhibition of the competitive H2 evolution reaction. Liquid products including formate, ethylene glycol, acetone, ethanol, acetate, and 1-buthanol were detected. Full article
(This article belongs to the Special Issue Heterogeneous Electrocatalysts for CO2 Reduction)
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14 pages, 2904 KiB  
Review
Waste Plastic Recycling Upgrade Design Nanogenerator for Catalytic Degradation of Pollutants
by Qian Zhang, Qiyu Peng, Wenbin Li, Yanzhang Liu and Xiaoxiong Wang
Catalysts 2023, 13(6), 1019; https://doi.org/10.3390/catal13061019 - 19 Jun 2023
Viewed by 1318
Abstract
In recent years, electrocatalytic degradation of pollutants based on nanogenerators has gradually emerged. Compared with the huge energy consumption of traditional electrocatalysis, this method can effectively use displacement current to induce charge transfer and complete catalysis, so it can directly use the existing [...] Read more.
In recent years, electrocatalytic degradation of pollutants based on nanogenerators has gradually emerged. Compared with the huge energy consumption of traditional electrocatalysis, this method can effectively use displacement current to induce charge transfer and complete catalysis, so it can directly use the existing water flow energy and other energy sources in nature. This work will explain the basic principles, methods, and measurement methods of preparing nanogenerators from waste plastics, as well as the classification of electrocatalytic principles and methods relative to nanogenerators, which provides important support for the research in this emerging field. At the same time, the analysis based on this knowledge will also lay the foundation for future design. Full article
(This article belongs to the Special Issue Chemical Catalysis for Waste Plastics Recycling and Upcycling)
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11 pages, 2813 KiB  
Article
Laser Irradiation-Induced Pt-Based Bimetallic Alloy Nanostructures without Chemical Reducing Agents for Hydrogen Evolution Reaction
by Taiping Hu, Yisong Fan, Yixing Ye, Yunyu Cai, Jun Liu, Yao Ma, Pengfei Li and Changhao Liang
Catalysts 2023, 13(6), 1018; https://doi.org/10.3390/catal13061018 - 18 Jun 2023
Cited by 2 | Viewed by 1185
Abstract
Binary metallic alloy nanomaterials (NMs) have received significant attention because of their widespread application in photoelectrocatalysis, electronics, and engineering. Although various synthetic methods have been adopted to prepare binary alloy NMs, the formation of bimetallic alloy NMs by irradiating the mixed solutions of [...] Read more.
Binary metallic alloy nanomaterials (NMs) have received significant attention because of their widespread application in photoelectrocatalysis, electronics, and engineering. Although various synthetic methods have been adopted to prepare binary alloy NMs, the formation of bimetallic alloy NMs by irradiating the mixed solutions of metal salts and metal powders, using a nanosecond pulsed laser in the absence of any reducing agent, is rarely reported. Herein, we report a simple method to fabricate PtX (X = Ag, Cu, Co, Ni) alloy NMs by laser irradiation. Taking PtAg alloys as an example, we present the growth dynamics of the PtAg alloys by laser irradiating a mixture solution of bulk Pt and AgNO3. The experimental process and evidenced characterization indicate that the photothermal evaporation induced by laser irradiation can cause the fragmentation of the bulk Pt into smaller parts, which alloy with Ag atoms extracted from Ag+ by solvated electrons (eaq) and free radicals (Haq). These alloys were used as electrocatalysts for the hydrogen evolution reaction (HER), proving their potential application. Notably, in a 0.5 M H2SO4 solution, the PtNi alloy exhibited higher HER activity (44 mV at 10 mA/cm−2) compared to the untreated bulk Pt (72 mV). Our work provides unique insights into the growth processing of valuable Pt-based bimetallic alloy NMs by laser-assisted metallic alloying, which paves a path for the development of bimetallic alloy electrocatalysts. Full article
(This article belongs to the Special Issue Advances in Photocatalysis and Electrocatalysis Applications)
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17 pages, 6066 KiB  
Article
CO2 to Value-Added Chemicals: Synthesis and Performance of Mono- and Bimetallic Nickel–Cobalt Nanofiber Catalysts
by John Schossig, Akash Gandotra, Kevin Arizapana, Daniel Weber, Michael Wildy, Wanying Wei, Kai Xu, Lei Yu, Robert Chimenti, Islam Mantawy, Dong Choon Hyun, Wenshuai Chen, Cheng Zhang and Ping Lu
Catalysts 2023, 13(6), 1017; https://doi.org/10.3390/catal13061017 - 18 Jun 2023
Cited by 3 | Viewed by 1593
Abstract
In an epoch dominated by escalating concerns over climate change and looming energy crises, the imperative to design highly efficient catalysts that can facilitate the sequestration and transformation of carbon dioxide (CO2) into beneficial chemicals is paramount. This research presents the [...] Read more.
In an epoch dominated by escalating concerns over climate change and looming energy crises, the imperative to design highly efficient catalysts that can facilitate the sequestration and transformation of carbon dioxide (CO2) into beneficial chemicals is paramount. This research presents the successful synthesis of nanofiber catalysts, incorporating monometallic nickel (Ni) and cobalt (Co) and their bimetallic blend, NiCo, via a facile electrospinning technique, with precise control over the Ni/Co molar ratios. Application of an array of advanced analytical methods, including SEM, TGA–DSC, FTIR-ATR, XRD, Raman, XRF, and ICP-MS, validated the effective integration and homogeneous distribution of active Ni/Co catalysts within the nanofibers. The catalytic performance of these mono- and bimetallic Ni/Co nanofiber catalysts was systematically examined under ambient pressure conditions for CO2 hydrogenation reactions. The bimetallic NiCo nanofiber catalysts, specifically with a Ni/Co molar ratio of 1:2, and thermally treated at 1050 °C, demonstrated a high CO selectivity (98.5%) and a marked increase in CO2 conversion rate—up to 16.7 times that of monometallic Ni nanofiber catalyst and 10.8 times that of the monometallic Co nanofiber catalyst. This significant enhancement in catalytic performance is attributed to the improved accessibility of active sites, minimized particle size, and the strong Ni–Co–C interactions within these nanofiber structures. These nanofiber catalysts offer a unique model system that illuminates the fundamental aspects of supported catalysis and accentuates its crucial role in addressing pressing environmental challenges. Full article
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23 pages, 4735 KiB  
Article
Gas-Phase Deoxygenation of Biomass Pyrolysis Tar Catalyzed by Rare Earth Metal Loaded Hβ Zeolite
by Ali A. Jazie, Juma Haydary, Suhad A. Abed and Jakub Husár
Catalysts 2023, 13(6), 1016; https://doi.org/10.3390/catal13061016 - 17 Jun 2023
Viewed by 1112
Abstract
Biomass pyrolysis tar (BPT) with a higher heating value of 24.23 MJ/kg was used as raw feed for the catalytic gas-phase deoxygenation (GDO) process using Hβ zeolite loaded with different amounts of active elements (Ce, La, and Nd). Acetone molecule was chosen as [...] Read more.
Biomass pyrolysis tar (BPT) with a higher heating value of 24.23 MJ/kg was used as raw feed for the catalytic gas-phase deoxygenation (GDO) process using Hβ zeolite loaded with different amounts of active elements (Ce, La, and Nd). Acetone molecule was chosen as a model compound to test the activity of pure Hβ zeolite, 1 wt% Ce/Hβ zeolite, 5 wt% Ce/Hβ zeolite, 1 wt% La/Hβ zeolite, 5 wt% La/Hβ zeolite, 1 wt% Nd/Hβ zeolite, and 5 wt% Nd/Hβ zeolite at 400 °C and process time of 3 h. BPT characterization showed a wide range of oxygenated compounds with the main components including water: 0.71%, furfural: 5.85%, 4-ethylguaiacol: 2.14%, phenol: 13.63%, methylethyl ketone: 5.34%, cyclohexanone: 3.23%, isopropanol: 4.78%, ethanol: 3.67%, methanol: 3.13%, acetic acid: 41.06%, and acetone: 16.46%. BPT conversion using 1 wt% Ce/Hβ zeolite catalyst showed the highest values of degree of deoxygenation (DOD) (68%) and conversion (16% for phenol, 88% for acetic acid, and 38% for 4-ethlyguaiacol). Yields of water, liquid phase, and gas phase in the GDO reaction using 1%Ce/Hβ zeolite were 18.33%, 47.42%, and 34.25%, respectively. Alkyl-substituted phenols and aromatic hydrocarbons achieved the highest yields of 37.34% and 35.56%, respectively. The main interaction pathways for BPT-GDO are also proposed. Full article
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33 pages, 5991 KiB  
Article
Tungsten Oxide Morphology-Dependent Au/TiO2/WO3 Heterostructures with Applications in Heterogenous Photocatalysis and Surface-Enhanced Raman Spectroscopy
by István Székely, Zoltán Kovács, Mihai Rusu, Tamás Gyulavári, Milica Todea, Monica Focșan, Monica Baia and Zsolt Pap
Catalysts 2023, 13(6), 1015; https://doi.org/10.3390/catal13061015 - 17 Jun 2023
Cited by 2 | Viewed by 2058
Abstract
Developing highly efficient Au/TiO2/WO3 heterostructures with applications in heterogeneous photocatalysis (photocatalytic degradation) and surface-enhanced Raman spectroscopy (dye detection) is currently of paramount significance. Au/TiO2/WO3 heterostructures were obtained via heat or time-assisted synthesis routes developed by slightly modifying [...] Read more.
Developing highly efficient Au/TiO2/WO3 heterostructures with applications in heterogeneous photocatalysis (photocatalytic degradation) and surface-enhanced Raman spectroscopy (dye detection) is currently of paramount significance. Au/TiO2/WO3 heterostructures were obtained via heat or time-assisted synthesis routes developed by slightly modifying the Turkevich–Frens synthesis methods and were investigated by TEM, SEM, XRD, Raman spectroscopy, XPS, photoluminescence, and UV–vis DRS techniques. Structural features, such as WO3 crystalline phases, TiO2 surface defects, as well as the WO3 (220) to TiO2-A (101) ratio, were the key parameters needed to obtain heterostructures with enhanced photocatalytic activity for removing oxalic acid, phenol, methyl orange, and aspirin. Photodegradation efficiencies of 95.9 and 96.9% for oxalic acid; above 96% (except one composite) for phenol; 90.1 and 97.9% for methyl orange; and 81.6 and 82.1% for aspirin were obtained. By employing the SERS technique, the detection limit of crystal violet dye, depending on the heterostructure, was found to be between 10−7–10−8 M. The most promising composite was Au/TiO2/WO3-HW-TA it yielded conversion rates of 82.1, 95.9 and 96.8% for aspirin, oxalic acid, and phenol, respectively, and its detection limit for crystal violet was 10−8 M. Au/TiO2/WO3-NWH-HA achieved 90.1, 96.6 and 99.0% degradation efficiency for methyl orange, oxalic acid, and phenol, respectively, whereas its limit of detection was 10−7 M. The Au/TiO2/WO3 heterojunctions exhibited excellent stability as SERS substrates, yielding strong-intensity Raman signals of the pollutant molecules even after a long period of time. Full article
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16 pages, 4991 KiB  
Article
Electrochemical Promotion of CO2 Hydrogenation Using Rh Catalysts Supported on O2− Conducting Solid Electrolyte
by Nikoleta Kokkinou, Fotios Xydas, Susanne Brosda, Georgios Kyriakou and Alexandros Katsaounis
Catalysts 2023, 13(6), 1014; https://doi.org/10.3390/catal13061014 - 16 Jun 2023
Cited by 2 | Viewed by 829
Abstract
Electrochemical promotion was used to modify the activity and selectivity of a Rh catalyst electrode in the CO2 hydrogenation reaction. The experiments were carried out in a temperature range of 350–430 °C at ambient pressure and at different CO2 to H [...] Read more.
Electrochemical promotion was used to modify the activity and selectivity of a Rh catalyst electrode in the CO2 hydrogenation reaction. The experiments were carried out in a temperature range of 350–430 °C at ambient pressure and at different CO2 to H2 gas feeding ratios (1:2 to 4:1). The only reaction products observed were CO and CH4, both under open- and closed-circuit conditions. The CH4 formation rate was found to increase with both positive and negative potential or current application. The CO formation rate followed the opposite trend. The selectivity to CH4 increased under high values of hydrogen partial pressure and decreased at high pressures of CO2. The results demonstrate how electrochemical promotion can be used to finely tune activity and selectivity for a reaction of high technical and environmental importance. Full article
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12 pages, 3902 KiB  
Article
Effect of Molecular Structure of C10 Hydrocarbons on Production of Light Olefins in Catalytic Cracking
by Lingyin Du, Yueyang Han and Youhao Xu
Catalysts 2023, 13(6), 1013; https://doi.org/10.3390/catal13061013 - 16 Jun 2023
Viewed by 1409
Abstract
The effect of the molecular structure of feedstock on the cracking reaction of C10 hydrocarbons to ethylene and propylene over H-ZSM-5 zeolite was investigated. To better compare the effect of decane on the production of light olefins, the thermal cracking and catalytic cracking [...] Read more.
The effect of the molecular structure of feedstock on the cracking reaction of C10 hydrocarbons to ethylene and propylene over H-ZSM-5 zeolite was investigated. To better compare the effect of decane on the production of light olefins, the thermal cracking and catalytic cracking performance of decane were first investigated. As a comparison, the thermal cracking and catalytic cracking of decane were studied by cracking over quartz sand and H-ZSM-5. Compared with the thermal cracking reaction over quartz sand, the catalytic cracking reaction of decane over H-ZSM-5 has a significantly higher conversion and light olefins selectivity, especially when the reaction temperature was lower than 600 °C. On this basis, the catalytic cracking reactions of decane and decene over H-ZSM-5 were further compared. It was found that decene with a double bond structure had high reactivity over H-ZSM-5 and was almost completely converted, and the product was mainly olefin. Compared with decane as feedstock, it has a lower methane yield and higher selectivity of light olefins. Therefore, decene was more suitable for the production of light olefins than decane. To this end, we designed a new light olefin production process. Through olefin cracking, the yield of light olefins in the product can be effectively improved, and the proportion of different light olefins such as ethylene, propylene and butene can be flexibly adjusted. Full article
(This article belongs to the Special Issue Catalytic Conversion of Low Carbon Alkane)
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16 pages, 28979 KiB  
Article
The Self-Supporting NiMn-LDHs/rGO/NF Composite Electrode Showing Much Enhanced Electrocatalytic Performance for Oxygen Evolution Reaction
by Jia Wang and Yongfu Lian
Catalysts 2023, 13(6), 1012; https://doi.org/10.3390/catal13061012 - 16 Jun 2023
Cited by 1 | Viewed by 1071
Abstract
The poor conductivity and instability of layered dihydroxides (LDHs) limit their widespread application in oxygen evolution reaction (OER). In this study, the composite electrode of NiMn-LDHs, reduced graphene oxide (rGO) and nickel foam (NF), i.e., NiMn-LDHs/rGO/NF, was prepared by a hydrothermal method. When [...] Read more.
The poor conductivity and instability of layered dihydroxides (LDHs) limit their widespread application in oxygen evolution reaction (OER). In this study, the composite electrode of NiMn-LDHs, reduced graphene oxide (rGO) and nickel foam (NF), i.e., NiMn-LDHs/rGO/NF, was prepared by a hydrothermal method. When subjected to oxygen evolution reaction (OER) catalytic performance in a solution of 1 M KOH, the NiMn-LDHs/rGO/NF composite catalyst exhibited an overpotential of only 140 mV at a current density of 10 mA cm−2 and a Tafel slope of 49 mV dec−1, which is not only better than the comparing RuO2/NF catalyst, but also better than most of the Mn-based and the Ni–Fe-containing bimetallic OER catalysts reported in the literature. The excellent electrocatalytic performance is ascribed to the efficient integration of ultrathin NiMn-LDH sheets, thin-layered rGO and NF, contributing significantly to the decrease in charge transfer resistance and the increase in electrochemically active surface area. Moreover, NF plays a role of current collector and a role of rigid support for the NiMn-LDHs/rGO composite, contributing extra conductivity and stability to the NiMn-LDHs/rGO/NF composite electrode. Full article
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13 pages, 5127 KiB  
Article
The Promotional Effect of Rare Earth on Pt for Ethanol Electro-Oxidation and Its Application on DEFC
by Alécio Rodrigues Nunes, José J. Linares, Rudy Crisafulli, Sabrina C. Zignani and Flávio Colmati
Catalysts 2023, 13(6), 1011; https://doi.org/10.3390/catal13061011 - 16 Jun 2023
Viewed by 1322
Abstract
Bimetallic Pt3Eu/C, Pt3La/C, and Pt3Ce/C electrocatalysts have been prepared, characterized, and tested for ethanol electro-oxidation (EEO). The materials were synthesized by chemical reduction with NaBH4, rendering nanosized particles with actual compositions close to the nominals [...] Read more.
Bimetallic Pt3Eu/C, Pt3La/C, and Pt3Ce/C electrocatalysts have been prepared, characterized, and tested for ethanol electro-oxidation (EEO). The materials were synthesized by chemical reduction with NaBH4, rendering nanosized particles with actual compositions close to the nominals and no alloy formation. X-ray photoelectron spectroscopy (XPS) confirmed that the auxiliary rare-earth metals were present on the surface in oxide form. The electrochemical analyses in acid and alkaline EEO evidenced that, compared to Pt/C, the addition of rare earth metals in the form of oxides reduced the onset potential, increased the current density, and enhanced the stability. The results were fully confirmed in the DEFC single-cell measurements. Finally, the presence of rare earth metals in the oxidized form increased the percentage of acetic acid as the final product, making the electrocatalysts more selective and efficient than Pt/C, where acetaldehyde was the main product. Full article
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15 pages, 6136 KiB  
Article
Synthesis of CaCO3/Cu2O/GO Nanocomposite Catalysts for Hydrogen Production from NaBH4 Methanolysis
by Majed Alshammari, Sultan Alhassan, Khulaif Alshammari, Turki Alotaibi, Taha Abdel Mohaymen Taha, Alhulw H. Alshammari and Ali Ismael
Catalysts 2023, 13(6), 1010; https://doi.org/10.3390/catal13061010 - 16 Jun 2023
Cited by 4 | Viewed by 1583
Abstract
The synthesis of CaCO3/Cu2O/GO nanocomposites was developed by sol-gel auto-combustion method. The analysis of structure was completed on X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and environmental scanning electron microscopy (ESEM). The XRD spectra of the [...] Read more.
The synthesis of CaCO3/Cu2O/GO nanocomposites was developed by sol-gel auto-combustion method. The analysis of structure was completed on X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and environmental scanning electron microscopy (ESEM). The XRD spectra of the nanocomposites matched the crystal structure of CaCO3/Cu2O. The average crystal size was 20 nm for Cu2O and 25 nm for CaCO3 nanoparticles. FTIR data showed the absorption bands of Cu2O and GO. Raman spectroscopy data confirmed the formation of GO sheets. ESEM micrographs displayed spherical nanoparticles dispersed in GO sheets. X-ray photoelectron spectroscopy showed the peaks of Cu 2p, O 1s, C 1s, Cu 3s, and Ca 2p. The spectra of optical absorption revealed an absorption band of around 450 nm. The calcium content increase led to a decrease in the optical energy gap from 2.14 to 1.5 eV. The production of hydrogen from NaBH4 across the methanolysis reaction was accelerated by the CaCO3/Cu2O/GO nanocomposites. Therefore, these nanocomposites are superior in catalytic hydrogen production systems. Full article
(This article belongs to the Special Issue Application of Nanosystems in Catalysis)
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16 pages, 2665 KiB  
Article
NiO/AC Active Electrode for the Electrosorption of Rhodamine B: Structural Characterizations and Kinetic Study
by Ahmed Chennah, Moonis Ali Khan, Mohamed Zbair and Hassan Ait Ahsaine
Catalysts 2023, 13(6), 1009; https://doi.org/10.3390/catal13061009 - 15 Jun 2023
Cited by 4 | Viewed by 1164
Abstract
In this work, the aim was to enhance the performance of activated carbon (AC) as an electroadsorbent by incorporating NiO particles, thereby increasing its electrochemical capacity and its ability to adsorb Rhodamine B (RhB) dye. The prepared NiO/AC material was characterized using X-ray [...] Read more.
In this work, the aim was to enhance the performance of activated carbon (AC) as an electroadsorbent by incorporating NiO particles, thereby increasing its electrochemical capacity and its ability to adsorb Rhodamine B (RhB) dye. The prepared NiO/AC material was characterized using X-ray diffraction, scanning electron microscopy, BET surface area analysis, and infrared spectroscopy. The study involved the preparation of AC from almond shell biomass and the subsequent formation of a composite structure with NiO. The objective was to investigate the electrochemical adsorption capacity of the NiO/AC composite for RhB dye removal from simulated wastewaters. The experimental results demonstrated that the removal efficiency of RhB dye increased with an increase in the applied cell voltage. At a voltage of 1.4 V, a remarkable 100% removal efficiency was achieved. The electroadsorption process was well described by fitting the experimental data to the Freundlich isotherm model. The maximum adsorption capacities for RhB dye at concentrations of 7, 8, and 9 ppm were determined to be 149, 150, and 168 mg/g, respectively. Based on the obtained results, an electroadsorption mechanism was proposed to explain the observed behavior of the NiO/AC composite in adsorbing RhB dye. Overall, this study highlights the potential of the NiO/AC composite as an effective electroadsorbent for the removal of Rhodamine B dye from wastewater. The improved electrochemical capacity, coupled with the high adsorption capacity of the composite, makes it a promising material for wastewater treatment applications. Full article
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12 pages, 2972 KiB  
Article
Identification of Cytochrome P450 Enzymes Responsible for Oxidative Metabolism of Synthetic Cannabinoid (1-Hexyl-1H-Indol-3-yl)-1-naphthalenyl-methanone (JWH-019)
by Ngoc Tran, William E. Fantegrossi, Keith R. McCain, Xinwen Wang and Ryoichi Fujiwara
Catalysts 2023, 13(6), 1008; https://doi.org/10.3390/catal13061008 - 15 Jun 2023
Viewed by 1040
Abstract
(1-Hexyl-1H-indol-3-yl)-1-naphthalenyl-methanone (JWH-019) is one of the second-generation synthetic cannabinoids which as a group have been associated with severe adverse reactions in humans. Although metabolic activation can be involved in the mechanism of action, the metabolic pathway of JWH-019 has not been [...] Read more.
(1-Hexyl-1H-indol-3-yl)-1-naphthalenyl-methanone (JWH-019) is one of the second-generation synthetic cannabinoids which as a group have been associated with severe adverse reactions in humans. Although metabolic activation can be involved in the mechanism of action, the metabolic pathway of JWH-019 has not been fully investigated. In the present study, we aimed to identify the enzymes involved in the metabolism of JWH-019. JWH-019 was incubated with human liver microsomes (HLMs) and recombinant cytochrome P450s (P450s or CYPs). An animal study was also conducted to determine the contribution of the metabolic reaction to the onset of action. Using an ultra-performance liquid chromatography system connected to a single-quadrupole mass detector, we identified 6-OH JWH-019 as the main oxidative metabolite in HLMs supplemented with NADPH. JWH-019 was extensively metabolized to 6-OH JWH-019 in HLMs with the KM and Vmax values of 31.5 µM and 432.0 pmol/min/mg. The relative activity factor method estimated that CYP1A2 is the primary contributor to the metabolic reaction in the human liver. The animal study revealed that JWH-019 had a slower onset of action compared to natural and other synthetic cannabinoids. CYP1A2 mediates the metabolic activation of JWH-019, contributing to the slower onset of its pharmacological action. Full article
(This article belongs to the Special Issue Enzymes in Biomedical, Cosmetic and Food Application)
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14 pages, 5297 KiB  
Article
Metal-Free Photoredox Intramolecular Cyclization of N-Aryl Acrylamides
by Zhaosheng Liu, Xiaochen Ji, Feng Zhao, Guojun Deng and Huawen Huang
Catalysts 2023, 13(6), 1007; https://doi.org/10.3390/catal13061007 - 14 Jun 2023
Viewed by 1160
Abstract
A novel metal-free photoredox-catalyzed cyclization reaction of N-aryl acrylamide is herein reported that provides synthetically valuable oxindole derivatives through the bis-mediation of H2O and aldehyde. In this work, sustainable visible light was used as the energy source, and the organic [...] Read more.
A novel metal-free photoredox-catalyzed cyclization reaction of N-aryl acrylamide is herein reported that provides synthetically valuable oxindole derivatives through the bis-mediation of H2O and aldehyde. In this work, sustainable visible light was used as the energy source, and the organic light-emitting molecule 4CzIPN served as the efficient photocatalyst. The main characteristics of this reaction are environmentally friendly and high yields. Full article
(This article belongs to the Special Issue Radical-Mediated Functionalization of Alkenes)
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15 pages, 5254 KiB  
Article
Black Phosphorus/WS2-TM (TM: Ni, Co) Heterojunctions for Photocatalytic Hydrogen Evolution under Visible Light Illumination
by Eminegül Genc Acar, Seda Yılmaz, Zafer Eroglu, İlknur Aksoy Çekceoğlu, Emre Aslan, İmren Hatay Patır and Onder Metin
Catalysts 2023, 13(6), 1006; https://doi.org/10.3390/catal13061006 - 14 Jun 2023
Cited by 5 | Viewed by 1574
Abstract
Black phosphorus (BP) has recently emerged as a versatile photocatalyst owing to its unique photophysical properties and tunable bandgap. Nonetheless, the rapid recombination of the photogenerated charges of pristine BP samples has significantly hindered its practical applications in photocatalysis. Herein, we report, for [...] Read more.
Black phosphorus (BP) has recently emerged as a versatile photocatalyst owing to its unique photophysical properties and tunable bandgap. Nonetheless, the rapid recombination of the photogenerated charges of pristine BP samples has significantly hindered its practical applications in photocatalysis. Herein, we report, for the first time, the effect of transition metal nanoparticles (Ni and Co) as co-catalysts on the photocatalytic activity of BP/tungsten disulfide (WS2) binary heterojunctions (BP/WS2-TM (TM: Ni, Co)) in the hydrogen evolution reaction (HER) under visible light irradiation (λ > 420 nm). Ternary heterojunctions named BP/WS2-TM (TM: Ni, Co) were synthesized via a chemical reduction method, leading to the formation of an S-scheme heterojunction, in which BP acts as a reduction catalyst and WS2 serves as an oxidation catalyst. BP/WS2-Ni and BP/WS2-Co performed substantial amounts of hydrogen generation of 9.53 mmol h−1g−1 and 12.13 mmol h−1g−1, respectively. Moreover, BP/WS2-Co exhibited about 5 and 15 times higher photocatalytic activity compared to the binary BP/WS2 heterojunctions and pristine BP, respectively. The enhanced photocatalytic activity of the heterojunction catalysts is attributed to the extended light absorption ability, enhanced charge separation, and larger active sites. This study is the first example of photocatalytic hydrogen evolution from water by using Ni- and Co-doped binary BP/WS2 heterojunctions. Full article
(This article belongs to the Special Issue Photocatalytic Water Splitting: Challenges and Prospects)
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12 pages, 4114 KiB  
Article
Techno-Economic Analysis of Electrocatalytic CO2 Reduction into Methanol: A Comparative Study between Alkaline Flow Cell and Neutral Membrane Electrode Assembly
by Ke Wang, Tongxin Qu, Qiang Li, Shuting Tan and Xiaoxiang Chen
Catalysts 2023, 13(6), 1005; https://doi.org/10.3390/catal13061005 - 14 Jun 2023
Cited by 1 | Viewed by 1493
Abstract
Electrocatalytic CO2-reduction technology can convert CO2 into methanol and other chemicals using renewable electricity, but the techno-economic prospects of the large-scale electrocatalytic reduction in CO2 into methanol are not clear. This paper conducted sensitivity analysis to confirm the key [...] Read more.
Electrocatalytic CO2-reduction technology can convert CO2 into methanol and other chemicals using renewable electricity, but the techno-economic prospects of the large-scale electrocatalytic reduction in CO2 into methanol are not clear. This paper conducted sensitivity analysis to confirm the key parameters affecting the cost of methanol production from an alkaline flow cell and a neutral MEA electrolyzer, compared the cost of the two electrolyzers under laboratory data and optimized data scenarios, and analyzed the key parameter requirements of the two electrocatalytic systems to achieve profitable methanol production. The results show that electricity price, Faradaic efficiency, cell voltage, and crossover/carbonate formation ratio are the most sensitive parameters affecting the cost of methanol production. The alkaline flow cell had higher energy efficiency than the MEA cell, but the saving cost of electricity and the eletrolyzer cannot cover the cost of the regeneration of the electrolyte and CO2 lost to carbonate/bicarbonate, resulting in higher methanol production costs than the MEA cell. When the crossover/carbonate formation ratio is zero, the cost of methanol production in an alkaline flow cell and a neutral MEA cell can reach under 400 USD/tonne in the cases of energy efficiency more than 70% and 50%, respectively. Therefore, enhancing energy efficiency and ensuring a low crossover/carbonate formation ratio is important for improving the economy of electrocatalytic methanol production from CO2 reduction. Finally, suggestions on the development of electrocatalytic CO2 reduction into methanol in the future were proposed. Full article
(This article belongs to the Special Issue Catalytic CO2 Conversion)
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16 pages, 5940 KiB  
Article
Valorization of Pyrolyzed Biomass Residues for the Transformation of Waste Cooking Oil into Green Diesel
by Ioannis Nikolopoulos, Eleana Kordouli, Nikolaos Mourgkogiannis, Hrissi K. Karapanagioti, Alexis Lycourghiotis and Christos Kordulis
Catalysts 2023, 13(6), 1004; https://doi.org/10.3390/catal13061004 - 14 Jun 2023
Cited by 2 | Viewed by 962
Abstract
This study aims to utilize biochars derived from residual biomass as supports for Ni-based catalysts. For the preparation of the biochars, byproducts of agro-industrial activities were used, such as espresso coffee residue (C) and rice husks (R). Sufficient quantities of the respective biochars [...] Read more.
This study aims to utilize biochars derived from residual biomass as supports for Ni-based catalysts. For the preparation of the biochars, byproducts of agro-industrial activities were used, such as espresso coffee residue (C) and rice husks (R). Sufficient quantities of the respective biochars (BioC and BioR) were prepared via pyrolysis at 850 °C of the aforementioned materials under limited oxygen conditions. The biochars were further treated with hot water (WBioC, WBioR), H3PO4 or H2SO4 solution (BioC-P, BioC-S, BioR-P, BioR-S), and NaOH solution (BioC-A and BioR-A), and the obtained solids were characterized using various physicochemical techniques. The biochars produced were microporous with high surface areas (367–938 m2g−1). The most promising biochars were selected as supports for the preparation of nickel catalysts (10 wt.% Ni) with high Ni dispersion (mean crystal size: 8.2–9.8 nm) and suitable acidity. The catalysts were evaluated in a high-pressure semi-batch reactor for the transformation of waste cooking oil (WCO) into green diesel. The 10Ni_BioC-P catalyst exhibited the best performance, resulting in a complete conversion of the WCO but a low hydrocarbon yield (7.5%). Yield improvement was achieved by promoting this catalyst with molybdenum. The addition of Mo increased the hydrocarbon yield by almost three times (19.5%). Full article
(This article belongs to the Section Biomass Catalysis)
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14 pages, 4294 KiB  
Article
Green Approach for Synthesizing Copper-Containing ZIFs as Efficient Catalysts for Click Chemistry
by Alireza Pourvahabi Anbari, Shima Rahmdel Delcheh, Philippe M. Heynderickx, Somboon Chaemcheun, Serge Zhuiykov and Francis Verpoort
Catalysts 2023, 13(6), 1003; https://doi.org/10.3390/catal13061003 - 14 Jun 2023
Cited by 2 | Viewed by 1383
Abstract
ZIF-8 and ZIF-67 containing various percentages of copper were successfully synthesized through a green in-situ thermal (IST) approach based on 2-methylimidazole (2-MIM) as the organic linker. The IST method has several advantages over previously reported studies, including solvent and additive-free reaction conditions, a [...] Read more.
ZIF-8 and ZIF-67 containing various percentages of copper were successfully synthesized through a green in-situ thermal (IST) approach based on 2-methylimidazole (2-MIM) as the organic linker. The IST method has several advantages over previously reported studies, including solvent and additive-free reaction conditions, a mild reaction temperature, a single-step procedure, no activation requirements, and the use of the smallest precursor ratio (M/L). The high catalytic performance of Cu/ZIF-8 and Cu/ZIF-67 in click chemistry is attributed to their high specific surface area, excellent porosity, and structural stability. To achieve these features, a range of parameters—such as time, temperature, gas atmosphere, and precursor ratio—were optimized. Several characterization methods were used to confirm the features of the produced catalysts. Overall, the synthesis strategy for achieving the targeted ZIFs with unique features is “green” and does not require further activation or treatment to eliminate side products. This method has great potential for manufacturing metal-organic frameworks on a large scale. Moreover, water was used as a solvent during the click reaction, resulting in high yields and making this an attractive, green, and eco-friendly procedure. Full article
(This article belongs to the Special Issue Metal-Organic Framework Materials as Catalysts)
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15 pages, 3151 KiB  
Article
An Efficient and Mild Method for the Alkylation of p-Cresol with tert-Butyl Alcohol
by Qi Wu, Dejin Zhang, Shu Sun, Chengcheng Liu and Cong Wang
Catalysts 2023, 13(6), 1002; https://doi.org/10.3390/catal13061002 - 14 Jun 2023
Viewed by 1091
Abstract
The synthesis 2-tert-butyl-4-methylphenol is of great significance because of its wide application in industry, and the development of a highly efficient catalyst is necessary for the alkylation of p-cresol and tert-butyl alcohol. Here, an efficient and mild method was established. Caprolactam was chosen [...] Read more.
The synthesis 2-tert-butyl-4-methylphenol is of great significance because of its wide application in industry, and the development of a highly efficient catalyst is necessary for the alkylation of p-cresol and tert-butyl alcohol. Here, an efficient and mild method was established. Caprolactam was chosen as the hydrogen-bonding acceptor; p-toluenesulfonic acid was employed as the hydrogen-bonding donor, and a deep eutectic solvent (DES) was prepared to catalyze the alkylation reaction. The structure of the deep eutectic solvent catalyst was characterized by 1H NMR spectra, thermogravimetric analysis, and Fourier transform infrared spectra (FT-IR). In addition, response surface design based on the Box–Behnken method was employed to optimize the alkylation reaction process parameters, and the study of reaction kinetics was also carried out subsequently. The recycle performance of the catalyst was evaluated by recovery experiments, and a good result was obtained. By drawing comparisons with the literature reported, we provide a mild method for the synthesis of 2-tert-butyl-4-methylphenol. Full article
(This article belongs to the Section Catalysis in Organic and Polymer Chemistry)
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23 pages, 3164 KiB  
Article
Anodic Catalyst Support via Titanium Dioxide-Graphene Aerogel (TiO2-GA) for A Direct Methanol Fuel Cell: Response Surface Approach
by Siti Hasanah Osman, Siti Kartom Kamarudin, Sahriah Basri and Nabila A. Karim
Catalysts 2023, 13(6), 1001; https://doi.org/10.3390/catal13061001 - 14 Jun 2023
Viewed by 1128
Abstract
The direct methanol fuel cell (DMFC) has the potential for portable applications. However, it has some drawbacks that make commercialisation difficult owing to its poor kinetic oxidation efficiency and non-economic cost. To enhance the performance of direct methanol fuel cells, various aspects should [...] Read more.
The direct methanol fuel cell (DMFC) has the potential for portable applications. However, it has some drawbacks that make commercialisation difficult owing to its poor kinetic oxidation efficiency and non-economic cost. To enhance the performance of direct methanol fuel cells, various aspects should be explored, and operational parameters must be tuned. This research was carried out using an experimental setup that generated the best results to evaluate the effectiveness of these variables on electrocatalysis performance in a fuel cell system. Titanium dioxide-graphene aerogel (TiO2-GA) has not yet been applied to the electrocatalysis area for fuel cell application. As a consequence, this research is an attempt to boost the effectiveness of direct methanol fuel cell electrocatalysts by incorporating bifunctional PtRu and TiO2-GA. The response surface methodology (RSM) was used to regulate the best combination of operational parameters, which include the temperature of composite TiO2-GA, the ratio of Pt to Ru (Pt:Ru), and the PtRu catalyst composition (wt%) as factors (input) and the current density (output) as a response for the optimisation investigation. The mass activity is determined using cyclic voltammetry (CV). The best-operating conditions were determined by RSM-based performance tests at a composition temperature of 202 °C, a Pt/Ru ratio of (1.1:1), and a catalyst composition of 22%. The best response is expected to be 564.87 mA/mgPtRu. The verification test is performed, and the average current density is found to be 568.15 mA/mgPtRu. It is observed that, after optimisation, the PtRu/TiO2-GA had a 7.1 times higher current density as compared to commercial PtRu. As a result, a titanium dioxide-graphene aerogel has potential as an anode electrocatalyst in direct methanol fuel cells. Full article
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13 pages, 1635 KiB  
Article
The Role of Ion Exchange Resins for Solving Biorefinery Catalytic Processes Challenges
by Yolanda Patiño, Laura Faba, Raquel Peláez, Jennifer Cueto, Pablo Marín, Eva Díaz and Salvador Ordóñez
Catalysts 2023, 13(6), 999; https://doi.org/10.3390/catal13060999 - 13 Jun 2023
Cited by 2 | Viewed by 1296
Abstract
Different possible applications of ion exchange resins in the framework of biorefinery catalytic applications are discussed in this article. Three case studies were selected for this approach, connected to three main routes for biomass upgrading: syngas upgrading to high-value chemicals, biomass hydrolysate upgrading, [...] Read more.
Different possible applications of ion exchange resins in the framework of biorefinery catalytic applications are discussed in this article. Three case studies were selected for this approach, connected to three main routes for biomass upgrading: syngas upgrading to high-value chemicals, biomass hydrolysate upgrading, and direct upgrading of oily fraction. The tailored acidic properties of these materials, as well as their stability in the presence of water, have made them promising catalysts for applications such as obtaining biodiesel from activated sludge wastes in batch reactors and obtaining polyoxymethylene methyl ether from syngas (via formaldehyde and methylal, and working in a continuous fixed bed reactor). However, the acidity of these materials may still be too low for acid-catalyzed aldol condensation reactions in the aqueous phase. Full article
(This article belongs to the Special Issue Advances in the Catalytic Behavior of Ion-Exchange Resins)
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14 pages, 1892 KiB  
Article
Nano-Magnetic CaO/Fe2O3/Feldspar Catalysts for the Production of Biodiesel from Waste Oils
by Maryam Hanif, Ijaz Ahmad Bhatti, Muhammad Asif Hanif, Umer Rashid, Bryan R. Moser, Asma Hanif and Fahad A. Alharthi
Catalysts 2023, 13(6), 998; https://doi.org/10.3390/catal13060998 - 13 Jun 2023
Cited by 2 | Viewed by 1287
Abstract
Production of biodiesel from edible vegetable oils using homogenous catalysts negatively impacts food availability and cost while generating significant amounts of caustic wastewater during purification. Thus, there is an urgent need to utilize low-cost, non-food feedstocks for the production of biodiesel using sustainable [...] Read more.
Production of biodiesel from edible vegetable oils using homogenous catalysts negatively impacts food availability and cost while generating significant amounts of caustic wastewater during purification. Thus, there is an urgent need to utilize low-cost, non-food feedstocks for the production of biodiesel using sustainable heterogeneous catalysis. The objective of this study was to synthesize a novel supported nano-magnetic catalyst (CaO/Fe2O3/feldspar) for the production of biodiesel (fatty acid methyl esters) from waste and low-cost plant seed oils, including Sinapis arvensis (wild mustard), Carthamus oxyacantha (wild safflower) and Pongamia pinnata (karanja). The structure, morphology, surface area, porosity, crystallinity, and magnetization of the nano-magnetic catalyst was confirmed using XRD, FESEM/EDX, BET, and VSM. The maximum biodiesel yield (93.6–99.9%) was achieved at 1.0 or 1.5 wt.% catalyst with methanol-to-oil molar ratios of 5:1 or 10:1 at 40 °C for 2 h. The CaO/Fe2O3/feldspar catalyst retained high activity for four consecutive cycles for conversion of karanja, wild mustard, and wild safflower oils. The effective separation of the catalyst from biodiesel was achieved using an external magnet. Various different physico-chemical parameters, such as pour point, density, cloud point, iodine value, acid value, and cetane number, were also determined for the optimized fuels and found to be within the ranges specified in ASTM D6751 and EN 14214, where applicable. Full article
(This article belongs to the Special Issue Biomass Derived Heterogeneous and Homogeneous Catalysts, 2nd Edition)
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15 pages, 6131 KiB  
Article
The Direct Synthesis of Aromatic Hydrocarbons from Syngas over Bifunctional MgZrOx/HZSM-5 Catalysts
by Dong Ma, Laizhi Sun, Lei Chen, Shuangxia Yang, Xinping Xie, Hongyu Si, Baofeng Zhao and Dongliang Hua
Catalysts 2023, 13(6), 997; https://doi.org/10.3390/catal13060997 - 13 Jun 2023
Cited by 1 | Viewed by 979
Abstract
ZrO2 and catalysts were prepared by a co-precipitate method and coupled with a HZSM-5 zeolite catalyst through a mechanical mixing method; these were applied to the direct synthesis of aromatic hydrocarbons from syngas through an oxygen-containing intermediate route. The physical and chemical [...] Read more.
ZrO2 and catalysts were prepared by a co-precipitate method and coupled with a HZSM-5 zeolite catalyst through a mechanical mixing method; these were applied to the direct synthesis of aromatic hydrocarbons from syngas through an oxygen-containing intermediate route. The physical and chemical properties of the catalysts were characterized by XRD, H2-TPR, CO2-TPD, and SEM methods. The comparative catalytic effects of ZrO2 and MgZrOx catalysts were discussed under different reaction conditions. The reaction results showed that the addition of Mg to a ZrO2 catalyst reduced the selectivity of CO2 by inhibiting the water–gas conversion reaction, and increased the selectivity of aromatics and the proportion of BTX in aromatic products. Full article
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