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Catalysts, Volume 13, Issue 4 (April 2023) – 145 articles

Cover Story (view full-size image): This review article focuses on catalysts for hydrogen production from waste-derived synthesis gas. Among WGS reaction catalysts for hydrogen production from combustible municipal solid waste, Fe, Cu, Ni, Co, and Pt-based catalysts, which are known to have outstanding performance and features, will be examined. Furthermore, the simple reducibility of the Fe-based catalyst, which considerably influences the performance in the WGS process, the degree of dispersion and redox capacity of Cu, the oxygen storage capacity of Ni and Co catalysts supported on CeO2, and a noble metal-based catalyst are all described in detail. The objective of this study is to gain a better understanding of the critical factors that must be considered while designing catalysts in changing conditions. View this paper
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24 pages, 18408 KiB  
Article
Application of Bio-Inspired Gold Nanoparticles as Advanced Nanomaterial in Halt Nociceptive Pathway and Hepatotoxicity via Triggering Antioxidation System
by Rehman Ullah, Sakina Bibi, Muhammad Nauman Khan, Amal M. Al Mohaimeed, Qirat Naz and Asif Kamal
Catalysts 2023, 13(4), 786; https://doi.org/10.3390/catal13040786 - 21 Apr 2023
Cited by 7 | Viewed by 1548
Abstract
This study aimed to investigate the pharmacological efficacy of gold nanoparticles (GNs) synthesized using a green route, employing the rhizome extract of Euphorbia wallichii (REEW) as a bioreductant and surface stabilizing agent. The GNs were characterized by a series of complementary analytical techniques [...] Read more.
This study aimed to investigate the pharmacological efficacy of gold nanoparticles (GNs) synthesized using a green route, employing the rhizome extract of Euphorbia wallichii (REEW) as a bioreductant and surface stabilizing agent. The GNs were characterized by a series of complementary analytical techniques including SEM-EDX, XRD, DLS, and IR spectroscopy. The reducing ability of REEW and synthesis of GNs were confirmed using UV–visible absorption spectroscopy, and the presence of spherical GNs with an fcc geometry was further confirmed through SEM and XRD analyses. The role of REEW’s extract as a stabilizing agent towards GNs was verified through FTIR and electronic absorption spectral measurement. The GC-MS analysis showed the presence of 41 different phytochemicals in REEW (chloromethyl 2-chloroundecanoate; cortisone; benzo[h]quinolone; piperidine, 2,4-dimethyl- 3,6,7-trimethoxyphenanthroindolizidine; 4-methyl-; 2-[2-quinolylmethyleneamino]ethanol, etc.), with RT values ranging from 3.10 to 27.22 min. The REEW-functionalized GNs exhibited promising antioxidant efficacy against H2O2 and *OH used as probe molecules. DPPH scavenging test showed significant EC50 values of 19.47 µg/mL, 13.53 µg/mL, and 10.57 µg/mL at 30, 60, and 90 min of incubation, respectively. Thermal nociceptive mice significantly acquired analgesia in a dose-dependent manner. Moreover, pre-treatment with REEW-GNs significantly restored serum ALT, AST, ALT, T.P, and Bilirubin levels in PCM-intoxicated mice. The antidiabetic activity in alloxan-induced diabetic rabbits fell in orders of metformin > GNs 300 mg/kg b.w > GNs 200 mg/kg b.w > GNs 100 mg/kg b.w > saline at 0.1 h of drug administration. To sum up, REEW functionalized GNs have tremendous potential for curing degenerative/metabolic diseases caused as a result of oxidative stresses. Full article
(This article belongs to the Special Issue Advanced Nanomaterials for a Green World II)
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17 pages, 6933 KiB  
Article
Functionalized Graphene-Incorporated Cupric Oxide Charge-Transport Layer for Enhanced Photoelectrochemical Performance and Hydrogen Evolution
by Ambati Mounika Sai Krishna, Brindha Ramasubramanian, Sheik Haseena, Priyanka Bamola, Himani Sharma, Chandreswar Mahata, Alexander Chroneos, Satheesh Krishnamurthy, Mahesh Kumar Ravva, Basavaiah Chandu, Yee-Fun Lim, Avishek Kumar, Seeram Ramakrishna, Sajal Biring, Sabyasachi Chakrabortty and Goutam Kumar Dalapati
Catalysts 2023, 13(4), 785; https://doi.org/10.3390/catal13040785 - 21 Apr 2023
Cited by 4 | Viewed by 1872
Abstract
The production of hydrogen (H2) through photoelectrochemical water splitting (PEC-WS) using renewable energy sources, particularly solar light, has been considered a promising solution for global energy and environmental challenges. In the field of hydrogen-scarce regions, metal oxide semiconductors have been extensively [...] Read more.
The production of hydrogen (H2) through photoelectrochemical water splitting (PEC-WS) using renewable energy sources, particularly solar light, has been considered a promising solution for global energy and environmental challenges. In the field of hydrogen-scarce regions, metal oxide semiconductors have been extensively researched as photocathodes. For UV-visible light-driven PEC-WS, cupric oxide (CuO) has emerged as a suitable photocathode. However, the stability of the photocathode (CuO) against photo-corrosion is crucial in developing CuO-based PEC cells. This study reports a stable and effective CuO and graphene-incorporated (Gra-COOH) CuO nanocomposite photocathode through a sol-gel solution-based technique via spin coating. Incorporating graphene into the CuO nanocomposite photocathode resulted in higher stability and an increase in photocurrent compared to bare CuO photocathode electrodes. Compared to cuprous oxide (Cu2O), the CuO photocathode was more identical and thermally stable during PEC-WS due to its high oxidation number. Additionally, the CuO:Gra-COOH nanocomposite photocathode exhibited a H2 evolution of approximately 9.3 µmol, indicating its potential as a stable and effective photocathode for PEC-WS. The enhanced electrical properties of the CuO:Gra-COOH nanocomposite exemplify its potential for use as a charge-transport layer. Full article
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26 pages, 4136 KiB  
Review
FCC Catalyst Accessibility—A Review
by José Marcos Moreira Ferreira, Eduardo Falabella Sousa-Aguiar and Donato Alexandre Gomes Aranda
Catalysts 2023, 13(4), 784; https://doi.org/10.3390/catal13040784 - 21 Apr 2023
Cited by 3 | Viewed by 2956
Abstract
Fluid catalytic cracking (FCC) is a critical process in the petroleum-refining industry, designed to break down large hydrocarbon molecules into smaller, more valuable products. Fluid-cracking catalyst accessibility dramatically influences the efficiency of the FCC process. Accessibility is a catalyst feature related to the [...] Read more.
Fluid catalytic cracking (FCC) is a critical process in the petroleum-refining industry, designed to break down large hydrocarbon molecules into smaller, more valuable products. Fluid-cracking catalyst accessibility dramatically influences the efficiency of the FCC process. Accessibility is a catalyst feature related to the ease with which large feedstock molecules can penetrate the catalyst particle to reach the internal active sites where reactions occur—and the ease with which products desorb and leave the catalyst. Accessibility plays a vital role in the activity, selectivity, and life of the catalyst, and various techniques can be applied during the manufacturing process to accomplish its increase. This work reviews FCC catalyst accessibility, its characterization, and the ways to increase it, covering the past three decades of technical paper and patent literature. Bibliometric results of a literature search are presented, and a search strategy is described, encompassing database identification, keyword selection, refinement terms, search criteria, and result evaluation. Full article
(This article belongs to the Special Issue Catalysis for Bitumen/Heavy Oil Upgrading and Petroleum Refining)
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16 pages, 9034 KiB  
Article
Conversion of Dimeric Diaryl Ethers over SiO2- and HZSM5-Supported Pd and Ru Catalysts: A Focus on the Role of the Metal and Acidity
by Raphaela Azevedo Rafael, Fabio Bellot Noronha, Eric Marceau and Robert Wojcieszak
Catalysts 2023, 13(4), 783; https://doi.org/10.3390/catal13040783 - 21 Apr 2023
Cited by 1 | Viewed by 1790
Abstract
The effect of metal and support acidity on the hydroconversion of dimeric aryl ethers, used as model molecules for lignin, is still under debate, both in terms of hydrogenolysis (cleavage of the ether bond) and formation of by-products (coupling of aromatic monomers to [...] Read more.
The effect of metal and support acidity on the hydroconversion of dimeric aryl ethers, used as model molecules for lignin, is still under debate, both in terms of hydrogenolysis (cleavage of the ether bond) and formation of by-products (coupling of aromatic monomers to dimers by alkylation reaction). Their role is investigated here in the conversion of three typical molecules representative of the α-O-4, β-O-4, and 4-O-5 ether linkages of lignin, respectively, benzyl phenyl ether (BPE), phenethoxybenzene (PEB), and diphenyl ether (DPE), at 503 K, under 18 bar of H2 in decalin. Ru- and Pd-based catalysts were synthesized on non-acidic SiO2 and on acidic HZSM5. Under these reaction conditions, the conversion of the ethers over the bare supports was observed in the presence of acidic sites; the effect decreased as the ether bond strength increased. The results also suggest that the product distribution is directly affected both by the support acidity and by the oxophilicity of Ru. Alkylated products from isomerization reactions, which are reported to be formed only over acidic sites, were also produced on the surface of the Ru nanoparticles. Full article
(This article belongs to the Special Issue The Role of Catalysts in Functionalization of C-H and C-C Bonds II)
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21 pages, 7023 KiB  
Article
An Evaluation of Glycerol Acetalization with Benzaldehyde over a Ferromagnetic Heteropolyacid Catalyst
by Rami Doukeh, Maria Râpă, Ecaterina Matei, Doina Prodan, Romuald Győrgy, Ancuta Trifoi and Ionut Banu
Catalysts 2023, 13(4), 782; https://doi.org/10.3390/catal13040782 - 21 Apr 2023
Cited by 2 | Viewed by 1848
Abstract
Tungstophosphoric acid (H3PW12O40) supported on silica-coated magnetite nanoparticles has been prepared and used as a heterogeneous acid catalyst (Fe3O4@SiO2@HPW) in the condensation of benzaldehyde (B) with glycerol (Gly) for the production [...] Read more.
Tungstophosphoric acid (H3PW12O40) supported on silica-coated magnetite nanoparticles has been prepared and used as a heterogeneous acid catalyst (Fe3O4@SiO2@HPW) in the condensation of benzaldehyde (B) with glycerol (Gly) for the production of cyclic acetals. Physicochemical techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectrometry (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and N2 physisorption were used to characterize the prepared catalyst. The effect of glycerol/benzaldehyde molar ratio (1/1 to 1/1.2), temperature (80–120 °C), and catalyst amount (1–5%) on glycerol conversion and the selectivity in main reaction products: benzoic acid, 2-phenyl-1,3-dioxolan-4-yl)methanol, 2-Phenyl-1,3-dioxan-5-ol, 2-phenyl-1,3-dioxolane, and methyl 2-hydroxy-3-phenylpropanoate was studied to evaluate the catalytic activity of the prepared Fe3O4@SiO2@HPW catalyst. The optimization of these process parameters was conducted using Box–Behnken design (BBD). Using the BBD methodology, the optimal parameters (120 °C, 1:1.15 glycerol: benzaldehyde, 5% catalyst) were determined, for a glycerol conversion of and cyclic acetals yield of 85.95% and 78.36%, respectively. The catalyst also exhibits excellent activity for glycerol acetalization with other aromatic aldehydes such as cinnamaldehyde, p-methyl-benzaldehyde, p-hydroxy-benzaldehyde, and vanillin. Full article
(This article belongs to the Topic Catalysis: Homogeneous and Heterogeneous)
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18 pages, 13955 KiB  
Article
Efficient Oxidative Dehydrogenation of Ethylbenzene over K/CeO2 with Exceptional Styrene Yield
by He Sun, Juping Zhang, Kongzhai Li, Hua Wang and Xing Zhu
Catalysts 2023, 13(4), 781; https://doi.org/10.3390/catal13040781 - 21 Apr 2023
Cited by 5 | Viewed by 2049
Abstract
Oxidative dehydrogenation (ODH) is an alternative for styrene (ST) production compared to the direct dehydrogenation process. However, ODH with O2 or CO2 suffers from either over-oxidation or endothermic property/low ethylbenzene conversion. Herein, we proposed an ODH process with a CO2 [...] Read more.
Oxidative dehydrogenation (ODH) is an alternative for styrene (ST) production compared to the direct dehydrogenation process. However, ODH with O2 or CO2 suffers from either over-oxidation or endothermic property/low ethylbenzene conversion. Herein, we proposed an ODH process with a CO2-O2 mixture atmosphere for the efficient conversion of ethylbenzene (EB) into styrene. A thermoneutral ODH is possible by the rationalizing of CO2/O2 molar ratios from 0.65 to 0.66 in the temperature range of 300 to 650 °C. K modification is favorable for ethylbenzene dehydrogenation, and 10%K/CeO2 achieved the highest ethylbenzene dehydrogenation activity due to the enhanced oxygen mobility and CO2 adsorbability. The catalyst achieved 90.8% ethylbenzene conversion and 97.5% styrene selectivity under optimized conditions of CO2-4O2 oxidation atmosphere, a temperature of 500 °C, and a space velocity of 5.0 h−1. It exhibited excellent catalytic and structural stability during a 50 h long-term test. CO2 induces oxygen vacancies in ceria and promotes oxygen exchange between gaseous oxygen and ceria. The ethylbenzene dehydrogenation in CO2-O2 follows a Mars-van Krevelen (MvK) reaction mechanism via Ce3+/Ce4+ redox pairs. The proposed ODH strategy by using oxygen vacancies enriched catalysts offers an important insight into the efficient dehydrogenation of ethylbenzene at mild conditions. Full article
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16 pages, 2236 KiB  
Article
β-Sitosterol Oleate Synthesis by Candida rugosa Lipase in a Solvent-Free Mini Reactor System: Free and Immobilized on Chitosan-Alginate Beads
by Adejanildo da S. Pereira, Jully L. Fraga, Camila P. L. Souza, Alexandre G. Torres and Priscilla F. F. Amaral
Catalysts 2023, 13(4), 780; https://doi.org/10.3390/catal13040780 - 21 Apr 2023
Cited by 1 | Viewed by 1379
Abstract
Candida rugosa lipase (CRL) was immobilized by the ionic gelling technique using alginate and chitosan as encapsulating agents. An immobilization yield of 99% and an immobilization efficiency of 51% were obtained. Maximum hydrolytic activity for free and immobilized CRL was detected at 40 [...] Read more.
Candida rugosa lipase (CRL) was immobilized by the ionic gelling technique using alginate and chitosan as encapsulating agents. An immobilization yield of 99% and an immobilization efficiency of 51% were obtained. Maximum hydrolytic activity for free and immobilized CRL was detected at 40 °C and for synthesis activity at 35 °C. The optimum pH for immobilized and free CRL hydrolysis activity was 8.0. The Vmax obtained for the hydrolysis reaction was higher for free CRL (4121.4 μmol/min/g) compared to immobilized CRL (2359.13 μmol/min/g). A Vmax of 2.24 μmol/min/g was detected for the synthetic activity of free CRL. The Km obtained for the hydrolysis reaction was higher (660.02 μmol/L) for immobilized CRL than for free CRL (403.06 μmol/L). For the synthetic activity, a Km of 234.44 μmol/L was calculated. The conversion of β-sitosterol oleate ranged from 80.85 to 96.84% for free CRL, higher than the maximum found for immobilized CRL (32%). The scale-up (scale factor: 50) with the free CRL was successfully performed, achieving a high conversion value (92%) in a 500 mL bioreactor. This conversion value was within the range predicted by the mathematical model obtained using mini reactors. These mini reactors are good models to test several conditions of enzyme reactions that are intended for large scales. Full article
(This article belongs to the Special Issue Lipase: A Multi-Purpose Biocatalyst at the Forefront of Biotechnology)
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13 pages, 2582 KiB  
Article
Fabrication of Lead-Free Bismuth Based Electroceramic Compositions for High-Energy Storage Density Applications in Electroceramic Capacitors
by Azam Khan, Taj Malook Khan, Jianbo Wu, Hazrat Bilal, Shahan Zeb Khan, Abdul Manan, Xiujian Wang and Noor Shad Gul
Catalysts 2023, 13(4), 779; https://doi.org/10.3390/catal13040779 - 21 Apr 2023
Cited by 2 | Viewed by 1491
Abstract
Lead-based electro-ceramic compositions are excellent energy storage materials used for high-energy storage density applications in dielectric ceramic capacitors. However, these materials have lead contents in their compositions, making them toxic, with a negative impact on human health and the environment. For this reason, [...] Read more.
Lead-based electro-ceramic compositions are excellent energy storage materials used for high-energy storage density applications in dielectric ceramic capacitors. However, these materials have lead contents in their compositions, making them toxic, with a negative impact on human health and the environment. For this reason, we synthesized a lead-free bismuth-based electro-ceramic perovskite, 0.80(0.92Bi1/5Na1/5TiO3-0.08BaTiO3)-0.20(Na0.73Bi0.09NbO3−xTa2O5), abbreviated (BNT-BT-NBN1−xTx), from mixed oxides with doping of tantalum (Ta) at different concentrations, using a conventional solid-state reaction method. The effects of Ta doping on the phase evolution, microstructure development, and energy storage applications were investigated. Detailed powder X-ray diffraction analysis revealed a pure perovskite phase with Ta doping at ≤0.05. Furthermore, it was observed that excessive addition of Ta has been resulted in secondary phase generation. Scanning electron microscopy validated the development of dense microstructures with a reduced grain size for the Ta concentration of ≤0.01. Electrochemical analysis revealed a maximum polarization (Pm) of ~22 µC/cm2 and a recoverable energy density of 1.57 J/cm3 with 80% efficiency for Ta doping at 0.05 with an applied field of 175 kV/cm. These results demonstrate the development of enhanced ferroelectric characteristics in an as-synthesized electro-ceramic perovskite for high-energy storage density applications in electro-ceramic capacitors. Full article
(This article belongs to the Special Issue Metal-Organic Frameworks in Electro and Photocatalysis)
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16 pages, 2323 KiB  
Article
Transition Metal-Free Synthesis of 3-Acylquinolines through Formal [4+2] Annulation of Anthranils and Enaminones
by Kai-Ling Zhang, Jia-Cheng Yang, Qin Guo and Liang-Hua Zou
Catalysts 2023, 13(4), 778; https://doi.org/10.3390/catal13040778 - 20 Apr 2023
Cited by 2 | Viewed by 1490
Abstract
A transition metal-free protocol has been developed for the synthesis of 3-acyl quinolines through aza-Michael addition and intramolecular annulation of enaminones with anthranils. Both methanesulfonic acid (MSA) and NaI play an important role in the reaction. This ring-opening/reconstruction strategy features easy operation, high [...] Read more.
A transition metal-free protocol has been developed for the synthesis of 3-acyl quinolines through aza-Michael addition and intramolecular annulation of enaminones with anthranils. Both methanesulfonic acid (MSA) and NaI play an important role in the reaction. This ring-opening/reconstruction strategy features easy operation, high yields, broad substrate scope and excellent efficiency. Full article
(This article belongs to the Special Issue Catalytic Annulation Reactions)
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20 pages, 8766 KiB  
Article
Optimization of the Geraniol Transformation Process in the Presence of Natural Mineral Diatomite as a Catalyst
by Anna Fajdek-Bieda
Catalysts 2023, 13(4), 777; https://doi.org/10.3390/catal13040777 - 20 Apr 2023
Viewed by 1003
Abstract
Process optimization is increasingly finding applications in chemical engineering. The reason for this increase in applications is to create more efficient and sustainable technological processes. Thanks to innovative models, it is possible to plan an experiment in a given field of study without [...] Read more.
Process optimization is increasingly finding applications in chemical engineering. The reason for this increase in applications is to create more efficient and sustainable technological processes. Thanks to innovative models, it is possible to plan an experiment in a given field of study without much complication and carry out the optimization of such a process, achieving goals in a much shorter time period. This paper describes the performance of optimization of the geraniol transformation process in the presence of a catalyst of natural origin—diatomite. Response surface methodology (RSM) was chosen as the method. For this purpose, the following parameters were used as variables: temperature (80, 110, and 150 °C), catalyst concentration (1 wt%, 5 wt%, and 10 wt%), and reaction time (0.25 h, 12 h, and 24 h). At the same time, the functions describing the process and response functions were the conversion of geraniol (GA) as well as the selectivity of conversion to beta-pinene (BP), respectively. The obtained results made it possible to identify the optimal set of parameters at which the highest values of GA conversion and the selectivity of conversion to BP are obtained. It turned out that the GA transformation process is best carried out at 80 °C at a diatomite concentration of 1.0 wt% and a reaction time of 0.25 h. Full article
(This article belongs to the Section Catalytic Reaction Engineering)
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11 pages, 2780 KiB  
Communication
Discrete Au1(0) Stabilized by 15-Crown-5 for High-Efficiency Catalytic Reduction of Nitrophenol and Nitroaniline
by Xing Shen and Kairui Liu
Catalysts 2023, 13(4), 776; https://doi.org/10.3390/catal13040776 - 20 Apr 2023
Viewed by 990
Abstract
Single-atom catalysts (SACs) have been synthesized using a variety of methods in recent years, and they have shown excellent catalytic activities. However, metal atoms show a high tendency to agglomerate in liquid media, making the single atom synthesis more difficult in liquid media. [...] Read more.
Single-atom catalysts (SACs) have been synthesized using a variety of methods in recent years, and they have shown excellent catalytic activities. However, metal atoms show a high tendency to agglomerate in liquid media, making the single atom synthesis more difficult in liquid media. The synthesis of such metal single-atom catalysts that do not have strong ligand coordination is rarely reported in the literature. Herein, we report the facile synthesis of monodispersed Au atoms (Au1) through the reduction in HAuCl4 in 15-crown-5. The complete reduction in HAuCl4 was confirmed through UV-Vis spectroscopy. In addition, the Au was found in a zero valence state after reduction, which was confirmed through XPS and XANES results. Moreover, the dispersion of Au was confirmed as a single atom (Au1) through transmission electron microscopy and spherical aberration electron microscopy. The possible structure of this catalyst was proposed by matching the EXAFS results with the structure of Au1@15-crown-5 as -(OC2H4O)-AuCl2H2. The Au1@15-crown-5 showed high activity (TOF as high as 22,075) in the reduction in nitrophenol and nitroaniline to aminophenol and phenylenediamine by sodium borohydride. Because of the monodispersion of Au atoms, its performance is much better than noble nanoparticles and non-precious metal catalysts. Full article
(This article belongs to the Special Issue Single-Atom Catalysts (SACs))
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12 pages, 3546 KiB  
Article
Sodium Silicates Modified Calcium Oxide as a High-Performance Solid Base Catalyst for Biodiesel Production
by Shunpan Zhang, Junying Fu, Shiyou Xing, Ming Li, Xiaochun Liu, Lingmei Yang and Pengmei Lv
Catalysts 2023, 13(4), 775; https://doi.org/10.3390/catal13040775 - 20 Apr 2023
Cited by 4 | Viewed by 1733
Abstract
Under the energy crisis and with greenhouse gases causing an ecological imbalance, biofuel has attracted worldwide attention due to its sustainability and low net-carbon emission. For years, the traditional biodiesel industry has been demanding a high-performance solid base catalyst. Its poor reusability is [...] Read more.
Under the energy crisis and with greenhouse gases causing an ecological imbalance, biofuel has attracted worldwide attention due to its sustainability and low net-carbon emission. For years, the traditional biodiesel industry has been demanding a high-performance solid base catalyst. Its poor reusability is the bottleneck for a promising calcium-based solid-base catalyst. In this work, we successfully adopted a new silicate-strength strategy to improve the stability while preserving the activity of the catalyst. The newly synthesized catalyst, NCSO, had two main catalytic phases, Na2CaSiO4 and CaO, and showed a 98.2% FAMEs yield in 60 min at 80 °C with a methanol/oil molar ratio of 9:1 and 5 wt.% catalyst loading. After 12 consecutive reuses, a 57.3% FAMEs yield could still be achieved. The effect of the reaction temperature, methanol ratio, catalyst loading, and reaction time on the FAMEs yield was also investigated. With a combined characterization of XRD, XPS, and SEM, etc., we confirmed that Na2CaSiO4 and CaO showed a synergistic effect in catalyzing the transesterification reaction: the addition of the Na2CaSiO4 phase in NCSO could significantly improve the activity of CaO, while the CaO phase, in turn, helps to stabilize the Na2CaSiO4 phase. This silicate-strength strategy provides a new route to synthesize stable and highly active solid base catalysts. Full article
(This article belongs to the Topic Biomass Transformation: Sustainable Development)
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3 pages, 187 KiB  
Editorial
Editorial Catalysts: Special Issue on “Advances in the Synthesis and Applications of Transition/Noble Metal Oxide Photocatalysts”
by Nina Kaneva
Catalysts 2023, 13(4), 774; https://doi.org/10.3390/catal13040774 - 20 Apr 2023
Viewed by 778
Abstract
Heterogeneous photocatalysis, due to its high efficiency, safety and profitability, has become an effective technology for solving environmental problems, for example, in wastewater treatment, for the removal of organic pollutants [...] Full article
53 pages, 77216 KiB  
Review
Non-Noble Metal Aromatic Oxidation Catalysis: From Metalloenzymes to Synthetic Complexes
by Eduard Masferrer-Rius and Robertus J. M. Klein Gebbink
Catalysts 2023, 13(4), 773; https://doi.org/10.3390/catal13040773 - 19 Apr 2023
Cited by 2 | Viewed by 2383
Abstract
The development of selective aromatic oxidation catalysts based on non-noble metals has emerged over the last decades, mainly due to the importance of phenol products as intermediates for the generation of pharmaceuticals or functional polymers. In nature, metalloenzymes can perform a wide variety [...] Read more.
The development of selective aromatic oxidation catalysts based on non-noble metals has emerged over the last decades, mainly due to the importance of phenol products as intermediates for the generation of pharmaceuticals or functional polymers. In nature, metalloenzymes can perform a wide variety of oxidative processes using molecular oxygen, including arene oxidations. However, the implementation of such enzymes in the chemical industry remains challenging. In this context, chemists have tried to mimic nature and design synthetic non-noble metal catalysts inspired by these enzymes. This review aims at providing a general overview of aromatic oxidation reactions catalyzed by metalloenzymes as well as synthetic first-row transition-metal complexes as homogeneous catalysts. The enzymes and complexes discussed in this review have been classified based on the transition-metal ion present in their active site, i.e., iron, copper, nickel, and manganese. The main points of discussion focus on enzyme structure and function, catalyst design, mechanisms of operation in terms of oxidant activation and substrate oxidation, and substrate scope. Full article
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16 pages, 4838 KiB  
Article
Immobilized KDN Lipase on Macroporous Resin for Isopropyl Myristate Synthesis
by Ming Song, Yuhan Xin, Sulan Cai, Weizhuo Xu and Wei Xu
Catalysts 2023, 13(4), 772; https://doi.org/10.3390/catal13040772 - 19 Apr 2023
Cited by 1 | Viewed by 1147
Abstract
Free enzymes often face economic problems because of their non-repeatability and variability, which limit their application in industrial production. In this study, KDN lipase was immobilized with the macroporous resin LXTE-1000 and glutaraldehyde. The optimal conditions of enzyme immobilization were defined by a [...] Read more.
Free enzymes often face economic problems because of their non-repeatability and variability, which limit their application in industrial production. In this study, KDN lipase was immobilized with the macroporous resin LXTE-1000 and glutaraldehyde. The optimal conditions of enzyme immobilization were defined by a single factor experiment and response surface methodology (RSM). The concentration of the cross-linking agent glutaraldehyde was 0.46% (v/v), the cross-linking temperature was 25.0 °C, and the cross-linking time was 157 min. The enzyme activity of the immobilized KDN lipase after adsorption/cross-linking was 291.36 U/g, and the recovery of the enzyme activity was 9.90%. The optimal conditions for the synthesis of isopropyl myristate were catalyzed by the immobilized KDN lipase in a solvent-free system: immobilized enzyme 53 mg, reaction temperature 36.1 °C, myristic acid 228.4 mg, isopropanol 114 µL, and reaction time 18 h. The yield of isopropyl myristate was 66.62%. After ten cycles, the activity of the immobilized KDN lipase preserved more than 46.87% of its initial enzyme activity, and it demonstrated high tolerance to solvents compared to free KDN lipase. Full article
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16 pages, 2977 KiB  
Review
Methane Production from Biomass by Thermochemical Conversion: A Review
by Yuke Wu, Xinchen Ye, Yutong Wang and Lian Wang
Catalysts 2023, 13(4), 771; https://doi.org/10.3390/catal13040771 - 19 Apr 2023
Cited by 3 | Viewed by 4721
Abstract
Methane, the main component of natural gas, is one of the primary sources of energy extensively employed worldwide. However, the utilization of natural gas is limited by reserves and geographical availability. Thus, a thermochemical method of converting biomass to methane is appealing, especially [...] Read more.
Methane, the main component of natural gas, is one of the primary sources of energy extensively employed worldwide. However, the utilization of natural gas is limited by reserves and geographical availability. Thus, a thermochemical method of converting biomass to methane is appealing, especially gasification. Important factors affecting methane production are discussed in the review including operating parameters, catalysts of methanation and gas conditioning effects. Low temperature and high pressure are beneficial to promote methanation reaction. Ni-based catalysts are widely used as methanation catalysts, but suffer from deactivation problems due to carbon deposition, sintering and poisoning. The methods of gas conditioning include using water gas shift reaction and adding hydrogen from electrolysis. In addition, environmental and economic views are discussed. Other thermochemical process including hydrothermal gasification, fast pyrolysis and direct methanation at low temperature are also introduced briefly. Based on the above discussion, potential research directions for optimizing methane production are proposed. Full article
(This article belongs to the Special Issue Advances in Catalytic Methane Activation)
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21 pages, 3696 KiB  
Article
Isoselective Ring-Opening Polymerization of rac-Lactide Catalyzed by Simple Potassium Amidate Complexes Containing Polycyclic Aryl Group
by Jiahao Gao, Wenjuan Zhang, Xing Wang, Rui Wang, Mingyang Han, Furong Cao and Xiang Hao
Catalysts 2023, 13(4), 770; https://doi.org/10.3390/catal13040770 - 19 Apr 2023
Viewed by 1260
Abstract
The isoselective ring-opening polymerization of rac-LA is a challenging goal. In this work, a series of potassium amidate complexes (K1K10) were easily prepared and characterized using the 1H/13C NMR spectrum. The molecular structures of potassium [...] Read more.
The isoselective ring-opening polymerization of rac-LA is a challenging goal. In this work, a series of potassium amidate complexes (K1K10) were easily prepared and characterized using the 1H/13C NMR spectrum. The molecular structures of potassium complexes K2 and K10 were determined by X-ray diffraction, which showed that both were two-dimensional coordination polymers due to the adjacent π interactions of the aryl. In the presence of benzyl alcohol (BnOH), all of the potassium complexes exhibited a high catalytic activity toward the ring-opening polymerization of L-lactide and rac-LA, yielding linear polylactides capped with BnO or CH3O end groups. A significant solvent effect on the ROP of the L-LA was observed, with a superior efficiency in toluene than in THF and CH2Cl2. These complexes are iso-selective and act as active catalysts for the controlled ring-opening polymerization of rac-lactide, with a Pm from 0.54 to 0.76. This is a rare example of simple alkali metal complexes for the isoselective ROP of rac-lactide. The substituent greatly affected the monomer conversion and isoselectivities. Full article
(This article belongs to the Special Issue Metal-Organic Catalyst for High Performance Materials)
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14 pages, 5147 KiB  
Article
First Two-Way Electrochemical Sensor for the Detection of the Pollutant 2,4-Dinitrophenylhydrazine and Its Metabolite Based on Cu-Containing Tungstophosphate and Graphene Oxide
by Xiaolei Yan, Xiaoxia Yu, Jianye Pei and Lihua Bi
Catalysts 2023, 13(4), 769; https://doi.org/10.3390/catal13040769 - 18 Apr 2023
Viewed by 969
Abstract
2,4-dinitrophenylhydrazine (2,4-DNPH) is a toxic organic pollutant which is highly threatening to human beings and their living environment. Therefore, it is of great significance to develop sensors for detecting 2,4-DNPH and its metabolites. To develop a two-way electrochemical sensor for the detection of [...] Read more.
2,4-dinitrophenylhydrazine (2,4-DNPH) is a toxic organic pollutant which is highly threatening to human beings and their living environment. Therefore, it is of great significance to develop sensors for detecting 2,4-DNPH and its metabolites. To develop a two-way electrochemical sensor for the detection of 2,4-DNPH and its metabolite, Cu-containing tungstophosphate (Na16P4W30Cu4(H2O)2O112·nH2O, Cu4P4W30) was selected to study its electrocatalytic activity for the reduction of 2,4-DNPH and oxidation of its metabolite. First, the electrochemical behavior of Cu4P4W30 was investigated in solution; then, the films containing Cu4P4W30 and graphene oxide (GO) were fabricated on indium tin oxide (ITO) to form the modified ITO/PDDA/(Cu4P4W30/PDDA-GO)n electrode and the effect of the layer number on the electrocatalytic performance of the modified electrode was studied, confirming the optimal film layer number. Furthermore, the sensing performance of the modified electrode was tested, giving a linear concentration range and detection limit. Finally, the stability, repeatability, and reproducibility of the modified electrode were evaluated. The findings demonstrated that the proposed electrode acted as a two-way electrochemical sensor for the detection of 2,4-DNPH and its metabolite. Full article
(This article belongs to the Special Issue Graphene in Photocatalysis/Electrocatalysis)
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30 pages, 13410 KiB  
Review
Heterobinuclear Metallocomplexes as Photocatalysts in Organic Synthesis
by Violetta A. Ionova, Anton S. Abel, Alexei D. Averin and Irina P. Beletskaya
Catalysts 2023, 13(4), 768; https://doi.org/10.3390/catal13040768 - 18 Apr 2023
Cited by 1 | Viewed by 1755
Abstract
Photocatalytic processes under visible light have constantly been finding more and more applications in organic synthesis as they allow a wide range of transformations to proceed under mild conditions. The combination of photoredox catalysis with metal complex catalysis gives an opportunity to employ [...] Read more.
Photocatalytic processes under visible light have constantly been finding more and more applications in organic synthesis as they allow a wide range of transformations to proceed under mild conditions. The combination of photoredox catalysis with metal complex catalysis gives an opportunity to employ the advantages of these two methodologies. Covalent bonding of photocatalyst and metal complex catalyst using bridging ligands increases the efficiency of the electron and energy transfer between these two parts of the catalyst, leading to more efficient and selective catalytic systems. Up to now, after numerous investigations of the photocatalytic reduction of CO2 and hydrogen generation, such a strategy was firmly established to substantially increase the catalyst’s activity. This review is aimed at the achievements and perspectives in the field of design and application of heterobinuclear metal complexes as photocatalysts in organic synthesis. Full article
(This article belongs to the Section Photocatalysis)
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10 pages, 3308 KiB  
Communication
Au Nanoparticles Supported on Mn- or/and La-Doped CeO2 Nanorods for One-Step Oxidative Esterification of Methacrolein and Methanol to Methyl Methacrylate
by Haojian Zhang
Catalysts 2023, 13(4), 767; https://doi.org/10.3390/catal13040767 - 18 Apr 2023
Viewed by 1074
Abstract
Mn- or/and La-doped CeO2 nanorods supporting Au catalysts were prepared using the hydrothermal method and deposition precipitation (DP) method and applied to the direct oxidative esterification of methacrolein (MAL) and methanol into methyl methacrylate (MMA). Various characterization techniques such as N2 [...] Read more.
Mn- or/and La-doped CeO2 nanorods supporting Au catalysts were prepared using the hydrothermal method and deposition precipitation (DP) method and applied to the direct oxidative esterification of methacrolein (MAL) and methanol into methyl methacrylate (MMA). Various characterization techniques such as N2-physical adsorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), H2 temperature programmed reduction (TPR) and CO2 temperature programmed desorption (TPD) were utilized to analyze the structural properties, reducibility and basicity of Au catalysts. The catalyst with Mn doping only showed the best performance, and particularly the highest conversion, while the catalyst with Mn and La doping showed the highest selectivity. Full article
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19 pages, 2815 KiB  
Review
Production of Hydrogen from Lignocellulosic Biomass: A Review of Technologies
by Lourdes Jara-Cobos, Mónica Abril-González and Verónica Pinos-Vélez
Catalysts 2023, 13(4), 766; https://doi.org/10.3390/catal13040766 - 18 Apr 2023
Cited by 8 | Viewed by 3911
Abstract
Hydrogen is considered one of the most important forms of energy for the future, as it can be generated from renewable sources and reduce CO2 emissions. In this review, the different thermochemical techniques that are currently used for the production of hydrogen [...] Read more.
Hydrogen is considered one of the most important forms of energy for the future, as it can be generated from renewable sources and reduce CO2 emissions. In this review, the different thermochemical techniques that are currently used for the production of hydrogen from biomass from plantations or crops, as well as those from industrial or agro-industrial processes, were analyzed, such as gasification, liquefaction, and pyrolysis. In addition, the yields obtained and the reactors, reaction conditions, and catalysts used in each process are presented. Furthermore, a brief comparison between the methods is made to identify the pros and cons of current technologies. Full article
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22 pages, 2956 KiB  
Review
Recent Progress in the Use of SnO2 Quantum Dots: From Synthesis to Photocatalytic Applications
by Babu Bathula, Thirumala Rao Gurugubelli, Jihyung Yoo and Kisoo Yoo
Catalysts 2023, 13(4), 765; https://doi.org/10.3390/catal13040765 - 17 Apr 2023
Cited by 8 | Viewed by 2311
Abstract
This review article provides current developments in SnO2 quantum dots (QDs) as effective catalysts over the last five years. SnO2 QDs are exceptional prospects for catalytic applications because of their high surface area, compact size, and tunable optical features. SnO2 [...] Read more.
This review article provides current developments in SnO2 quantum dots (QDs) as effective catalysts over the last five years. SnO2 QDs are exceptional prospects for catalytic applications because of their high surface area, compact size, and tunable optical features. SnO2 QDs have recently made strides in their production and functionalization, which has enabled successful use of them as photocatalytic catalysts. The basic concepts of SnO2 QDs, including their electrical and optical characteristics, are described in this review paper, along with the most current findings on their production and functionalization. Additionally, it covers the fundamental mechanisms that support SnO2 QDs’ catalytic activity and emphasizes the difficulties involved in using them as catalysts. Lastly, it offers a forecast for the direction of research in this quickly evolving topic. Overall, our analysis demonstrates SnO2 QDs’ potential as a successful and cutting-edge catalytic system in recent years. Full article
(This article belongs to the Special Issue Nanomaterials for Photocatalysis II)
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16 pages, 3236 KiB  
Article
Effect of Decoration of C@TiO2 Core-Shell Composites with Nano-Ag Particles on Photocatalytic Activity in 4-Nitrophenol Degradation
by Karol Sidor, Róża Lehmann, Anna Rokicińska, Tomasz Berniak, Marek Dębosz and Piotr Kuśtrowski
Catalysts 2023, 13(4), 764; https://doi.org/10.3390/catal13040764 - 17 Apr 2023
Viewed by 1648
Abstract
Photoactive TiO2 materials based on a C@TiO2 core-shell structure synthesized according to the bottom-up strategy using a spherical resin core were presented in relation to commercial TiO2 (P25) used as a reference material. The studied TiO2 materials were modified [...] Read more.
Photoactive TiO2 materials based on a C@TiO2 core-shell structure synthesized according to the bottom-up strategy using a spherical resin core were presented in relation to commercial TiO2 (P25) used as a reference material. The studied TiO2 materials were modified with Ag nanoparticles using two alternative methods: impregnation and precipitation. Depending on the deposition technique used, different distributions of the Ag modifier were achieved within the TiO2 structure. As confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements, the precipitation technique resulted in the formation of almost twice smaller, highly dispersed Ag nanoparticles compared to impregnation. Furthermore, the effect of the performed modification on the textural properties (low-temperature N2 adsorption) and surface composition (X-ray photoelectron spectroscopy) was determined. The phase composition of the TiO2 support as well as the dispersion of the Ag modifier significantly affected the energy gap determined from UV–Vis spectra and, consequently, their performance in the process photodegradation of 4-nitrophenol tested as a model molecule. In the case of the @TiO2 material modified with highly dispersed Ag, significantly higher photoactivity in the visible light range was observed than in the presence of analogous P25-based materials. Full article
(This article belongs to the Special Issue Photocatalysts for Treatment of Pollutants in Wastewater)
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14 pages, 1202 KiB  
Article
Biochemical and Spectroscopic Characterization of a Recombinant Laccase from Thermoalkaliphilic Bacillus sp. FNT with Potential for Degradation of Polycyclic Aromatic Hydrocarbons (PAHs)
by Constanza Bueno-Nieto, Rodrigo Cortés-Antiquera, Giannina Espina, Joaquín Atalah, Javiera Villanueva, Carolina Aliaga, Gustavo E. Zuñiga and Jenny M. Blamey
Catalysts 2023, 13(4), 763; https://doi.org/10.3390/catal13040763 - 17 Apr 2023
Cited by 4 | Viewed by 1389
Abstract
Laccases are industrially relevant enzymes that are known for the wide variety of substrates they can use. In recent years, fungal laccases have been progressively replaced by bacterial laccases in applied contexts due to their capacity to work on harsh conditions including high [...] Read more.
Laccases are industrially relevant enzymes that are known for the wide variety of substrates they can use. In recent years, fungal laccases have been progressively replaced by bacterial laccases in applied contexts due to their capacity to work on harsh conditions including high temperatures, pHs, and chloride concentrations. The focus of researchers has turned specifically towards enzymes from extremophilic organisms because of their robustness and stability. The recombinant versions of enzymes from extremophiles have shown to overcome the problems associated with growing their native host organisms under laboratory conditions. In this work, we further characterize a recombinant spore-coat laccase from Bacillus sp. FNT, a thermoalkaliphilic bacterium isolated from a hot spring in a geothermal site. This recombinant laccase was previously shown to be very active and thermostable, working optimally at temperatures around 70–80 °C. Here, we showed that this enzyme is also resistant to common inhibitors, and we tested its ability to oxidize different polycyclic aromatic hydrocarbons, as these persistent organic pollutants accumulate in the environment, severely damaging ecosystems and human health. So far, the enzyme was found to efficiently oxidize anthracene, making it a compelling biotechnological tool for biocatalysis and a potential candidate for bioremediation of aromatic contaminants that are very recalcitrant to degradation. Full article
(This article belongs to the Section Biocatalysis)
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19 pages, 8794 KiB  
Article
ZnO-ZnFe2O4 Catalyst for Hydrogen Production from Methanol Steam Reforming
by Bing-Zhen Hsu, Chung-Lun Yu, Subramanian Sakthinathan, Te-Wei Chiu, Bing-Sheng Yu, Chia-Cheng Lin, Liangdong Fan and Yi-Hsuan Lee
Catalysts 2023, 13(4), 762; https://doi.org/10.3390/catal13040762 - 17 Apr 2023
Cited by 2 | Viewed by 1918
Abstract
In this study, ZnFe2O4 and ZnO-ZnFe2O4 catalysts were prepared using the glycine–nitrate process (GNP). The prepared ZnFe2O4 and ZnO-ZnFe2O4 catalyst powders were characterized using a scanning electron microscope, transmission electron microscope, [...] Read more.
In this study, ZnFe2O4 and ZnO-ZnFe2O4 catalysts were prepared using the glycine–nitrate process (GNP). The prepared ZnFe2O4 and ZnO-ZnFe2O4 catalyst powders were characterized using a scanning electron microscope, transmission electron microscope, XRD diffraction studies, and selected area diffraction pattern studies. In addition, the specific surface area was measured using a Brunauer–Emmett–Teller specific surface area analysis. The hydrogen reduction in different temperature ranges was analyzed using the H2 temperature-programmed reduction technique. The specific surface area of the ZnFe2O4 was 5.66 m2/g, and the specific surface area of the ZnO-ZnFe2O4 was 8.20 m2/g at a G/N ratio of 1.5 and at a G/N ratio of 1.7, respectively. The specific surface area of the ZnFe2O4 was 6.03 m2/g, and the specific surface area of the ZnO-ZnFe2O4 was 11.67 m2/g. The ZnFe2O4 and ZnO-ZnFe2O4 were found to have the best catalytic effect at 500 °C. In particular, the highest H2 generation rate of the ZnO-ZnFe2O4 (GN = 1.7) at 500 °C was 7745 mL STP min−1 g-cat−1. Moreover, the ZnO-ZnFe2 O4 catalyst demonstrated good H2 selectivity and stability during the process of steam reforming methanol. Therefore, the ZnO-ZnFe2O4 catalyst powder exhibited high catalytic activity due to the good dispersibility of the ZnO, which increased the specific surface area of the catalyst. In the future, the catalyst can be applied to the steam reforming of methanol for industrial purposes. Full article
(This article belongs to the Special Issue Catalytic Steam Reforming Reactions)
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24 pages, 8329 KiB  
Review
Advances in the Application of Acetonitrile in Organic Synthesis since 2018
by Pinyong Zhong, Linjun Zhang, Nianhua Luo and Jinbiao Liu
Catalysts 2023, 13(4), 761; https://doi.org/10.3390/catal13040761 - 16 Apr 2023
Cited by 5 | Viewed by 5089
Abstract
Acetonitrile is commonly used as an organic solvent and can also be used as an important intermediate in organic synthesis. Its widespread use has led to the development of new methods for the synthesis of a variety of important compounds. In the past [...] Read more.
Acetonitrile is commonly used as an organic solvent and can also be used as an important intermediate in organic synthesis. Its widespread use has led to the development of new methods for the synthesis of a variety of important compounds. In the past decades, the conversion reactions of acetonitrile as a building block have become one of the most-attractive fields in organic synthesis. Especially in the field of electrochemical conversions involving acetonitrile, due to its good conductivity and environmentally friendly features, it has become a powerful and compelling tool to afford nitrogen-containing compounds or nitrile-containing compounds. In this review, we mainly discuss the research progress involving acetonitrile in the past five years, covering both conventional synthesis methods and electrochemical synthesis. Besides, a detailed discussion of the substrate scope and mechanistic pathways is provided. Full article
(This article belongs to the Special Issue Catalyzed Carbon-Heteroatom Bond Formation)
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20 pages, 12373 KiB  
Article
Divergent Reactivity of D-A Cyclopropanes under PTC Conditions, Ring-Opening vs. Decyanation Reaction
by Giorgiana Denisa Bisag, Pietro Viola, Luca Bernardi and Mariafrancesca Fochi
Catalysts 2023, 13(4), 760; https://doi.org/10.3390/catal13040760 - 16 Apr 2023
Viewed by 1410
Abstract
The divergent reactivity of D-A cyclopropane, under PTC conditions, is herein reported. Thus, a ring-opening or a decyanation reaction can be achieved by reacting 2-arylcyclopropane-1,1-dicarbonitriles 1 with thioacetic acid in different reaction conditions. The use of solid Cs2CO3 leads unexpectedly [...] Read more.
The divergent reactivity of D-A cyclopropane, under PTC conditions, is herein reported. Thus, a ring-opening or a decyanation reaction can be achieved by reacting 2-arylcyclopropane-1,1-dicarbonitriles 1 with thioacetic acid in different reaction conditions. The use of solid Cs2CO3 leads unexpectedly to the synthesis of new D-A cyclopropane derivatives via a decyanation reaction, followed by diastereoselective acetylation, whereas the use of an aqueous solution of Cs2CO3 results in a typical ring-opening reaction with the formation of S-thiolate products. Therefore, the use of tailored reaction conditions allows one to obtain either cyclic or open-chain products in moderate to good yields. Full article
(This article belongs to the Special Issue Feature Papers in Catalysis in Organic and Polymer Chemistry)
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10 pages, 3217 KiB  
Communication
Characterization and Structural Insights of a Novel Arylsulfatase from Pseudoalteromonas atlantica T6c
by Panpan Dong, Wendi Yang, Lifang Sun, Dingding Jing, Hong Zhang, Jinbo Yang, Linjiao Wu, Leiqing Chen and Yunkun Wu
Catalysts 2023, 13(4), 759; https://doi.org/10.3390/catal13040759 - 15 Apr 2023
Viewed by 1551
Abstract
Arylsulfatases exhibit great potential in industry for desulfation applications, but less is known about the metallo-β-lactamase (MBL) fold arylsulfatases. To learn more about them, an MBL fold arylsulfatase from Pseudoalteromonas atlantica T6c (PaAst) was identified and characterized, and its structure was elaborated in [...] Read more.
Arylsulfatases exhibit great potential in industry for desulfation applications, but less is known about the metallo-β-lactamase (MBL) fold arylsulfatases. To learn more about them, an MBL fold arylsulfatase from Pseudoalteromonas atlantica T6c (PaAst) was identified and characterized, and its structure was elaborated in this study. PaAst was sequence analyzed, heterologously expressed in E. coli, purified by Ni2+-NTA resin affinity chromatography and size-exclusion chromatography, functionally studied by p-nitrophenyl sulfate (pNPS), and crystallized for structure determination. The MBL fold arylsulfatase was identified by sequence analysis and confirmed by enzymatic assay on pNPS with Km 1.00 mM and Vmax 60.80 U/mg at 50 °C and pH 7.5. Furthermore, its crystals were obtained in 0.2 M sodium thiocyamate, 20% PEG3350, and its structure was determined at 2.0 Å that formed a dimer with MBL fold. Our work highlighted the MBL fold arylsulfatases from structural insights and could be the theoretical foundation for investigations into their catalytic mechanism. Full article
(This article belongs to the Section Biocatalysis)
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32 pages, 15346 KiB  
Review
Recent Combinations of Electrospinning with Photocatalytic Technology for Treating Polluted Water
by He Lv, Yanan Liu, Yubin Bai, Hongpu Shi, Wen Zhou, Yaoning Chen, Yang Liu and Deng-Guang Yu
Catalysts 2023, 13(4), 758; https://doi.org/10.3390/catal13040758 - 15 Apr 2023
Cited by 32 | Viewed by 2224
Abstract
Dyes, antibiotics, heavy metal ions, and bacteria are important sources of water pollution. How to solve these issues has become a problem in the fields of science and technology. People have developed a variety of technologies to treat pollutants in water. Photocatalytic technology [...] Read more.
Dyes, antibiotics, heavy metal ions, and bacteria are important sources of water pollution. How to solve these issues has become a problem in the fields of science and technology. People have developed a variety of technologies to treat pollutants in water. Photocatalytic technology came into being. As a simple and environmentally friendly treatment technology, it has been widely studied by the scientific community. Traditional powder photocatalysts cause secondary pollution to the environment and are not conducive to recycling. Therefore, large specific surface area and reusable membrane photocatalysts built by electrospinning technology have become a favorite of today’s scientific community. Nanofiber membranes prepared by electrospinning technology have a variety of structures, which can meet the needs of different occasions. This review summarizes and discusses research progress in electrospinning technology, the relationship between the structure and treatment of electrospun fiber membranes, and their impacts on the photocatalytic performance of nanofiber membranes. The performance, challenges, and future development directions of nanofiber membranes with different structures, prepared by different kinds of electrospinning techniques using photocatalysis to treat different pollutants, are reviewed. Full article
(This article belongs to the Special Issue Trends in Environmental Applications of Advanced Oxidation Processes)
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22 pages, 4394 KiB  
Article
C-H versus C-O Addition: A DFT Study of the Catalytic Cleavage of the β-O-4 Ether Linkage in Lignin by Iridium and Cobalt Pincer Complexes
by Mary Mensah, Richard Tia, Evans Adei and Nora H. de Leeuw
Catalysts 2023, 13(4), 757; https://doi.org/10.3390/catal13040757 - 15 Apr 2023
Viewed by 1470
Abstract
The potential energy surfaces of the reactions involved in the catalytic cleavage of 2-phenoxy-1-phenylethanol, a model of the β-O-4 linkage in lignin, by (iprPCP)-Ir, (iprPCOP)-Ir, (iprPCP)-Co and (iprPCOP)-Co complexes have been studied [...] Read more.
The potential energy surfaces of the reactions involved in the catalytic cleavage of 2-phenoxy-1-phenylethanol, a model of the β-O-4 linkage in lignin, by (iprPCP)-Ir, (iprPCOP)-Ir, (iprPCP)-Co and (iprPCOP)-Co complexes have been studied using the M06/6-311G**/LANL2TZ level of theory. Both iridium and cobalt are found to be active towards the cleavage of the β-O-4 linkage, with rate constants of 44.7 s−1 and 5.1 × 106 s−1, respectively. The iridium catalysts prefer the ‘initial C-H addition’ pathway, showing a kinetic preference of 16.8 kcal mol−1 over the ‘direct C-O insertion’ pathway, while the cobalt catalysts prefer the ‘direct C-O insertion’ route which is kinetically favored by 15.7 kcal mol−1 over the ‘initial C-H addition’ pathway. A two-state reactivity occurs along the preferred pathway for the cobalt-catalyzed reaction. Full article
(This article belongs to the Special Issue Metallic Nanoparticles and Metal-Mediated Synthesis in Catalysis)
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