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Catalysts, Volume 12, Issue 9 (September 2022) – 145 articles

Cover Story (view full-size image): The reaction of [Ti(OR)4] (R = Me, nPr, iPr, tBu) with the acids 2,2’-Ph2C(X)(CO2H), where X = OH, NH2 (i.e., benzilic acid and 2,2’-diphenylglycine, respectively), led to the isolation of mono-, bi-, tri-, or tetra-metallic products. In the case of the ring-opening polymerization (ROP) of ε-caprolactone, all systems except for R = nPr, X = NH2 (this system exhibited the best performance: ≥ 99% within 6 min at 100 °C) exhibited a lengthy induction period (≤ 285 min) and were quite sluggish; products were of a moderate to high molecular weight. For the ROP of rac-lactide, there was no induction period, and higher molecular weight products were obtained; the system R = iPr, X = OH exhibited the fastest kinetics. Comparative ROP studies using the parent [Ti(OR)4] starting materials revealed high conversions but poorer control versus the acid-derived complexes. View this paper
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14 pages, 4872 KiB  
Article
Magnetically Recoverable Biomass-Derived Carbon-Aerogel Supported ZnO (ZnO/MNC) Composites for the Photodegradation of Methylene Blue
by Renathung C. Ngullie, K. Bhuvaneswari, Paramasivam Shanmugam, Supakorn Boonyuen, Siwaporn Meejoo Smith and Munusamy Sathishkumar
Catalysts 2022, 12(9), 1073; https://doi.org/10.3390/catal12091073 - 19 Sep 2022
Cited by 10 | Viewed by 1844
Abstract
Hydrothermally assisted magnetic ZnO/Carbon nanocomposites were prepared using the selective biowaste of pomelo orange. Initially, the carbon aerogel (CA) was prepared hydrothermally followed by a freeze-drying method. Furthermore, the iron oxide nanoparticles were deposited onto the surface of carbon using the co-precipitation method [...] Read more.
Hydrothermally assisted magnetic ZnO/Carbon nanocomposites were prepared using the selective biowaste of pomelo orange. Initially, the carbon aerogel (CA) was prepared hydrothermally followed by a freeze-drying method. Furthermore, the iron oxide nanoparticles were deposited onto the surface of carbon using the co-precipitation method and we obtained magnetic carbon nanocomposite, i.e., Fe3O4/C (MNC). Moreover, the ZnO photocatalysts were incorporated onto the surface of MNC composites using a hydrothermal process, and we obtained ZnO/MNC composites. The ZnO/MNC (55%), ZnO/MNC (65%) and ZnO/MNC (75%) composites were prepared by a similar experimental method in order to change the weight ratio of ZnO NPs. Using a similar synthetic procedure, the standard ZnO and Fe3O4 nanoparticles were prepared without the addition of CA. The experimental results were derived from several analytical techniques, such as: X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman and diffuse reflectance spectroscopy (DRS-UV). The synthesized carbon, ZnO, Fe3O4, ZnO/MNC (55%), ZnO/MNC (65%) and ZnO/MNC (75%) composites were examined through the photocatalytic degradation of methylene blue (MB) under visible-light irradiation (VLI). The obtained results revealed that the composites were more active than carbon, ZnO and Fe3O4. In particular, the ZnO/MNC (75%) composites showed more activity than the rest of the composites. Furthermore, the recycling abilities of the prepared ZnO/MNC (75%) composites were examined through the degradation of MB under identical conditions and the activity remained constant up to the fifth cycle. The synthetic procedure and practical applications proposed here can be used in chemical industries, biomedical fields and energy applications. Full article
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12 pages, 7538 KiB  
Article
Semi-Hydrogenation of Acetylene to Ethylene Catalyzed by Bimetallic CuNi/ZSM-12 Catalysts
by Song Hu, Chong Zhang, Mingyu Wu, Runping Ye, Depan Shi, Mujin Li, Peng Zhao, Rongbin Zhang and Gang Feng
Catalysts 2022, 12(9), 1072; https://doi.org/10.3390/catal12091072 - 19 Sep 2022
Cited by 4 | Viewed by 1961
Abstract
The purpose of this work is to develop a low-cost and high-performance catalyst for the selective catalytic hydrogenation of acetylene to ethylene. Non-precious metals Cu and Ni were selected as active ingredients for this study. Using ZSM-12 as a carrier, Cu-Ni bimetallic catalysts [...] Read more.
The purpose of this work is to develop a low-cost and high-performance catalyst for the selective catalytic hydrogenation of acetylene to ethylene. Non-precious metals Cu and Ni were selected as active ingredients for this study. Using ZSM-12 as a carrier, Cu-Ni bimetallic catalysts of CuNix/ZSM-12 (x = 5, 7, 9, 11) with different Ni/Cu ratios were prepared by incipient wetness impregnation method. The total Cu and Ni loading were 2 wt%. Under the optimal reaction conditions, the acetylene conversion was 100%, and the ethylene selectivity was 82.48%. The CuNi7/ZSM-12 prepared in this work exhibits good performance in the semi-hydrogenation of acetylene to ethylene with low cost and has potential for industrial application. Full article
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10 pages, 2354 KiB  
Article
Enhancing Acetophenone Tolerance of Anti-Prelog Short-Chain Dehydrogenase/Reductase EbSDR8 Using a Whole-Cell Catalyst by Directed Evolution
by Hui Zhang, Bei Wang, Shengli Yang, Hongwei Yu and Lidan Ye
Catalysts 2022, 12(9), 1071; https://doi.org/10.3390/catal12091071 - 19 Sep 2022
Cited by 2 | Viewed by 1474
Abstract
The short-chain dehydrogenase/reductase (SDR) from Empedobacter brevis ZJUY-1401 (EbSDR8, GenBank: ALZ42979.1) is a promising biocatalyst for the reduction of acetophenone to (R)-1-phenylethanol, but its industrial application is restricted by its insufficient tolerance to acetophenone. In this paper, we developed a chromogenic [...] Read more.
The short-chain dehydrogenase/reductase (SDR) from Empedobacter brevis ZJUY-1401 (EbSDR8, GenBank: ALZ42979.1) is a promising biocatalyst for the reduction of acetophenone to (R)-1-phenylethanol, but its industrial application is restricted by its insufficient tolerance to acetophenone. In this paper, we developed a chromogenic reaction-based high-throughput screening method and employed directed evolution to enhance the acetophenone tolerance of EbSDR8. The resulting variant, M190V, showed 74.8% improvement over the wild-type in specific activity when catalyzing the reduction of 200 mM acetophenone. Kinetic analysis revealed a 70% enhancement in its catalytic efficiency (kcat/Km). Molecular docking was conducted to reveal the possible mechanism behind the improved acetophenone tolerance, and the result implied that the M190V mutation is conducive to the binding and release of coenzyme. Aside from the improved catalytic performance when dealing with a high concentration of acetophenone, other features of M190V, such as a broad pH range (6.0 to 10.5), low optimal cosubstrate concentration (1% isopropanol), and a temperature optimum close to that of E. coli cells (35 °C), also contribute to its practical application as a whole-cell catalyst. In this study, we first designed a directed evolution means to engineer the enzyme and obtained the positive variant which has a high activity under high concentrations of acetophenone. After that, we optimized the catalytic performance of the variant to adapt to industrial applications. Full article
(This article belongs to the Special Issue Microbial Biocatalysis)
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15 pages, 2979 KiB  
Article
C–O Hydrogenolysis of C3–C4 Polyols Selectively to Terminal Diols over Pt/W/SBA-15 Catalysts
by Susmita Bhowmik, Nagasuresh Enjamuri, Banu Marimuthu and Srinivas Darbha
Catalysts 2022, 12(9), 1070; https://doi.org/10.3390/catal12091070 - 19 Sep 2022
Cited by 4 | Viewed by 2249
Abstract
Pt/W/SBA-15 catalysts (with Pt-loading = 0.5–4 wt% and W-loading = 1 wt%) prepared by the sequential impregnation method were evaluated for selective C–O cleavage of erythritol and glycerol in an aqueous medium. The Pt and W particles dispersed on SBA-15 approached close proximity [...] Read more.
Pt/W/SBA-15 catalysts (with Pt-loading = 0.5–4 wt% and W-loading = 1 wt%) prepared by the sequential impregnation method were evaluated for selective C–O cleavage of erythritol and glycerol in an aqueous medium. The Pt and W particles dispersed on SBA-15 approached close proximity at higher Pt loadings and afforded synergistic enhancement in C–O hydrogenolysis activity/selectivity. 1,4-Butanediol yields of 30.9% (at 190 °C, 50 bar H2 and 24 h) and 1,3-propanediol yields of 34.4% (at 190 °C, 50 bar H2 and 12 h of reaction) were obtained over these catalysts. Pt nanoparticles (facilitating dissociative H2 adsorption and spillover) and W (present as acidic oligomeric WOx species; activating and coordinating the polyol via 1°-OH group) worked in tandem for the selective hydrogenolysis of polyols yielding terminal diols of industrial demand. Full article
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17 pages, 2741 KiB  
Article
Design of γ-Alumina-Supported Phosphotungstic Acid-Palladium Bifunctional Catalyst for Catalytic Liquid-Phase Citral Hydrogenation
by Abdul Karim Shah, Syed Nizam-uddin Shah Bukhari, Ayaz Ali Shah, Abdul Sattar Jatoi, Muhammad Azam Usto, Zubair Hashmi, Ghulam Taswar Shah, Yeung Ho Park, Moo-Seok Choi, Arshad Iqbal, Tahir Hussain Seehar and Aamir Raza
Catalysts 2022, 12(9), 1069; https://doi.org/10.3390/catal12091069 - 19 Sep 2022
Cited by 1 | Viewed by 1743
Abstract
This study primarily addresses the development of dynamic, selective and economical metal–acid (bifunctional) catalysts for one-pot menthol production by citral hydrogenation. Specifically, various metals such as Pd, Pt, Ni, Cs and Sn were doped over alumina support. Additionally, bifunctional composite catalysts were also [...] Read more.
This study primarily addresses the development of dynamic, selective and economical metal–acid (bifunctional) catalysts for one-pot menthol production by citral hydrogenation. Specifically, various metals such as Pd, Pt, Ni, Cs and Sn were doped over alumina support. Additionally, bifunctional composite catalysts were also prepared with the impregnation of heteropoly acids and Pd precursors over alumina support. Analytical techniques (e.g., BET, PXRD, FT-IR, pyridine adsorption and amine titration methods) were applied for characterization of the most efficient and selective catalysts (e.g., Al2O3 and PTA-Cat-I). Similarly, most of the essential operational variables (e.g., loading rate of metal precursor, type of heteropoly acid, temperature, gas pressure and reaction time) were examined during this study. The experimental data shows that the bifunctional catalyst (PTA-Cat-I) produced 45% menthol at full citral substrate conversion (r = 0.038 mmoles.min−1) in liquid-phase citral hydrogenation (at optimized operating conditions: 70 °C, 0.5 MPa and 8 h). However, the heteropoly acid-supported bifunctional catalysts (e.g., PTA-Cat-I, PMA-Cat-I, SMA-Cat-I and STA-Cat-I) resulted in cracking and the dehydration of isopulegol/menthol by the generation of side products (e.g., 4-isopropyl-1-methyl, cyclohex-1-ane/ene); therefore, menthol yield was extensively diminished. On the other hand, non-acidic catalysts (e.g., Cat-I, Cat-II, Cat-III, Cat-IV and Cat-V) readily promoted hydrogenation reactions. The optimum menthol yield occurred due to the presence of strong Lewis and weak Bronsted acid sites. Mass transfer and reaction rate were substantially diminished due to acidity strength, heteropoly acid type and blockage of pores by the applied bifunctional catalysts. Full article
(This article belongs to the Special Issue Catalysis for Flavours and Fragrances)
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12 pages, 1444 KiB  
Article
The Utilization of Two-Phase Catalytic System in Enantioselective Biotransformation of Racemic Atenolol
by Joanna Chałupka, Adam Sikora and Michał Piotr Marszałł
Catalysts 2022, 12(9), 1068; https://doi.org/10.3390/catal12091068 - 19 Sep 2022
Cited by 2 | Viewed by 1210
Abstract
There are several methods that allow enantiomerically pure compounds to be obtained. In the study presented herein, the enantioselective biotransformations of (R,S)-atenolol were performed with the use of various catalytic systems containing ionic liquids and toluene as a reaction [...] Read more.
There are several methods that allow enantiomerically pure compounds to be obtained. In the study presented herein, the enantioselective biotransformations of (R,S)-atenolol were performed with the use of various catalytic systems containing ionic liquids and toluene as a reaction medium, vinyl acetate as an acetylating agent as well as lipases from Candida rugosa. The conducted studies profs that, the use of the two-phase reaction system enables the reuse of the biocatalyst in another cycle and allows to achieve satisfactory kinetic resolution parameters. Full article
(This article belongs to the Special Issue Supported Biocatalysts for Sustainable Chemistry)
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30 pages, 34347 KiB  
Review
Value-Added Products from Catalytic Pyrolysis of Lignocellulosic Biomass and Waste Plastics over Biochar-Based Catalyst: A State-of-the-Art Review
by Peng Li, Kun Wan, Huan Chen, Fangjuan Zheng, Zhuo Zhang, Bo Niu, Yayun Zhang and Donghui Long
Catalysts 2022, 12(9), 1067; https://doi.org/10.3390/catal12091067 - 19 Sep 2022
Cited by 13 | Viewed by 3774
Abstract
As the only renewable carbon resource on Earth, lignocellulosic biomass is abundant in reserves and has the advantages of environmental friendliness, low price, and easy availability. The pyrolysis of lignocellulosic biomass can generate solid biochar with a large specific surface area, well-developed pores, [...] Read more.
As the only renewable carbon resource on Earth, lignocellulosic biomass is abundant in reserves and has the advantages of environmental friendliness, low price, and easy availability. The pyrolysis of lignocellulosic biomass can generate solid biochar with a large specific surface area, well-developed pores, and plentiful surface functional groups. Therefore, it can be considered as a catalyst for upgrading the other two products, syngas and liquid bio-oil, from lignocellulosic biomass pyrolysis, which has the potential to be an alternative to some non-renewable and expensive conventional catalysts. In addition, as another carbon resource, waste plastics can also use biochar-based catalysts for catalytic pyrolysis to solve the problem of accumulation and produce fuels simultaneously. This review systematically introduces the formation mechanism of biochar from lignocellulosic biomass pyrolysis. Subsequently, the activation and modification methods of biochar catalysts, including physical activation, chemical activation, metal modification, and nonmetallic modification, are summarized. Finally, the application of biochar-based catalysts for lignocellulosic biomass and waste plastics pyrolysis is discussed in detail and the catalytic mechanism of biochar-based catalysts is also investigated. Full article
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14 pages, 2603 KiB  
Article
Effect of Modified Alumina Support on the Performance of Ni-Based Catalysts for CO2 Reforming of Methane
by Salwa Bader Alreshaidan, Ahmed A. Ibrahim, Anis H. Fakeeha, Abdulaziz M. Almutlaq, Fekri Abdulraqeb Ahmed Ali and Ahmed S. Al-Fatesh
Catalysts 2022, 12(9), 1066; https://doi.org/10.3390/catal12091066 - 18 Sep 2022
Cited by 9 | Viewed by 1889
Abstract
The CO2 reforming of methane to syngas was examined over five different supported catalysts. In this study, 5% Ni was used as the active metal part of the catalyst. To better comprehend the impact of the supports on the catalytic properties, 5% [...] Read more.
The CO2 reforming of methane to syngas was examined over five different supported catalysts. In this study, 5% Ni was used as the active metal part of the catalyst. To better comprehend the impact of the supports on the catalytic properties, 5% Ni-based catalysts were characterized using nitrogen adsorption–desorption isotherms, XRD, H2-TPR, CO2-TPD, TGA, TPO, FTIR, and Raman. The results showed that the catalyst support with the highest surface area provided the best catalytic activity. The acquired CH4 and CO2 conversions at 700 °C were 58.2% and 67.6%, respectively, with a hydrogen/carbon ratio of 0.85. The TGA investigation of the high-surface-area sample produced a minimum carbon deposition of 11.2 wt.%, and in the CO2-TPD investigation, the high-surface-area sample exhibited the absence of a peak in the strong-basic-sites zone. The formation of NiAl2O4 spinel, moderate basicity, and the high surface area explained the outperformance of the high-surface-area catalyst sample. Full article
(This article belongs to the Special Issue Catalytic Reforming of Light Hydrocarbons)
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16 pages, 3122 KiB  
Article
A Convenient U-Shape Microreactor for Continuous Flow Biocatalysis with Enzyme-Coated Magnetic Nanoparticles-Lipase-Catalyzed Enantiomer Selective Acylation of 4-(Morpholin-4-yl)butan-2-ol
by Ali O. Imarah, Fausto M. W. G. Silva, László Tuba, Ágnes Malta-Lakó, József Szemes, Evelin Sánta-Bell and László Poppe
Catalysts 2022, 12(9), 1065; https://doi.org/10.3390/catal12091065 - 17 Sep 2022
Cited by 9 | Viewed by 2175
Abstract
This study implements a convenient microreactor for biocatalysis with enzymes immobilized on magnetic nanoparticles (MNPs). The enzyme immobilized onto MNPs by adsorption or by covalent bonds was lipase B from Candida antarctica (CaLB). The MNPs for adsorption were obtained by covering the magnetite [...] Read more.
This study implements a convenient microreactor for biocatalysis with enzymes immobilized on magnetic nanoparticles (MNPs). The enzyme immobilized onto MNPs by adsorption or by covalent bonds was lipase B from Candida antarctica (CaLB). The MNPs for adsorption were obtained by covering the magnetite core with a silica shell and later with hexadecyltrimethoxysilane, while for covalent immobilization, the silica-covered MNPs were functionalized by a layer forming from mixtures of hexadecyl- and 3-(2-aminoethylamino)propyldimethoxymethylsilanes in 16:1 molar ratio, which was further activated with neopentyl glycol diglycidyl ether (NGDE). The resulting CaLB-MNPs were tested in a convenient continuous flow system, created by 3D printing to hold six adjustable permanent magnets beneath a polytetrafluoroethylene tube (PTFE) to anchor the MNP biocatalyst inside the tube reactor. The anchored CaLB-MNPs formed reaction chambers in the tube for passing the fluid through and above the MNP biocatalysts, thus increasing the mixing during the fluid flow and resulting in enhanced activity of CaLB on MNPs. The enantiomer selective acylation of 4-(morpholin-4-yl)butan-2-ol (±)-1, being the chiral alcohol constituent of the mucolytic drug Fedrilate, was carried out by CaLB-MNPs in the U-shape reactor. The CaLB-MNPs in the U-shape reactor were compared in batch reactions to the lyophilized CaLB and to the CaLB-MNPs using the same reaction composition, and the same amounts of CaLB showed similar or higher activity in flow mode and superior activity as compared to the lyophilized powder form. The U-shape permanent magnet design represents a general and easy-to-access implementation of MNP-based flow microreactors, being useful for many biotransformations and reducing costly and time-consuming downstream processes. Full article
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13 pages, 2764 KiB  
Article
Exploring the Effect of Hierarchical Porosity in BEA Zeolite in Friedel-Crafts Acylation of Furan and Benzofuran
by Nelson Nunes, Ana P. Carvalho, Ruben Elvas-Leitão, Filomena Martins, Auguste Fernandes, João Rocha and Angela Martins
Catalysts 2022, 12(9), 1064; https://doi.org/10.3390/catal12091064 - 17 Sep 2022
Cited by 4 | Viewed by 1366
Abstract
Hierarchical BEA zeolite was prepared through desilication or desilication followed by acid treatment. The catalytic performance of BEA zeolite samples was evaluated using Friedel-Crafts acylations with two substrates of different molecular sizes, furan (5.7 Å) and benzofuran (6.9 Å), in the presence of [...] Read more.
Hierarchical BEA zeolite was prepared through desilication or desilication followed by acid treatment. The catalytic performance of BEA zeolite samples was evaluated using Friedel-Crafts acylations with two substrates of different molecular sizes, furan (5.7 Å) and benzofuran (6.9 Å), in the presence of acetic anhydride as acylating agent. The application of the simplified Langmuir-Hinshelwood kinetic model showed that the size of the substrate leads to different catalytic activities, with improved rate constant and turnover frequency (TOF) solely in the presence of benzofuran for both desilicated and further acid treated samples. The mesopores developed during the zeolite treatments have an important role as transportation channels by reducing diffusion limitations. The application of Quantitative Structure–Property Relationships (QSPR) allowed the finding of the most relevant properties of the zeolite and substrate with impact on the catalytic parameters. Full article
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17 pages, 5371 KiB  
Article
Effective Removal of Refractory Pollutants through Cinnamic Acid-Modified Wheat Husk Biochar: Experimental and DFT-Based Analysis
by Umme Habiba, Sadaf Mutahir, Muhammad Asim Khan, Muhammad Humayun, Moamen S. Refat and Khurram Shahzad Munawar
Catalysts 2022, 12(9), 1063; https://doi.org/10.3390/catal12091063 - 17 Sep 2022
Cited by 11 | Viewed by 1964
Abstract
The removal of refractory pollutants, i.e., methylene blue (MB) and ciprofloxacin (CIP), relies heavily on sorption technologies to address global demands for ongoing access to clean water. Because of the poor adsorbent–pollutant contact, traditional sorption procedures are inefficient. To accomplish this, a wheat [...] Read more.
The removal of refractory pollutants, i.e., methylene blue (MB) and ciprofloxacin (CIP), relies heavily on sorption technologies to address global demands for ongoing access to clean water. Because of the poor adsorbent–pollutant contact, traditional sorption procedures are inefficient. To accomplish this, a wheat husk biochar (WHB), loaded with cinnamic acid, was created using a simple intercalation approach to collect dangerous organic pollutants from an aqueous solution. Batch experiments, detecting technologies, and density functional theory (DFT) calculations were used to investigate the interactions at the wheat husk biochar modified with cinnamic acid (WHB/CA) and water interface to learn more about the removal mechanisms. With MB (96.52%) and CIP (94.03%), the functionalized WHB exhibited outstanding adsorption capabilities, with model fitting results revealing that the adsorption process was chemisorption and monolayer contact. Furthermore, DFT studies were performed to evaluate the interfacial interaction between MB and CIP with the WHB/CA surface. The orbital interaction diagram provided a visual representation of the interaction mechanism. These findings open up a new avenue for researchers to better understand adsorption behavior for the utilization of WHB on an industrial scale. Full article
(This article belongs to the Special Issue Advanced Oxidation Catalysts)
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18 pages, 10256 KiB  
Article
Catalytic Hydrogenation of Nitrocyclohexane with CuCo/SiO2 Catalysts in Gas and Liquid Flow Reactors
by Emil Kowalewski, Krzysztof Matus, Arkadiusz Gajek and Anna Śrębowata
Catalysts 2022, 12(9), 1062; https://doi.org/10.3390/catal12091062 - 17 Sep 2022
Cited by 3 | Viewed by 1530
Abstract
Catalytic hydrogenation of nitrocyclohexane proved to be an attractive alternative source of various chemical compounds: cyclohexanone oxime, cyclohexanone, cyclohexanol, cyclohexylamine and dicyclohexylamine. A growing interest in this reaction has been observed in the last few years. Herein, we present the catalytic performance of [...] Read more.
Catalytic hydrogenation of nitrocyclohexane proved to be an attractive alternative source of various chemical compounds: cyclohexanone oxime, cyclohexanone, cyclohexanol, cyclohexylamine and dicyclohexylamine. A growing interest in this reaction has been observed in the last few years. Herein, we present the catalytic performance of Cu/SiO2, Co/SiO2 and CuCo/SiO2 in gas and liquid flow nitrocyclohexane hydrogenation. The analysis of synthesized catalysts morphology (BET, TPR, XRD, TEM) in terms of their catalytic behavior allows us to draw general conclusions and determine the optimal conditions for the production of desired products. Application of the monometallic copper leads to the formation of cyclohexanone as the main product, but with low activity. On the other hand, Co/SiO2 shows high activity but gives cyclohexylamine. Bimetallic system CuCo(3:1)/SiO2 allows for the efficient production of 100% cyclohexanone at 5 bar and 75 °C. Full article
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12 pages, 3150 KiB  
Article
Tailorable Formation of Hierarchical Structure Silica (HMS) and Its Application in Hydrogen Production
by Luming Li, Jie Deng, Zhanglong Guo, Wei Chu and Yan Liu
Catalysts 2022, 12(9), 1061; https://doi.org/10.3390/catal12091061 - 17 Sep 2022
Viewed by 1306
Abstract
Relentless endeavors have been committed to seeking simple structure-directing agents for synthesizing hierarchical mesoporous silica (HMS) materials but remaining challenges. In this contribution, we offered an improved one-pot hydrothermal route to prepare HMS materials using a single non-ionic triblock copolymer (F127) structure-directing agent [...] Read more.
Relentless endeavors have been committed to seeking simple structure-directing agents for synthesizing hierarchical mesoporous silica (HMS) materials but remaining challenges. In this contribution, we offered an improved one-pot hydrothermal route to prepare HMS materials using a single non-ionic triblock copolymer (F127) structure-directing agent under a mild polycarboxylic (citric acid) mediated condition. Via studies of key synthetic parameters including acid concentration, crystallization temperature and aging time, it was found that citric acid medium presents an important bridging effect under the optimal concentration from 0.018 M (pH = 2.57) to 1.82 M (pH = 1.09), contributing to the self-assemblage of partially protonated non-ionic triblock copolymer and tetraethyl orthosilicate (TEOS) into a high-quality multistage structure of silica materials. The specific surface area (SSA) of HMS shows a volcanic trend and is closely associated with the concentration of citric acid while the highest SSA of 739.9 m2/g can be achieved at the citric concentration of 0.28 M. Moreover, the as-synthesized HMS-CTA supported Ni/CeO2 catalysts indicate an excellent production of hydrogen through dry reforming of methane (DRM) reaction over 172 h stability. The improved, facile synthesis strategy under polycarboxylic medium displays an expanded perspective for synthesizing other mesoporous materials in a wide range of applications such as catalytic material carriers and drug inhibitors. Full article
(This article belongs to the Special Issue Advanced Catalysts for Achieving Hydrogen Economy from Liquids)
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11 pages, 1269 KiB  
Article
Ozone as a Catalyst of Surplus Activated Sludge Hydrolysis for the Biogas Production Enhancement
by Katarzyna Paździor, Marlena Domińska and Magdalena Olak-Kucharczyk
Catalysts 2022, 12(9), 1060; https://doi.org/10.3390/catal12091060 - 17 Sep 2022
Viewed by 1449
Abstract
The biogas produced in the methane fermentation is valuable due to its use as a renewable energy source. A promising method of biogas production intensification is sludge flocs disintegration via ozonation. The aim of this study was to check the impact of the [...] Read more.
The biogas produced in the methane fermentation is valuable due to its use as a renewable energy source. A promising method of biogas production intensification is sludge flocs disintegration via ozonation. The aim of this study was to check the impact of the ozonation on the efficiency and kinetics of biogas production from surplus activated sludge (SAS). Processes were carried out batchwise at 37 °C. The following analyses were performed: pH, alkalinity, dry matter, dry organic matter, chemical oxygen demand, total organic carbon, total nitrogen, elemental analysis (CHNS), the biochemical potential of methane by NIR spectroscopy, and the amount and composition of biogas. The results showed that the ozonation process had no effect on the elemental composition and chemical structure of SAS. The chemical formula of SAS (C2.97H4.68O1.20N0.3) and a simplified equation describing the methane fermentation process were determined. Ozonation caused the hydrolysis of some organic compounds from sludge flocs and increased the efficiency of biogas production. The methane content in biogas was higher by about 2.5%, while the amount of produced biogas rose by up to 21% for the ozonized sludge. The kinetic constants of first-order reaction were between 0.219 and 0.323 d−1, with an upward trend due to ozonation. Full article
(This article belongs to the Special Issue Catalysis for Environmental and Renewable Energy Applications)
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15 pages, 4381 KiB  
Article
Thermogravimetry Applied for Investigation of Coke Formation in Ethanol Conversion over Heteropoly Tungstate Catalysts
by Orsina Verdeş, Alexandru Popa, Silvana Borcănescu, Mariana Suba and Viorel Sasca
Catalysts 2022, 12(9), 1059; https://doi.org/10.3390/catal12091059 - 16 Sep 2022
Cited by 3 | Viewed by 1841
Abstract
Thermogravimetric analysis (TGA) was used to evaluate the thermal stability and the amount of coke deposition resulting from the deactivation of catalysts during ethanol dehydration reaction in a fixed bed continuous flow reactor. In this study, a series of catalysts containing 30% of [...] Read more.
Thermogravimetric analysis (TGA) was used to evaluate the thermal stability and the amount of coke deposition resulting from the deactivation of catalysts during ethanol dehydration reaction in a fixed bed continuous flow reactor. In this study, a series of catalysts containing 30% of Pd doped and pure 12-tungstophosphoric acid and its insoluble Cs2.5H0.5PW12O40 salt supported on SBA-15 were prepared. The catalytic efficiency of ethanol dehydration reaction was also evaluated. Two types of coke are identified from the TPO (Temperature programmed oxidation) profiles and assigned to the coke precursor and hard coke, respectively. The results indicate that cesium salts reduced the formation of hard coke. The amount of total coke formed was significantly reduced by supporting the catalysts on mesoporous SBA-15 molecular sieves. Full article
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23 pages, 1983 KiB  
Review
A Review of Persulfate Activation by Magnetic Catalysts to Degrade Organic Contaminants: Mechanisms and Applications
by Ke Tian, Fengyin Shi, Menghan Cao, Qingzhu Zheng and Guangshan Zhang
Catalysts 2022, 12(9), 1058; https://doi.org/10.3390/catal12091058 - 16 Sep 2022
Cited by 7 | Viewed by 1961
Abstract
All kinds of refractory organic pollutants in environmental water pose a serious threat to human health and ecosystems. In recent decades, sulfate radical-based advanced oxidation processes (SR-AOPs) have attracted extensive attention in the removal of these organic pollutants due to their high redox [...] Read more.
All kinds of refractory organic pollutants in environmental water pose a serious threat to human health and ecosystems. In recent decades, sulfate radical-based advanced oxidation processes (SR-AOPs) have attracted extensive attention in the removal of these organic pollutants due to their high redox potential and unique selectivity. This review first introduces persulfate activation by magnetic catalysts to degrade organic contaminants. We present the advances and classifications in the generation of sulfate radicals using magnetic catalysts. Subsequently, the degradation mechanisms in magnetic catalysts activated persulfate system are summarized and discussed. After an integrated presentation of magnetic catalysts in SR-AOPs, we discuss the application of persulfate activation by magnetic catalysts in the treatment of wastewater, landfill leachate, biological waste sludge, and soil containing organic pollutants. Finally, the current challenges and perspectives of magnetic catalysts that activated persulfate systems are summarized and put forward. Full article
(This article belongs to the Special Issue Advanced Catalysts for Persulfate Activation)
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23 pages, 541 KiB  
Review
Development of Adsorptive Materials for Selective Removal of Toxic Metals in Wastewater: A Review
by Moeng Geluk Motitswe, Kassim Olasunkanmi Badmus and Lindiwe Khotseng
Catalysts 2022, 12(9), 1057; https://doi.org/10.3390/catal12091057 - 16 Sep 2022
Cited by 13 | Viewed by 2480
Abstract
Removal of toxic metals is essential to achieving sustainability in wastewater purification. The achievement of efficient treatment at a low cost can be seriously challenging. Adsorption methods have been successfully demonstrated for possession of capability in the achievement of the desirable sustainable wastewater [...] Read more.
Removal of toxic metals is essential to achieving sustainability in wastewater purification. The achievement of efficient treatment at a low cost can be seriously challenging. Adsorption methods have been successfully demonstrated for possession of capability in the achievement of the desirable sustainable wastewater treatment. This review provides insights into important conventional and unconventional materials for toxic metal removal from wastewater through the adsorption process. The importance of the role due to the application of nanomaterials such as metal oxides nanoparticle, carbon nanomaterials, and associated nanocomposite were presented. Besides, the principles of adsorption, classes of the adsorbent materials, as well as the mechanisms involved in the adsorption phenomena were discussed. Full article
(This article belongs to the Special Issue Heterogeneous Catalysts for Organic Wastewater Treatment)
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14 pages, 3196 KiB  
Article
Versatile Bifunctional and Supported IrNi Oxide Catalyst for Photoelectrochemical Water Splitting
by Sifani Zavahir, Umme Hafsa, Hyunwoong Park and Dong Suk Han
Catalysts 2022, 12(9), 1056; https://doi.org/10.3390/catal12091056 - 16 Sep 2022
Viewed by 1536
Abstract
Designing a high-performance electrocatalyst that operates with photon-level energy is of the utmost importance in order to address the world’s urgent energy concerns. Herein, we report IrNi nanoparticles uniformly distributed on cost-effective activated carbon support with a low mass loading of 3% by [...] Read more.
Designing a high-performance electrocatalyst that operates with photon-level energy is of the utmost importance in order to address the world’s urgent energy concerns. Herein, we report IrNi nanoparticles uniformly distributed on cost-effective activated carbon support with a low mass loading of 3% by weight to drive the overall water splitting reaction under light illumination over a wide pH range. The prepared IrNi nanomaterials were extensively characterized by SEM/EDX, TEM, XRD, Raman, and UV-visible absorption spectroscopy. The experimental results demonstrate that when the Ir:Ni ratio is 4:1, the water splitting rate is high at 32 and 25 mA cm−2 for hydrogen (at −1.16 V) and oxygen evolution reactions (at 1.8 V) in alkaline electrolyte, respectively, upon the light irradiation (100 mW cm−2). The physical and electrochemical characterization of metal and alloy combinations show that the cumulative effect of relatively high crystallinity (among the materials used in this study), reduced charge recombination rate, and improved oxygen vacancies observed with the 4Ir1Ni@AC electrode is the reason for the superior activity obtained. A high level of durability for hydrogen and oxygen evolution under light illumination is seen in the chronoamperometric study over 15 h of operation. Overall water splitting examined in 0.1 M of NaOH medium at a 50 mV s−1 scan rate showed a cell voltage of 1.94 V at a 10 mA cm−2 current density. Full article
(This article belongs to the Topic Electromaterials for Environment & Energy)
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10 pages, 4593 KiB  
Article
Se-Doped Ni5P4 Nanocatalysts for High-Efficiency Hydrogen Evolution Reaction
by Cuihua An, Yuchen Wang, Penggang Jiao, Shuai Wu, Lingxiao Gao, Chunyou Zhu, Junsheng Li and Ning Hu
Catalysts 2022, 12(9), 1055; https://doi.org/10.3390/catal12091055 - 16 Sep 2022
Cited by 3 | Viewed by 1613
Abstract
Increasing energy consumption and environmental pollution problems have forced people to turn their attention to the development and utilization of hydrogen energy, which requires that hydrogen energy can be efficiently prepared. However, the sluggish kinetics of hydrogen evolution reaction (HER) requires higher overpotential. [...] Read more.
Increasing energy consumption and environmental pollution problems have forced people to turn their attention to the development and utilization of hydrogen energy, which requires that hydrogen energy can be efficiently prepared. However, the sluggish kinetics of hydrogen evolution reaction (HER) requires higher overpotential. It is urgent to design and fabricate catalysts to drive the procedure and decrease the overpotential of HER. It is well known that platinum catalysts are the best for HER, but their high cost limits their wide application. Transition metals such as Fe, Co, Mo and Ni are abundant, and transition metal phosphides are considered as promising HER catalysts. Nevertheless, catalysts in powder form are very easily soluble in the electrolyte, which leads to inferior cycling stability. In this work, Ni5P4 anchored on Ni foam was doped with Se powder. After SEM characterization, the Ni5P4-Se was anchored on Ni foam, which circumvents the use of the conductive additives and binder. The Ni5P4-Se formed a porous nanosheet structure with enhanced electron transfer capability. The prepared Ni5P4-Se exhibited high electrochemical performances. At 10 mA cm−2, the overpotential was only 128 mV and the Tafel slope is 163.14 mV dec−1. Additionally, the overpotential was stabilized at 128 mV for 30 h, suggesting its excellent cycling stability. The results show that Se doping can make the two phases achieve a good synergistic effect, which makes the Ni5P4-Se catalyst display excellent HER catalytic activity and stability. Full article
(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)
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19 pages, 7460 KiB  
Article
CO2 Methanation of Biogas over Ni-Mg-Al: The Effects of Ni Content, Reduction Temperature, and Biogas Composition
by Danbee Han, Wonjun Cho and Youngsoon Baek
Catalysts 2022, 12(9), 1054; https://doi.org/10.3390/catal12091054 - 16 Sep 2022
Cited by 2 | Viewed by 1358
Abstract
Biogas is mainly composed of CH4 and CO2, so it is used as an alternative energy to CH4 with high energy density by separating and removing CO2 from biogas. In addition, it can be utilized by producing synthesis [...] Read more.
Biogas is mainly composed of CH4 and CO2, so it is used as an alternative energy to CH4 with high energy density by separating and removing CO2 from biogas. In addition, it can be utilized by producing synthesis gas (CO and H2) through thermal decomposition of biogas or by synthesizing CH4 by methanation of CO2. The technique of CO2 methanation is a method that can improve the CH4 concentration without CO2 separation. This study aims to produce more efficient methane through CO2 methanation of biogas over Ni-Mg-Al catalyst. So, the effect of Ni contents in catalyst, catalyst reduction temperature, CO2 concentration in biogas, and the initial concentration of CH4 on CO2 conversion rate and CH4 selectivity was investigated. In addition, the effect of increasing CO2 concentration, H2/CO2 ratio, and GHSV (gas space velocity per hour) on H2 conversion, CH4 productivity, and product was investigated. In particular, the durability and stability of CO2 methanation was tested over 60 wt% Ni-Mg-Al catalyst at 350 °C and 30,000/h for 130 h. From the long-term test results, the catalyst shows stability by maintaining a constant CO2 conversion rate of 72% and a CH4 selectivity of 95%. Full article
(This article belongs to the Special Issue CO2 Catalytic Conversion and Utilization)
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19 pages, 2516 KiB  
Article
Design of a Multi-Tubular Catalytic Reactor Assisted by CFD Based on Free-Convection Heat-Management for Decentralised Synthetic Methane Production
by Andreina Alarcón, Raquel Busqué, Teresa Andreu and Jordi Guilera
Catalysts 2022, 12(9), 1053; https://doi.org/10.3390/catal12091053 - 16 Sep 2022
Cited by 2 | Viewed by 2815
Abstract
A simple reactor design for the conversion of CO2 methanation into synthetic methane based on free convection is an interesting option for small-scale, decentralised locations. In this work, we present a heat-management design of a multi-tubular reactor assisted by CFD (Ansys Fluent [...] Read more.
A simple reactor design for the conversion of CO2 methanation into synthetic methane based on free convection is an interesting option for small-scale, decentralised locations. In this work, we present a heat-management design of a multi-tubular reactor assisted by CFD (Ansys Fluent®) as an interesting tool for scaling-up laboratory reactor designs. The simulation results pointed out that the scale-up of an individual reactive channel (d = 1/4′, H = 300 mm) through a hexagonal-shaped distribution of 23 reactive channels separated by 40 mm allows to obtain a suitable decreasing temperature profile (T = 487–230 °C) for the reaction using natural convection cooling. The resulting heat-management configuration was composed of three zones: (i) preheating of the reactants up to 230 °C, followed by (ii) a free-convection zone (1 m/s air flow) in the first reactor section (0–25 mm) to limit overheating and, thus, catalyst deactivation, followed by (iii) an isolation zone in the main reactor section (25–300 mm) to guarantee a proper reactor temperature and favourable kinetics. The evaluation of the geometry, reactive channel separation, and a simple heat-management strategy by CFD indicated that the implementation of an intensive reactor cooling system could be omitted with natural air circulation. Full article
(This article belongs to the Special Issue Catalysts: Reactor Modeling Using Computational Fluid Dynamics)
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20 pages, 3192 KiB  
Article
Utilization of Response Surface Methodology in Optimization and Modelling of a Microbial Electrolysis Cell for Wastewater Treatment Using Box–Behnken Design Method
by Nhlanganiso Ivan Madondo, Sudesh Rathilal and Babatunde Femi Bakare
Catalysts 2022, 12(9), 1052; https://doi.org/10.3390/catal12091052 - 16 Sep 2022
Cited by 8 | Viewed by 1938
Abstract
A vast quantity of untreated wastewater is discharged into the environment, resulting in contamination of receiving waters. A microbial electrolysis cell (MEC) is a promising bioelectrochemical system (BES) for wastewater treatment and energy production. However, poor design and control of MEC variables may [...] Read more.
A vast quantity of untreated wastewater is discharged into the environment, resulting in contamination of receiving waters. A microbial electrolysis cell (MEC) is a promising bioelectrochemical system (BES) for wastewater treatment and energy production. However, poor design and control of MEC variables may lead to inhibition in the system. This study explored the utilization of Response Surface Methodology (RSM) on the synergistic aspects of MEC and magnetite nanoparticles for wastewater treatment. Influences of temperature (25–35 °C), voltage supply (0.3–1.3 V) and magnetite nanoparticle dosage (0.1–1.0 g) on the biochemical methane potentials (BMPs) were investigated with the aim of optimizing biogas yield, chemical oxygen demand removal and current density. The analysis of variance (ANOVA) technique verified that the quadratic models obtained were substantial, with p-values below 0.05 and high regression coefficients (R2). The optimum biogas yield of 563.02 mL/g VSfed, chemical oxygen demand (COD) removal of 97.52%, and current density of 26.05 mA/m2 were obtained at 32.2 °C, 0.77 V and 0.53 g. The RSM revealed a good comparison between the predicted and actual responses. This study revealed the effective utilization of statistical modeling and optimization to improve the performance of the MEC to achieve a sustainable and eco-friendly situation. Full article
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20 pages, 3518 KiB  
Review
Recent Advances in Vehicle Exhaust Treatment with Photocatalytic Technology
by Jianyong Zhao, Jianpeng Sun, Xiangchao Meng and Zizhen Li
Catalysts 2022, 12(9), 1051; https://doi.org/10.3390/catal12091051 - 15 Sep 2022
Cited by 6 | Viewed by 2780
Abstract
Vehicle exhaust has been acknowledged as an essential factor affecting human health due to the extensive use of cars. Its main components include volatile organic compounds (VOCs) and nitrogen oxides (NOx), which can cause acute irritation and chronic diseases, and significant [...] Read more.
Vehicle exhaust has been acknowledged as an essential factor affecting human health due to the extensive use of cars. Its main components include volatile organic compounds (VOCs) and nitrogen oxides (NOx), which can cause acute irritation and chronic diseases, and significant research on the treatment of vehicle exhaust has received increasing attention in recent decades. Recently, photocatalytic technology has been considered a practical approach for eliminating vehicle emissions. This review highlights the crucial role of photocatalytic technology in eliminating vehicle emissions using semiconductor catalysts. A particular emphasis has been placed on various photocatalytic materials, such as TiO2-based materials, Bi-based materials, and Metal–Organic Frameworks (MOFs), and their recent advances in the performance of VOC and NOx photodegradation. In addition, the applications of photocatalytic technology for the elimination of vehicle exhaust are presented (including photocatalysts combined with pavement surfaces, making photocatalysts into architectural coatings and photoreactors), which will offer a promising strategy for photocatalytic technology to remove vehicle exhaust. Full article
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8 pages, 2168 KiB  
Article
Facile Synthesis of FeCoNiCuIr High Entropy Alloy Nanoparticles for Efficient Oxygen Evolution Electrocatalysis
by Chen Cai, Zongwei Xin, Xuefan Zhang, Jian Cui, Hui Lv, Wanjie Ren, Cunyuan Gao and Bin Cai
Catalysts 2022, 12(9), 1050; https://doi.org/10.3390/catal12091050 - 15 Sep 2022
Cited by 5 | Viewed by 2407
Abstract
The lack of an efficient and stable electrocatalyst for oxygen evolution reaction (OER) greatly hinders the development of various electrochemical energy conversion and storage techniques. In this study, we report a facile synthesis of FeCoNiCuIr high-entropy alloy nanoparticles (HEA NPs) by a one-step [...] Read more.
The lack of an efficient and stable electrocatalyst for oxygen evolution reaction (OER) greatly hinders the development of various electrochemical energy conversion and storage techniques. In this study, we report a facile synthesis of FeCoNiCuIr high-entropy alloy nanoparticles (HEA NPs) by a one-step heat-up method. The involvement of glucose made the NPs grow uniformly and increased the valence of Ir. The resulting FeCoNiCuIr NPs exhibit excellent OER performance in alkaline solution, with a low overpotential of 360 mV to achieve a current density of 10 mA cm−2 at a Tafel slope of as low as 70.1 mV dec−1. In addition, high stability has also been observed, which remained at 94.2% of the current density after 10 h constant electrolysis, with a constant current of 10 mA cm−2. The high electrocatalytic activity and stability are ascribed to the cocktail effect and synergistic effect between the constituent elements. Our work holds the potential to be extended to the design and synthesis of high-performance electrocatalysts. Full article
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19 pages, 3762 KiB  
Article
Uniformly Dispersed Cu Nanoparticles over Mesoporous Silica as a Highly Selective and Recyclable Ethanol Dehydrogenation Catalyst
by Yan Hao, Dajie Zhao, Wen Liu, Min Zhang, Yixiao Lou, Zhenzhen Wang, Qinghu Tang and Jinghe Yang
Catalysts 2022, 12(9), 1049; https://doi.org/10.3390/catal12091049 - 15 Sep 2022
Cited by 6 | Viewed by 2285
Abstract
Selective dehydrogenation of ethanol to acetaldehyde has been considered as an important pathway to produce acetaldehyde due to the atom economy and easy separation of acetaldehyde and hydrogen. Copper catalysts have attracted much attention due to the high activity of Cu species in [...] Read more.
Selective dehydrogenation of ethanol to acetaldehyde has been considered as an important pathway to produce acetaldehyde due to the atom economy and easy separation of acetaldehyde and hydrogen. Copper catalysts have attracted much attention due to the high activity of Cu species in O-H and C-H bonds oxidative cleavage, and low process cost; however, the size of the Cu nanoparticle is difficult to control since it is easily suffers from metal sintering at high temperatures. In this work, the Cu/KIT-6 catalyst exhibited an ultra-high metal dispersion of 62.3% prepared by an electrostatic adsorption method, due to the advantages of the confinement effect of mesoporous nanostructures and the protective effect of ammonia water on Cu nanoparticles. The existence of an oxidation atmosphere had a significant effect on the valence state of copper species and enhancing moderate acid sites. The catalyst treated by reduction and then oxidation possessed a moderate/weak acid site ratio of ~0.42 and a suitable proportion of Cu+/Cu0 ratio of ~0.53, which conceivably rendered its superior ethanol conversion of 96.8% and full acetaldehyde selectivity at 250 °C. The catalyst also maintained a high selectivity of >99% to acetaldehyde upon time-on-stream of 288 h. Full article
(This article belongs to the Special Issue Advanced Catalysts for Achieving Hydrogen Economy from Liquids)
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9 pages, 5271 KiB  
Article
Enzymatic Formation of Recombinant Antibody-Conjugated Gold Nanoparticles in the Presence of Citrate Groups and Bacteria
by Maryam Rad, Gholamhossein Ebrahimipour, Mojgan Bandehpour, Omid Akhavan and Fatemeh Yarian
Catalysts 2022, 12(9), 1048; https://doi.org/10.3390/catal12091048 - 14 Sep 2022
Cited by 2 | Viewed by 1455
Abstract
With the spread of deadly diseases worldwide, the design of rapid tests to identify causative microorganisms is necessary. Due to the unique properties of gold nanoparticles, these nanoparticles are used in designing rapid diagnostic tests, such as strip tests. The current study aimed [...] Read more.
With the spread of deadly diseases worldwide, the design of rapid tests to identify causative microorganisms is necessary. Due to the unique properties of gold nanoparticles, these nanoparticles are used in designing rapid diagnostic tests, such as strip tests. The current study aimed to investigate the ability of gold nanoparticles to bind to single-chain variable fragment antibodies. In this study, the biological and chemical methods included Escherichia coli TOP-10 and the Turkevich method to synthesize the gold nanoparticles, respectively. Then, the effect of synthetic nanoparticles on their capability of binding to recombinant antibodies was assessed by agarose gel and UV-vis spectroscopy. Our result showed that gold nanoparticles had a spherical morphology, and their average size was ~45 nm. Additionally, the citrate groups in gold nanoparticles were able to bind to serine residues in the antibody linker sequence; so, the chemical synthesis of gold nanoparticles is an effective strategy for binding these nanoparticles to antibodies that can be used in designing rapid diagnostic tests to promptly identify infectious microorganisms. Full article
(This article belongs to the Special Issue Advances in Enzyme Engineering, Biocatalysis and Biosynthesis)
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29 pages, 5140 KiB  
Review
Recent Advances on Metal Oxide Based Nano-Photocatalysts as Potential Antibacterial and Antiviral Agents
by Jai Prakash, Suresh Babu Naidu Krishna, Promod Kumar, Vinod Kumar, Kalyan S. Ghosh, Hendrik C. Swart, Stefano Bellucci and Junghyun Cho
Catalysts 2022, 12(9), 1047; https://doi.org/10.3390/catal12091047 - 14 Sep 2022
Cited by 14 | Viewed by 2396
Abstract
Photocatalysis, a unique process that occurs in the presence of light radiation, can potentially be utilized to control environmental pollution, and improve the health of society. Photocatalytic removal, or disinfection, of chemical and biological species has been known for decades; however, its extension [...] Read more.
Photocatalysis, a unique process that occurs in the presence of light radiation, can potentially be utilized to control environmental pollution, and improve the health of society. Photocatalytic removal, or disinfection, of chemical and biological species has been known for decades; however, its extension to indoor environments in public places has always been challenging. Many efforts have been made in this direction in the last two–three years since the COVID-19 pandemic started. Furthermore, the development of efficient photocatalytic nanomaterials through modifications to improve their photoactivity under ambient conditions for fighting with such a pandemic situation is a high research priority. In recent years, several metal oxides-based nano-photocatalysts have been designed to work efficiently in outdoor and indoor environments for the photocatalytic disinfection of biological species. The present review briefly discusses the advances made in the last two to three years for photocatalytic viral and bacterial disinfections. Moreover, emphasis has been given to the tailoring of such nano-photocatalysts in disinfecting surfaces, air, and water to stop viral/bacterial infection in the indoor environment. The role of such nano-photocatalysts in the photocatalytic disinfection of COVID-19 has also been highlighted with their future applicability in controlling such pandemics. Full article
(This article belongs to the Special Issue Recent Advances on Nano-Catalysts for Biological Processes)
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14 pages, 3232 KiB  
Article
BaCO3 Nanoparticles-Modified Composite Cathode with Improved Electrochemical Oxygen Reduction Kinetics for High-Performing Ceramic Fuel Cells
by Halefom G. Desta, Quan Yang, Dong Tian, Shiyue Zhu, Xiaoyong Lu, Kai Song, Yang Yang, Yonghong Chen, Baihai Li and Bin Lin
Catalysts 2022, 12(9), 1046; https://doi.org/10.3390/catal12091046 - 14 Sep 2022
Cited by 4 | Viewed by 1493
Abstract
The effects of the electrochemical oxygen reduction reaction (ORR) on the surface of single-phase perovskite cathodes are well understood, but its potential for use in a complex system consisting of different material types is unexplored. Herein, we report how BaCO3 nanoparticles-modified La [...] Read more.
The effects of the electrochemical oxygen reduction reaction (ORR) on the surface of single-phase perovskite cathodes are well understood, but its potential for use in a complex system consisting of different material types is unexplored. Herein, we report how BaCO3 nanoparticles-modified La0.6Sr0.4Co0.2Fe0.8O3-δ-Gd0.2Ce0.8O2-δ (LSCF–GDC)-composite cathodes improved the electrochemical oxygen reduction kinetics for high-performing ceramic fuel cells. Both X-ray diffraction (XRD) and thermogravimetric analysis (TGA) studies reveal that BaCO3 is stable, and that it does not show any solid-state reaction with LSCF–GDC at SOFCs’ required operating temperature. The electrochemical conductivity relaxation (ECR) study reveals that during the infiltration of BaCO3 nanoparticles into LSCF–GDC, the surface exchange kinetics (Kchem) are enhanced up to a factor of 26.73. The maximum power density of the NiO-YSZ anode-support cell is increased from 1.08 to 1.48 W/cm2 via surface modification at 750 °C. The modified cathode also shows an ultralow polarization resistance (Rp) of 0.027 Ω.cm2, which is ~4.4 times lower than that of the bare cathode (~0.12 Ω.cm2) at 750 °C. Such enhancement can be attributed to the accelerated oxygen surface exchange process, possibly through promoting the dissociation of oxygen molecules via the infiltration of BaCO3 nanoparticles. The density functional theory (DFT) illustrates the interaction mechanism between oxygen molecules and the BaCO3 surface. Full article
(This article belongs to the Special Issue Featured Papers in Electrochemistry and Electrocatalysis in China)
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15 pages, 4162 KiB  
Article
Synthesis of Fe2O3/Mn2O3 Nanocomposites and Impregnated Porous Silicates for Dye Removal: Insights into Treatment Mechanisms
by Soyoung Baek, Yasaman Ghaffari and Jiyeol Bae
Catalysts 2022, 12(9), 1045; https://doi.org/10.3390/catal12091045 - 14 Sep 2022
Cited by 5 | Viewed by 1561
Abstract
Fe2O3/Mn2O3 nanocomposites and impregnated porous silicates (Fe2O3/Mn2O3@SiO2 [FMS]) were prepared and investigated as catalytic adsorbents. The catalysts were applied for cationic and anionic dye pollutants in the [...] Read more.
Fe2O3/Mn2O3 nanocomposites and impregnated porous silicates (Fe2O3/Mn2O3@SiO2 [FMS]) were prepared and investigated as catalytic adsorbents. The catalysts were applied for cationic and anionic dye pollutants in the adsorption, Fenton reaction, and photocatalysis processes at a pH of 7. Fe2O3/Mn2O3 nanoparticles (FM-NPs) were prepared using the co-precipitation method and were impregnated in SiO2 by the sol–gel process. The synthesized materials were characterized using various sophisticated techniques. Results indicated that the impregnation of bi-metallic NPs in SiO2 increased the surface area, and the function of the adsorbent also improved. FMS showed a significant adsorption effect, with 79.2% rhodamine B removal within 15 min. Fenton and photocatalyst reaction showed removal rates of 85.3% and 97.9%, respectively, indicating that negatively charged porous silicate attracts cationic pollutants. In the case of the anionic pollutant, Congo red, the adsorption reaction of FMS did not occur, and the removal rate of the photocatalyst reaction was 79%, indicating the repulsive force between the negatively charged silica and the anionic dye. Simultaneously, bi-metal-bonded FM-NPs facilitated the photocatalytic reaction, reducing the recombination of electron-hole pairs. This study provides new insights into the synthesis of FM-NPs and FMS as photocatalytic adsorbents and their photocatalytic mechanisms based on reaction conditions and contaminant characteristics. The developed materials have potential applications for environmental mitigation. Full article
(This article belongs to the Section Environmental Catalysis)
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13 pages, 2438 KiB  
Article
Use of Photocatalytically Active Supramolecular Organic–Inorganic Magnetic Composites as Efficient Route to Remove β-Lactam Antibiotics from Water
by Sabina G. Ion, Octavian D. Pavel, Nicolae Guzo, Madalina Tudorache, Simona M. Coman, Vasile I. Parvulescu, Bogdan Cojocaru and Elisabeth E. Jacobsen
Catalysts 2022, 12(9), 1044; https://doi.org/10.3390/catal12091044 - 14 Sep 2022
Cited by 3 | Viewed by 1806
Abstract
Considerable efforts have been made in recent years to identify an optimal treatment method for the removal of antibiotics from wastewaters. A series of supramolecular organic-inorganic magnetic composites containing Zn-modified MgAl LDHs and Cu-phthalocyanine as photosensitizers were prepared with the aim of removing [...] Read more.
Considerable efforts have been made in recent years to identify an optimal treatment method for the removal of antibiotics from wastewaters. A series of supramolecular organic-inorganic magnetic composites containing Zn-modified MgAl LDHs and Cu-phthalocyanine as photosensitizers were prepared with the aim of removing β-lactam antibiotics from aqueous solutions. The characterization of these materials confirmed the anchorage of Cu-phthalocyanine onto the edges of the LDH lamellae, with a negligible part inserted in the interlayer space. The removal of the β-lactam antibiotics occurred via concerted adsorption and photocatalytic degradation. The efficiency of the composites depended on (i) the LDH: magnetic nanoparticle (MP) ratio, which was strongly correlated with the textural properties of the catalysts, and (ii) the phthalocyanine loading in the final composite. The maximum efficiency was achieved with a removal of ~93% of the antibiotics after 2 h of reaction. Full article
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