Journal Description
Catalysts
Catalysts
is a peer-reviewed open access journal of catalysts and catalyzed reactions published monthly online by MDPI. The Romanian Catalysis Society (RCS) are partners of Catalysts journal and its members receive a discount on the article processing charge.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), Inspec, CAPlus / SciFinder, CAB Abstracts, and other databases.
- Journal Rank: JCR - Q2 (Chemistry, Physical) / CiteScore - Q1 (General Environmental Science)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 14.3 days after submission; acceptance to publication is undertaken in 2.7 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Impact Factor:
3.9 (2022);
5-Year Impact Factor:
4.2 (2022)
Latest Articles
Study on NH3-SCR Activity and HCl/H2O Tolerance of Titanate-Nanotube-Supported MnOx-CeO2 Catalyst at Low Temperature
Catalysts 2024, 14(5), 306; https://doi.org/10.3390/catal14050306 (registering DOI) - 05 May 2024
Abstract
Manganese oxide-cerium oxide supported on titanate nanotubes (i.e., MnCe/TiNTs) were prepared and their catalytic activities towards NH3-SCR of NO were tested. The results indicated that the MnCe/TiNT catalyst can achieve a high NO removal efficiency above 95% within the temperature range
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Manganese oxide-cerium oxide supported on titanate nanotubes (i.e., MnCe/TiNTs) were prepared and their catalytic activities towards NH3-SCR of NO were tested. The results indicated that the MnCe/TiNT catalyst can achieve a high NO removal efficiency above 95% within the temperature range of 150–350 °C. Even after exposure to a HCl-containing atmosphere for 2 h, the NO removal efficiency of the MnCe/TiNT catalyst maintains at approximately 90% at 150 °C. This is attributed to the large specific surface area as well as the unique hollow tubular structure of TiNTs that exposes more Ce atoms, which preferentially react with HCl and thus protect the active Mn atoms. Moreover, the abundant OH groups on TiNTs serve as Brønsted acid sites and provide H protons to expel Cl atom from the catalyst surface. The irreversible deactivation caused by HCl can be alleviated by H2O. That is because the dissociated adsorption of H2O on TiNTs forms additional OH groups and relieves HCl poisoning.
Full article
(This article belongs to the Special Issue NOx, VOCs (Volatile Organic Compounds) and Soot Emission Control in Catalysis, 2nd Edition)
Open AccessFeature PaperArticle
Binuclear Dioxomolybdenum(VI) Complex Based on Bis(2-pyridinecarboxamide) Ligand as Effective Catalyst for Fuel Desulfurization
by
Fátima Mirante, Catarina N. Dias, André Silva, Sandra Gago and Salete S. Balula
Catalysts 2024, 14(5), 305; https://doi.org/10.3390/catal14050305 (registering DOI) - 04 May 2024
Abstract
A binuclear dioxomolybdenum catalyst [(MoO2Cl2)2(L)] (1) (with L (1S,2S)-N,N′-bis(2-pyridinecarboxamide)-1,2-cyclohexane) was prepared and used as catalyst for the desulfurization of a multicomponent model fuel containing the most refractory
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A binuclear dioxomolybdenum catalyst [(MoO2Cl2)2(L)] (1) (with L (1S,2S)-N,N′-bis(2-pyridinecarboxamide)-1,2-cyclohexane) was prepared and used as catalyst for the desulfurization of a multicomponent model fuel containing the most refractory sulfur compounds in real fuels. This complex was shown to have a high efficiency to oxidize the aromatic benzothiophene derivative compounds present in fuels, mainly using a biphasic 1:1 model fuel/MeOH system. This process conciliates catalytic oxidative and extractive desulfurization, resulting in the oxidation of the sulfur compounds in the polar organic solvent. The oxidative catalytic performance of (1) was shown to be influenced by the presence of water in the system. Using 50% aq. H2O2, it was possible to reuse the catalyst and the extraction solvent, MeOH, during ten consecutive cycles without loss of desulfurization efficiency.
Full article
(This article belongs to the Special Issue Advances in Green Catalysis for Sustainable Organic Synthesis, 2nd Edition)
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Open AccessArticle
Functionalized Chitosan and Alginate Composite Hydrogel-Immobilized Laccase with Sustainable Biocatalysts for the Effective Removal of Organic Pollutant Bisphenol A
by
Hong Zhang, Xin Zhang, Lei Wang, Bo Wang, Xu Zeng and Bo Ren
Catalysts 2024, 14(5), 304; https://doi.org/10.3390/catal14050304 - 03 May 2024
Abstract
The immobilization of enzymes is an important strategy to improve their stability and reusability. Enzyme immobilization technology has broad application prospects in biotechnology, biochemistry, environmental remediation, and other fields. In this study, composites of chitosan (CS) and sodium alginate (SA) with Cu2+
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The immobilization of enzymes is an important strategy to improve their stability and reusability. Enzyme immobilization technology has broad application prospects in biotechnology, biochemistry, environmental remediation, and other fields. In this study, composites of chitosan (CS) and sodium alginate (SA) with Cu2+ forming a double-network crosslinked structure of hydrogels were prepared and used for the immobilization of laccase. Fourier infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy tests revealed that laccase molecules were immobilized on the composite hydrogel surface by a covalent bonding method. Compared to free laccase, the pH, temperature, and storage stability of the immobilized laccase were markedly improved. In addition, the immobilized laccase could be easily separated from the reaction system and reused, and it maintained 81.6% of its initial viability after six cycles of use. Bisphenol A (BPA) in polluted water was efficiently degraded using immobilized laccase, and the factors affecting the degradation efficiency were analyzed. Under the optimal conditions, the BPA removal was greater than 82%, and the addition of a small amount of ABTS had a significant effect on BPA degradation, with a removal rate of up to 99.1%. Experimental results indicated that immobilized laccases had enormous potential in actual industrial applications.
Full article
(This article belongs to the Section Biocatalysis)
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Open AccessFeature PaperReview
Recent Advances in the Development of Nanocarbon-Based Electrocatalytic/Electrode Materials for Proton Exchange Membrane Fuel Cells: A Review
by
Adelina A. Zasypkina, Nataliya A. Ivanova, Dmitry D. Spasov, Ruslan M. Mensharapov, Matvey V. Sinyakov and Sergey A. Grigoriev
Catalysts 2024, 14(5), 303; https://doi.org/10.3390/catal14050303 - 03 May 2024
Abstract
The global issue for proton exchange membrane fuel cell market development is a reduction in the device cost through an increase in efficiency of the oxygen reduction reaction occurring at the cathode and an extension of the service life of the electrochemical device.
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The global issue for proton exchange membrane fuel cell market development is a reduction in the device cost through an increase in efficiency of the oxygen reduction reaction occurring at the cathode and an extension of the service life of the electrochemical device. Losses in the fuel cell performance are due to various degradation mechanisms in the catalytic layers taking place under conditions of high electric potential, temperature, and humidity. This review is devoted to recent advances in the field of increasing the efficiency and durability of electrocatalysts and other electrode materials by introducing structured carbon components into their composition. The main synthesis methods, physicochemical and electrochemical properties of materials, and performance of devices on their basis are presented. The main correlations between the composition and properties of structured carbon electrode materials, which can provide successful solutions to the highlighted issues, are revealed.
Full article
(This article belongs to the Special Issue Feature Review Papers in Electrocatalysis)
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Open AccessArticle
Electrochemical Properties of NiCo2O4/WO3/Activated Carbon Wheat Husk Nano-Electrocatalyst for Methanol and Ethanol Oxidation
by
Mohammad Bagher Askari, Parisa Salarizadeh, Seyed Rouhollah Samareh Hashemi, Mohsen Shojaeifar and Sadegh Azizi
Catalysts 2024, 14(5), 302; https://doi.org/10.3390/catal14050302 - 02 May 2024
Abstract
It is common to use efficient catalysts in the anodes and cathodes of methanol and ethanol fuel cells, such as platinum and ruthenium. However, due to their expansivity and rarity, finding a suitable alternative is important. In this work, multi-component catalysts consisting of
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It is common to use efficient catalysts in the anodes and cathodes of methanol and ethanol fuel cells, such as platinum and ruthenium. However, due to their expansivity and rarity, finding a suitable alternative is important. In this work, multi-component catalysts consisting of tungsten oxide, nickel cobaltite, and activated carbon were synthesized through the hydrothermal method. The performance of catalysts in the processes of methanol and ethanol oxidation reactions (MOR and EOR) were investigated. The addition of activated carbon obtained from wheat husk, with an excellent active surface and acceptable electrical conductivity, to the matrix of the catalyst significantly facilitated the oxidation process of alcohols and enhanced the efficiency of the catalyst. The physical and electrochemical characterization of the NiCo2O4/WO3 hybridized with the wheat husk-derived activated carbon (ACWH) catalyst indicated its successful synthesis and good performance in the alcohol oxidation process. NiCo2O4/WO3/ACWH with an oxidation current density of 63.39 mA/cm2 at the peak potential of 0.58 V (1.59 vs. RHE), a cyclic stability of 98.6% in the methanol oxidation reaction (MOR) and 27.98 mA/cm2 at the peak potential of 0.67 V (1.68 vs. RHE), and a cyclic stability of 95.7% in the ethanol oxidation reaction (EOR) process can be an interesting option for application in the anodes of alcohol fuel cells.
Full article
(This article belongs to the Section Catalysis for Sustainable Energy)
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Open AccessEditorial
New Trends in the Use of Catalysts for Biofuel and Bioproduct Generation
by
José María Encinar Martín and Sergio Nogales-Delgado
Catalysts 2024, 14(5), 301; https://doi.org/10.3390/catal14050301 - 02 May 2024
Abstract
Green technologies are gaining a vital role in the energy and industrial fields, as society faces challenges such as geopolitical conflicts and pollution related to the exploitation of petroleum resources [...]
Full article
(This article belongs to the Special Issue New Trends in the Use of Catalysts for Biofuel and Bioproduct Generation)
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Open AccessArticle
Preparation of Oxygen Reduction Catalyst Electrodes by Electrochemical Acidification and Synergistic Electrodeposition
by
Liheng Zhou, Yongjian Guo, Yu Xu, Ping Li and Qi Zhang
Catalysts 2024, 14(5), 300; https://doi.org/10.3390/catal14050300 - 02 May 2024
Abstract
A proton exchange membrane fuel cell (PEMFC) is an efficient and environmentally friendly power production technology that uses hydrogen energy. The cathodic oxygen reduction electrode is a critical component in the development of PEMFC. Most techniques deposit catalyst nanoparticles in areas that are
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A proton exchange membrane fuel cell (PEMFC) is an efficient and environmentally friendly power production technology that uses hydrogen energy. The cathodic oxygen reduction electrode is a critical component in the development of PEMFC. Most techniques deposit catalyst nanoparticles in areas that are inaccessible for catalytic processes, reducing platinum utilization. The substrate used in this study was carbon paper (CP) with a self-supporting structure. First, electrochemical acidification technology was employed to modify the CP’s surface, followed by nanoparticle manufacturing and fixation on the CP in a single step by electrodeposition. The Pt/C0.5V2.24CP catalyst electrode demonstrated high-quality activity in the oxygen reduction reaction (ORR), with a homogeneous particle dispersion and particle size of around 50 nm. The mass activity and electrochemical active surface area (ECSA) of the Pt/C0.5V2.24CP catalyst electrode were 1.74 and 3.98 times higher than those of the Pt/C/CP-1 electrodes made with commercial catalysts, respectively. After 5000 cycles of accelerated durability testing (ADT), the mass activity and ECSA were 1.28 times and 6.16 times more than Pt/C/CP-1. This paper successfully proved the viability of electrodepositing Pt nanoparticles on CP following acidification, and that the electrochemical acidification methods have a positive influence on improving electrode ORR activity.
Full article
(This article belongs to the Topic Hydrogen Energy Technologies, 2nd Volume)
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Open AccessArticle
Insights into the Reactivation Process of Thermal Aged Bimetallic Pt-Pd/CeO2-ZrO2-La2O3 Catalysts at Different Treating Temperatures and Their Structure–Activity Evolutions for Three-Way Catalytic Performance
by
Jie Wan, Kai Chen, Qi Sun, Yuanyuan Zhou, Yanjun Liu, Jin Zhang, Jiancong Dong, Xiaoli Wang, Gongde Wu and Renxian Zhou
Catalysts 2024, 14(5), 299; https://doi.org/10.3390/catal14050299 - 01 May 2024
Abstract
CeO2-ZrO2-La2O3 supported Pt-Pd bimetallic three-way catalysts (0.6Pt-0.4Pd/CZL) were synthesized through the conventional impregnation method and then subjected to severe thermal aging. Reactivating treatments under different temperatures were then applied to the aged catalysts above. Three-way catalytic
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CeO2-ZrO2-La2O3 supported Pt-Pd bimetallic three-way catalysts (0.6Pt-0.4Pd/CZL) were synthesized through the conventional impregnation method and then subjected to severe thermal aging. Reactivating treatments under different temperatures were then applied to the aged catalysts above. Three-way catalytic performance evaluations and dynamic operation window tests along with detailed physio-chemical characterizations were carried out to explore possible structure–activity evolutions during the reactivating process. Results show that the reactivating process conducted at proper temperatures (500~550 °C) could effectively restore the TWC catalytic performance and widen the operation window width. The suitable reactivating temperature ranges are mainly determined by the decomposing temperature of PMOx species, the thermal stability of PM-O-Ce species, and the encapsulation temperature of precious metals by CZL support. Reactivating under appropriate temperature helps to restore the interaction between Pt and CZL support to a certain extent and to re-expose part of the encapsulated precious metals. Therefore, the dynamic oxygen storage/release capacity, redox ability, as well as thermal stability of PtOx species, can be improved, thus benefiting the TWC catalytic performances. However, the excessively high reactivating temperature would cause further embedment of Pd by CZL support, thus leading to a further decrease in both dynamic oxygen storage/release capacity and the TWC catalytic performance after reactivating treatment.
Full article
(This article belongs to the Special Issue Rare Earth Catalysis: From Synthesis to Sustainable Applications)
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Open AccessFeature PaperArticle
Ultrathin-Shelled Zn-AgIn5S8/ZnS Quantum Dots with Partially Passivated Trap States for Efficient Hydrogen Production
by
Yanhong Liu, Xianjin Wang, Guan Gong, Afaq Ullah Khan, Geru Li, Tong Ren, Qitao Chen, Lixia Li and Baodong Mao
Catalysts 2024, 14(5), 298; https://doi.org/10.3390/catal14050298 - 30 Apr 2024
Abstract
The manipulation of trap states plays a crucial role in the development of efficient photocatalysts. An ultrathin-shelled Zn-AgIn5S8/ZnS quantum dots (QDs) photocatalyst was synthesized via in situ growth using a low-temperature hydrothermal method. The optical properties of the samples
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The manipulation of trap states plays a crucial role in the development of efficient photocatalysts. An ultrathin-shelled Zn-AgIn5S8/ZnS quantum dots (QDs) photocatalyst was synthesized via in situ growth using a low-temperature hydrothermal method. The optical properties of the samples coated with ZnS shell were studied vis UV-vis absorption and fluorescence spectra. The ultrathin ZnS shell plays an important role in the Zn-AgIn5S8/ZnS core–shell heterostructure photocatalytic water splitting system, which could reduce surface defects, prolong the carrier lifetime and improve the photo-generated electron–hole pair separation effectively, resulting in the improved photocatalytic efficiency and enhanced stability of the catalyst. The results provide an effective guideline for shell thickness design in future constructions of the core–shell heterostructure photocatalyst.
Full article
(This article belongs to the Special Issue Advances in Photo(electro)catalytic Hydrogen Production)
Open AccessFeature PaperArticle
Catalytic Hydrogenation of γ-Butyrolactone to Butanediol over a High-Performance Cu-SiO2 Catalyst
by
Xiaoni Ren, Mo Zhou, Wenguang Yu, Mingyuan Zheng and Qingda An
Catalysts 2024, 14(5), 297; https://doi.org/10.3390/catal14050297 - 29 Apr 2024
Abstract
High-performance Cu catalysts were developed for the selective hydrogenation of γ-butyrolactone (GBL) to 1,4-butanediol (BDO). Among the various catalysts prepared by ammonia evaporation (AE) and impregnation (IM) methods with silica or MFI zeolite supports, the 5% Cu-SiO2-AE catalyst was the best
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High-performance Cu catalysts were developed for the selective hydrogenation of γ-butyrolactone (GBL) to 1,4-butanediol (BDO). Among the various catalysts prepared by ammonia evaporation (AE) and impregnation (IM) methods with silica or MFI zeolite supports, the 5% Cu-SiO2-AE catalyst was the best one. It exhibited 95% selectivity for BDO and 71% conversion of GBL after 2–8 h reaction at 200 °C and 4 MPa H2, with high stability in five-cycle runs. Comprehensive characterizations showed that the AE method favored generating nano Cu particles with an average size of 2.9 nm on the 5% Cu-SiO2-AE catalyst. The silica support derived from a sol demonstrated an advantage over the MFI zeolite in the preparation of a highly dispersed and stable Cu catalyst, in view of its anti-sintering and robust composition of Cu0, Cu+, and Cu2+ in the cycling operation. The reaction pathways for GBL to BDO over the Cu catalysts were found to commonly involve reversible reactions of hydrogenation and dehydrogenation, along with subsequent dehydration to form THF. The high performance of the Cu catalysts in the conversion of GBL to BDO was attributed to the high dispersion of Cu, the presence of stable active sites, and fewer strong acid sites in the catalyst.
Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Selective Hydrogenation)
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Large-Scale and Simple Synthesis of NiFe(OH)x Electrode Derived from Raney Ni Precursor for Efficient Alkaline Water Electrolyzer
by
Tianshui Li, Wei Liu, Huijun Xin, Qihao Sha, Haijun Xu, Yun Kuang and Xiaoming Sun
Catalysts 2024, 14(5), 296; https://doi.org/10.3390/catal14050296 - 29 Apr 2024
Abstract
Water electrolysis is a crucial technology in the production of hydrogen energy. Due to the escalating industrial demand for green hydrogen, the required electrode size for a traditional alkaline water electrolyzer has been increasing. Numerous studies have focused on developing highly active oxygen
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Water electrolysis is a crucial technology in the production of hydrogen energy. Due to the escalating industrial demand for green hydrogen, the required electrode size for a traditional alkaline water electrolyzer has been increasing. Numerous studies have focused on developing highly active oxygen evolution reaction (OER) catalysts for water electrolysis. However, there remains a significant gap between the microscale synthesis of catalysts in laboratory settings and the macroscale preparation required for industrial scenarios. This challenge is particularly pronounced in the synthesis of sizable self-supported electrodes. In this work, we employed a commercially available Raney Ni-coated Ni mesh as a precursor material to fabricate a self-supported NiFe(OH)x@Raney Ni anode with a substantial dimension exceeding 300 mm through a straightforward immersion technique. The as-prepared electrode exhibited remarkable electrocatalytic OER activity, as an overpotential of only 240 mV is required to achieve 10 mA cm−2. This performance is comparable to that of NiFe-LDHs synthesized via a hydrothermal method, which is difficult to scale up for industrial applications. Furthermore, the electrode demonstrated exceptional durability, maintaining stable operation for over 100 h at a current density of 500 mA cm−2. The large-scale electrode displayed consistent overpotentials across various areas, indicating uniform catalytic activity. When integrated into an alkaline water electrolysis device, it delivered an average cell voltage of 1.80 V at 200 mA cm−2 and achieved a direct current hydrogen production energy consumption as low as 4.3 kWh/Nm3. These findings underline the suitability of electrodes for industrial scale applications, offering a promising alternative for energy-efficient hydrogen production.
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(This article belongs to the Special Issue Study on Electrocatalytic Activity of Metal Oxides)
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Open AccessArticle
Palladium Complexes Derived from Waste as Catalysts for C-H Functionalisation and C-N Bond Formation
by
Khairil A. Jantan, Gregor Ekart, Sean McCarthy, Andrew J. P. White, D. Christopher Braddock, Angela Serpe and James D. E. T. Wilton-Ely
Catalysts 2024, 14(5), 295; https://doi.org/10.3390/catal14050295 - 29 Apr 2024
Abstract
Three-way catalysts (TWCs) are widely used in vehicles to convert the exhaust emissions from internal combustion engines into less toxic pollutants. After around 8–10 years of use, the declining catalytic activity of TWCs causes them to need replacing, leading to the generation of
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Three-way catalysts (TWCs) are widely used in vehicles to convert the exhaust emissions from internal combustion engines into less toxic pollutants. After around 8–10 years of use, the declining catalytic activity of TWCs causes them to need replacing, leading to the generation of substantial amounts of spent TWC material containing precious metals, including palladium. It has previously been reported that [NnBu4]2[Pd2I6] is obtained in high yield and purity from model TWC material using a simple, inexpensive and mild reaction based on tetrabutylammonium iodide in the presence of iodine. In this contribution, it is shown that, through a simple ligand exchange reaction, this dimeric recovery complex can be converted into PdI2(dppf) (dppf = 1,1′-bis(diphenylphosphino)ferrocene), which is a direct analogue of a commonly used catalyst, PdCl2(dppf). [NnBu4]2[Pd2I6] displayed high catalytic activity in the oxidative functionalisation of benzo[h]quinoline to 10-alkoxybenzo[h]quinoline and 8-methylquinoline to 8-(methoxymethyl)quinoline in the presence of an oxidant, PhI(OAc)2. Near-quantitative conversions to the desired product were obtained using a catalyst recovered from waste under milder conditions (50 °C, 1–2 mol% Pd loading) and shorter reaction times (2 h) than those typically used in the literature. The [NnBu4]2[Pd2I6] catalyst could also be recovered and re-used multiple times after the reaction, providing additional sustainability benefits. Both [NnBu4]2[Pd2I6] and PdI2(dppf) were also found to be active in Buchwald–Hartwig amination reactions, and their performance was optimised through a Design of Experiments (DoE) study. The optimised conditions for this waste-derived palladium catalyst (1–2 mol% Pd loading, 3–6 mol% of dppf) in a bioderived solvent, cyclopentyl methyl ether (CPME), offer a more sustainable approach to C-N bond formation than comparable amination protocols.
Full article
(This article belongs to the Special Issue State-of-the-Art in Molecular Catalysis in Europe)
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A DFT Study of CO Hydrogenation on Graphene Oxide: Effects of Adding Mn on Fischer–Tropsch Synthesis
by
Hanieh Bakhtiari, Saeedeh Sarabadani Tafreshi, Mostafa Torkashvand, Majid Abdouss and Nora H. de Leeuw
Catalysts 2024, 14(5), 294; https://doi.org/10.3390/catal14050294 - 28 Apr 2024
Abstract
The hydrogenation of carbon monoxide (CO) offers a promising avenue for reducing air pollution and promoting a cleaner environment. Moreover, by using suitable catalysts, CO can be transformed into valuable hydrocarbons. In this study, we elucidate the mechanistic aspects of the catalytic conversion
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The hydrogenation of carbon monoxide (CO) offers a promising avenue for reducing air pollution and promoting a cleaner environment. Moreover, by using suitable catalysts, CO can be transformed into valuable hydrocarbons. In this study, we elucidate the mechanistic aspects of the catalytic conversion of CO to hydrocarbons on the surface of manganese-doped graphene oxide (Mn-doped GO), where the GO surface includes one OH group next to one Mn adatom. To gain insight into this process, we have employed calculations based on the density functional theory (DFT) to explore both the thermodynamic properties and reaction energy barriers. The Mn adatoms were found to significantly activate the catalyst surface by providing stronger adsorption geometries. Our study concentrated on two mechanisms for CO hydrogenation, resulting in either CH4 production via the reaction sequence CO → HCO → CH2O → CH2OH → CH2 → CH3 → CH4 or CH3OH formation through the CO → HCO → CH2O → CH2OH → CH3OH pathway. The results reveal that both products are likely to be formed on the Mn-doped GO surface on both thermodynamic grounds and considering the reaction energy barriers. Furthermore, the activation energies associated with each stage of the synthesis show that the conversion reactions of CH2 + OH → CH3 + O and CH2O + OH → CH2OH + O with energy barriers of 0.36 and 3.86 eV are the fastest and slowest reactions, respectively. The results also indicate that the reactions: CH2OH + OH → CH2 + O+H2O and CH2OH + OH → CH3OH + O are the most exothermic and endothermic reactions with reaction energies of −0.18 and 1.21 eV, respectively, in the catalytic pathways.
Full article
(This article belongs to the Special Issue Catalysis for Selective Hydrogenation of CO and CO2, 2nd Edition)
Open AccessEditorial
Engineering Materials for Catalysis
by
Albin Pintar, Nataša Novak Tušar and Günther Rupprechter
Catalysts 2024, 14(5), 293; https://doi.org/10.3390/catal14050293 - 27 Apr 2024
Abstract
The Special Issue “Engineering Materials for Catalysis” was inspired by the preceding 2020 Summer School of the European Federation of Catalysis Societies (EFCATS, https://skd2020 [...]
Full article
(This article belongs to the Special Issue Engineering Materials for Catalysis)
Open AccessFeature PaperArticle
Coke Formation and Regeneration during Fe-ZSM-5-Catalyzed Methane Dehydro-Aromatization
by
Sanjana Karpe and Götz Veser
Catalysts 2024, 14(5), 292; https://doi.org/10.3390/catal14050292 - 26 Apr 2024
Abstract
Coke formation poses a significant obstacle in the direct conversion of methane into valuable chemicals such as ethylene, benzene, and hydrogen via methane dehydro-aromatization (MDA). At the elevated temperatures necessary for this reaction, coke is the thermodynamically favored product, causing rapid catalyst deactivation
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Coke formation poses a significant obstacle in the direct conversion of methane into valuable chemicals such as ethylene, benzene, and hydrogen via methane dehydro-aromatization (MDA). At the elevated temperatures necessary for this reaction, coke is the thermodynamically favored product, causing rapid catalyst deactivation and hence necessitating frequent catalyst regeneration. Successful industrial implementation of MDA requires the advancement of catalyst regeneration processes and a comprehensive understanding of coke formation to enhance catalyst performance. Here, we examined the types of coke generated during MDA over a Fe-ZSM-5 catalyst and their impact on deactivation. By combining reactivity studies using catalysts with carefully controlled coke populations with the characterization of the catalyst via XRD, H2-TPR, and pyridine FTIR, we find that soft coke is formed at the Brønsted acid sites, resulting in loss of selectivity, while hard coke is formed at the metal sites causing a loss of activity. While soft coke can be removed at low regeneration temperatures, the removal of hard coke requires harsh conditions which compromise catalyst stability. An investigation into the use of CO2 as an alternative, mild oxidant for catalyst regeneration, however, shows that the mild oxidation strength of CO2 requires even higher regeneration temperatures and hence irreversible loss of Brønsted acid sites.
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(This article belongs to the Section Catalytic Materials)
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Open AccessArticle
Three-Dimensional Mesoporous Ni-CeO2 Catalyst for Dry Reforming of Methane
by
Huiyao Jin, Yuanqiao Liu, Lizhi Huang, Yali Liu, Sha Cui, Hui Liu, Jing Xu and Luhui Wang
Catalysts 2024, 14(5), 291; https://doi.org/10.3390/catal14050291 - 26 Apr 2024
Abstract
Using the colloidal solution combustion approach, a three-dimensional mesoporous 5%Ni-CeO2-M catalyst was developed, with Ni incorporated into the pores, and applied in the dry reforming of methane. Comprehensive characterization revealed that the 5%Ni-CeO2-M catalyst had a large specific surface
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Using the colloidal solution combustion approach, a three-dimensional mesoporous 5%Ni-CeO2-M catalyst was developed, with Ni incorporated into the pores, and applied in the dry reforming of methane. Comprehensive characterization revealed that the 5%Ni-CeO2-M catalyst had a large specific surface area and a three-dimensional mesoporous structure. A rich Ni-CeO2 interface was formed by closely spaced tiny CeO2 and NiO nanoparticles within the spherical pore wall. With very little carbon deposition over a 100 h period at 700 °C, the catalyst showed excellent activity and stability. The tiny Ni nanoparticles, along with the substantial Ni-CeO2 interfaces that make up this three-dimensional in-form mesoporous catalyst, are responsible for the outstanding effectiveness of this 5%Ni-CeO2-M catalyst.
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(This article belongs to the Section Industrial Catalysis)
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Open AccessFeature PaperReview
Application of Mesoporous/Hierarchical Zeolites as Catalysts for the Conversion of Nitrogen Pollutants: A Review
by
Małgorzata Rutkowska and Lucjan Chmielarz
Catalysts 2024, 14(5), 290; https://doi.org/10.3390/catal14050290 - 25 Apr 2024
Abstract
Mesoporous/hierarchical zeolites (HZs) are a relatively new group of materials, and interest in their application in catalysis is continuously growing. This paper presents recent achievements in the application of mesoporous zeolites in catalytic reactions of nitrogen pollutant conversion. The analysis presented includes processes
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Mesoporous/hierarchical zeolites (HZs) are a relatively new group of materials, and interest in their application in catalysis is continuously growing. This paper presents recent achievements in the application of mesoporous zeolites in catalytic reactions of nitrogen pollutant conversion. The analysis presented includes processes such as selective catalytic reduction of NOx with ammonia (NH3-SCR, DeNOx), selective catalytic oxidation of ammonia (NH3-SCO, AMOx), and catalytic decomposition of N2O. Different zeolite topologies and methods of their modification focused on mesoporosity generation (e.g., desilication, dealumination, steaming, self-assembly techniques, and application of hard and soft templates) are reviewed and compared with respect to catalytic processes. Special attention is paid to the role of porous structure and acidity, as well as the form of deposited transition metals, in the catalytic activation of modified zeolites in the elimination of nitrogen pollutants from flue gases.
Full article
(This article belongs to the Special Issue Catalytic Methods for Nitrogen Pollutants Conversion in Flue Gases)
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Open AccessArticle
Photoelectrocatalytic Reduction of Cr(VI) in Wastewater with a CuBi2O4 Thin Film Photocathode
by
Sai An, Ying Wang, Huajian Qiao, Hao Xiu, Deyu Liu and Yongbo Kuang
Catalysts 2024, 14(5), 289; https://doi.org/10.3390/catal14050289 - 25 Apr 2024
Abstract
Photoelectrocatalytic approaches show promise for contaminate removal in wastewater through redox reactions. However, the direct treatment of very low concentration heavy metals is a challenging task. Copper bismuth oxide is considered as a potential photocathode material due to its appropriate bandgap width and
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Photoelectrocatalytic approaches show promise for contaminate removal in wastewater through redox reactions. However, the direct treatment of very low concentration heavy metals is a challenging task. Copper bismuth oxide is considered as a potential photocathode material due to its appropriate bandgap width and excellent light absorption properties. In this work, we utilize copper bismuth oxide photoelectrodes with micrometer-scale pores to achieve the efficient and complete reduction of micromolar-level hexavalent chromium(VI) in wastewater. In a continuous 180 min experiment, the reduction rate of 5 µM hexavalent chromium reached 97%, which is an order lower than the drinking standard. Such a process was facilitated by the unique hierarchical microstructure of the oxide thin film and the porous morphology. On the other hand, the structural evolution during the operation was analyzed. A surface passivation was observed, suggesting the possible long-term practical application of this material. This study serves as an important reference for the application of photoelectrocatalysis in addressing Cr(VI) pollution in wastewater, with implications for improving water quality and environmental protection.
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(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy, 2nd Volume)
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Open AccessArticle
One-Step Production of Highly Selective Ethylbenzene and Propylbenzene from Benzene and Carbon Dioxide via Coupling Reaction
by
Tianyun Wang, Yingjie Guan, Haidan Wu, Zhaojie Su, Jianguo Zhuang, Siyan Yan, Xuedong Zhu and Fan Yang
Catalysts 2024, 14(5), 288; https://doi.org/10.3390/catal14050288 - 24 Apr 2024
Abstract
Utilizing carbon dioxide as a carbon source for the synthesis of olefins and aromatics has emerged as one of the most practical methods for CO2 reduction. In this study, an improved selectivity of 85% for targeting products (ethylbenzene and propylbenzene) is achieved
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Utilizing carbon dioxide as a carbon source for the synthesis of olefins and aromatics has emerged as one of the most practical methods for CO2 reduction. In this study, an improved selectivity of 85% for targeting products (ethylbenzene and propylbenzene) is achieved with a benzene conversion of 16.8% by coupling the hydrogenation of carbon dioxide to olefins over the bifunctional catalyst “Oxide-Zeolite” (OX-ZEO) and the alkylation of benzene with olefins over ZSM-5. In addition to investigating the influence of SAPO-34 and ZSM-5 zeolite acidity on product distribution, catalyst deactivation due to coke formation is addressed by modifying both molecular sieves to be hierarchical to extend the catalyst lifespan. Even after 100 h of operation at 400 °C, the catalysts maintained over 80% selectivity towards the target products, with benzene conversion over 14.2%. Furthermore, the pathway of propylbenzene formation is demonstrated through simple experimental design, revealing that the surface Brønsted acid sites of SAPO-34 serve as its primary formation sites. This provides a novel perspective for further investigation of the reaction network.
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(This article belongs to the Special Issue Sustainable Catalytic Routes for the Production of Green Synthetic Fuels and Other Value-Added Products)
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Optimizing the Incorporation Modes of TiO2 in TiO2-Al2O3 Composites for Enhancing Hydrodesulfurization Performance of Corresponding NiMoP-Supported Catalysts
by
Ranran Hou, Qinghe Yang, Shuangqin Zeng, Jun Bao, Hong Nie, Chuangchuang Yang, Yanzi Jia, Anpeng Hu and Qiaoling Dai
Catalysts 2024, 14(5), 287; https://doi.org/10.3390/catal14050287 - 24 Apr 2024
Abstract
TiO2-Al2O3 supports with different incorporation methods of titania were synthesized via three methods: impregnation (TA-I), co-precipitation (TA-CP), and co-precipitation–hydrothermal treatment (TA-HT). And the NiMoP catalysts prepared on the corresponding supports were evaluated for hydrodesulfurization (HDS) reactions. The results
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TiO2-Al2O3 supports with different incorporation methods of titania were synthesized via three methods: impregnation (TA-I), co-precipitation (TA-CP), and co-precipitation–hydrothermal treatment (TA-HT). And the NiMoP catalysts prepared on the corresponding supports were evaluated for hydrodesulfurization (HDS) reactions. The results demonstrated that the Ti atoms in TA-I are attached to alumina through hydroxyl groups, while the Ti atoms in TA-CP and TA-HT can be dispersed in the alumina skeleton. Variations in the incorporation modes of TiO2 affect the support properties, consequently influencing the nature of the active metal on the supports. The Ti atoms dispersed in the Al2O3 skeleton allow an increase in the basic hydroxyl groups. Meanwhile, TiO2 in TA-CP and TA-HT can absorb hydrogen molecules and be partially reduced. Furthermore, metal species supported on the TA-CP and TA-HT are more easily reduced and better dispersed. For the NiMoP catalysts prepared with TA-CP and TA-HT, the Ti element promotes the sulfidation degree of Mo, besides shortening the average (Ni)MoS2 slab. The catalysts prepared with TA-CP exhibited superior activity for 4,6-DMDBT hydrodesulfurization. This can be ascribed not only to the relatively high sulfidation degree of Mo and proportion of the NiMoS active phase but also to the well-dispersed (Ni)MoS2 slabs. Moreover, the Ti4+ ions dispersed in the Al2O3 skeleton can be partially reduced to act as electron donors, enhancing the metallic character of the S layers in MoS2, which facilitates the improvement of the hydrogenation desulfurization activity.
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(This article belongs to the Section Catalytic Materials)
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