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
Highly Efficient PtSn/Al2O3 and PtSnZnCa/Al2O3 Catalysts for Ethane Dehydrogenation: Influence of Catalyst Pretreatment Atmosphere
Catalysts 2024, 14(5), 312; https://doi.org/10.3390/catal14050312 - 9 May 2024
Abstract
Increased demand for ethylene has motivated direct ethane dehydrogenation over Pt-based catalysts. PtSn/γ-Al2O3 and PtSnZnCa/γ-Al2O3 catalysts were investigated with the aim of understanding the effect of the pretreatment environment on the state of dispersed Pt for ethane
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Increased demand for ethylene has motivated direct ethane dehydrogenation over Pt-based catalysts. PtSn/γ-Al2O3 and PtSnZnCa/γ-Al2O3 catalysts were investigated with the aim of understanding the effect of the pretreatment environment on the state of dispersed Pt for ethane dehydrogenation. The catalysts were prepared by the impregnation method and pretreated in different environments like static air (SA), flowing air (FA), and nitrogen (N2) atmospheres. A comprehensive characterization of the catalysts was performed using Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), Temperature-Programmed Reduction (TPR), NH3 Temperature-Programmed Desorption (NH3-TPD), X-ray photoelectron spectroscopy (XPS), and Transmission Electron Microscopy (TEM) techniques. The results reveal that the PtSn on Al2O3 catalyst pretreated in the static air environment (PtSn-SA) exhibits 21% ethylene yield with 95% selectivity at 625 °C. XPS analysis found more platinum and tin on the catalyst surface after static air treatment. The overall acidity of the catalysts decreased after thermal treatment in static air. Elemental mapping demonstrated that Pt agglomeration was pronounced in catalysts calcined under flowing air and nitrogen. These factors are responsible for the enhanced activity of the PtSn-SA catalyst compared to the other catalysts. The addition of Zn and Ca to the PtSn catalysts increases the yield of the catalyst calcined in static air (PtSnZnCa-SA). The PtSnZnCa-SA catalyst showed the highest ethylene yield of 27% with 99% selectivity and highly stable activity at 625 °C for 10 h.
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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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Remediation of Polycyclic Aromatic Hydrocarbon-Contaminated Soil by Using Activated Persulfate with Carbonylated Activated Carbon Supported Nanoscale Zero-Valent Iron
by
Changzhao Chen, Zhe Yuan, Shenshen Sun, Jiacai Xie, Kunfeng Zhang, Yuanzheng Zhai, Rui Zuo, Erping Bi, Yufang Tao and Quanwei Song
Catalysts 2024, 14(5), 311; https://doi.org/10.3390/catal14050311 - 8 May 2024
Abstract
Soil contamination by polycyclic aromatic hydrocarbons (PAHs) has been an environmental issue worldwide, which aggravates the ecological risks faced by animals, plants, and humans. In this work, the composites of nanoscale zero-valent iron supported on carbonylated activated carbon (nZVI-CAC) were prepared and applied
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Soil contamination by polycyclic aromatic hydrocarbons (PAHs) has been an environmental issue worldwide, which aggravates the ecological risks faced by animals, plants, and humans. In this work, the composites of nanoscale zero-valent iron supported on carbonylated activated carbon (nZVI-CAC) were prepared and applied to activate persulfate (PS) for the degradation of PAHs in contaminated soil. The prepared nZVI-CAC catalyst was characterized by scanning electron microscopy (SEM), X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). It was found that the PS/nZVI-CAC system was superior for phenanthrene (PHE) oxidation than other processes using different oxidants (PS/nZVI-CAC > PMS/nZVI-CAC > H2O2/nZVI-CAC) and it was also efficient for the degradation of other six PAHs with different structures and molar weights. Under optimal conditions, the lowest and highest degradation efficiencies for the selected PAHs were 60.8% and 90.7%, respectively. Active SO4−• and HO• were found to be generated on the surface of the catalysts, and SO4−• was dominant for PHE oxidation through quenching experiments. The results demonstrated that the heterogeneous process using activated PS with nZVI-CAC was effective for PAH degradation, which could provide a theoretical basis for the remediation of PAH-polluted soil.
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(This article belongs to the Special Issue Recent Catalytic Progresses for Environmental Remediation and Pollutant Degradation)
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Open AccessCorrection
Correction: Zhou et al. Removal of Emerging Organic Pollutants by Zeolite Mineral (Clinoptilolite) Composite Photocatalysts in Drinking Water and Watershed Water. Catalysts 2024, 14, 216
by
Pengfei Zhou, Fei Wang, Yanbai Shen, Xinhui Duan, Sikai Zhao, Xiangxiang Chen and Jinsheng Liang
Catalysts 2024, 14(5), 310; https://doi.org/10.3390/catal14050310 - 8 May 2024
Abstract
There was an error in the original publication [...]
Full article
Open AccessFeature PaperArticle
Strong and Hierarchical Ni(OH)2/Ni/rGO Composites as Multifunctional Catalysts for Excellent Water Splitting
by
Lixin Wang, Ailing Song, Yue Lu, Manman Duanmu, Zhipeng Ma, Xiujuan Qin and Guangjie Shao
Catalysts 2024, 14(5), 309; https://doi.org/10.3390/catal14050309 - 7 May 2024
Abstract
The lack of efficient and non-precious metal catalysts poses a challenge for electrochemical water splitting in hydrogen and oxygen evolution reactions. Here, we report on the preparation of growing Ni(OH)2 nanosheets in situ on a Ni and graphene hybrid using supergravity electrodeposition
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The lack of efficient and non-precious metal catalysts poses a challenge for electrochemical water splitting in hydrogen and oxygen evolution reactions. Here, we report on the preparation of growing Ni(OH)2 nanosheets in situ on a Ni and graphene hybrid using supergravity electrodeposition and the hydrothermal method. The obtained catalyst displays outstanding performance with small overpotentials of 161.7 and 41 mV to acquire current densities of 100 and 10 mA cm−2 on hydrogen evolution reaction, overpotentials of 407 and 331 mV to afford 100 and 50 mA cm−2 on oxygen evolution reaction, and 10 mA·cm−2 at a cell voltage of 1.43 V for water splitting in 1 M KOH. The electrochemical activity of the catalyst is higher than most of the earth-abundant materials reported to date, which is mainly due to its special hierarchical structure, large surface area, and good electrical conductivity. This study provides new tactics for enhancing the catalytic performance of water electrolysis.
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(This article belongs to the Special Issue Hierarchically Catalysts for Water Splitting and Selective Hydrogenation)
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Open AccessFeature PaperReview
Dehydration of Methanol to Dimethyl Ether—Current State and Perspectives
by
Lucjan Chmielarz
Catalysts 2024, 14(5), 308; https://doi.org/10.3390/catal14050308 - 7 May 2024
Abstract
The main groups of catalytic materials used in the conversion of methanol to dimethyl ether (the MTD process) were presented with respect to their advantages, disadvantages, and the methods of their modifications, resulting in catalysts with improved activity, selectivity, and stability. In particular,
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The main groups of catalytic materials used in the conversion of methanol to dimethyl ether (the MTD process) were presented with respect to their advantages, disadvantages, and the methods of their modifications, resulting in catalysts with improved activity, selectivity, and stability. In particular, the effects of strength, surface concentration, and the type of acid sites, the porous structure and morphology of the catalytic materials, the role of catalyst activators, and others, were considered. The prosed mechanisms of the MTD process over various types of catalysts are presented. Moreover, the advantages of membrane reactors for the MTD process are presented and analysed. The perspectives in the development of effective catalysts for the dehydration of methanol to dimethyl ether are presented and discussed.
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(This article belongs to the Section Catalytic Materials)
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Open AccessArticle
Influence of Power Fluctuation on Ni-Based Electrode Degradation and Hydrogen Evolution Reaction Performance in Alkaline Water Splitting: Probing the Effect of Renewable Energy on Water Electrolysis
by
Congying Liu, Bing Lin, Hailong Zhang, Yingying Wang, Hangzhou Wang, Junlei Tang and Caineng Zou
Catalysts 2024, 14(5), 307; https://doi.org/10.3390/catal14050307 - 6 May 2024
Abstract
The combination of water electrolysis and renewable energy to produce hydrogen is a promising way to solve the climate and energy crisis. However, the fluctuating characteristics of renewable energy not only present a significant challenge to the use of water electrolysis electrodes, but
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The combination of water electrolysis and renewable energy to produce hydrogen is a promising way to solve the climate and energy crisis. However, the fluctuating characteristics of renewable energy not only present a significant challenge to the use of water electrolysis electrodes, but also limit the development of the hydrogen production industry. In this study, the effects of three different types of waveforms (square, step, and triangle, which were used to simulate the power input of renewable energy) on the electrochemical catalysis behavior of Ni plate cathodes for HER was investigated. During the test, the HER performance of the Ni cathode increased at first and then slightly decreased. The fluctuating power led to the degradation of the Ni cathode surface, which enhanced the catalysis effect by increasing the catalytic area and the active sites. However, prolonged operation under power fluctuations could have damaged the morphology of the electrode surface and the substances comprising this surface, potentially resulting in a decline in catalytic efficiency. In addition, the electrochemical catalysis behavior of the prepared FeNiMo-LDH@NiMo/SS cathode when subjected to square-wave potential with different fluctuation amplitudes was also extensively studied. A larger amplitude of fluctuating power led to a change in the overpotential and stability of the LDH electrode, which accelerated the degradation of the cathode. This research provides a technological basis for the coupling of water electrolysis and fluctuating renewable energy and thus offers assistance to the development of the “green hydrogen” industry.
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(This article belongs to the Section Electrocatalysis)
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Open AccessArticle
Study on NH3-SCR Activity and HCl/H2O Tolerance of Titanate-Nanotube-Supported MnOx-CeO2 Catalyst at Low Temperature
by
Qiulin Wang, Feng Liu, Zhihao Wu, Jing Jin, Xiaoqing Lin, Shengyong Lu and Juan Qiu
Catalysts 2024, 14(5), 306; https://doi.org/10.3390/catal14050306 - 5 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)
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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 - 4 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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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 - 3 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+
[...] Read more.
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.
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(This article belongs to the Section Biocatalysis)
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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 - 3 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.
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(This article belongs to the Special Issue Feature Review Papers in Electrocatalysis)
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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 - 2 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
[...] Read more.
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.
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(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 - 2 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 [...]
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(This article belongs to the Special Issue New Trends in the Use of Catalysts for Biofuel and Bioproduct Generation)
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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 - 2 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.
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(This article belongs to the Topic Hydrogen Energy Technologies, 2nd Volume)
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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 - 1 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.
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(This article belongs to the Special Issue Advances in Photo(electro)catalytic Hydrogen Production)
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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
[...] Read more.
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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Open AccessFeature PaperArticle
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
[...] Read more.
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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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.
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(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.
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(This article belongs to the Special Issue Catalysis for Selective Hydrogenation of CO and CO2, 2nd Edition)
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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 [...]
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(This article belongs to the Special Issue Engineering Materials for Catalysis)
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