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Search Results (884)

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Keywords = in situ catalytic

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14 pages, 2584 KiB  
Article
Enhanced Catalytic Ozonation of Formaldehyde over MOFs- Derived MnOx Catalysts with Diverse Morphologies: The Role of Oxygen Vacancies
by Yulin Sun, Yiwei Zhang, Yong He, Wubin Weng, Yanqun Zhu and Zhihua Wang
Catalysts 2025, 15(8), 752; https://doi.org/10.3390/catal15080752 - 6 Aug 2025
Abstract
Metal–organic frameworks (MOFs) have become a hot topic in various research fields nowadays. And MOF-derived metal oxides prepared by the sacrificial template method have been widely applied as catalysts for pollutant removal. Accordingly, we prepared a series of MOF-derived MnOx catalysts with [...] Read more.
Metal–organic frameworks (MOFs) have become a hot topic in various research fields nowadays. And MOF-derived metal oxides prepared by the sacrificial template method have been widely applied as catalysts for pollutant removal. Accordingly, we prepared a series of MOF-derived MnOx catalysts with diverse morphologies (rod-like, flower-like, slab-like) via the pyrolysis of MOF precursors, and the as-prepared MnOx catalysts demonstrated superior performance compared to the one prepared using the co-precipitation method. MnOx-II, with a flower-like structure, exhibited excellent activity for formaldehyde (HCHO) catalytic ozonation at room temperature, reaching complete HCHO conversion at O3/HCHO of 1.5 and more than 90% CO2 selectivity at an O3/HCHO ratio of 2.5. On the basis of various characterization methods, it was clarified that the enhanced catalytic performance of MnOx-II benefited from its larger BET surface area, abundant oxygen vacancies, better redox ability at lower temperature, and more Lewis acid sites. The H2O resistance and stability tests were also conducted. Furthermore, DFT calculations substantiated the enhanced adsorption of HCHO and O3 on oxygen vacancies, while in–situ DRIFTS measurements elucidated the degradation pathway of HCHO during catalytic ozonation through detected intermediates. Full article
(This article belongs to the Special Issue Catalysis Accelerating Energy and Environmental Sustainability)
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23 pages, 5217 KiB  
Article
High-Performance Pd-Pt/α-MnO2 Catalysts for the Oxidation of Toluene
by Ning Dong, Wenjin Wang, Xuelong Zheng, Huan Liu, Jingjing Zhang, Qing Ye and Hongxing Dai
Catalysts 2025, 15(8), 746; https://doi.org/10.3390/catal15080746 - 5 Aug 2025
Abstract
Herein, α-MnO2-supported Pt-Pd bimetal (xPd-yPt/α-MnO2; x and y are the weight loadings (wt%) of Pd and Pt, respectively; x = 0, 0.23, 0.47, 0.93, and 0.92 wt%; and y = 0.91, 0.21, [...] Read more.
Herein, α-MnO2-supported Pt-Pd bimetal (xPd-yPt/α-MnO2; x and y are the weight loadings (wt%) of Pd and Pt, respectively; x = 0, 0.23, 0.47, 0.93, and 0.92 wt%; and y = 0.91, 0.21, 0.46, 0.89, and 0 wt%) catalysts were prepared using the polyvinyl alcohol-protected NaBH4 reduction method. The physicochemical properties of the catalysts were determined by means of various techniques and their catalytic activities for toluene oxidation were evaluated. It was found that among the xPd-yPt/α-MnO2 samples, 0.93Pd-0.89Pt/α-MnO2 showed the best catalytic performance, with the toluene oxidation rate at 156 °C (rcat) and space velocity = 60,000 mL/(g h) being 6.34 × 10−4 mol/(g s), much higher than that of 0.91Pt/α-MnO2 (1.31 × 10−4 mol/(g s)) and that of 0.92Pd/α-MnO2 (6.13 × 10−5 mol/(g s)) at the same temperature. The supported Pd-Pt bimetallic catalysts possessed higher Mn3+/Mn4+ and Oads/Olatt molar ratios, which favored the enhancement in catalytic activity of the supported Pd-Pt bimetallic catalysts. Furthermore, the 0.47Pd-0.46Pt/α-MnO2 sample showed better resistance to sulfur dioxide poisoning. The partial deactivation of 0.47Pd-0.46Pt/α-MnO2 was attributed to the formation of sulfate species on the sample surface, which covered the active site of the sample, thus decreasing its toluene oxidation activity. In addition, the in situ DRIFTS results demonstrated that benzaldehyde and benzoate were the intermediate products of toluene oxidation. Full article
(This article belongs to the Section Environmental Catalysis)
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12 pages, 2954 KiB  
Article
Electrochemical Hydrogenation of Furfural Enhancing Furfuryl Alcohol Selectivity over Flower-like Zn-Based MBON-2 in Alkaline Medium
by Yingxin Zhang, Hengxing Qiu, Chunyu Shen, Shuwen Hou, Qiuju Fu and Xuebo Zhao
Chemistry 2025, 7(4), 124; https://doi.org/10.3390/chemistry7040124 - 30 Jul 2025
Viewed by 238
Abstract
To address the low selectivity in the electrocatalytic conversion of furfural (FFR) to furfuryl alcohol (FFA) under alkaline conditions, a Zn-based metal–organic framework (MBON-2) featuring a 3D hierarchical flower-like architecture self-assembled from nanosheets was synthesized via a simple hydrothermal method. Under optimal conditions, [...] Read more.
To address the low selectivity in the electrocatalytic conversion of furfural (FFR) to furfuryl alcohol (FFA) under alkaline conditions, a Zn-based metal–organic framework (MBON-2) featuring a 3D hierarchical flower-like architecture self-assembled from nanosheets was synthesized via a simple hydrothermal method. Under optimal conditions, MBON-2 exhibited an extremely high selectivity of FFA (100%) and a high Faradaic efficiency (FE) of 93.19% at −0.2 V vs. RHE. Electrochemical impedance spectroscopy (EIS) revealed the excellent electron transfer and mass transport properties of MBON-2. In addition, in situ Fourier transform infrared (FTIR) spectroscopy studies confirmed the adsorption of FFR molecules onto the Zn and B sites of MBON-2 during the ECH of FFR, providing key insights into the hydrogenation mechanism. The numerous exposed B and Zn sites of the MBON-2, as well as its robust structural stability contributed to its outstanding catalytic performance in the electrochemical hydrogenation (ECH) of FFR. This work provides valuable guidelines for developing efficient Zn-based catalysts for the ECH of FFR. Full article
(This article belongs to the Special Issue Catalytic Conversion of Biomass and Its Derivatives)
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16 pages, 2707 KiB  
Article
Ultrasound-Activated BiOI/Ti3C2 Heterojunctions in 3D-Printed Piezocatalytic Antibacterial Scaffolds for Infected Bone Defects
by Juntao Xie, Zihao Zhang, Zhiheng Yu, Bingxin Sun, Yingxin Yang, Guoyong Wang and Cijun Shuai
Materials 2025, 18(15), 3533; https://doi.org/10.3390/ma18153533 - 28 Jul 2025
Viewed by 278
Abstract
Piezocatalytic therapy (PCT) is a promising strategy for combating implant-associated infections due to its high tissue penetration depth and non-invasive nature. However, its catalytic efficiency remains limited by inefficient electron–hole separation. In this work, an ultrasound-responsive heterojunction (BiOI/Ti3C2) was [...] Read more.
Piezocatalytic therapy (PCT) is a promising strategy for combating implant-associated infections due to its high tissue penetration depth and non-invasive nature. However, its catalytic efficiency remains limited by inefficient electron–hole separation. In this work, an ultrasound-responsive heterojunction (BiOI/Ti3C2) was fabricated through in situ growth of bismuth iodide oxide on titanium carbide nanosheets. Subsequently, we integrated BiOI/Ti3C2 into poly(e-caprolactone) (PCL) scaffolds using selective laser sintering. The synergistic effect between BiOI and Ti3C2 significantly facilitated the redistribution of piezo-induced charges under ultrasound irradiation, effectively suppressing electron–hole recombination. Furthermore, abundant oxygen vacancies in BiOI/Ti3C2 provide more active sites for piezocatalytic reactions. Therefore, it enables ultrahigh reactive oxygen species (ROS) yields under ultrasound irradiation, achieving eradication rates of 98.87% for Escherichia coli (E. coli) and 98.51% for Staphylococcus aureus (S. aureus) within 10 minutes while maintaining cytocompatibility for potential tissue integration. This study provides a novel strategy for the utilization of ultrasound-responsive heterojunctions in efficient PCT therapy and bone regeneration. Full article
(This article belongs to the Section Biomaterials)
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16 pages, 4134 KiB  
Article
Effect of Oxygen-Containing Functional Groups on the Performance of Palladium/Carbon Catalysts for Electrocatalytic Oxidation of Methanol
by Hanqiao Xu, Hongwei Li, Xin An, Weiping Li, Rong Liu, Xinhong Zhao and Guixian Li
Catalysts 2025, 15(8), 704; https://doi.org/10.3390/catal15080704 - 24 Jul 2025
Viewed by 326
Abstract
The methanol oxidation reaction (MOR) of direct methanol fuel cells (DMFCs) is limited by the slow kinetic process and high reaction energy barrier, significantly restricting the commercial application of DMFCs. Therefore, developing MOR catalysts with high activity and stability is very important. In [...] Read more.
The methanol oxidation reaction (MOR) of direct methanol fuel cells (DMFCs) is limited by the slow kinetic process and high reaction energy barrier, significantly restricting the commercial application of DMFCs. Therefore, developing MOR catalysts with high activity and stability is very important. In this paper, oxygen-functionalised activated carbon (FAC) with controllable oxygen-containing functional groups was prepared by adjusting the volume ratio of H2SO3/HNO3 mixed acid, and Pd/AC and Pd/FAC catalysts were synthesised via the hydrazine hydrate reduction method. A series of characterisation techniques and electrochemical performance tests were used to study the catalyst. The results showed that when V(H2SO3):V(HNO3) = 2:3, more defects were generated on the surface of the AC, and more oxygen-containing functional groups represented by C=O and C–OH were attached to the surface of the support, which increased the anchor sites of Pd and improved the dispersion of Pd nanoparticles (Pd NPs) on the support. At the same time, the mass–specific activity of Pd/FAC for MOR was 2320 mA·mgPd, which is 1.5 times that of Pd/AC, and the stability was also improved to a certain extent. In situ infrared spectroscopy further confirmed that oxygen functionalisation treatment promoted the formation and transformation of *COOH intermediates, accelerated the transformation of COL into COB, reduced the poisoning of COads species adsorbed to the catalyst, optimised the reaction path and improved the catalytic kinetic performance. Full article
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13 pages, 25732 KiB  
Article
Simple Cobalt Nanoparticle-Catalyzed Reductive Amination for Selective Synthesis of a Broad Range of Primary Amines
by Bingxiao Zheng, Liqin Yang, Yashuang Hei, Ling Yu, Sisi Wen, Lisi Ba, Long Ao and Zhiju Zhao
Molecules 2025, 30(15), 3089; https://doi.org/10.3390/molecules30153089 - 23 Jul 2025
Viewed by 228
Abstract
In the field of green chemistry, the development of more sustainable and cost-efficient methods for synthesizing primary amines is of paramount importance, with catalyst research being central to this effort. This work presents a facile, aqueous-phase synthesis of highly active cobalt catalysts (Co-Ph@SiO [...] Read more.
In the field of green chemistry, the development of more sustainable and cost-efficient methods for synthesizing primary amines is of paramount importance, with catalyst research being central to this effort. This work presents a facile, aqueous-phase synthesis of highly active cobalt catalysts (Co-Ph@SiO2(x)) via pyrolysis of silica-supported cobalt–phenanthroline complexes. The optimized Co-Ph@SiO2(900) catalyst achieved exceptional performance (>99% conversion, >98% selectivity) in the reductive amination of acetophenone to 1-phenylethanamine using NH3/H2. Systematic studies revealed that its exceptional performance originates from the in situ pyrolysis of the cobalt–phyllosilicate complex. This process promotes the uniform distribution of metal cobalt nanoparticles, simultaneously enhancing porosity and imparting bifunctional (acidic and basic) properties to the catalyst, resulting in outstanding catalytic activity and selectivity. The catalyst demonstrated broad applicability, efficiently converting diverse ketones (aryl-alkyl, dialkyl, bioactive) and aldehydes (halogenated, heterocyclic, biomass-derived) into primary amines with high yields (up to 99%) and chemoselectivity (>40 examples). This sustainable, non-noble metal-based catalyst system offers significant potential for industrial primary amine synthesis and provides a versatile tool for developing highly selective and active heterogeneous catalysts. Full article
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11 pages, 2972 KiB  
Article
ZnCu Metal–Organic Framework Electrocatalysts for Efficient Ammonia Decomposition to Hydrogen
by Mingguang Ouyang, Geng Chen, Weitao Ning, Xiaoyang Wang, Xiaojiang Mu and Lei Miao
Energies 2025, 18(14), 3871; https://doi.org/10.3390/en18143871 - 21 Jul 2025
Viewed by 335
Abstract
The electrocatalytic decomposition of ammonia represents a promising route for sustainable hydrogen production, yet current systems rely heavily on noble metal catalysts with prohibitive costs and limited durability. A critical challenge lies in developing non-noble electrocatalysts that simultaneously achieve high active site exposure, [...] Read more.
The electrocatalytic decomposition of ammonia represents a promising route for sustainable hydrogen production, yet current systems rely heavily on noble metal catalysts with prohibitive costs and limited durability. A critical challenge lies in developing non-noble electrocatalysts that simultaneously achieve high active site exposure, optimized electronic configurations, and robust structural stability. Addressing these requirements, this study strategically engineered Cu-doped ZIF-8 architectures via in situ growth on nickel foam (NF) substrates through a facile room-temperature hydrothermal synthesis approach. Systematic optimization of the Cu/Zn molar ratio revealed that Cu0.7Zn0.3-ZIF/NF achieved optimal performance, exhibiting a distinctive nanoflower-like architecture that substantially increased accessible active sites. The hybrid catalyst demonstrated superior electrocatalytic performance with a current density of 124 mA cm−2 at 1.6 V vs. RHE and a notably low Tafel slope of 30.94 mV dec−1, outperforming both Zn-ZIF/NF (39.45 mV dec−1) and Cu-ZIF/NF (31.39 mV dec−1). Combined XPS and EDS analyses unveiled a synergistic electronic structure modulation between Zn and Cu, which facilitated charge transfer and enhanced catalytic efficiency. A gas chromatography product analysis identified H2 and N2 as the primary gaseous products, confirming the predominant occurrence of the ammonia oxidation reaction (AOR). This study not only presents a noble metal-free electrocatalyst with exceptional efficiency and durability for ammonia decomposition but also demonstrates the significant potential of MOF-derived materials in sustainable hydrogen production technologies. Full article
(This article belongs to the Special Issue Advanced Energy Conversion Technologies Based on Energy Physics)
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19 pages, 3119 KiB  
Article
Aquathermolytic Upgrading of Zarafshanian Extra Heavy Oil Using Ammonium Alum
by Amirjon Ali Akhunov, Firdavs Aliev, Nurali Mukhamadiev, Oscar Facknwie Kahwir, Alexey Dengaev, Mohammed Yasin Majeed, Mustafa Esmaeel, Abdulvahhab Al-Qaz, Oybek Mirzaev and Alexey Vakhin
Molecules 2025, 30(14), 3013; https://doi.org/10.3390/molecules30143013 - 18 Jul 2025
Viewed by 343
Abstract
The growing global demand for energy necessitates the efficient utilization of unconventional petroleum resources, particularly heavy oil reserves. However, extracting, transporting, and processing these resources remain challenging due to their low mobility, low API gravity, and significant concentrations of resins, asphaltenes, heteroatoms, and [...] Read more.
The growing global demand for energy necessitates the efficient utilization of unconventional petroleum resources, particularly heavy oil reserves. However, extracting, transporting, and processing these resources remain challenging due to their low mobility, low API gravity, and significant concentrations of resins, asphaltenes, heteroatoms, and metals. In recent years, various in situ upgrading techniques have been explored to enhance heavy oil quality, with catalytic aquathermolysis emerging as a promising approach. The effectiveness of this process largely depends on the development of cost-effective, environmentally friendly catalysts. This study investigates the upgrading performance of water-soluble ammonium alum, (NH4)Al(SO4)2·12H2O, for an extra-heavy oil sample from the Zarafshan Depression, located along the Tajikistan–Uzbekistan border. Comprehensive analyses demonstrate that the catalyst facilitates the breakdown of heavy oil components, particularly resins and asphaltenes, into lighter fractions. As a result, oil viscosity was significantly reduced by 94%, while sulfur content decreased from 896 ppm to 312 ppm. Furthermore, thermogravimetric (TG-DTG) analysis, coupled with Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD), revealed that the thermal decomposition of ammonium alum produces catalytically active Al2O3 nanoparticles. These findings suggest that ammonium alum is a highly effective water-soluble pre-catalyst for hydrothermal upgrading, offering a viable and sustainable solution for the development of extra-heavy oil fields. Full article
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22 pages, 7389 KiB  
Article
FeCo-LDH/CF Cathode-Based Electrocatalysts Applied to a Flow-Through Electro-Fenton System: Iron Cycling and Radical Transformation
by Heng Dong, Yuying Qi, Zhenghao Yan, Yimeng Feng, Wenqi Song, Fengxiang Li and Tao Hua
Catalysts 2025, 15(7), 685; https://doi.org/10.3390/catal15070685 - 15 Jul 2025
Viewed by 344
Abstract
In this investigation, a hierarchical FeCo-layered double hydroxide (FeCo-LDH) electrochemical membrane material was prepared by a simple in situ hydrothermal method. The prepared material formed a 3D honeycomb-structured FeCo-LDH-modified carbon felt (FeCo-LDH/CF) catalytic layer with uniform open pores on a CF substrate with [...] Read more.
In this investigation, a hierarchical FeCo-layered double hydroxide (FeCo-LDH) electrochemical membrane material was prepared by a simple in situ hydrothermal method. The prepared material formed a 3D honeycomb-structured FeCo-LDH-modified carbon felt (FeCo-LDH/CF) catalytic layer with uniform open pores on a CF substrate with excellent catalytic activity and was served as the cathode in a flow-through electro-Fenton (FTEF) reactor. The electrocatalyst demonstrated excellent treatment performance (99%) in phenol simulated wastewater (30 mg L−1) under the optimized operating conditions (applied voltage = 3.5 V, pH = 6, influent flow rate = 15 mL min−1) of the FTEF system. The high removal rate could be attributed to (i) the excellent electrocatalytic oxidation performance and low interfacial charge transfer resistance of the FeCo-LDH/CF electrode as the cathode, (ii) the ability of the synthesized FeCo-LDH to effectively promote the conversion of H2O2 to •OH under certain conditions, and (iii) the flow-through system improving the mass transfer efficiency. In addition, the degradation process of pollutants within the FTEF system was additionally illustrated by the •OH dominant ROS pathway based on free radical burst experiments and electron paramagnetic resonance tests. This study may provide new insights to explore reaction mechanisms in FTEF systems. Full article
(This article belongs to the Special Issue Environmentally Friendly Catalysis for Green Future)
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26 pages, 9003 KiB  
Article
A Pilot-Scale Gasifier Freeboard Equipped with Catalytic Filter Candles for Particulate Abatement and Tar Conversion: 3D-CFD Simulations and Experimental Tests
by Alessandra Tacconi, Pier Ugo Foscolo, Sergio Rapagnà, Andrea Di Carlo and Alessandro Antonio Papa
Processes 2025, 13(7), 2233; https://doi.org/10.3390/pr13072233 - 12 Jul 2025
Viewed by 450
Abstract
This work deals with the catalytic steam reforming of raw syngas to increase the efficiency of coupling gasification with downstream processes (such as fuel cells and catalytic chemical syntheses) by producing high-temperature, ready-to-use syngas without cooling it for cleaning and conditioning. Such a [...] Read more.
This work deals with the catalytic steam reforming of raw syngas to increase the efficiency of coupling gasification with downstream processes (such as fuel cells and catalytic chemical syntheses) by producing high-temperature, ready-to-use syngas without cooling it for cleaning and conditioning. Such a combination is considered a key point for the future exploitation of syngas produced by steam gasification of biogenic solid fuel. The design and construction of an integrated gasification and gas conditioning system were proposed approximately 20 years ago; however, they still require further in-depth study for practical applications. A 3D model of the freeboard of a pilot-scale, fluidized bed gasification plant equipped with catalytic ceramic candles was used to investigate the optimal operating conditions for in situ syngas upgrading. The global kinetic parameters for methane and tar reforming reactions were determined experimentally. A fluidized bed gasification reactor (~5 kWth) equipped with a 45 cm long segment of a fully commercial filter candle in its freeboard was used for a series of tests at different temperatures. Using a computational fluid dynamics (CFD) description, the relevant parameters for apparent kinetic equations were obtained in the frame of a first-order reaction model to describe the steam reforming of key tar species. As a further step, a CFD model of the freeboard of a 100 kWth gasification plant, equipped with six catalytic ceramic candles, was developed in ANSYS FLUENT®. The composition of the syngas input into the gasifier freeboard was obtained from experimental results based on the pilot-scale plant. Simulations showed tar catalytic conversions of 80% for toluene and 41% for naphthalene, still insufficient compared to the threshold limits required for operating solid oxide fuel cells (SOFCs). An overly low freeboard temperature level was identified as the bottleneck for enhancing gas catalytic conversions, so further simulations were performed by injecting an auxiliary stream of O2/steam (50/50 wt.%) through a series of nozzles at different heights. The best simulation results were obtained when the O2/steam stream was fed entirely at the bottom of the freeboard, achieving temperatures high enough to achieve a tar content below the safe operating conditions for SOFCs, with minimal loss of hydrogen content or LHV in the fuel gas. Full article
(This article belongs to the Section Chemical Processes and Systems)
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18 pages, 3089 KiB  
Article
Biomass-Derived Catalysts with Dual Functions for Electrochemical Water Splitting
by Wangchuang Zhu, Xinghua Zhang, Qi Zhang, Lungang Chen, Xiuzheng Zhuang and Longlong Ma
Energies 2025, 18(14), 3592; https://doi.org/10.3390/en18143592 - 8 Jul 2025
Viewed by 253
Abstract
With the continuous consumption of fossil energy and the related environmental problems, clean energy, especially the hydrogen energy-derived water electrolysis, has attracted wide attention. However, as a result of the high energy consumption of water electrolysis and the limitations of single-function catalysts, there [...] Read more.
With the continuous consumption of fossil energy and the related environmental problems, clean energy, especially the hydrogen energy-derived water electrolysis, has attracted wide attention. However, as a result of the high energy consumption of water electrolysis and the limitations of single-function catalysts, there is an urgent need for cheap and simple-to-make bifunctional catalysts. In this work, based on the NiFe-LDH that is usually used for OER (Oxygen Evolution Reaction), doping of heteroatoms was carried out and a bifunctional catalyst could be then prepared using biomass as the carbon source. The preparation of catalyst precursors and in situ reduction were performed through the coupling process of hydrothermal and pyrolysis to enhance the electrolytic activity of the catalyst. Results showed that the overpotentials required to reach a current density of 10 mA·cm−2 for the HER and OER processes were 305.2 mV and 310.4 mV, respectively, which are superior to the commercial catalysts. In the subsequent characterization, the structural characteristics of the catalyst support and their structure–activity correlation with active metals were systematically investigated by TEM, XRD, and XPS analysis, providing mechanistic insights into the catalytic behavior. The basic catalytic mechanisms of HER and OER were also obtained: the HER process was due to the formation of a Ni3Fe alloy structure during catalyst preparation, which changed the electronic structure of the catalyst, while the OER process was induced by the formation of a NiOOH intermediate. The research results are expected to provide new ideas and data support for the preparation of bifunctional catalysts. Full article
(This article belongs to the Section A4: Bio-Energy)
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20 pages, 925 KiB  
Review
Catalytic Ammonia Combustion: Legacy Catalytic Burner Designs and Catalyst Requirements for In Situ Hydrogen Production
by Khalid Al Sadi, Ebrahim Nadimi and Dawei Wu
Energies 2025, 18(13), 3505; https://doi.org/10.3390/en18133505 - 2 Jul 2025
Cited by 1 | Viewed by 411
Abstract
Ammonia is increasingly recognised as a promising carbon-free fuel and hydrogen carrier due to its high hydrogen content, ease of liquefaction, and existing global infrastructure. However, its direct utilisation in combustion systems poses significant challenges, including low flame speed, high ignition temperature, and [...] Read more.
Ammonia is increasingly recognised as a promising carbon-free fuel and hydrogen carrier due to its high hydrogen content, ease of liquefaction, and existing global infrastructure. However, its direct utilisation in combustion systems poses significant challenges, including low flame speed, high ignition temperature, and the formation of nitrogen oxides (NOX). This review explores catalytic ammonia cracking as a viable method to enhance combustion through in situ hydrogen production. It evaluates traditional catalytic burner designs originally developed for hydrocarbon fuels and assesses their adaptability for ammonia-based applications. Special attention is given to ruthenium- and nickel-based catalysts supported on various oxides and nanostructured materials, evaluating their ammonia conversion efficiency, resistance to sintering, and thermal stability. The impact of the main operational parameters, including reaction temperature and gas hourly space velocity (GHSV), is also discussed. Strategies for combining partial ammonia cracking with stable combustion are studied, with practical issues such as catalyst degradation, NOX regulation, and system scalability. The analysis highlights recent advancements in structural catalyst support, which have potential for industrial-scale application. This review aims to provide future development of low-emission, high-efficiency catalytic burner systems and advance ammonia’s role in next-generation hydrogen energy technologies. Full article
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14 pages, 3484 KiB  
Article
Al2O3@SiO2 Supported NiMo Catalyst with Hierarchical Meso-Macroporous Structure for Hydrodemetallization
by Weichu Li, Jun Bao, Shuangqin Zeng, Jinbao Zheng, Weiping Fang, Xiaodong Yi, Qinghe Yang and Weikun Lai
Catalysts 2025, 15(7), 646; https://doi.org/10.3390/catal15070646 - 1 Jul 2025
Viewed by 387
Abstract
The pore structure of a hydrotreating catalyst plays a pivotal role in hydrodemetallization (HDM) reactions. To effectively construct a meso-macroporous catalyst, we employed a CTAB-guided in situ TEOS hydrolysis approach to prepare silica-coated γ-Al2O3@SiO2 composite supports. The silica [...] Read more.
The pore structure of a hydrotreating catalyst plays a pivotal role in hydrodemetallization (HDM) reactions. To effectively construct a meso-macroporous catalyst, we employed a CTAB-guided in situ TEOS hydrolysis approach to prepare silica-coated γ-Al2O3@SiO2 composite supports. The silica shell incorporation significantly enhances specific surface area and reduces the metal–support interactions, thereby improving the dispersion of NiMo active components and boosting the deposition of metal impurity. Hence, the NiMo/Al2O3@SiO2 catalyst (2.8 wt.% NiO, 4.3 wt.% MoO3) exhibits much higher HDM activity than that of NiMo/Al2O3. This is evidenced by markedly higher demetallization rate constant (1.38 h−1) and turnover frequency (0.56 h−1) of the NiMo/Al2O3@SiO2. The NiMo/Al2O3@SiO2 catalyst further demonstrates excellent recyclability during sequential HDM reactions. This superior catalytic behavior stems from the hierarchical meso-macroporous structure, which simultaneously facilitates the deposition of metal impurities and mitigates deactivation by pore blockage. Full article
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15 pages, 5017 KiB  
Article
Constructing Hydrazone-Linked Chiral Covalent Organic Frameworks with Different Pore Sizes for Asymmetric Catalysis
by Haichen Huang, Kai Zhang, Yuexin Zheng, Hong Chen, Dexuan Cai, Shengrun Zheng, Jun Fan and Songliang Cai
Catalysts 2025, 15(7), 640; https://doi.org/10.3390/catal15070640 - 30 Jun 2025
Viewed by 336
Abstract
Chiral covalent organic frameworks (COFs) hold great promise in heterogeneous asymmetric catalysis due to their designable structures and well-defined chiral microenvironments. However, precise control over the pore size of chiral COFs to optimize asymmetric catalytic performance remains challenging. Herein, we designed a proline-derived [...] Read more.
Chiral covalent organic frameworks (COFs) hold great promise in heterogeneous asymmetric catalysis due to their designable structures and well-defined chiral microenvironments. However, precise control over the pore size of chiral COFs to optimize asymmetric catalytic performance remains challenging. Herein, we designed a proline-derived dihydrazide chiral monomer (L-DBP-Boc), which was subjected to Schiff-base reactions with two aromatic aldehydes of different lengths, 1,3,5-triformyl phloroglucinol (BTA) and 4,4′,4″-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde (TZ), to construct two hydrazone-linked chiral COFs with distinct pore sizes (L-DBP-BTA COF and L-DBP-TZ COF). Interestingly, the Boc protecting groups were removed in situ during COF synthesis. We systematically investigated the catalytic performance of these two chiral COFs in asymmetric aldol reactions and found that their pore sizes significantly influenced both catalytic activity and enantioselectivity. The large-pore L-DBP-TZ COF (pore size: 3.5 nm) exhibited superior catalytic performance under aqueous conditions at room temperature, achieving a yield of 98% and an enantiomeric excess (ee) value of 78%. In contrast, the small-pore L-DBP-BTA COF (pore size: 2.0 nm) showed poor catalytic performance. Compared to L-DBP-BTA COF, L-DBP-TZ COF demonstrated a 1.69-fold increase in yield and a 1.56-fold enhancement in enantioselectivity, possibly attributed to the facilitated diffusion and transport of substrates and products within the larger pore, thus improving the accessibility of active sites. This study presents a facile synthesis of pyrrolidine-functionalized chiral COFs and establishes the possible structure–activity relationship in their asymmetric catalysis, offering new insights for the design of efficient chiral COF catalysts. Full article
(This article belongs to the Special Issue Asymmetric Catalysis: Recent Progress and Future Perspective)
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14 pages, 7989 KiB  
Article
Polyacrylonitrile/Silver Nanoparticles Composite for Catalytic Dye Reduction and Real-Time Monitoring
by Christian Narváez-Muñoz, Sebastián Ponce, Carlos Durán, Cristina Aguayo, Cesar Portero, Joseph Guamán, Alexis Debut, Magaly Granda, Frank Alexis, Ezequiel Zamora-Ledezma and Camilo Zamora-Ledezma
Polymers 2025, 17(13), 1762; https://doi.org/10.3390/polym17131762 - 26 Jun 2025
Viewed by 371
Abstract
This study presents a one-step electrospinning method to fabricate polyacrylonitrile (PAN) nanofibers embedded with green-synthesized silver nanoparticles (AgNPs) for efficient catalytic dye reduction and real-time monitoring. Utilizing avocado seed extract for AgNP synthesis, the resulting composite nanofibers exhibit uniform nanoparticle dispersion and enhanced [...] Read more.
This study presents a one-step electrospinning method to fabricate polyacrylonitrile (PAN) nanofibers embedded with green-synthesized silver nanoparticles (AgNPs) for efficient catalytic dye reduction and real-time monitoring. Utilizing avocado seed extract for AgNP synthesis, the resulting composite nanofibers exhibit uniform nanoparticle dispersion and enhanced surface area, significantly improving adsorption and catalytic properties. The membranes demonstrated outstanding catalytic activity, achieving over 95% degradation of methyl orange within 45 min when paired with sodium borohydride, and maintained structural integrity and performance over ten reuse cycles. The integration of a novel 3D-printed support enabled scalability, allowing a 60-fold increase in treatment volume without compromising efficiency. Additionally, the composite’s electrical conductivity changes enabled the real-time monitoring of the dye reduction process, highlighting its dual functionality as both catalyst and sensor. These results encourage the potential of PAN/AgNPs supported on a 3D-printed structure nanofiber membranes for scalable, sustainable wastewater treatment and in situ reaction monitoring. Full article
(This article belongs to the Section Polymer Composites and Nanocomposites)
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