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12 pages, 3285 KiB  
Article
Ceria Promoted Ni/SiO2 as an Efficient Catalyst for Carbon Dioxide Reforming of Methane
by Hua-Ping Ren, Lin-Feng Zhang, Yu-Xuan Hui, Xin-Ze Wu, Shao-Peng Tian, Si-Yi Ding, Qiang Ma and Yu-Zhen Zhao
Catalysts 2025, 15(7), 649; https://doi.org/10.3390/catal15070649 - 2 Jul 2025
Viewed by 411
Abstract
The Ni/SiO2 and the ceria-promoted Ni-CeO2/SiO2 were prepared by the impregnation method and co-impregnation method, respectively. The performance of the carbon dioxide reforming of methane (CDR) over Ni/SiO2 and Ni-CeO2/SiO2 was investigated under the conditions [...] Read more.
The Ni/SiO2 and the ceria-promoted Ni-CeO2/SiO2 were prepared by the impregnation method and co-impregnation method, respectively. The performance of the carbon dioxide reforming of methane (CDR) over Ni/SiO2 and Ni-CeO2/SiO2 was investigated under the conditions of CH4/CO2 = 1.0, T = 800 °C, and GHSV = 60,000 mL·g−1·h−1. As a result, a high CDR performance, especially stability, was obtained over Ni-CeO2/SiO2, in which the conversion of CH4 was very similar to that of the thermodynamic equilibrium (88%), and a negligible decrease in CH4 conversion was observed after 50 h of the CDR reaction. Ni/SiO2 and Ni-CeO2/SiO2 before and after the CDR reaction were subjected to structural characterization by XRD, TEM, TG–DSC, and physical adsorption. It was found that the addition of CeO2 into Ni/SiO2 significantly affected its surface area, the size and dispersion of Ni, the reduction behavior, and the coking properties. Moreover, the redox property of Ce3+-Ce4+, which accelerates the gasification of the coke, made Ni-CeO2/SiO2 successfully operate for 50 h without observable deactivation. Thus, the developed catalyst is very promising for the CDR. Full article
(This article belongs to the Special Issue Trends and Prospects in Catalysis for Sustainable CO2 Conversion)
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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 377
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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19 pages, 5729 KiB  
Article
Highly Engineered Cr-In/H-SSZ-39 Catalyst for Enhanced Performance in CH4-SCR of NOx
by Jiuhu Zhao, Jingjing Jiang, Guanyu Chen, Meng Wang, Xiaoyuan Zuo, Yanjiao Bi and Rongshu Zhu
Molecules 2025, 30(13), 2691; https://doi.org/10.3390/molecules30132691 - 21 Jun 2025
Viewed by 355
Abstract
The selective catalytic reduction of NOx with CH4 (CH4-SCR) holds the potential to simultaneously abate harmful NOx and CH4 greenhouse gases. In this study, a series of bimetallic M-In/H-SSZ-39 catalysts (where M represents Cr, Co, Ce, and [...] Read more.
The selective catalytic reduction of NOx with CH4 (CH4-SCR) holds the potential to simultaneously abate harmful NOx and CH4 greenhouse gases. In this study, a series of bimetallic M-In/H-SSZ-39 catalysts (where M represents Cr, Co, Ce, and Fe) were prepared via an ion exchange method and subsequently evaluated for their CH4-SCR activity. The influences of the preparation parameters, including the metal ion concentration and calcination temperature, as well as the operating conditions, such as the CH4/NO ratio, O2 concentration, water vapor content, and gas hourly space velocity (GHSV), on the catalytic activity of the optimal Cr-In/H-SSZ-39 catalyst were meticulously examined. The results revealed that the Cr-In/H-SSZ-39 catalyst exhibited peak CH4-SCR catalytic performance when the Cr(NO3)3 concentration was 0.0075 M, the In(NO3)3 concentration was 0.066 M, and the calcination temperature was 500 °C. Under optimal operating conditions, namely GHSV of 10,000 h−1, 400 ppm NO, 800 ppm CH4, 15 vol% O2, and 6 vol% H2O, the NOx conversion rate reached 93.4%. To shed light on the excellent performance of Cr-In/H-SSZ-39 under humid conditions, a comparative analysis of the crystalline phase, chemical composition, pore structure, surface chemical state, surface acidity, and redox properties of Cr-In/H-SSZ-39 and In/H-SSZ-39 was conducted. The characterization results indicated that the incorporation of Cr into In/H-SSZ-39 enhanced its acidity and also facilitated the generation of InO+ active species, which promoted the oxidation of NO and the activation of CH4, respectively. A synergistic effect was observed between Cr and In species, which significantly improved the redox properties of the catalyst. Consequently, the activated CH4 could further interact with InO+ to produce carbon-containing intermediates such as HCOO, which ultimately reacted with nitrate-based intermediates to yield N2, CO2, and H2O. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Sustainability and Carbon-Neutrality)
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13 pages, 3851 KiB  
Article
Ce/Mn Co-Doping Induces Synergistic Effects for Low-Temperature NH3-SCR over Ba2Ti5O12 Catalysts
by Wei Zhao, Wang Zhao, Haiwen Wang, Dingwen Zhang, Qian Wang, Aijian Wang, Danhong Shang and Qin Zhong
Catalysts 2025, 15(6), 593; https://doi.org/10.3390/catal15060593 - 15 Jun 2025
Viewed by 564
Abstract
To develop eco-friendly low-temperature NH3-SCR catalysts for the non-electric industry, a series of CeMn-modified Ba2Ti5O12 catalysts were synthesized using the sol-gel method to achieve denitrification. Activity tests revealed that Ce-Mn-modified Ba2Ti5O12 [...] Read more.
To develop eco-friendly low-temperature NH3-SCR catalysts for the non-electric industry, a series of CeMn-modified Ba2Ti5O12 catalysts were synthesized using the sol-gel method to achieve denitrification. Activity tests revealed that Ce-Mn-modified Ba2Ti5O12 catalysts exhibit excellent low-temperature denitrification performance with a broad operational temperature window. Characterization through XRD, XPS, BET, NH3-TPD, and EPR indicated that Ce-Mn modification enhances surface oxygen chemisorption and increases acidity, significantly improving NOx reduction. Notably, the optimal catalyst achieved NOx conversion rates exceeding 90% within the temperature range of 90 to 240 °C under a gas hourly space velocity (GHSV) of 28,000 h−1. In particular, the coexistence of Ce and Mn species promotes the oxidation of NO to NO2, facilitating the “fast SCR” reaction. The abundance of valence states further enhances the catalyst’s ultra-low-temperature NH3-SCR denitration performance. Full article
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15 pages, 1691 KiB  
Article
Simultaneous Adsorption and Purification of Low-Concentration SO2 and H2S
by Xiaoli Cao, Lin Zhang, Qun Cui and Haiyan Wang
Molecules 2025, 30(11), 2302; https://doi.org/10.3390/molecules30112302 - 24 May 2025
Viewed by 468
Abstract
The simultaneous adsorption and removal of low concentrations of SO2 and H2S using experimental and simulation methods were investigated in this paper. The adsorption breakthrough performance of the single-component SO2 or H2S was determined in the activated [...] Read more.
The simultaneous adsorption and removal of low concentrations of SO2 and H2S using experimental and simulation methods were investigated in this paper. The adsorption breakthrough performance of the single-component SO2 or H2S was determined in the activated carbon fixed-bed test. Langmuir and extended Langmuir equations in the Aspen adsorption module were used to describe the adsorption equilibrium of the single and bi-component SO2 and H2S system, respectively. The effects of gas hourly space velocity (GHSV) and temperature on the dynamic adsorption process of the bi-component SO2/H2S system were investigated. The concentration distribution and adsorption capacity of SO2/H2S in the bed were simulated. The results showed that the simulation for the single-component breakthrough curves of SO2 or H2S agreed well with the experimental data. It indicated that the model and simulation yielded engineering acceptable accuracy. For the bi-component adsorption, the competitive adsorption effect was observed, with H2S as the weakly adsorbed component and SO2 as the strongly adsorbed component. The dynamic adsorption process showed the sequence of initial adsorption, breakthrough, replacement, and equilibrium. The breakthrough curves were characterized by the distinct hump (roll-up) for H2S, resulting from the replacement effect. The influence of GHSV and the temperature on the dynamic adsorption process were investigated, revealing that the lower velocity and temperature enhanced the adsorption. This work might be used for the design and optimization of adsorption bed for the simultaneous removal of SO2 and H2S in Claus tail gas. Full article
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13 pages, 2020 KiB  
Article
Efficient Hydrogen Production from Ammonia Using Ru Nanoparticles on Ce-Based Metal–Organic Framework (MOF)-Derived CeO2 with Oxygen Vacancies
by Wenying Wu, Wenhao Yao, Yitong Liu, Senliang Xi and Teng Zhang
Molecules 2025, 30(11), 2301; https://doi.org/10.3390/molecules30112301 - 23 May 2025
Viewed by 572
Abstract
Ammonia is a promising hydrogen storage material because it is easy to store and decompose into COX-free hydrogen. A Ru-based catalyst exhibits good catalytic performance in ammonia decomposition, and enhancing the interaction between the Ru atoms and the support is an [...] Read more.
Ammonia is a promising hydrogen storage material because it is easy to store and decompose into COX-free hydrogen. A Ru-based catalyst exhibits good catalytic performance in ammonia decomposition, and enhancing the interaction between the Ru atoms and the support is an important way to further improve its catalytic activity. In this study, CeO2 was prepared by calcination using a cerium-based metal–organic framework (MOF) as the precursor, and the number of oxygen vacancies on the surface of CeO2 was regulated by hydrogen reduction. The XPS and Raman results showed that abundant oxygen vacancies were formed on the surface of these CeO2, and their number increased with an increase in the reduction time. The Ru/CeO2-4 h catalyst, using CeO2 reduced for 4 h as the support, exhibited good catalytic activity in ammonia decomposition, reaching 98.9% ammonia conversion and 39.74 mmol gcat−1 min−1 hydrogen yield under the condition of GHSV = 36,000 mL gcat−1 h−1 at 500 °C. The XAFS results demonstrated that Ru was stably anchored with oxygen vacancies on the surface of CeO2 via Ru-O-Ce bonds. Density functional theory calculations further showed that these bondings lower the reaction energy barrier for N-H bond cleavage, thereby significantly enhancing the catalytic activity. Full article
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15 pages, 1749 KiB  
Article
Optimizing Methane Oxidative Coupling over La2O3: Kinetic and Product Analysis
by Zhehao Qiu and Yulu Cai
Catalysts 2025, 15(5), 499; https://doi.org/10.3390/catal15050499 - 20 May 2025
Viewed by 545
Abstract
The oxidative coupling of methane (OCM) is a promising process for converting methane directly into more valuable ethane and ethylene. In this work, high time resolution online mass spectrometry was employed to track the OCM reaction over a commercial La2O3 [...] Read more.
The oxidative coupling of methane (OCM) is a promising process for converting methane directly into more valuable ethane and ethylene. In this work, high time resolution online mass spectrometry was employed to track the OCM reaction over a commercial La2O3 catalyst, focusing on the effects of methane to oxygen ratio, gas hourly space velocity (GHSV), and the presence of H2O and CO in the feed gas on methane conversion and C2 yield. The results demonstrated that an optimized GHSV (44,640 to 93,000 mL·g−1·h−1) and methane to oxygen ratio (CH4/O2 = 3) would achieve the highest methane conversion and C2 yield at 740 °C. Furthermore, at a GHSV of 44,640 mL·g−1·h−1, the introduction of 1% H2O into the reaction mixture resulted in a twofold increase in C2 yield at 650 °C, while the addition of 1% CO led to a threefold increase in C2 yield at 550 °C. A model in which only the front-end catalyst is active was also developed to show excellent agreement with the experimental data. The relationship between catalytic performance and the effective catalyst position in the catalyst bed provides important insights into optimizing reactor design and operating conditions to maximize C2 yield and selectivity in the OCM reaction. Full article
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12 pages, 3552 KiB  
Article
Facilitation of CO2 Hydrogenation to Methanol by Spinel ZnGa2O4 in Cu-ZnO Catalysts
by Xiulin Wang, Yuanshuang Zheng, Yu Zhang, Jiajun Qiu, Lun He and Bang Gu
Processes 2025, 13(5), 1420; https://doi.org/10.3390/pr13051420 - 7 May 2025
Viewed by 565
Abstract
The hydrogenation of CO2 to methanol is an effective approach for utilizing carbon resources. Cu-ZnO-based catalysts have attracted significant attention due to their ability to activate CO2; however, improving methanol selectivity remains a challenge. In this study, the incorporation of [...] Read more.
The hydrogenation of CO2 to methanol is an effective approach for utilizing carbon resources. Cu-ZnO-based catalysts have attracted significant attention due to their ability to activate CO2; however, improving methanol selectivity remains a challenge. In this study, the incorporation of an appropriate amount of Ga into Cu-ZnO catalysts, resulting in the formation of spinel ZnGa2O4 crystals, significantly enhances the conversion of CO2 to methanol. Ternary CuZnGa composite oxides with varying Ga contents were synthesized, and their effects on CO2 hydrogenation were investigated. The optimal Cu6Zn3Ga1 catalyst achieved a CO2 conversion rate of 13% and a methanol selectivity of 59% under reaction conditions of 240 °C, 4 MPa, and a GHSV of 7500 mL⋅gcat−1⋅h−1. In contrast, the undoped Cu6Zn4 catalyst exhibited a lower CO2 conversion of 9.8% and a methanol selectivity of 38%. Characterization results indicate that the introduction of Ga promotes the formation of oxygen vacancies, enhances CO2 activation, and facilitates electronic interactions between spinel ZnGa2O4 and Cu sites, thereby improving methanol production. Furthermore, the spinel ZnGa2O4-modified Cu catalyst demonstrated excellent stability over 90 h of continuous operation. This study presents a novel approach to designing spinel ZnGa2O4-modified Cu-ZnO-based catalysts and offers a new strategy for enhancing CO2 hydrogenation to methanol. Full article
(This article belongs to the Special Issue Design and Performance Optimization of Heterogeneous Catalysts)
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20 pages, 3643 KiB  
Article
Unlocking Catalytic Efficiency: How Preparation Strategies and Copper Loading Enhance Hydroxyapatite Catalysts for NH3 Oxidation
by Sebastiano Campisi, Melissa Greta Galloni and Antonella Gervasini
Catalysts 2025, 15(4), 405; https://doi.org/10.3390/catal15040405 - 21 Apr 2025
Viewed by 663
Abstract
The selective catalytic oxidation of ammonia (NH3-SCO) is gaining attention due to the hazardous nature of NH3 and its inclusion in emission reduction frameworks such as the National Emission Ceilings Directive and the Gothenburg Protocol (1999). Copper-based hydroxyapatite (Cu/HAP) catalysts [...] Read more.
The selective catalytic oxidation of ammonia (NH3-SCO) is gaining attention due to the hazardous nature of NH3 and its inclusion in emission reduction frameworks such as the National Emission Ceilings Directive and the Gothenburg Protocol (1999). Copper-based hydroxyapatite (Cu/HAP) catalysts have emerged as a promising solution, offering high activity and cost-effectiveness. This study evaluated two preparation methods: a one-pot co-precipitation technique and post-synthesis copper deposition, varying both the contact time and copper concentration. The influence of copper loading and preparation method on catalyst performance in NH3-SCO was investigated in a continuous flow reactor over a temperature range of 200–500 °C, with a fixed gas hourly space velocity (GHSV) of 120,000 h1 and an NH3/O2 ratio of 0.03. X-ray diffraction and DR-UV spectroscopy confirmed the high crystallinity of HAP and provided insights into copper speciation. X-ray photoelectron spectroscopy revealed that Cu/HAP catalysts prepared via one-pot co-precipitation predominantly contained isolated Cu2+ species, which were associated with high catalytic activity in selective NH3-SCO. Conversely, a higher degree of copper structuring was observed in catalysts prepared by post-synthesis deposition, particularly at higher Cu loadings. These findings highlight the potential to tailor Cu structuring on HAP to enhance performance in NH3-SCO through optimized preparation strategies. Full article
(This article belongs to the Special Issue New Trends in Catalysis: ELITECAT 2024)
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20 pages, 4474 KiB  
Article
Revisiting the Impact of CO2 on the Activity and Selectivity of Cobalt-Based Catalysts for Fischer–Tropsch Synthesis Under Industrial-Relevant Conditions
by Zhiyu Chen, Jinbo Du, Denghui Chen, Fuqing Gong, Yang Gao, Zhen Huang, De Chen and Jia Yang
Catalysts 2025, 15(4), 329; https://doi.org/10.3390/catal15040329 - 31 Mar 2025
Viewed by 759
Abstract
Understanding the impact of CO2 on cobalt-based Fischer–Tropsch synthesis catalysts is critical for optimizing system efficiency, particularly in scenarios employing solid oxide electrolysis cells for syngas production, given the inevitable incorporation of CO2 into syngas during the SOEC co-electrolysis process. In [...] Read more.
Understanding the impact of CO2 on cobalt-based Fischer–Tropsch synthesis catalysts is critical for optimizing system efficiency, particularly in scenarios employing solid oxide electrolysis cells for syngas production, given the inevitable incorporation of CO2 into syngas during the SOEC co-electrolysis process. In this study, we conducted comparative experiments using a Co-Re/γ-Al2O3 catalyst in a fixed-bed reactor under industrial conditions (2 MPa, 493 K, GHSV = 6000–8000 Ncm3/gcat/h), varying the feed gas compositions of H2, CO, CO2, and Ar. At an H2/CO ratio of 2, the addition of CO2 led to a progressive decline in catalyst performance, attributed to carbon deposition and cobalt carbide formation, as confirmed by Raman spectroscopy, XRD analyses, and TPH. Furthermore, DFT calculations combined with ab initio atomistic thermodynamics (AIAT) were performed to gain molecular insights into the loss of catalyst activity arising from multiple factors, including (sub)surface carbon derived from CO or CO2, polymeric carbon, and carbide formation. Full article
(This article belongs to the Section Catalysis for Sustainable Energy)
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15 pages, 2176 KiB  
Article
A Promising Monolithic Catalyst for Advanced VOCs Oxidation by Graphene-Doped α-MnO2 Loaded on Cordierite Honeycomb
by Yilin Dong, Yiyang Zhao, Jing Sun, Yafang Shen, Xiqiang Zhao, Wenlong Wang, Zhanlong Song and Yanpeng Mao
Catalysts 2025, 15(4), 321; https://doi.org/10.3390/catal15040321 - 27 Mar 2025
Cited by 1 | Viewed by 624
Abstract
A high-activity, low-cost, and easy-to-prepare monolithic catalyst is crucial for the industrial catalytic combustion of volatile organic compounds (VOCs) in a cost-effective manner. In this study, a highly efficient monolithic catalyst, designated as 4GM/COR, was developed by loading 4% graphene-doped α-MnO2 (4GM) [...] Read more.
A high-activity, low-cost, and easy-to-prepare monolithic catalyst is crucial for the industrial catalytic combustion of volatile organic compounds (VOCs) in a cost-effective manner. In this study, a highly efficient monolithic catalyst, designated as 4GM/COR, was developed by loading 4% graphene-doped α-MnO2 (4GM) catalyst onto pre-etched cordierite (COR) blocks using a straightforward “ball-milling-assisted impregnation” method. The anchoring force of the cordierite pores, generated through oxalic acid etching, enables the uniform and robust loading of powdered 4GM onto COR, preventing detachment under high temperatures or high gas flow rates. The loading rate, specific surface area, and concentrations of Mn3+ and surface-lattice and absorbed oxygen species in the monolithic catalyst increase with impregnation times from 2 to 4, indicating that catalytic activity is optimized through repeated impregnation. Catalytic performance tests demonstrated that the 4-4GM/COR exhibited the highest activity, achieving 90% degradation of toluene at 200 °C under both dry and humid (relative humidity is 85%) conditions. Furthermore, the 4-4GM/COR maintains high catalytic stability and activity even at a large GHSV of 6000 h−1. To conclude, the 4-4GM/COR monolithic catalyst developed in this study not only represents a promising option for industrial applications but also serves as an important reference for the synthesis of monolithic catalysts. Full article
(This article belongs to the Special Issue Catalytic Removal of Volatile Organic Compounds (VOCs))
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18 pages, 5651 KiB  
Article
Methane Decomposition over a Titanium-Alumina and Iron Catalyst Assisted by Lanthanides to Produce High-Performance COx-Free H2 and Carbon Nanotubes
by Hamid Ahmed, Anis H. Fakeeha, Fayez M. Al-Alweet, Ahmed E. Abasaeed, Ahmed A. Ibrahim, Rawesh Kumar, Alaaddin M. M. Saeed and Ahmed S. Al-Fatesh
Catalysts 2025, 15(1), 77; https://doi.org/10.3390/catal15010077 - 15 Jan 2025
Cited by 2 | Viewed by 1541
Abstract
COx-free H2, along with uniform carbon nanotubes, can be achieved together in high yield by CH4 decomposition. It only needs a proper catalyst and reaction condition. Herein, Fe-based catalyst dispersed over titania-incorporated-alumina (Fe/Ti-Al), with the promotional addition of lanthanides, like [...] Read more.
COx-free H2, along with uniform carbon nanotubes, can be achieved together in high yield by CH4 decomposition. It only needs a proper catalyst and reaction condition. Herein, Fe-based catalyst dispersed over titania-incorporated-alumina (Fe/Ti-Al), with the promotional addition of lanthanides, like CeO2 and La2O3, over it, is investigated for a methane decomposition reaction at 800 °C with GHSV 6 L/(g·h) in a fixed-bed reactor. The catalysts are characterized by temperature-programmed reduction (TPR), powder X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM). The promoted catalysts are facilitated with higher surface area and enhanced dispersion and concentration of active sites, resulting in higher H2 and carbon yields than unpromoted catalysts. Ceria-promoted 20Fe/Ti-Al catalyst had the highest concentration of active sites and always attained the highest activity in the initial hours. The 20Fe-2.5Ce/Ti-Al catalyst attains >90% CH4 conversion, >80% H2-yield, and 92% carbon yield up to 480 min time on stream. The carbon nanotube over this catalyst is highly uniform, consistent, and has the highest degree of crystallinity. The supremacy of ceria-promoted catalyst attained >90% CH4 conversion even after the second cycle of regeneration studies (against 87% in lanthanum-promoted catalyst), up to 240 min time on stream. This study plots the path of achieving catalytic and carbon excellence over Fe-based catalysts through CH4 decomposition. Full article
(This article belongs to the Section Industrial Catalysis)
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15 pages, 5385 KiB  
Article
The Synergistic Effect of Pore Architect and Reducibility in Ceria-Promoted Ni Molecular Sieve for Methane Dry Reforming
by Norah Alwadai, Abdulaziz A. M. Abahussain, Vijay Kumar Shrivastava, Salma A. Al-Zahrani, Anis H. Fakeeha, Naif Alarifi, Mohammed O. Bayazed, Khaled M. Banabdwin, Rawesh Kumar and Ahmed Al-Fatesh
Catalysts 2024, 14(12), 852; https://doi.org/10.3390/catal14120852 - 24 Nov 2024
Cited by 2 | Viewed by 1143
Abstract
Methane and carbon dioxide, the primary contributors to global warming, are now at critical levels, threatening the extinction of numerous organisms on our planet. In this regard, dry reforming of methane reactions have gained considerable attention because of the conversion capacity of CH [...] Read more.
Methane and carbon dioxide, the primary contributors to global warming, are now at critical levels, threatening the extinction of numerous organisms on our planet. In this regard, dry reforming of methane reactions have gained considerable attention because of the conversion capacity of CH4 and CO2 into synthetic/energy-important syngas (H2 and CO). Herein, a molecular sieve (CBV3024E; SiO2/Al2O3 = 30) with ZSM-8-type pore architect, is utilized as the support for the active site of Ni and Ce promoters. Catalysts are characterized by surface area and porosity, X-ray diffraction study, Raman and infrared spectroscopy, thermogravimetry analysis, and temperature-programmed reduction/desorption techniques. A total of 2 wt.% ceria is added over 5Ni/CBV3024E to induce the optimum connectivity of aluminum in the silicate framework. NiO residing in these porous cages are mostly under “prominent interaction with support” which is reduced easily into metallic Ni as the active sites for DRM reactions. The active sites over 5Ni2Ce/CBV3024E remain stable during the DRM reaction and achieve ~58% H2 yield after 300 min TOS at 42,000 mL/(gcat.h) GHSV and ~70% H2 yield after 20 h at 26,000 mL/(gcat.h) GHSV. The high activity after a longer time stream justifies using CBV3024E molecular sieves as the support and ceria as the promoter for Ni-based catalyst towards the DRM reaction. Full article
(This article belongs to the Special Issue Advances in Catalytic Dry Reforming of Methane)
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16 pages, 4661 KiB  
Article
Synthesis and Experimental Screening of Catalysts for H2S to H2 Decomposition Under Close-to-Industry Conditions
by Timur Palankoev, Anton Manakhov, Andrey Kovalskii, Ekaterina Sukhanova, Zakhar Popov, Dmitry Chareev, Konstantin Dement’ev, Anton Maximov and Abdulaziz Al-Qasim
Catalysts 2024, 14(11), 839; https://doi.org/10.3390/catal14110839 - 20 Nov 2024
Cited by 1 | Viewed by 1247
Abstract
The chemical engineering community has shown significant interest in investigating methods to decompose hydrogen sulfide into hydrogen and sulfur. However, there is still a lack of detailed experimental data enabling us to choose the optimal catalyst, reaction, and regeneration conditions, as well as [...] Read more.
The chemical engineering community has shown significant interest in investigating methods to decompose hydrogen sulfide into hydrogen and sulfur. However, there is still a lack of detailed experimental data enabling us to choose the optimal catalyst, reaction, and regeneration conditions, as well as the overall process design. The purpose of this work is to synthesize a series of catalysts and compare their catalytic activity under the same conditions, chosen on the basis of a possible large-scale H2S conversion process. To achieve this, the obtained catalysts were characterized by BET, XRD, SEM, TEM, and XPS before and after the reaction. Decomposition was conducted in a laboratory fixed-bed reactor at a temperature of 500 °C, 10 vol% of H2S in the feed, and a GHSV of 540–1000 h−1. DFT calculations evaluated the H2S bond cleavage on various catalyst surfaces. It was shown that the most promising catalyst was Ni3S2, offering an acceptable H2S conversion of 40%. We also observed that Ni3S2 catalyst regeneration could be conducted at much milder conditions compared to those previously reported in the literature. These results highlight the viability of upscaling the process with the selected catalyst. Full article
(This article belongs to the Section Industrial Catalysis)
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20 pages, 5958 KiB  
Article
Dry Reforming of Methane (DRM) over Hydrotalcite-Based Ni-Ga/(Mg, Al)Ox Catalysts: Tailoring Ga Content for Improved Stability
by Ahmed Y. Elnour, Ahmed E. Abasaeed, Anis H. Fakeeha, Ahmed A. Ibrahim, Salwa B. Alreshaidan and Ahmed S. Al-Fatesh
Catalysts 2024, 14(10), 721; https://doi.org/10.3390/catal14100721 - 16 Oct 2024
Cited by 1 | Viewed by 2070
Abstract
Dry reforming of methane (DRM) is a promising way to convert methane and carbon dioxide into syngas, which can be further utilized to synthesize value-added chemicals. One of the main challenges for the DRM process is finding catalysts that are highly active and [...] Read more.
Dry reforming of methane (DRM) is a promising way to convert methane and carbon dioxide into syngas, which can be further utilized to synthesize value-added chemicals. One of the main challenges for the DRM process is finding catalysts that are highly active and stable. This study explores the potential use of Ni-based catalysts modified by Ga. Different Ni-Ga/(Mg, Al)Ox catalysts, with various Ga/Ni molar ratios (0, 0.1, 0.3, 0.5, and 1), were synthesized by the co-precipitation method. The catalysts were tested for the DRM reaction to evaluate their activity and stability. The Ni/(Mg, Al)Ox and its Ga-modified Ni-Ga/(Mg, Al)Ox were characterized by N2 adsorption–desorption, Fourier Transform Infrared Spectroscopy (FTIR), H2-temperature-programmed reduction (TPR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Raman techniques. The test of catalytic activity, at 700 °C, 1 atm, GHSV of 42,000 mL/h/g, and a CH4: CO2 ratio of 1, revealed that Ga incorporation effectively enhanced the catalyst stability. Particularly, the Ni-Ga/(Mg, Al)Ox catalyst with Ga/Ni ratio of 0.3 exhibited the best catalytic performance, with CH4 and CO2 conversions of 66% and 74%, respectively, and an H2/CO ratio of 0.92. Furthermore, the CH4 and CO2 conversions increased from 34% and 46%, respectively, when testing at 600 °C, to 94% and 96% when the catalytic activity was operated at 850 °C. The best catalyst’s 20 h stream performance demonstrated its great stability. DFT analysis revealed an alteration in the electronic properties of nickel upon Ga incorporation, the d-band center of the Ga modified catalyst (Ga/Ni ratio of 0.3) shifted closer to the Fermi level, and a charge transfer from Ga to Ni atoms was observed. This research provides valuable insights into the development of Ga-modified catalysts and emphasizes their potential for efficient conversion of greenhouse gases into syngas. Full article
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