Enhanced catalytic performance for methane dehydro-aromatization on Mo/HMCM-49 prepared with citric acid

Article Energy & Fuels

Enhanced catalytic performance of the hollow Mo/HZSM-5 nanocrystal for methane dehydroaromatization

Mengmeng Huang et al.

Summary: Hollow HZSM-5 zeolite catalysts with different cavity sizes and tunable shell thickness were prepared and exhibited higher conversion and selectivity in methane dehydroaromatization reaction compared to conventional solid catalyst.

FUEL (2023)

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Article Chemistry, Applied

Effect of the NiO particle size on the activity of Mo/HZSM-5 catalyst physically mixed with NiO in methane dehydroaromatization

Hae Won Ryu et al.

Summary: This study evaluates the efficiency of NiO particles with various sizes (4, 22, 36, 45, and 101 nm) as promoters, and it is found that NiO(36 nm) has the optimum size for enhancing the activity of Mo/HZSM-5. The analysis reveals that NiO(36 nm)-Mo/HZSM-5 has the highest dispersion of MoCx active sites because it has the lowest reduction temperature for NiO and MoOx. When the NiO particle size is smaller than 22 nm, the formation of inactive NiMoO4 is preferred, resulting in severe agglomeration and low dispersion of MoCx.

CATALYSIS TODAY (2023)

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Article Chemistry, Physical

Elucidation of quantitative effects of zeolitic pores in Mo-impregnated MWW type zeolites on catalytic activities and stabilities of methane dehydroaromatization reaction

Gihoon Lee et al.

Summary: The effects of the pore structure of Mo-impregnated zeolites on the catalytic activity and stability during methane dehydroaromatization (MDA) were studied. Different zeolites with similar topologies but varying structures were used. It was found that despite different structures, all Mo-impregnated catalysts showed similar initial benzenetoluene formation rates per zeolitic pore. Coke deposition inside the zeolitic channels was identified as the cause of catalyst deactivation, and preferential deposition in the 12-membered-ring supercage delayed zeolite channel blocking and catalyst deactivation. Therefore, the amount of zeolitic pores is crucial for determining the catalytic performance and stability during MDA.

APPLIED CATALYSIS A-GENERAL (2023)

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Article Chemistry, Applied

Catalytic conversion of methane into benzene over ceria-zirconia-promoted molybdenum-supported zeolite for methane dehydroaromatization

Deepti Mishra et al.

Summary: The promotional effect of mixed ceria-zirconia oxides (CZO) on the Mo/HZSM-5 catalyst for methane dehydroaromatization (MDA) reaction was studied. The surface and structural properties of the synthesized catalyst were thoroughly characterized, and the correlation between catalytic properties and MDA reaction performance was discussed. The impregnation of CZO solid solution on Mo/HZSM-5 improved the catalytic performance and benzene production rate, while reducing coke formation. The redox properties of CZO-deposited Mo/HZSM-5, acting as a selective oxygen supplier and performing hydrogen combustion, were identified as the main reasons for the enhanced catalytic activity.

APPLIED ORGANOMETALLIC CHEMISTRY (2023)

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Article Chemistry, Physical

Stable Ce0.8Gd0.2O2-8 oxygen transport membrane reactor for hydrogen production

Wenyuan Liang et al.

Summary: Hydrogen production using oxygen transport membrane reactors is a hot research topic, but the stability of membrane materials in harsh reducing atmospheres remains a challenge. In this study, a 2 mol.% cobalt-doped Ce0.8Gd0.2O2-8 (CoCGO) ultrathin membrane was successfully fabricated and applied for hydrogen production from water splitting (WS) and simultaneous syngas production through partial oxidation of methane (POM). Two catalysts, La0.4Sr0.6CoO3-8 (LSC) and Ni/Al2O3, were used to promote WS and POM, respectively. The results showed a hydrogen production rate above 1.8 mL min-1 cm-2 and methane conversion of around 80%, with no noticeable degradation during 100 hours of operation, indicating its potential stability advantages as a membrane reactor for hydrogen production from water.

APPLIED CATALYSIS A-GENERAL (2023)

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Article Chemistry, Physical

Dual-template synthesis of thinner-layered MCM-49 zeolite to boost its alkylation performance

Shiwei Cao et al.

Summary: In this study, a thinner-layered C18-MCM-49 zeolite microsphere was successfully synthesized using diquaternary ammonium salts in the sol-gel process. The C18-MCM-49 displayed enhanced solid acid catalytic activity due to its higher number of external acid sites and larger external surface area compared to traditional MCM-49 zeolite. The research also demonstrated the importance of aluminosilicate species in the synthesis process and provided a convenient method for synthesizing other types of zeolites.

MOLECULAR CATALYSIS (2022)

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Article Chemistry, Physical

How do the products in methane dehydroaromatization impact the distinct stages of the reaction?

Antoine Beuque et al.

Summary: The study investigated the mechanism of methane dehydroaromatization over Mo/ZSM-5 at 700°C, revealing key steps such as calcination, activation, induction, and deactivation. Chemical reactions between methane and the catalyst, as well as the inhibitory effect of aromatics, play important roles in determining the catalyst's activity and lifetime.

APPLIED CATALYSIS B-ENVIRONMENTAL (2022)

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Article Chemistry, Physical

Reaction regeneration cycle of Mo/HZSM-5 catalyst in methane dehydroaromatization with the addition of oxygen-containing components

Ruiyao Gao et al.

Summary: The study investigated the impact of oxygen-containing gas components on the reaction regeneration cycle of methane dehydroaromatization (MDA). The results indicated that the addition of oxygen components can prolong the reaction time but cannot prevent the deactivation of the regenerated catalyst. After regeneration, the species and texture properties of the catalyst were restored, leading to complete recovery of methane conversion and aromatic formation. However, the increase in the size of Mo species during regeneration disrupted carbon deposition and significantly reduced methane dissociation. The crystallinity and number of strong acid sites of the catalyst decreased to a stable level before the collapse of the zeolite framework, without hindering aromatic formation. The recovered large-sized Mo species may accelerate the irreversible collapse of the zeolite framework, thereby destroying the Mo/HZSM-5 catalyst.

APPLIED CATALYSIS A-GENERAL (2022)

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Article Chemistry, Physical

Unraveling the Mo/HZSM-5 reduction pre-treatment effect on methane dehydroaromatization reaction

Angeles Lopez-Martin et al.

Summary: The reduction temperature has a crucial effect on the catalytic performance of Mo/HZSM-5 catalyst for methane dehydroaromatiztion reaction. The optimum performance is achieved at 550 degrees C, which may be attributed to the higher fraction of reduced Mo species.

APPLIED CATALYSIS B-ENVIRONMENTAL (2022)

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Article Chemistry, Applied

Hierarchically modified Mo/HZSM-5 via alkali treatment for improved activity in methane dehydroaromatization

Deepti Mishra et al.

Summary: This study modifies the HZSM-5 support to improve the catalytic activity and coke tolerance in methane dehydroaromatization reaction.

FUEL PROCESSING TECHNOLOGY (2022)

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Article Chemistry, Applied

Influence of desilication route of ZSM-5 zeolite in mesoporous zeolite supported calcium oxide catalyst for biodiesel production

Nurul Saadiah Lani et al.

Summary: The application of mesoporous zeolite as a support for calcium oxide (CaO) catalyst in biodiesel production has been studied. The surfactant-assisted desilication method was found to be the most effective in incorporating CaO species into the zeolite framework, resulting in a highly crystalline material. The CaO/Zeo-CTAB catalyst exhibited the best performance, with high biodiesel yield and resistance against leaching of calcium species. This study provides an efficient route for the production of mesoporous zeolite for catalyst support.

MICROPOROUS AND MESOPOROUS MATERIALS (2022)

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Article Chemistry, Physical

Molybdenum Carbonyl Grafted on Amine-Functionalized MCM-22 as Potential Catalyst for Iso-Eugenol Oxidation

Preeti Sahu et al.

Summary: By incorporating different concentrations of molybdenum carbonyl on the surface of MCM-22, the uniform distribution of molybdenum species was achieved, leading to a catalyst with good liquid-phase oxidation activity, high conversion rate, and good product selectivity. The catalyst retained its activity even after several runs, indicating its potential for practical applications.

CATALYSIS LETTERS (2021)

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Article Chemistry, Multidisciplinary

Dual Active Sites on Molybdenum/ZSM-5 Catalyst for Methane Dehydroaromatization: Insights from Solid-State NMR Spectroscopy

Wei Gao et al.

Summary: This study identified proximate dual active sites on Mo/ZSM-5 catalyst, revealing the crucial role of spatial interaction between Bronsted acid sites and Mo species in methane conversion and aromatics formation. The evolution of olefins and aromatics in Mo/ZSM-5 channels was monitored, showing the intermediate role of olefins in the hydrocarbon pool process during the MDA reaction.

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION (2021)

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Article Chemistry, Physical

Coking mechanism of Mo/ZSM-5 catalyst in methane dehydroaromatization

Yu Gu et al.

Summary: The study shows that Brønsted acid sites play a key role in coke formation during methane dehydroaromatization. Modified catalysts exhibit lower naphthalene selectivity and higher C2 selectivity. It is proposed that aromatization is an intrinsic property of Mo, and Mo-associated carbonaceous species act as precursors for both coke and aromatics production.

APPLIED CATALYSIS A-GENERAL (2021)

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Review Chemistry, Multidisciplinary

Recent advances in heterogeneous catalysis for the nonoxidative conversion of methane

Tianyu Zhang

Summary: The direct conversion of methane to high-value chemicals is an attractive process that efficiently utilizes natural/shale gas for energy supply. Nonoxidative conversion of methane is noteworthy due to its economic selectivity to bulk chemicals like aromatics and olefins, with innovations in catalysts for C-H activation and C-C coupling playing a key role. The review summarizes recent advances in conventional catalysts and single-atom based catalysts, focusing on experimental findings and theoretical understanding for improving industrial applications of methane conversion.

CHEMICAL SCIENCE (2021)

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Article Chemistry, Multidisciplinary

Elucidating the nature of Mo species on ZSM-5 and its role in the methane aromatization reaction

Angeles Lopez-Martin et al.

Summary: Researchers have identified different Mo precursors in the Mo/ZSM-5 catalytic system and clarified their roles in promoting or hindering the transformation of methane into aromatics, providing important experimental basis for improving catalytic efficiency.

REACTION CHEMISTRY & ENGINEERING (2021)

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Article Chemistry, Inorganic & Nuclear

Green synthesis route for MCM-49 zeolite using a seed-assisted method by virtue of an ultraphonic aging procedure

Yanan Wang et al.

Summary: By utilizing seed-assistance and ultraphonic aging treatment, MCM-49 zeolite can be synthesized without deliberately adding OSDA, resulting in a more efficient, eco-friendly, and simple process.

INORGANIC CHEMISTRY FRONTIERS (2021)

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Review Chemistry, Multidisciplinary

Methane activation by ZSM-5-supported transition metal centers

Daniyal Kiani et al.

Summary: This review focuses on recent fundamental insights into methane dehydroaromatization (MDA) to benzene over ZSM-5-supported transition metal oxide-based catalysts. It critically analyzes the findings from MDA catalysis literature, emphasizing in situ and operando spectroscopic characterization to understand molecular level details regarding catalytic sites before and during the MDA reaction. Specific aspects discussed include anchoring sites of supported MOx species on ZSM-5 support, nature of active sites during MDA, reaction mechanisms, rate-determining step, kinetics and catalyst activity. Future experimental investigations to address gaps in the literature are also suggested.

CHEMICAL SOCIETY REVIEWS (2021)

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Article Chemistry, Physical