H₂ Production from Methane Reforming over Molybdenum Carbide Catalysts: From Surface Properties and Reaction Mechanism to Catalyst Development

Abstract

Hydrogen, with its high energy content and environmental-friendly properties, is considered an effective energy carrier in addition to fossil fuels. Methane reforming represents a major method of hydrogen production, although the applied catalysts often suffer from coke deposition and metal sintering at high operating temperatures. Transition-metal carbides (TMCs), particularly molybdenum carbides (Mo x C), possess features such as Pt-like behaviors, affinity with oxidants such as CO2 and H2O, and a strong metal–support interaction for metal dispersion and stabilization, rendering them great prospective candidates for catalyzing the methane reforming reactions (MRRs). This review focuses on the recent applications and challenges of TMCs in MRRs, with an emphasis on the strategies to improve their performance by (1) engineering the operational conditions, (2) designing a dual M–Mo x C (M = Ni or Co etc.) active site, (3) dispersing M–Mo x C on supports, and (4) generating a M–Mo x C/MoO x C y interface in situ. The present review will provide guidance for the future design of efficient catalysts for H2 production from MRRs.

Role of H2O in Catalytic Conversion of C1 Molecules

“…149,150 It is generally accepted that the RDS in SRM is the dissociative adsorption of CH 4 , i.e., cleavage of the C−H bond of CH 4 that usually occurs on a metal site, 150−152 while H 2 O seems play a supporting role. 153−157 For instance, adsorbed OH from H 2 O dissociation may assist in the breaking of the first C−H bond in CH 4 , 158,157 and the reactive hydroxyl groups are responsible for the further oxidation of carboncontaining intermediates. 159 However, Vogt et al 160 find that the activation of CH 4 may not be the only RDS based on isotopically labeled experiments showing the formation of CH 3 D upon pulsing D 2 O.…”

“…The reaction between H 2 O and CH 4 occurs in a high-temperature environment (typically 973–1173 K) and is typically catalyzed by metal-based catalysts . The main pathway of SRM involves the adsorption and dissociation of CH 4 and H 2 O molecules on active metal sites or supports, as well as the subsequent oxidation of carbon-containing intermediates. , It is generally accepted that the RDS in SRM is the dissociative adsorption of CH 4 , i.e., cleavage of the C–H bond of CH 4 that usually occurs on a metal site, − while H 2 O seems play a supporting role. − For instance, adsorbed OH from H 2 O dissociation may assist in the breaking of the first C–H bond in CH 4 , , and the reactive hydroxyl groups are responsible for the further oxidation of carbon-containing intermediates . However, Vogt et al find that the activation of CH 4 may not be the only RDS based on isotopically labeled experiments showing the formation of CH 3 D upon pulsing D 2 O.…”

Optimizing Pt-Based Alloy Electrocatalysts for Improved Hydrogen Evolution Performance in Alkaline Electrolytes: A Comprehensive Review

“…The escalating global need for energy, combined with the exhaustion of nonrenewable energy sources and their detrimental ecological impacts, have accelerated the development of renewable, stable, eco-friendly, and nonhazardous energy conversion and storage technologies. − In this scenario, hydrogen is widely regarded as a promising and potentially green energy carrier. − While most of the hydrogen currently used is gray hydrogen obtained from fossil fuels, several strategies to produce green hydrogen have been developed. − Among them, water splitting via an electrocatalytic reaction has notable advantages over alternatives such as photo- and thermocatalytic water splitting, , biomethane catalytic reforming, gasification of biomass-derived coal, and alcohol catalytic reforming . The electrocatalytic production of green hydrogen via the hydrogen evolution reaction (HER) yields high-purity hydrogen under mild temperature and pressure conditions while simultaneously emitting no carbon dioxide. , …”

“…4−6 While most of the hydrogen currently used is gray hydrogen obtained from fossil fuels, several strategies to produce green hydrogen have been developed. 7−9 Among them, water splitting via an electrocatalytic reaction has notable advantages over alternatives such as photo-and thermocatalytic water splitting, 10,11 biomethane catalytic reforming, 12 gasification of biomass-derived coal, 13 and alcohol catalytic reforming. 14 The electrocatalytic production of green hydrogen via the hydrogen evolution reaction (HER) yields high-purity hydrogen under mild temperature and pressure conditions while simultaneously emitting no carbon dioxide.…”

Toward the Rational Design of More Efficient Mo2C Catalysts for Hydrodeoxygenation–Mechanism and Descriptor Identification

“…12 Experimentally, TMCs have been shown to be active for reactions such as hydrogenation, hydrodeoxygenation, isomerization, methanation, etc. [19][20][21][22][23][24][25]31 For instance, Oyama et al 14 reported that in reforming n-hexane at 670 K, a tungsten carbide (β-W 2 C) catalyst shows yields close to that of Pt/SiO 2 (8.6% vs This article is licensed under CC-BY 4 11.6%), and β-W 2 C exhibits even better selectivity for isomerization products compared to that of Pt/SiO 2 (71% vs 60%) for the same reaction. Stellwagen et al 23 performed experiments determining the activity and selectivity differences in W 2 C and Mo 2 C supported on carbon nanofibers for a stearic acid hydrodeoxygenation reaction.…”