Impact of Morphological Effects on the Activity and Stability of Tungsten Carbide Catalysts for Dry Methane Reforming

Abstract

Fundamental understanding of the effects of phase and exposed facets of transition metal carbide (TMC) catalysts on reactivity is a route to preparing more active and stable materials for targeted applications. In this work, two geometries of tungsten carbide nanomaterials, nanorods, and nanoparticles with different exposed facets were synthesized to investigate the impact of morphological effects on the catalytic performance for the dry methane reforming (DMR) reaction. β-W 2 C nanoparticles maintained high activity and exhibited less coke formation for more than 40,000 turnovers, while α-WC nanorods began to deactivate after only 8000 turnovers. The difference in reactivity is attributed to the promotion of coke formation by the exposed facets of the nanorods, while the diverse facets of the nanoparticles inhibit coke formation and promote the DMR reaction. The synthesis of a variety of TMC morphologies provides an avenue for the future study and design of viable catalysts for a wide range of applications.

Transition Metal Carbides (TMCs) Catalysts for Gas Phase CO2 Upgrading Reactions: A Comprehensive Overview

“…At same condition, high activity was maintained for 144 h with no bulk carbon deposition at 8 bar [73]. β-W 2 C nanoparticles exhibited higher stability than α-WC nanorods due to the inherent disorder and presence of carbon vacancies in the β-W 2 C phase nanoparticles which can facilitate the reaction and prevent from coking [76].…”

“…By contrast, α-WC nanorods do not have the same degree of defects. These inherent carbon vacancies in the carbide lattice likely facilitate the oxidation/recarburization reaction that leads to higher activity while preserving the active catalyst and minimizing coke deposition [76].…”

Metal (Mo, W, Ti) Carbide Catalysts: Synthesis and Application as Alternative Catalysts for Dry Reforming of Hydrocarbons—A Review

“…Comparing the phases of WC that occur, it may be concluded that the hexagonal close-packed β-W 2 C is the most active, while the hexagonal α-WC is slightly less active, and the fcc WC 1-x is twofold less active [196]. β-W 2 C nanoparticles are characterized by a disordered structure and the presence of carbon vacancies [28], as a result of which they have greater stability compared to α-WC nanorods [196,197]. According to research conducted by Zhang et al [198], during dry methane reforming, oxidation of β-W 2 C by CO 2 readily occurs, resulting in phase transformation to α-WC.…”

W2N/WC composite nanofibers as an efficient electrocatalyst for photoelectrochemical hydrogen evolution

“…[8][9][10][11][12][13] Among the earth-abundant and inexpensive catalysts, tungstenbased catalysts, such as carbides and nitrides, have gained considerable interest for HER because of their unique properties, such as Pt-like electronic structure, good electrical conductivity and chemical inertness in acidic and basic solutions. [14][15][16] Especially, due to the narrow band gap of 2.2 eV, W 2 N was usually used as a potential photocatalyst for photoelectrochemical hydrogen production. 17 Moreover, it has been theoretically and experimentally displayed that tungsten nitride/tungsten carbide (W 2 N/WC) heterostructure catalyst exhibits outstanding synergistic enhancement in HER activity, which is much better than their individual material.…”