Issue 22, 2023

Role and dynamics of transition metal carbides in methane coupling

Abstract

Transition metal carbides have numerous applications and are known to excel in terms of hardness, thermal stability and conductivity. In particular, the Pt-like behavior of Mo and W carbides has led to the popularization of metal carbides in catalysis, ranging from electrochemically-driven reactions to thermal methane coupling. Herein, we show the active participation of carbidic carbon in the formation of C2 products during methane coupling at high temperature that is associated with the dynamics of Mo and W carbides. A detailed mechanistic study reveals that the catalyst performance of these metal carbides can be traced back to its carbon diffusivity and exchange capability upon interaction with methane (gas phase carbon). A stable C2 selectivity over time on stream for Mo carbide (Mo2C) can be rationalized by fast carbon diffusion dynamics, while W carbide (WC) shows loss of selectivity due to slow diffusion leading to surface carbon depletion. This finding showcases that the bulk carbidic carbon of the catalyst plays a crucial role and that the metal carbide is not only responsible for methyl radical formation. Overall, this study evidences the presence of a carbon equivalent to the Mars–Van Krevelen type mechanism for non-oxidative coupling of methane.

Graphical abstract: Role and dynamics of transition metal carbides in methane coupling

Supplementary files

Article information

Article type
Edge Article
Submitted
25 Feb 2023
Accepted
02 May 2023
First published
03 May 2023
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2023,14, 5899-5905

Role and dynamics of transition metal carbides in methane coupling

S. B. X. Y. Zhang, Q. Pessemesse, L. Lätsch, K. M. Engel, W. J. Stark, A. P. van Bavel, A. D. Horton, P. Payard and C. Copéret, Chem. Sci., 2023, 14, 5899 DOI: 10.1039/D3SC01054F

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