We present density-functional theory calculations of the dehydrogenation of methane and CHx (x=1-3) on a Cu/Ni(111) surface, where Cu atoms are substituted on the Ni surface at a coverage of 1/4 monolayer. As compared to the results on other metal surfaces, including Ni(111), a similar activation mechanism with different energetics is found for the successive dehydrogenation of CH4 on the Cu/Ni(111) surface. In particular, the activation energy barrier (Eact) for CH→C+H is found to be 1.8 times larger than that on Ni(111), while Eact for CH4 → CH3 +H is 1.3 times larger. Considering the proven beneficial effect of Cu observed in the experimental systems, our findings reveal that the relative Eact in the successive dehydrogenation of CH4 plays a key role in impeding carbon formation during the industrial steam reforming of methane. Our calculations also indicate that previous scaling relationships of the adsorption energy (Eads) for CHx (x=1-3) and carbon on pure metals also hold for several Ni(111)-based alloy systems.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry