Theoretical investigation of the methane cracking reaction pathways on Ni (111) surface

A comprehensive methane cracking reaction pathway was investigated by performing density functional theory (DFT) calculations. In addition to the sequential dissociation reaction, i.e. CH4 -> CHx +(4 - x)H -> C + 2H(2), a more sophisticated surface reaction network was studied, i.e. CHx + C -> CHx-1 + CH. The results show that CHx dehydrogenation is promoted with a low energy barrier through bimolecular reaction and provide an alternative kinetic favorable route for methane cracking. This study also demonstrates that the production of gas phase C-2 hydrocarbon species, e.g. C2H2 and C2H4, in methane cracking reaction is unlikely due to the high barrier energy of C2H3 formation and their strong adsorption energy on Ni (1 1 1). (C) 2015 Elsevier B.V. All rights reserved.