Theoretical investigation on the dehydrogenation mechanism of CH₃OH on Cu (100) surface

Periodic DFT calculations have been employed to investigate the adsorption and dissociation mechanism of CH₃OH on Cu (100) surface. For the adsorption, all possible adsorption configurations of relevant intermediates are identified. It is found that CH₃OH and CHOH prefer to adsorb on the top sites, CH₂OH and CO adsorb preferentially on the bridge sites, while CH₃O, CH₂O, CHO, COH and H occupy the hollow sites. Methanol and formaldehyde are weakly bound on the Cu (100) surface and are easily desorbed. CH₂OH, CH₃O, CHOH, CO, CHO, COH and H are adsorbed strongly on the surface. Additionally, four possible pathways of CH₃OH dissociation initiated through the activation of O[sbnd]H and C[sbnd]H bonds, have been proposed and studied systematically. It is revealed that the breaking of the H[sbnd]O bond is more favorable for CH₃OH, CH₂OH and CHOH species. Consequently, the pathway (CH₃OH[sbnd]CH₃O[sbnd]CH₂O[sbnd]CHO[sbnd]CO) is the most probable dehydrogenation route, where the highest energy barrier of CH₃O dissociation makes it to be the rate-determining step of the whole dehydrogenation reaction.