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

Abstract

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 OH and CH bonds, have been proposed and studied systematically. It is revealed that the breaking of the HO bond is more favorable for CH3OH, CH2OH and CHOH species. Consequently, the pathway (CH3OHCH3OCH2OCHOCO) 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.