Syngas conversion catalyzed by copper-embedded graphene

Abstract

A detailed reaction mechanism for syngas conversion into ethanol over copper-embedded graphene catalyst has been studied by periodic density functional theory calculations. The preferential pathway for syngas conversion starts with CO hydrogenation to the key species CHO, followed by successive hydrogenation to form CH2OH and next obtain the pivotal intermediates CH2 or CH3via CH2OH direct dissociation or H-assisted dissociation. Then CH3CHO is formed via CHO insertion into CH3, finally the target product C2H5OH could be synthesized by successive hydrogenation of CH3CHO. On one hand the CH2 coupling and CH2 hydrogenation to CH3 are highly competitive elementary reactions, so the possible product C2H4 could be formed. On the other hand, the CHO insertion into CH3 and CH3 hydrogenation are also competitive, therefore CH4 could become another possible product. During the whole process, the copper-embedded graphene shows good catalytic activity for the key intermediate CH3 formation and carbon chain growth due to the coexistence of Cu and C components. Detailed Bader charge analyses offer strong support for in-depth understanding the reaction mechanism of syngas conversion. The work could provide valuable information for designing and preparation of direct and efficient catalysts for syngas conversion.