The Role of Single-Electron Oxygen Vacancies on the Cu/ZnO Surface in the Hydrogenation of Methyl Acetate

Ethanol production from syngas via methyl acetate (MA) hydrogenation has been an attractive alternative route in the industry. Cu/ZnO catalysts have been widely used in MA hydrogenation, but clarifying the detailed roles of surface oxygen vacancies is still challenging. Herein, we prepared two Cu/ZnO catalysts with similar properties of active species but different types of surface oxygen vacancies by using zinc peroxide and zinc glycerate as ZnO precursors, respectively. It is demonstrated that the CuZnO_x-ZnGly catalyst, prepared from zinc glycerate with abundant surface single-electron oxygen vacancies, exhibited excellent performance in MA hydrogenation at a low H₂/MA ratio of 10. This probably resulted from the spillover of hydrogen to single-electron oxygen vacancies, generating hydrogenated oxygen vacancies that facilitate hydrogen transfer and utilization. This study may provide insights into the role of single-electron oxygen vacancies in ester hydrogenation and guidance for the further design of high-performance Cu/ZnO catalysts.