Optimizing surface oxygen vacancy sites for CO hydrogenation to isobutanol over ZnCr catalyst

• Calcination at N 2 resulted in the formation of more surface oxygen vacancies. • The formation of oxygen vacancies facilitated the un-dissociated adsorption of CO. • The C–C coupling and isobutanol producing were promoted over ZnCr-N 2 catalyst. During the synthesis of high alcohols, surface oxygen vacancies play a crucial role in CO/H 2 activity and catalytic performance. Herein, the Zn-Cr catalysts with different O species were obtained by heating the Zn-Cr catalysts in different atmospheres (N 2 , H 2 , and O 2 ), aiming to figure out the influences of O species in the surface structure and catalytic behavior. Using a series of characterizations (in situ DRIFTS, CO-TPD) and DFT calculation, the nature and contributions to catalyst activity of different oxygen species were confirmed for calcined ZnCr catalysts. It was found that the ZnCr catalyst calcined at an inert atmosphere exhibited more abundant oxygen vacancies and more surface hydroxyls with high activity. These two species determined the formation of non-dissociative adsorption CO and the stabilization of formate intermediate. As a result, the ZnCr-N 2 obtained remarkably improved catalytic performance.