K–ZrO2 Interfaces Boost CO2 Hydrogenation to Higher Alcohols

Abstract

Alkali metal promoters are widely used to modify active metal sites/interfaces of heterogeneous catalysts for numerous industrial processes. However, the interplay between an alkali metal and support, a crucial catalytic parameter, has been scarcely investigated in controlling the activation behaviors of intermediates and improving catalysis. Herein, we report that K–ZrO2 interfaces can boost the production of higher alcohols (HA) from CO2 hydrogenation over an amorphous ZrO2-supported K–Cu–Fe catalyst (KFeCu/a-ZrO2). In situ spectroscopy and chemisorption demonstrate that the strong interactions between K and ZrO2 induce the formation of surface Zrδ+ sites/oxygen vacancies at K–ZrO2 interfaces, thus providing plenty of nondissociative CO activation sites. The improved molecular CO adsorption capacity at the K–ZrO2 interfaces expedites the CO insertion reaction (*CHx + *CO → *CHx-CO) at Cu–Fe5C2 interfaces, thereby driving the HA synthesis reaction with nearly 4.6 times higher activity of HA in comparison to the KFeCu/SiO2 catalyst. At the optimal conditions of 320 °C, 4 MPa, and 12 L gcat–1 h–1, the KFeCu/a-ZrO2 catalyst shows the HA space time yield of 125.0 mg gcat–1 h–1, ranking the top level among the reported single-component catalysts in the literature. Most importantly, this work provides an in-depth insight into alkali promoter–support interactions for promoting catalytic performance.