K–ZrO<sub>2</sub> Interfaces Boost CO<sub>2</sub> Hydrogenation to Higher Alcohols
Tangkang Liu, Di Xu, Mengyang Song, Xinlin Hong, Guoliang Liu
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–ZrO 2 interfaces can boost the production of higher alcohols (HA) from CO 2 hydrogenation over an amorphous ZrO 2 -supported K–Cu–Fe catalyst (KFeCu/a-ZrO 2 ). In situ spectroscopy and chemisorption demonstrate that the strong interactions between K and ZrO 2 induce the formation of surface Zr δ+ sites/oxygen vacancies at K–ZrO 2 interfaces, thus providing plenty of nondissociative CO activation sites. The improved molecular CO adsorption capacity at the K–ZrO 2 interfaces expedites the CO insertion reaction (*CH x + *CO → *CH x -CO) at Cu–Fe 5 C 2 interfaces, thereby driving the HA synthesis reaction with nearly 4.6 times higher activity of HA in comparison to the KFeCu/SiO 2 catalyst. At the optimal conditions of 320 °C, 4 MPa, and 12 L g cat –1 h –1, the KFeCu/a-ZrO 2 catalyst shows the HA space time yield of 125.0 mg g cat –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.