Tuning the Electronic Metal–Support Interaction in Cu/ZnAl<sub>2</sub>O<sub>4</sub> Spinel via La Modification for Efficient CO<sub>2</sub> Hydrogenation to Methanol
Lixin Song, Guobin Liu, Xiao Jiang, Zhenping Qu
Abstract
The Cu/ZnAl 2 O 4 spinel holds significant promise for the conversion of CO 2 to methanol, which serves as a pivotal link in the carbon cycle network. However, the design of electron-rich supports to further boost the catalytic performance of Cu/ZnAl 2 O 4 catalysts remains challenging. Here, Cu/ZnAl 2– x La x O 4 catalysts enriched with electrons at the Zn and Al sites have been ingeniously constructed. The Cu/ZnAl 1.8 La 0.2 O 4 catalyst exhibits a high CO 2 conversion of 16.8% and a methanol selectivity of 86.9% at 240 °C, accompanied by a 39.6% improvement (344.2 g CH3OH ·kg cat –1 ·h –1 ) in STY of methanol compared to the Cu/ZnAl 2 O 4 catalyst. The CO 2 adsorption capacity of the Cu/ZnAl 1.8 La 0.2 O 4 catalyst with an electron-rich state support has been dramatically increased. And the electron-rich Zn sites promote the hydrogen storage in the spinel, thus facilitating the rapid formation of formate species. Furthermore, the enhanced EMSI effect promotes the formation of smaller Cu species over the Cu/ZnAl 1.8 La 0.2 O 4 catalyst, which is beneficial for the dissociation and spillover of hydrogen, thus accelerating the conversion of CO 2 to methanol via the formate pathway. This work elucidates the utility of developing electron-rich supports for CO 2 hydrogenation and offers valuable insights into the rational refinement of high-performance catalysts.