Modulating Electronic Interaction over Zr–ZnO Catalysts to Enhance CO<sub>2</sub> Hydrogenation to Methanol
Xiaoyue Wang, Zhengyang Yao, Xiaohong Guo, Zhiqiang Yan, Hongyan Ban, Pengfei Wang, Ruwei Yao, Lei Li, Congming Li
Abstract
ZnZrO x catalysts have been widely used to catalyze CO 2 hydrogenation to methanol, the catalytic characteristics of active sites being closely related to the electronic interaction between components. However, the electronic interaction between Zn and Zr sites for ZnZrO x catalysts is not clear. Herein, we investigate the impact of electronic interaction between Zn and Zr on the catalytic behavior of ZnZrO x catalysts. XPS results and DFT calculations demonstrate that there is an electronic interaction between Zr and Zn with the electron transfer from Zr to Zn, resulting in the formation of electron-rich Zn sites. Combined with H 2 -TPD, propylene hydrogenation reaction, H 2 –D 2 exchange experiments, in situ DRIFTS, and solid-state 1 H NMR results, it is evident that more electron transfer from Zr to Zn is conductive to accelerate H 2 dissociation to form more hydride species, likely due to the formation of electron-rich Zn sites. Meanwhile, such electron transfers can promote CO 2 adsorption to form more bidentate bicarbonate and bidentate carbonate species and also boost their hydrogenation to formate and methoxy species with the assistance of hydride species. The experimental results show that more electron transfer from Zr to Zn is favorable to enhance the CH 3 OH selectivity and yield, indicating that such an electronic interaction is more dominant in enhancing the CO 2 hydrogenation to CH 3 OH. This work reveals the pivotal role of the electronic interaction of active sites of catalysts for CO 2 hydrogenation, which is beneficial to rationally design and optimize the required catalysts.