Enhancing CO<sub>2</sub> Hydrogenation to Methanol at Mixed-Phase Interfaces on ZnZrO<sub><i>x</i></sub> Solid Solution Catalysts
Zhiwei Liang, Shan Tang, Siyu Chen, Lanqi Ning, Jijie Wang, Can Li
Abstract
Zinc–zirconium oxides (ZnZrO x ) are highly selective and stable catalysts for the hydrogenation of CO 2 to CH 3 OH. However, their catalytic activity has remained relatively moderate, and the influence of the ZnZrO x crystalline phase on performance is not yet fully elucidated. Here, we report a mixed-phase ZnZrO x, comprising coexisting tetragonal and monoclinic domains, and correlate this biphasic architecture with the catalytic performance. At 320 °C, the mixed-phase ZnZrO x catalyst delivers a CO 2 conversion of 9.2% coupled with an impressive CH 3 OH selectivity of 87%, representing a 1.4-fold increase in conversion compared to its purely tetragonal counterpart while maintaining equivalent selectivity. In-depth characterizations attribute this improved performance primarily to the emergence of a two-phase interface, which enhances the dissociation and activation of H 2 . Density functional theory calculations further reveal that this interfacial region plays a vital role in promoting heterolytic H 2 dissociation, boosting the formation of HCOO* and lowering the energy barriers of the rate-determining step for CH 3 OH formation. This work highlights the effectiveness of the crystal-phase architecture in optimizing ZnZrO x catalysts for CO 2 hydrogenation to CH 3 OH, offering strategic insights for the design of advanced oxide-based hydrogenation systems.