Surface-Engineered ZnZrO _<i>x</i> Solid Solution by Kinetics-Controlled Precipitation for Efficient CO ₂ Hydrogenation to Light Olefins

The catalytic hydrogenation of CO2 to light olefins (LOs) via a methanol-mediated pathway offers a promising approach toward carbon neutrality. However, the efficiency of this process is limited by the performance of conventional metal–oxide catalysts due to the surface-related shortcomings. Traditional ZnZrOx catalysts, typically prepared by the coprecipitation or sol–gel method, exhibit relatively low surface area (<50 m2·g–1), and inadequately exposed Zn–O–Zr sites and oxygen vacancies on the catalyst surface, which restrict H2 activation and CO2 adsorption. To overcome these shortcomings, a novel ZnZrOx solid-solution catalyst was developed via a gas diffusion (GD) strategy, which achieves a high surface area (89.4 m2·g–1) and surface Zn enrichment, significantly promoting the formation of surface Zn–O–Zr sites and oxygen vacancies. This synthesis leverages controlled precipitation kinetics by the slow GD of ammonia and the differential solubility of metal hydroxides to achieve surface-selective Zn deposition, thereby enhancing the density of the surface-active sites. When coupled with SAPO-34, the bifunctional catalyst demonstrates exceptional performance, achieving a CO2 conversion of 28.2%, LO selectivity of 86.6%, and LO yield of 13.5%, along with remarkable stability (<0.4 percentage point yield drop over 100 h). A mechanism study using in situ DRIFTS analysis demonstrates that the surface enrichment of Zn species simultaneously enhances the CO2 adsorption and cleavage of H2, thereby effectively promoting the formation of HCOO* and CH3O* intermediates, which subsequently facilitates stable LO production. This work provides an effective strategy for designing efficient and stable bifunctional catalysts for direct CO2-to-light olefin conversion.