Engineering Cu-ZnO in Hydroxyl-Rich Zeolite for High-Performance CO2-to-Methanol Conversion

A strategy for synthesizing bimetallic catalysts confined within zeolite frameworks, offering a promising approach for stabilizing metal species under harsh reaction conditions, is disclosed. A dual-stage synthesis strategy including alkali etching to open the channels of Silicalite-1 (S-1) zeolite, exposing internal hydroxyl defects that serve as anchoring sites for Cu and Zn species, is presented. This was followed by a dry-gel conversion encapsulation step to yield Cu-ZnO@S-1 catalyst. The competitive occupation of these sites by Cu and Zn facilitates the formation of high-density Cu-ZnO interfaces. Under reaction conditions of 3 MPa and 250 °C, the catalyst achieves a methanol selectivity above 99.2% and a space-time yield (STY) of 2.1 g gCu–1 h–1, nearly four times higher than that of copper-containing catalyst (Cu@S-1, 0.54 g gCu–1 h–1) and significantly outperforming the sample prepared by conventional impregnation (Cu-ZnO/S-1, 1.6 g gCu–1 h–1). The oxygen-deficient Cu-ZnO1–x sites at the Cu-ZnO interface are further demonstrated to serve as genuine active centers for methanol synthesis. The methanol formation reaction proceeds via the formate pathway, and the high density of Cu-ZnO1–x sites effectively lowers the activation barrier for the hydrogenation of *HCOO to *H2COO.