Hydrophobically modified Cu-ZnO-Al2O3 catalyst for CO2 hydrogenation to methanol

Herein, the well-studied Cu-ZnO-Al2O3 methanol synthesis catalyst was functionalized by bridging triethoxy (octyl)silane (TEOOS) molecules to achieve a surface hydrophobic. Water droplet contact angle measurements confirmed the successful construction of the hydrophobic surface. Various characterization techniques, including XRD, SEM, TG, H2-TPR, CO2-TPD, and XPS, were systematically employed to elucidate the impact of the hydrophobic modification on the structure and catalytic performance of the catalyst in CO2 hydrogenation. The results showed that after the hydrophobic modification, the morphology and physical structure of the catalyst remained nearly unchanged, and it kinetically enhanced the methanol synthesis by repelling the produced water molecules. Moreover, the decoration of hydrophobic alkyl chains on Cu-ZnO-Al2O3 catalyst surface not only prevented the retention of by-product most water on its surface and protects the Cu0 species from over-oxidation but also stabilized surface Cu+ species during the reaction process. Activity evaluation results demonstrated that the hydrophobic Cu-ZnO-Al2O3 catalyst facilitated the enhancement of methanol yield and CO2 conversion.