CuO nanoclusters coated with mesoporous SiO2 as highly active and stable catalysts for olefin epoxidation

Abstract

A one-pot solvothermal synthetic method to prepare uniform CuO colloidal nanocrystal clusters (CNCs) with sizes of approximately 60 nm was developed. To enhance their stabilities, the CuO CNCs were coated with mesoporous SiO₂ shells to form CuO CNCs@meso-SiO₂ nanocomposites. The CuO CNCs as well as the CuO CNCs@meso-SiO₂ composite catalyst were characterized by transmission electron microscopy, small-angle X-ray diffraction and N₂adsorption-desorption methods. These results indicate that the SiO₂ shells have winding mesoporous channels with an average size of 3.7 nm, which are very favorable for mass transfer and catalytic reactions. This nanocomposite catalyst exhibited excellent activity and stability in olefin epoxidation reactions. The structure of the composite catalyst remained intact after eight consecutive runs, while pure CuO CNCs severely aggregated after only 1 run.