Porous silica as supports for controlled fabrication of Au/CeO2/SiO2 catalysts for CO oxidation: Influence of the silica nanostructures

Porous silica with different nanostructures, namely two-dimensional hexagonal SBA-15, three-dimensional cubic KIT-6 and hierarchical monolith silica (HMS), were used as supports to fabricate gold catalysts using a liquid-phase deposition–precipitation method. Pre-loading of ceria on porous silica can significantly improve the dispersion of the subsequently introduced gold nanoparticles and the catalytic activity of the final composite (Au/CeO2/SiO2) catalysts in CO oxidation. The composite catalysts were characterized by N2 adsorption, X-ray diffraction. The results indicate that different nanostructures of silica imposed significant influence on the catalytic activity of Au/CeO2/SiO2 catalysts. Gold catalyst supported on HMS exhibited the highest activity for the conversion of CO to CO2 with a complete conversion (T100%) at a temperature of 60 °C and at a space velocity of 80,000 mL gcat−1 h−1, whereas T100% shifted to 120–130 °C for SBA-15 and KIT-6 supported gold catalysts.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Various structured SiO2 modified with CeO2 were used to construct gold catalysts. ► Nanostructures of SiO2 had great effect on the catalytic activity for CO oxidation. ► Different structures of the supports exert great influence on the diffusion rate. ► Hierarchical monolith silica supported Au had the highest activity (T100% = 60 °C).