A comprehensive study on the effect of preparation methods for Au-core@shell silica materials in room temperature oxidative amide formation

Abstract

Core–shell silica comprising mesoporous SiO₂ shell and solid SiO₂ core (SiO₂@mSiO₂) was utilized as catalytic support to prepare highly active and efficient Au–SiO₂@mSiO₂ catalysts for room temperature catalysis. Results showed that the mesoporous shell significantly contributed to the high surface area of SiO₂@mSiO₂. Au nanocatalysts prepared by different methods (impregnation, IM and deposition–precipitation-DP) exhibited remarkably different structural properties. Au–SiO₂@mSiO₂ catalysts exhibited excellent catalytic activity and high stability. Conversion could reach ca. 54% in the amidation of benzaldehyde and morpholine, with a complete selectivity to the target amide product at room temperature.