Preparation of highly active silica-supported Au catalysts for CO oxidation by a solution-based technique

Au nanoparticles deposited on metal oxides are being actively investigated as catalysts. However, few reports concerning gold deposited on silica as catalysts have appeared because Au particles with < 5 nm on silica supports are difficult to be synthesized on silica surfaces without capping agents for the protection of Au surfaces. Haruta et. al were the first to report that the Au nanoparticles with high catalysis activities can be introduced on silica surfaces via chemical vapor deposition. This method involves complex apparatus and expensive reagents, which hamper the wide application of this deposition method for preparation of silica-supported catalysts. An efficient method for synthesis of silica-supported Au catalysts through a Au cationic complex precursor is presented. A unique precipitation-deposition method has been developed to immobilize the cationic precursor on negatively charged surfaces of silica. The Au nanoparticles are subsequently generated by reduction and are highly active for CO oxidation at room temperature and even at below 0°C. This is an abstract of a paper presented at the 231th ACS National Meeting (Atlanta, GA 3/26-30/2006).