Oxidative carbonylation of phenol to diphenyl carbonate catalyzed by ultrafine embedded catalyst Pd-Cu-O/SiO2

An ultrafine embedded catalyst Pd-Cu-O/SiO2 was prepared in a water-in-oil (W/O) microemulsion for the direct synthesis of diphenyl carbonate (DPC) by oxidative carbonylation of phenol with carbon monoxide and oxygen. In this catalyst, there are palladium-copper oxide cores surrounded by the silica shell, which provides protection for the active constituents during the reaction. This can reduce the leaching of the active components and then prolong the catalysts' service time. The embedded catalyst shows higher activity than the catalyst prepared by sol-gel process and longer service time than the catalyst prepared by impregnation method. The turnover number reached about 117.50 (mol-DPC/mol-Pd) at certain conditions. But the leaching of Pd and Cu in the embedded catalyst is still serious for some of them are located on the surface of the silica supports and easily enter into the solvent.