Oxidative carbonylation of phenol to diphenyl carbonate catalyzed by palladium complexes bridged with N,N-ligands over functionalized silica

摘要

Heterogeneous palladium catalysts anchored on functionalized silica were prepared by sol-gel methods and their catalytic properties for the oxidative carbonylation of phenol to diphenyl carbonate (DPC) were investigated.The catalysts were characterized by means of IR,XPS,EA and BET.The Pd loading in the heterogeneous catalysts and leaching in solution were detected by atomic absorption.The effects of different reaction parameters such as temperature,solvent and inorganic cocatalyst on the yield of DPC and Pd leaching were also studied.It was found that Cu_2O and tetrahydrofuran (THF) were the best partners with these heterogeneous catalysts.In the presence of 3 A molecular sieves as dehydrating agent,the heterogeneous palladium catalyst prepared from 2-acylpyridine revealed excellent catalytic performance and stability at 110 deg C for 5 h,giving 13.7% yield of DPC based on phenol and 4.0% Pd loss in solution.The heterogeneous catalyst was more active and stable compared with traditional supported Pd-C catalyst under the same reaction conditions.