Study On The Synthesis Of Diphenyl Carbonate By Oxidative Carbonylation Of Phenol

The catalyst system and technics for oxidative carbonylation of phenol to diphenyl carbonate (DPC) has been studied.The oxidative carbonylation of phenol to DPC catalyzed by palladium complexes catalyst system (PdCl2+ Cu(OAc)2+ TBAB+ H2BQ) has been studied. The role of each component in the catalytic system is as follows: PdCl2 is the active component. TBAB is known to act both as stabilizing agent for Pd2+, and as surfactant agent for Pd?complexes. H2BQ promotes the reoxidation of Pd? Cu(OAc)2 is found to be the efficient inorganic redox promoter. The homogeneous reaction mechanism that is multistep eletron transfer catalytic cycle is proposed here. The suitable molar ratio of the components is: PdCl2/ Cu(OAc)2/ TBAB/ H2BQ= 1/3/30/40. The suitable reaction conditions have been confirmed and the highest yield of DPC is 40.5%.A new supported catalyst PdCl2-Cu(OAc)2/HZSM-5 with high activity has been developed. The best activity of the supported catalyst is obtained when the molar ratio of Pd/Cu is 1/15 and the loading of PdCl2 is 1.5wt%. The effect of solvent has been studied, DPC yield increasing as the following order: CH3OH< C6HM< DMC < CH2C12 In addition, DMC may become the substitution for CH2C12. The activity of catalyst is largely affected by supports, the activity of catalysts increasing with the following order of the supports: ZnO-Cr2O3 < 5A molecular sieve < MgO < 4A molecular sieve