Study On Synthesis Of Diphenyl Carbonate By Transesterification Of Phenol And Dimethyl Carbonate

Clean synthesis of diphenyl carbonate (DPC) by transesterification of phenol and dimethyl carbonate (DMC) has been studied.The homogeneous synthesis of DPC has been investigated over n-Bu2SnO catalyst. The suitable conditions have been determined by orthogonal experiment, and the effect of each factor on the yield of DPC has been studied by single factor experiment. The highest yield of DPC is 32.8% under the suitable conditions in homogeneous reaction. Supported n-Bu2SnO catalyst is prepared, and the effect of support, loading quantity, calcination temperature on DPC yield has been studied. The reason for deactivation of supported n-Bu2SnO catalyst has been found out. The highest yield of DPC is 21.8% over n-BuaSnO/SiOa catalyst.A new heterogeneous catalyst, i.e. lead-zinc double oxide has been developed. The activity of single lead oxide and zinc oxide has been studied. Coprecipitation is used to prepare lead-zinc double oxide. The effect of calcination temperature, molar ration of Pb/Zn and different precursors on the catalytic activity has been investigated. The catalyst gets high activity and DPC yield is 44.8%, when calcination temperature is 500癈, Pb(NO3)2and Zn(NO3)2 as precursors, and Pb:Zn=2:l. DPC yield achieves 45.6% over the catalyst prepared by mechanical milling. XRD, TPR and atomic absorption spectroscopy are employed for catalyst characterization. PbaC^ is found as the main catalyst, and amorphous ZnO as promoter. Reuse of the catalyst has been studied and the reason of deactivation is valence state of Pb dropping from +8/3 to +2 due to its reaction with phenol.Different methods have been employed in the preparation of supported lead -zinc double oxide. DPC yield is 3.37% over PbO-ZnO/SiO2 catalyst prepared by impregnation. Pillared interlayered clay (PILC) catalyst has been prepared by titration, over which DPC yield is 9.08%. Influence of OH7Pb2+, temperature of pillaring process and calcination temperature on the activity of catalyst has been studied. Gel method has also been used to prepare PILC. Effect of addition amount of H2O, NH3 -H2O, and calcination temperature on the properties of PILC has been investigated.The influence of surfactant is discussed. Single Ti-PILC has catalytic activity to the transesterification reaction, and DPC yield is 14.6%. PbZnTi-PILC catalyst is prepared by introducing Pb and Zn into Ti-PILC; DPC yield is 10.1%. There does not exist the crystalline structure of the active component in XRD characterization. Reuse of the catalyst has been studied and the reason of deactivation has been discussed.