Technology Study On Synthesis Of Diphenyl Carbonate By Transesterification

Diphenyl carbonate, short for DPC, is a green organic carbonate, which is used in many fields. This paper focuses on the study of technological conditions, kinetics and possible reaction mechanism of synthesis of methyl phenyl carbonate by transterification between dimethyl carbonate and phenol through reactive distillation under pressure. Besides, the disproportionation of methyl phenyl carbonate has aslo been studied.Synthesis of methyl phenyl carbonate by transterification between dimethyl carbonate and phenol was studied in a pressure reaction distillation unit. By screening catalyst, HLcat-1was chosen. Then the effect of temperature, refluxing time, molar ratio and mass fraction of catalyst on the reaction results were discussed. After that, the technological conditions were determined as follows, the reaction temperature at463.15K, the refluxing time at3hours, the molar ratio of dimethyl carboante and phenol at6and the catalyst concentration at1.0wt%, the convension of phenol was70.5%, and the selection of methyl phenyl carboante was99.6%.The kinetic properties of the reaction between dimethyl carbonate and phenol was studied by using HLcat-1as catalyst. Through reasonable simplification, the kinetic model was established and the model parameters were determined. Equilibrium yields of the main reaction to produce methyl phenol carbonate and the side reaction to produce anisole was increased with the increase of reaction temperature, which meant that both the main reaction and the side reaction were endothermic. By comparing activation energy of the main reaction and the side reaction, we found activation energy of the main reaction was smaller. So in order to improve the selection of methyl phenyl carbonate, relatively low temperature was favorable.The disproportionation of methyl phenyl carbonate was researched under vacuum reactive distillation. Through investigating several catalysts, HLcat-1was proved to be the best one. Then the effect of reaction temperature, vacuum degree and mass fraction of catalyst on the reaction results were discussed. After that, the disproportionation conditions were determined as follows,the reaction time at4h, the reaction temperature at473.15K, the vacuum degree at0.055Mpa and the catalyst concentration at1.0wt%, the convension of methyl phenyl carbonate was96.7%, and the selection of diphenyl carboante was95.6%.The purification of product of disproportionation was studied. After purification, the final product was white crystal, the purity of diphenyl carbonate was99.4%, the chromaticity was30Hazen, and the yield of diphenyl carbonate was90.3%.