Study On Catalyst Screening And Kinetics In Synthesis Of Diphenyl Carbonate By Transesterification

Diphenyl Carbonate(DPC)is indispensable to produce polycarbonate(PC)using non-phosgene processes.This paper has studied catalytic activity of organo-metallic catalyst and acidic ionic liquid catalyst to transesterification from phenol and dimethyl carbonate(DMC)to diphenyl carbonate in the reactive distillation reactor.Meanwhile,the kinetics for this reaction has been measured.After conducting research on catalytic performance for two organo-metallic catalyst inclucding n-Bu2SnO and Ti(OBu)4,optimization for reaction condition from two catalysts to this transesterification.It is found that,for both two catalysts including n-Bu2SnO and Ti(OBu)4,the most suitable reaction conditioning is Phenol:catalyst(mole ratio)=1:0.01,T=443.15 K.Under this reaction condition,the catalytic activity from n-Bu2SnO is a little higher than Ti(OBu)4.Meanwhile,both of these two catalysts have delivered good performance in selectivity and only infinitesimal by-product as anisole has emerged.Under the optimum reaction conditions,the catalytic activity for B-acid ionic liquids has been studied.It is found that the catalytic activity of B-acid ionic liquids is basically same with their acidity level,which has indicated that the acidity of B-acid ionic liquids is an important factor influencing their catalytic activity.The catalytic performance of six kinds of L-acid ionic liquids has been studied under the optimum reaction conditions and it is found that stannous chloride ionic liquids has expressed highest catalytic activity.Meanwhile,conclusion has been drawn that the catalytic activity of L-acid ionic liquids is not only related to categories of metal ions in active center of L-acid but also will be affected by structure of cations.At the same time,for L-acid ionic liquids with the same anion and cation,such as[cation]Cl[MCly]x(M representing metal),the strength of L-acid will increase along with the rising of X value so that the catalytic activity will go up.However,with the increase of acidity,the selectivity for main products may decrease.Therefore,when we consider L-acid ionic liquids as catalysts,both catalytic activity and selectivity should be considered and the ionic liquids with moderate acidity should be selected.On the basis of transesterification mechanism of catalyzed by n-Bu2SnO,some reasonable assumptions have been made and kinetic model is established so that kinetic differential equation has been obtained.According to the kinetic data acquired from experiment,the kinetic equation has been fitted by genetic algorithm and kinetic parameters are concluded.The correlation between kinetic parameters in model&experimental data is verified by statistical test method in non-linear model and it is believed that the selected model¶meters from estimation are very credible.