Synthesis Of Diethyl Carbonate By Catalytic Alcoholysis Of Urea

The synthesis of diethyl carbonate from urea and alcohol is a new synthetic process and has drawn much attention in recent years。The raw materials are facile and low-cost so that this method can greatly reduce the synthesis cost of diethyl carbonate. This is a short process without polluting substances released. In this paper, the synthesis process was studied with the materials of urea and alcohol with different catalysis.The thermodynamic data of diethyl carbonate were calculated by means of Benson's group contribution method. A thermodynamic analysis was carried out about reactions which provided thermodynamic basis for the synthesis process of diethyl carbonate by means of urea alcoholysis.The quantitative analysis of the product was studied by means of internal standard method on a gas chromatograph analysis instrument. Under certain chromatographic conditions, diethyl carbonate, ethyl carbonate and ethanol in the reaction product get a good separation. The linear fit of diethyl carbonate and ethyl carbonate standard spectrum was carried out, and the result of recovery and precision indicated that the internal standard method is more accurate than external standard method, and can be used to analyze the product of the synthesis of diethyl carbonate.The catalytic properties of metal oxides on this process are studied. The experimental results indicate that the catalytic activity ZnO, MgO and Al2O3 among the single metal oxide is relatively good, the yield of DEC is to 30.65% in the suitable reaction conditions with ZnO as the catalyst; Zn-Mg-Al(2:1:3)metal oxide showed excellent catalytic activity among the four complex metal oxides, the yield of DEC is to 35.82% in the suitable reaction conditions. Characterization of some catalysts by BET and XRD was carried out to study the relationship between their catalytic activities with characteristics.Hydrotalcite-like compounds containing different cation were prepared and used to catalyze urea alcoholysis. ZnMgAl hydrotalcite-like compound (ZnMgAl LDHs) was screened out to study the catalytic activity differences before and after calcinations. The influences of reaction temperature, catalyst concentration and reaction time were investigated by analysis of orthogonal experiment on the base of single factor analysis with the calcinated product ZnMgAl LDHs as catalyst. Characterization of some catalysts by BET, XRD and TG was carried out to study the relationship between their catalytic activities with characteristics.Experiments on the recovery and activation of the catalysts about different catalytic system were carried out, and the activated catalysts still has a good catalytic performance when they have been used several times.