KINETIC REGULARITIES OF THE PROCESS OF ETHYLENE CARBONATE SYNTHESIS BY INTERACTION OF UREA AND ETHYLENE GLYCOL

Ethylene carbonate has a wide range of applications in the chemical industry. Polyurethanes, electrolytes, herbicides and insecticides, dimethyl carbonate and polycarbonates, modifiers for polymers - this is only a small part of what can be produced with ethylene carbonate and its other homologues - cyclocarbonates. Since the end of the XIX century, a wide range of methods for obtaining compounds of the cyclocarbonate class has been studied, such as phosgene method, obtaining from oxirane compounds and carbon dioxide, alkylene chlorohydrins and inorganic carbonates and others. KazanOrgSintez PJSC has mastered large-capacity production of ethylene carbonate by interaction of ethylene oxide with carbon dioxide. An important advantage of this method is that it allows the utilization of carbon dioxide. However, it has significant drawbacks. Mixtures of ethylene oxide with air are extremely explosive and flammable. Also, ethylene oxide is toxic with mutagenic and carcinogen effects. Additionally, process is carrying out under extremely high pressure (60-80 atmospheres). Therefore, in the present, there is a challenging problem of cyclic carbonates obtaining by non-toxic safe method. The most progressive method is synthesis via urea and alkylene glycols. In the present work, the influence of the nature of catalysts, their concentrations, and temperature on the yield of ethylene carbonate during the interaction of urea with ethylene glycol was studied. The highest ethylene carbonate yield is provided by zinc oxide. Also, yield extremally depends of zinc oxide weight. Large amounts of zinc oxide drastically reduce the yield of the target product. The optimal zinc oxide weight is 4,13 % mass. The optimum process temperature of 150 ℃ was determined. Reaction orders for urea and ethylene glycol was determined. The reaction has first order for urea and zero order for ethylene glycol. It is suggested that the rate of ethylene carbonate formation is determined by the stage of formation of the catalytic complex of zinc oxide with urea. This complex quickly reacts with ethylene glycol with further transformation into ethylene carbonate.