Kinetic Analysis of Cyclic Carbonate Formation from Oxirane and Supercritical Carbon Dioxide and Selective Separation of Cyclic Carbonate from Supercritical Mixture

Abstract

Supercritical carbon dioxide was reacted with 2-methyloxirane in the presence of LiBr catalyst in a continuous tank reactor to produce a cyclic carbonate, i. e., 4-methyl-1, 3-dioxolan-2-one. High conversion (>70%) and high product selectivity (>90%) were achieved when the reaction was carried out for 30 min at 80-90°C and 15-20 MPa. The reaction rate constants of main and side reactions were determined from the experimental data and their dependence on the temperature, pressure, and amount of catalyst was analyzed in detail. The selective separation of cyclic carbonate from the supercritical mixture was also investigated. When the temperature and pressure of the supercritical mixture flowing out of the reactor were lowered from 80-90°C and 15-20 MPa to 35-40°C and 4-6 MPa, 4-methyl-1, 3-dioxolan-2-one with a purity of more than 90% was obtained with a recovery rate higher than 70%.