CATALYTIC CONVERSION OF CARBON-DIOXIDE USING PHASE-TRANSFER CATALYSTS

In the present study, synthesis of 5-membered cyclic carbonates from C O2 and epoxides, such as glycidyl methacrylate(GMA) and diglycidyl 1,2 -cyclohexane dicarboxylate(DCD), were investigated in view of the char acteristics of phase transfer catalysts, reaction mechanisms and kinet ics. Quaternary salts showed a good conversion of epoxide at 1atm of C O2 pressure. Among the salts tested, the one having a larger alkyl gro up and a more nucleophilic counter anion exhibited a better catalytic activity. Kinetic studies in a semi-batch reactor, through which a slo w stream of CO2 is continuously passed, showed that the reaction rate was pseudo-first order with respect to the concentration of epoxide. I n a batch autoclave reactor with high CO2 pressure, however, the react ion rate showed second order kinetics. The reaction was also carried o ut with an insoluble phase transfer catalyst, quaternary ammonium chlo ride(QCl) anchored to metal oxide, to facilitate the recovery of catal yst. (C) 1997 Elsevier Science Ltd.