A continuous process for cyclic carbonate synthesis from CO2 catalyzed by the ionic liquid in a microreactor system: Reaction kinetics, mass transfer, and process optimization

The reaction of CO2 and propylene oxide (PO) for the synthesis of propylene carbonate (PC) is an important reaction, but the reaction is generally carried out under high-temperature and high-pressure conditions due to the limitations of reaction kinetics and mass transfer. Here, we propose a novel microreaction system catalyzed by ionic liquids (ILs). The reaction processes (e.g., catalyst, temperature, pressure, gas–liquid flow rate, catalyst concentration, residence time) were optimized within microreactors of different inner diameters. The kinetics for carbonate synthesis with CO2 catalyzed by ionic liquid (IL-[HMIM]Br) in a microreactor was evaluated, and the activation energy of [HMIM]Br was obtained. Based on the rough numerical estimation of mass transfer characteristics, coupled with the reaction characteristics, the microreactor enhancement can reduce the reaction time for this fast reaction to minutes, typically several hours in conventional reactors. This provides new opportunities for enhancing gas–liquid reactions with typical mass transfer control and for CO2 utilization to achieve carbon neutrality.