Polymeric ionic liquid membranes for the absorption-conversion of CO2 and epoxides into cyclic carbonates

Abstract

Polymeric ionic liquid membranes (PILMs) were prepared by photo-initiated polymerization of DMAEMA-based ionic liquids (ILs) and co-monomers for the conversion of CO2 into cyclic carbonates. The influences of functional groups and anions were investigated to find the optimal ionic liquid monomer. The PILM based on [DMAEMA-EtOH]Br exhibited the highest propyl carbonate (PC) yield (98%), which was close to that of the [DMAEMA-EtOH]Br monomer. Moreover, the PILMs can catalyze the gas state propylene oxide (PO) and CO2 into PC with a PO conversion of 87.3%, while the PO conversion of the pure polymeric ionic liquids was only 3.1% for gas state PO. The excellent catalytic activity can be attributed to the highly active catalytic sites and superb swelling ability of PILMs. The dry PILMs could absorb the PO vapor and swell into membranes with abundant pores, which contained plentiful active sites to catalyze PO and CO2 to PC efficiently.