A three-component mixed-matrix membrane with enhanced CO2 separation properties based on zeolites and ionic liquid materials

A mixed-matrix membrane containing three components of polymerizable room-temperature ionic liquids (poly(RTIL)), RTIL and zeolite materials was fabricated, and its transport properties were studied. A previous study showed that 20 mol% of RTIL in a poly(RTIL) membrane increased the gas permeability of the composite membrane due to more rapid gas diffusion in the RTIL. At the same time the selectivity of these membranes remains relatively constant with respect to the original poly(RTIL). On the contrary, mixed-matrix membranes consisting of a polymeric matrix and dispersed inorganic particles have the potential for outstanding separation properties, but some challenges such as a good adherence at the inorganic/organic interface still remain uncertain. In this article, we used an RTIL to both increase the permeability of the membrane, and to better facilitate interaction between the poly(RTIL) (polymer) and zeolite (inorganic particles). Our results showed that the RTIL component may have served as an interfacial material for better adhesion between the inorganic zeolite surface and organic polymer. We have shown that addition of the ionic liquid increased the selectivity of the MMM, which demonstrated that the membrane is without defects. Moreover, the performance of this membrane was in agreement with the Maxwell model prediction, which is important because it also indicated that the membrane is defect-free. We believe that this approach may be extended as a novel general method for forming zeolite/polymer-based MMMs with better performance properties.