Constructing the high-efficiency “celluveyor conveyor” transport systems in membranes by IL@ZIF-8 for efficient CO2/CH4 separation

Abstract

Inspired by the high-efficiency transport systems combined the “conveyor” transport pathways with the “celluveyor” transport pathways, the ionic liquid imide modified ZIF-8 (IL@ZIF-8) was prepared as a filler and incorporated into the self-polymerization-confined Pebax/polyethylene glycol methyl ether acrylate matrix (SPM) to prepare mixed matrix membranes (MMMs) for efficient CO2/CH4 separation. The incorporated IL@ZIF-8 can construct the high-efficiency “celluveyor conveyor” transport systems that consisted of the “celluveyor” transport pathways and the “conveyor” transport pathways, and it played important roles in MMMs. Therein, the “celluveyor” transport pathways can be constructed with the help of CO2 carriers (Zn2+) in oriented and ordered pore channels of IL@ZIF-8, contributing to promoting rapid CO2 transport in multiple direction. IL was uniformly distributed on ZIF-8, and it acted as “binder” between adjacent ZIF-8 in IL@ZIF-8. IL in IL@ZIF-8 can adsorb CO2 molecules as a consequence of its strong chemical affinity for CO2, and the “conveyor” transport pathways can be constructed with the help of CO2 carriers ([Tf2N]-) in IL for rapid CO2 transport between the adjacent ZIF-8, improving CO2 separation performance of MMMs. Consequently, it was possible to enhance the performance of CO2 separation by constructing the high-efficiency “celluveyor conveyor” transport systems in SPM/IL@ZIF-8 MMMs. Therefore, SPM/IL@ZIF-8 MMMs were endowed with the excellent CO2 separation performance. It showed an enhanced permeability for CO2, which increased by 96.9 %, and a better CO2/CH4 selectivity, which improved by 56.6 %, when compared to the performance of the pure SPM membrane. It implied that the constructed high-efficiency “celluveyor conveyor” transport systems in MMMs were a promising strategy for efficient CO2 separation.