Selective Gas Permeation in Mixed Matrix Membranes Accelerated by Hollow Ionic Covalent Organic Polymers

Mixed
matrix membranes (MMMs) have gained great attention for the
efficient CO2 removal from raw nature gas or biogas (CO2/CH4 separation) and flue gas (CO2/N2 separation). Nevertheless, the development of high-performance
MMMs for industrial applications is largely limited by the lack of
suitable porous fillers. Herein, a novel ionic covalent organic polymer
(ICOP-1) consisting of gas selective pores and hollow cavities is
facilely fabricated using a metal triflate catalyzed condensation
reaction. Considering its unique structural properties, ICOP-1 is
explored as a novel filler to enhance the gas separation properties
of polysulfone (PSf) membranes. Defect-free MMMs are successfully
prepared owing to the high polymer–filler affinity originating
from the organic nature of these two phases. Besides, the large cavities
and size-selective pores of ICOP-1 lead to a simultaneous increase
in membrane CO2 permeability and CO2/CH4, CO2/N2 selectivities. With the addition
of only 0.5 wt % of ICOP-1 fillers, the as-prepared MMM demonstrates
the optimal gas separation performance with a CO2/CH4 selectivity of 39.7 (at a CO2 permeability of
6.19 Barrer) and a CO2/N2 selectivity of 36.7
(at a CO2 permeability of 6.85 Barrer), opening new opportunities
in membrane-based industrial CO2 capture applications.