An MOF-tailored hierarchical porous microenvironment for CO2 as an efficient filler for mixed matrix membranes

Abstract

Mixed matrix membranes (MMMs) for separating CO2/CH4 mixture were prepared through incorporating Cu@Al(bpydc) into a Pebax polymer in which Cu@Al(bpydc) synthesized through a competitive coordination method achieved a controllable micro/mesopores structure and abundant functional sites for CO2. The hierarchical pores of Cu@Al(bpydc) provided multidimensional diffusion channels in the Pebax matrix, which increased the diffusion of CO2. In addition, the abundant chemical groups, such as the polar group COO– and nitrogen Lewis basic groups, created a microenvironment with multiple CO2 affinity sites in the membrane, increasing the selectivity of CO2. A MMM loaded with 5 wt% Cu@Al(bpydc) exhibited excellent CO2 separating property under wet mixed-gas test conditions. In particular, the CO2 permeability and selectivity of the MMMs were increased by 92.90% and 27.10% respectively, compared with those of pure Pebax, showing exceptional potential for the separation and capture of CO2 from biological natural gas.