Bimodal-porous hollow MgO sphere embedded mixed matrix membranes for CO2 capture

We reported the use of high-performance, CO2-accelerated mixed matrix membranes (MMMs) consisting of sub-micron porous magnesium oxide (MgO) fillers and an amphiphilic polymer matrix. Bimodal-porous, hollow MgO (bh-MgO) spheres were synthesized through a one-step spray pyrolysis and precipitation method. The synthesized bh-MgO spheres were introduced into poly(vinyl chloride)-graft-poly(oxyethylene methacrylate) (PVC-g-POEM), forming MMMs for CO2/N-2 separation. The amphiphilic property of PVC-g-POEM ensured an intimate contact between the bh-MgO filler and polymer matrix with the encapsulation of bh-MgO spheres. The bimodal porous and hollow structure of bh-MgO decreased the gas diffusion resistance in the membranes. Moreover, specific interactions between the surfaces of the bh-MgO and CO2 molecules enhanced the CO2 solubility and accelerate the CO2 molecules more than the N-2 molecules. The dual-functional bh-MgO sphere enhanced the CO2 permeability through physical and chemical mechanisms, simultaneously. The best gas separation performance was obtained in the MMM with 10 wt% bh-MgO fillers, which demonstrated a CO2 permeability of 179.2 Barrer and 42.6 of CO2/N-2 selectivity.