Mixed matrix membrane containing metal oxide nanosheets for efficient CO2 separation

Abstract The two-dimensional (2D) nanosheet zinc cobaltate (ZnCo2O4) was added into polyether block amide (Pebax) matrix to prepare mixing matrix membrane (MMM) for separating carbon dioxide (CO2)/methane (CH4) gas mixture. The 2D porous ZnCo2O4 nanosheets were composed of chemically interconnected metal oxide nanoparticles. The ZnCo2O4 nanoparticles in the nanosheets constructed large-quantity pores of 11.78 nm and provided abundant transfer channels for gas molecule. Moreover, the synergistic effect of bimetallic Zn2+ and Co2+ would promote the generation of oxygen vacancies (Oδ-), which could provide more CO2 (Cδ+) adsorption sites, thereby increased the selectivity of the membrane. The large aspect ratio of the ultra-thin ZnCo2O4 nanosheets showed better dispersion in the membrane. The pure gas separation performance data showed the CO2 permeability and CO2/CH4 selectivity of Pebax/ZnCo2O4 membrane were 139.10 Barrer and 15.38, respectively, when the filling amount was 0.5 wt%. Compared with pure Pebax membrane, the separation performance (permeability and selectivity) were increased with 165.67% and 75.57%, respectively.