Two-dimensional basic cobalt carbonate supported ZIF-67 composites towards mixed matrix membranes for efficient CO2/N2 separation

Two-dimensional (2D) porous materials have great potential in high-performance gas separation membranes. Herein, we demonstrate a facile synthesis of basic cobalt carbonate supported zeolitic imidazolate framework-67 (BCoC-ZIF) nanoplates via a template conversion method in aqueous solutions. Basic cobalt carbonate nanosheets were used as the metal source and BCoC-ZIF composites with various ZIF-67 loadings were obtained through adjusting the reaction time in an aqueous solution of 2-methylimidazole. Numerous mixed matrix membranes (MMMs) are prepared with different loadings of BCoC-ZIF composite nanoplates in the polymer of intrinsic porosity-1 (PIM-1), ranging from 1 to 20 wt% of filler loadings. The typical MMM with 10 wt% loading shows a CO2 permeability of 7326 Barrer and CO2/N2 separation factor of 32.5, exceeding the latest 2019 upper bound. The improved separation performance greatly relies on the multiply synergistic effect of high CO2 adsorption capacity, alignment of 2D morphology and molecular sieving ability of BCoC-ZIF. This study may offer a new direction for the rational design of MMMs for gas separation applications.