Construction of high-performance mixed matrix membranes with unique gas channels using MIL@ZIF core-shell filler for CO2 separation

The mixed matrix membrane (MMM) can combine the advantages of organic matrix and inorganic fillers, but it has the problem of limited compatibility between the fillers and the matrix. In this work, we constructed a metal-organic framework material (MOF) with a functional shell. Through the induced grafting effect of surfactants, a layer of zeolite imidazolate framework structure material (ZIF-8) was formed on the chromium-based metal-organic framework material (MIL-101(Cr)). Utilizing the microporous structure of the shell ZIF-8 and the micropore-mesopore structure of the core MIL-101(Cr), a “separation-diffusion” gas mass transfer pathway was formed within the membrane, effectively enhancing the CO 2 separation and purification performance of the membrane. Then, the MIL@ZIF filler was incorporated into the cross-linked PEO polymer matrix to obtain the XLPEO/MIL@ZIF membrane. It was demonstrated that the MIL@ZIF core-shell filler has a more excellent ability to enhance the gas separation performance of the membrane compared to the single MIL-101(Cr) and ZIF fillers. Under the optimal loading condition, the XLPEO/MIL@ZIF membrane achieves a CO 2 permeability of 328 Barrer and a CO 2 /N 2 selectivity of 93.1, which are 83.2 % and 72.1 % higher than the pure membrane, surpassing the upper limit (2019). This filler preparation strategy and MMM preparation method provide a promising direction for subsequent related research.