Organosilica functionalized zeolitic imidazolate framework ZIF-90 membrane for CO₂/CH₄ separation

The separation of CO₂/CH₄ is reported by using 3-aminopropyltriethoxysilane (APTES) modified zeolitic imidazolate framework ZIF-90 membrane. The as-prepared ZIF-90 membrane was modified by APTES based on an imine condensation reaction between the free aldehyde groups of the ZIF-90 frameworks and the amino groups of APTES. After APTES modification, the morphology, purity and crystallinity of the ZIF-90 membrane keep unchanged. Attributing to both pore mouth narrowing and sealing of invisible intercrystalline defects of the polycrystalline ZIF-90 layer, the separation performances of the APTES-modified ZIF-90 membrane are remarkably enhanced. For the separation of equimolar CO₂/CH₄ mixture at 225 °C and 1 bar, a CO₂ permeance of 1.26 × 10^-8 mol m ^-2 s^-1 Pa^-1 and a CO₂/CH₄ selectivity of 4.7 are obtained, which is of promising in the potential application of CO₂ separation and removal.