Mixed-matrix membranes comprising porous organic molecular cage for efficient CO2 capture

Abstract

Membrane-based separation technology exhibits significant potential in the fields of CO2 capture and gas purification. Mixed-matrix membranes (MMMs) integrate the easy processing of polymeric materials with excellent transport properties of fillers, and thereby have become a focus for the next-generation gas separation membranes. Herein, we demonstrated a novel mixed-matrix membrane comprising porous organic molecular cages (POCs) and amine-rich polyvinylamine (PVAm) polymer matrix for efficient CO2 separation. Micro-sized CC3 crystals featuring a pore size of ∼4.9 Å, a high micropore volume of 0.16 cm3 g−1 and specific surface area of 326 m2 g−1 were synthesized and immobilized onto the surface of the PVAm thin selective layer to generate rapid CO2-transport channels. The resulting CC3/PVAm/mPSf MMM displayed excellent binary gas mixture (CO2/N2 15/85 vol %) separation performance, with a high CO2 permeance of 1546 GPU, and appreciable CO2/N2 selectivity of 33 at 1.5 bar, which was superior to most reported POCs-based membranes and thin film composite membranes, accompanied with excellent long-term operational stability. The CO2-selective separation facilitated by the incorporation of POCs provided a new inspiration for the development of novel MMMs for efficient CO2 capture.