Controlled synthesis of high performance carbon/zeolite T composite membrane materials for gas separation

A simple and versatile approach has been developed to synthesize different carbon/zeolite T functional membrane materials. The precursors of the membrane are composed of polyimide matrix and dispersed zeolite T particles. Membranes prepared by pyrolysis at 973 K showed excellent gas (H2, CO2, O2, N2, CH4) permeability and selectivity and the gas selectivity (O2/N2, CO2/CH4) of the functional membranes for both single gas and mixed-gas can be controlled in a wide range by changing the zeolite T particle size and morphology without altering the final pyrolysis temperature and zeolite loadings. The maximum achieved selectivity for O2 over N2 (21/79 mol. %) of the functional membranes with the least zeolite T particle (0.5 μm) was 15 with an O2 permeability of 347 Barrers (1 Barrer=7.5×10 m s Pa) and the CO2 over CH4 (50/50 mol. %) selectivity reached a value of 179 with a CO2 permeability of 1532 Barrers. It is believed that the ordered microchannels in the zeolite and the bypasses around zeolite in the functional membranes increase the gas permeability. And the gas selectivity of the membranes was tuned by the interfacial gaps between zeolite and carbon phase via changing the zeolite particle size. This technique will provide a simple and convenient route to efficiently improve the trade-off relationship between the permeability and the selectivity, and will enable the construction of carbon-based functional materials with novel functionalities in membrane science.