MIXED MATRIX MEMBRANES BASED ON 6FDA-DURENE POLYIMIDE/ZEOLITIC IMIDAZOLATE FRAMEWORK (ZIF)-71 FOR NATURAL GAS AND HYDROGEN PURIFICATION

Abstract

Zeolitic imidazolate framework (ZIF)-71 nano-particles have been demonstrated as potential inorganic fillers for fabricating high performance membranes for gas separation. The newly synthesized ZIF-71 nano-particles were compatibly incorporated in 6FDA-Durene polyimide membranes as novel mixed matrix membranes (MMMs) for gas separation. The effect of ZIF-71 loading on gas separation performance was first investigated for H2, O2, N2, CO2, CH4, C2H4, C2H6, C3H6 and C3H8. In a subsequent study, the H2/CO2 separation properties of the fabricated MMMs was molecularly tuned from CO2-selective to H2-selective by vapor cross-linking with tris(2-aminoethyl) amine. The proposed vapor cross-linking method was discovered to solve the non-selective interfacial voids formation in MMM fabrication. The thermal H2/CO2 separation properties of di/tri-amine vapor cross-linked MMMs were successively investigated. Finally, the effect of ZIF-71 particle size on gas separation performance of MMMs was studied. A trade-off between ZIF-71 particle size vs. gas separation performance must be taken into account when designing an MMM suitable for industrial gas separation applications.