High loading and high-selectivity H2 purification using SBC@ZIF based thin film composite hollow fiber membranes

Abstract

Membrane-based separation systems have been widely explored for hydrogen production and purification in the development of next-generation fuels. In this work, we propose a thin film composite hollow fiber membrane (TFCHFM) for H2 purification, incorporating poly(styrene-co-butadiene) copolymers (SBC, 4% butadiene, for flexibility and ease of processing) and ZIF-8 nanoparticles. The TFC was supported on a PEI-based hollow fiber substrate. SBC containing a flexible butadiene segment showed enhanced compatibility through π-π interactions. The morphology of ZIF-8 was altered from a cubic shape to a smaller spherical shape by altering the molar ratio of NH4+/Zn2+. The gas separation mechanism of the ZIF-8 based TFC membrane was predicted by the Maxwell model. In the binary gas permeation test (5 vol% H2), the H2 permeance and H2/CH4 selectivity of TFCHFMs were 6.85 GPU and 152.20, respectively, with 50 wt% ZIF-8 loading. We believe that the high loading weight (50 wt% ZIF-8) and H2/CH4 selectivity presented here are unprecedented for ZIF-8 based TFC membranes reported in the literature.