A sustainable method to prepare ultra-thin MOF hollow fiber membranes for H2 separation

Abstract

Ultra-thin metal-organic framework (MOF) membranes have the potential to achieve high gas permeance and selectivity simultaneously. Current methods of depositing a compact ultra-thin MOF layer on polymer hollow fibers are neither environmentally friendly nor economical. Here, we propose a second repair growth method for preparing ultra-thin ZIF-8 membranes on a flexible polymer hollow fiber support (ZIF-8@PAN HF membranes). The thickness of the ZIF-8 layer on PAN hollow fibers can be adjusted from 326.7 nm to 174.6 nm. The optimized performance of ZIF-8@PAN HF membranes reaches H₂ permeance of 662 GPU and H₂/N₂ selectivity of 26.7. Additionally, a life cycle assessment of ZIF-8 hydrogen-selective membranes revealed that the second repair growth method exhibits the lowest environmental impacts compared to the other three methods typically reported in literature. This study may potentially drive the development of a more environmentally friendly and efficient preparation method of MOF membranes for gas separation.