Continuous processing of sustainable mixed-matrix carbon hollow fiber precursors for ethylene/ethane separation membranes

Abstract

Membrane-based separations constitute energy-lean alternatives to olefin/paraffin purification, however, it remains challenging to translate sub-ångström discrimination into defect-free, large-area membranes via manufacturing-compatible routes. In this work, we realize a multiscale engineering design that strategically integrates engineered metal-organic frameworks (MOFs) with renewable, low-cost biomass-derived polymers via continuous-flow processing, followed by semi-batch carbonization into mixed-matrix carbon hollow fiber membranes. Controlled molecular entanglement imparts robust colloidal stability and interfacial cohesion, enabling thermal conversion of the monolithic precursor into contiguous inorganic-inorganic carbon nanophases. The intergrown, triphasic heterogeneous nanodomain enables fast ethylene transport and ultra-precise ethylene/ethane discrimination (C2H4/C2H6 selectivity of 75) under practical high-pressure conditions (20 bar) with long-term stability over 21 days. We also demonstrate a large-area membrane module (125 cm2) that retains attractive ethylene/ethane separation performance with an ideal single-gas C2H4/C2H6 selectivity of 51 and a mixed-gas selectivity of ~30 at 10 bar. A techno-economic analysis further confirms their cost competitiveness, highlighting module-relevant scalability and sustainability for petrochemical and broader gas separation applications. This continuous-flow hybrid strategy provides an applicable toolbox to translating sub-nanometer precision into robust, module-relevant molecular-sieving membranes. Continuous-flow processing of MOF-biopolymer precursors enables large-area mixed-matrix carbon hollow fiber membranes with triphasic carbon nanodomains, thereby translating molecular-sieving precision into practical ethylene/ethane separation.