Syngas hydrogen upgrading using green-based ultra-microporous carbon hollow fibre membranes

This study investigates the use of ultra-microporous carbon hollow fibre membranes for the H 2 upgrading from syngas. The hollow fibres were spun from a P84 polyimide dope using the green solvent γ-butyrolactone, thereby avoiding conventional dipolar aprotic solvents (e.g., NMP/DMF). Together with a simple water-based post-treatment and N 2 carbonisation, this approach reduces solvent hazards compared to traditional routes while yielding ultra-microporous, as confirmed by Sips isotherm fitting, carbon HFs with high selectivity. Their separation performance was examined through mixed-gas permeation experiments using binary (H 2 /CO 2 , H 2 /CO) and ternary (H 2 /CO 2 /CO) gas mixtures over a range of feed compositions and temperatures. H 2 exhibited the highest permeance, increasing with its feed molar fraction, while CO 2 and CO displayed progressively lower permeance due to competitive sorption and kinetic restrictions. For ternary gas mixtures feed, the membranes enriched H 2 from ∼30 % to 57 % in the permeate, while reducing CO by 86 M%, demonstrating strong selectivity also in mixed gas conditions. Permeation data were incorporated into process simulations to investigate membrane configurations for H 2 upgrading from syngas. A two-stage configuration achieved up to 90 M% H 2 purity at 86 % recovery. Overall, the combination of green fabrication, tailored microporosity and promising process-level performance positions these carbon hollow fibre membranes as attractive candidates for H 2 purification, post-combustion CO 2 capture and broader membrane-based gas separation applications. • Ultra-microporous carbon hollow fibre membranes for H 2 upgrading from syngas. • Polyimide-derived carbon hollow fibre membranes fabricated using green solvents. • H 2 concentration enhanced from 30 % to 57 %, while reducing CO by 86 %. • Multistage membrane configuration designed to obtain a H 2 -rich streams. • The two-stage membrane process achieved 86 % H 2 recovery with a purity of 90 %.