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 H2 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 N2 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 (H2/CO2, H2/CO) and ternary (H2/CO2/CO) gas mixtures over a range of feed compositions and temperatures. H2 exhibited the highest permeance, increasing with its feed molar fraction, while CO2 and CO displayed progressively lower permeance due to competitive sorption and kinetic restrictions. For ternary gas mixtures feed, the membranes enriched H2 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 H2 upgrading from syngas. A two-stage configuration achieved up to 90 M% H2 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 H2 purification, post-combustion CO2 capture and broader membrane-based gas separation applications.