Synthesis of P84 co-polyimide hollow fiber carbon membrane for CO 2 separation

Abstract

Carbon membranes derived from pyrolyzed polyimide precursors offer a viable route to overcome the permeability–selectivity trade-off limiting conventional polymeric membranes in CO₂ separation. This study examines the structure, morphology, and gas transport properties of a P84 carbon membrane obtained via pyrolysis at 600°C, compared directly to the as-spun P84 neat precursor. X-ray diffraction confirmed conversion to amorphous turbostratic carbon, indicated by the (002) reflection at 2θ = 24° and a d-spacing of 2.054 Å, while FTIR revealed pronounced decomposition of imide carbonyl bands (1780, 1713 cm⁻¹) accompanied by emergence of sp-carbon (C≡C) intermediates (1800–2200 cm⁻¹). HFCM600 showed substantially improved gas transport H₂ permeability rise from 103.48 ± 2.46 to 162.18 ± 0.18 Barrer, while H₂/CO₂ selectivity increased from 1.28 ± 0.03 to 2.11 ± 0.11, which was the highest among all variants tested. These results show that even moderate-temperature (600°C) pyrolysis substantially enhances H₂ through molecular sieving effects, making HFCM600 particularly suited for H₂/CO₂ separation applications such as pre-combustion hydrogen recovery.