Ultraselective carbon molecular sieve membrane for hydrogen purification

Hydrogen is a green clean fuel and chemical feedstock. Its separation and purification from hydrogen-containing mixtures is the key step in the production of hydrogen with high purity (>99.99%). In this work, carbon molecular sieve (CMS) membranes with ultrahigh permselectivity for hydrogen purification were fabricated by high-temperature (700–900 °C) pyrolysis of polymeric precursor of phenolphthalein-based cardo poly(arylene ether ketone) (PEK-C). The evolution of the microstructural texture and ultramicroporous structure and gas separation performance of the CMS membrane were characterized via TG-MS, FT-IR, XRD, TEM, CO2 sorption analysis and gas permeation measurements. CMS membranes prepared at 700 °C exhibited amorphous turbostratic carbon structures and high H2 permeability of 5260 Barrer with H2/CH4, H2/N2 and H2/CO selectivities of 311, 142, 75, respectively. When carbonized at 900 °C, the CMS membrane with ultrahigh H2/CH4 selectivity of 1859 was derived owing to the formation of the dense and ordered carbon structure. CMS membranes with ultrahigh permselectivity exhibit an attractive application prospect in hydrogen purification.