Gas separation properties of molecular sieving carbon membranes with nanopore channels

Hydrogen separation properties in pore channels with the diameter comparable to CO2 or less were investigated by using molecular sieving carbon membranes from polyimide. The accurate control of the pore channels in sub-nanometer scale gave membranes with quite high H-2/CO selectivity on permeation, which can be used for hydrogen purification system. Adsorption and diffusion properties of hydrogen in the very narrow nano-channels were measured by the permeability measurement through the membranes. The activation energy of hydrogen diffusion in the nano-channels, which depends on the pore diameter and is 2-6 times higher than that on graphite surface, was determined from the temperature dependence of the diffusion coefficient. (C) 2004 Elsevier Ltd. All rights reserved.