Surface structure modification on the gas separation performance of carbon molecular sieve membranes

Short and optimized surface treatment periods were required to ensure high efficiency. Without pyrolysis, surface treatments alone markedly reduced the H2 and N2 permeances but did not affect selectivity. Besides, without any surface treatment, pyrolysis alone markedly increased the H2 and N2 permeances, but did not improve selectivity, because the desorption of carbon left large pores. Surface treatment must be combined with pyrolysis to enhance simultaneously the permeance and selectivity of CMS membranes, in a manner very different from that associated with conventional pore-plugging mechanism in typical CVD.