| The technology on carbon membranes for gases separation, as one of important methods on separation process, had a great advance on gas separation. Carbon molecular sieve membranes presented a superior performance in gas separation compared to the polymer membranes, and had high stability in the presence of organic compound as well as at atmosphere of acids or bases. Therefore, the research on the preparation of carbon membranes was extensively carried out in many countries and regions, and it displayed a broad prospect in the application in the future.Carbon membranes were prepared by a procedure of carbonizing polymer at high temperature and the performance were investigated by separating small molecule gases, such as H2, CO2, N2, and CH4. Meanwhile, an ideal separation factors were calculated on the ratio of permeances between two pure gases. The conditions on the fabrication of carbon membrane, for example, fabrication of polymer membrane, heating rates, were optimized.There were two methods on preparation of carbon membranes.At the first, theα–Al2O3 tube modified by means of sol-gel technique was used as the supports, and carbon membrane was prepared through pyrolyzing polyimide. From the data of permeances of carbon membranes, a Knudsen mechanism was deduced in the process of separation.Secondly, carbon membranes were prepared by means of the combination of the carbonizing polymer at high temperature with catalytic decomposition of methane using the Ni/polyimide as a template. The difference on separation performance between carbon membranes with nickel and without nickel showed that the introduction of nickel improved the performance of membrane separation and saved the preparation time and cost. Meanwhile, ideal separation factor of H2/N2, H2/CH4 were 24 and 48, respectively, higher than theoretical value of Knudsen diffusion.Precursor and carbon membranes were characterized by means of techniques, such as FT-IR, AFM, XRD and TEM.
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