Hydrogen Separation of Carbon Molecular Sieve Membranes Derived from Polyimides Having Decomposable Side Groups

Carbon molecular sieve (CMS) membranes were prepared by pyrolysis of polyimides having carboxylic acid groups and applied to the hydrogen separation. The polymeric membranes having carboxylic acid groups showed different steric properties as compared with polymeric membranes having other side groups ($-CH_3$ and $-CF_3$) because of the hydrogen bond between the carboxylic acid groups. However, the microporous CMS membranes were significantly affected by the decomposable side groups evidenced from the wide angle X-rat diffraction, nitrogen adsorption isotherms, and single gas permeation measurement. Furthermore, the gas separation properties of the CMS membranes were essentially affected by the pyrolysis temperature. As a result, the CMS membranes Prepared by Pyrolysis of polyimide containing carboxylic acid froups at $700^{\circ}C$ showed the $H_2$ permeability of 3,809 Baller [$1{\times}10^{-10}$ H $\textrm{cm}^$(STP)cm/$\textrm{cm}^2$.s.cmHg], $H_2$/$N_2$, selectivity of 46 and $H_2$/$CH_4$ selectivity of 130 while the CMS membranes derived from polyimide showed the H$_2$ permeability of 3,272 Barrer, $H_2$/$N_2$ selectivity of 136 and $H_2$/$CH_4$ selectivity of 177.

열분해성 그룹이 도입된 폴리이미드로부터 유도된 탄소분자체막의 수소 분리 특성