Supported carbon molecular sieve membranes based on a phenolic resin

The preparation of a composite carbon membrane for separation of gas mixtur es is described. The membrane is formed by a thin microporous carbon layer (thickness, 2 mu m) obtained by pyrolysis of a phenolic resin film supporte d over a macroporous carbon substrate (pore size, 1 mu m; porosity, 30%). T he microporous carbon layer exhibits molecular sieving properties and it al lows the separation of gases depending on their molecular size. The micropo re size was estimated to be around 4.2 Angstrom. Single and mixed gas perme ation experiments were performed at different temperatures between 25 degre es C and 150 degrees C, and pressures between 1 and 3.5 bar. The carbon mem brane shows high selectivities for the separation of permanent gases like O -2/N-2 system (selectivity approximate to 10 at 25 degrees C). Gas mixtures like CO2/N-2 and CO2/CH4 are successfully separated by means of prepared m embranes. For example, the membrane prepared by carbonization at 700 degree s C shows at 25 degrees C the following separation factors: CO2/N(2)approxi mate to 45 and CO2/CH(4)approximate to 160. (C) 1999 Elsevier Science B.V. All rights reserved.