Carbon molecular sieve membranes derived from a phenolic resin supported on porous ceramic tubes

The preparation of a composite carbon membrane from a phenolic resin is des cribed. The membrane is formed by a thin microporous carbon layer (thicknes s: 2 mum) obtained by pyrolysis (700 degreesC, under vacuum) of a phenolic resin film supported on the inner face of a porous alumina tube. The separa tion characteristics of the resulting carbon membranes were analysed from p ermeation experiments with pure gases of different molecular size (He, CO2, O-2, N-2 and CH4) and separation of binary gas mixtures O-2-N-2 and CO2-CH 4. An almost defect-free carbon membrane is obtained in only one casting st ep, The effective micropore size was estimated to be around 4.4 Angstrom. T he prepared carbon membranes have demonstrated to be effective for separati ng gas mixtures such as O-2-N-2 (O-2 permeance: 100 Barrer; O-2-N-2 separat ion factor: 12) and CO2-CH4 (CO2 permeance: 400 Barrer; CO2-CH4 separation factor: 150). The oxidation of the phenolic resin film with air at temperat ures ranging from 150 to 300 degreesC improves the gas permeance and origin ates a decrease in the permselectivity. (C) 2001 Elsevier Science B.V. All rights reserved.