On the preparation of supported nanoporous carbon membranes

New preparation techniques for synthesis of thin film supported nanoporous carbon membranes (SNPCM) using ultrasonic deposition (UD) have been examine d. In contrast to other work we have published, in which membranes were pre pared either by brush or spray coating of the polymer precursor onto the po rous stainless steel support, the ultrasonic deposition method provides a g reater degree of control over the deposition step. Permeation experiments o n the UD-SNPCM with pure gases such as nitrogen (N-2) and oxygen (O-2) were used to benchmark properties and characteristics as a function of synthesi s variables. The UD-SNPCM display ideal separation factors for O-2/N-2 rang ing from 2 to 30 depending on synthesis conditions. With other gases ideal separation factors were as large as: H-2/CH4 = 600, CO2/CH4 = 45, N2O/N-2 = 171 and H-2/CO2 = 14 at 295 K. Permeation rates ranged from 7.9 x 10(-13) to 4.1 x 10(-8) mol m(-2) Pa-1 s(-1) and were largely independent of pressu re. Oxygen versus nitrogen selectivities were inversely proportional to oxy gen flux. (C) 2000 Published by Elsevier Science B.V.