Gas separation characteristics of DDR type zeolite membrane

The molecular-sieve DDR type zeolite membrane with an aperture of 0.36 x 0.44 nm was formed on a porous alumina substrate by hydrothermal process. The permeance through the membrane in the single gas feed of helium, hydrogen, carbon dioxide, oxygen, nitrogen, methane, n-butane, i-butane and sulfur hexafluoride were measured at 301 and 373 K up to 0.5 MPa. The permeance decreased by more than three orders of magnitude between 0.35 and 0.40 nm of the kinetic diameter of permeated gas at both 301 and 373 K. The separation factor of CO2 to CH4 in 50% CO2 and 50% CH4 mixed gas feed was 220 and 100 at 301 and 373 K, respectively at 0.5 MPa total gas feed pressure. The permeation properties were slightly affected by the water addition at 301 K. We conclude that the DDR type membrane has few defects and worked as molecular-sieving membrane. (C) 2003 Elsevier Inc. All rights reserved.