A membrane was prepared on an alumina tubular support. This membrane appears to exhibit molecular sieving properties with permeances that decrease as the kinetic diameter increases. The room-temperature permeances of H2 and n-C4H10 were 2.4 x 10-8 and 1.9 x 10-10mol/m2sPa, respectively, and the permeances were in the order H2 > CO2 > N2 > CH4 > n-C4H10. As the temperature increased, the single gas permeances of H2 and N2 exhibited minima, whereas the permeance of CO2 decreased and that of CH4 increased. As the pressure increased with a constant pressure drop across the membrane, the permeances of H2, CO2, N2, and CH4 decreased. The H2/CH4, CO2/CH4, H2/N2, and CO2/N2 ideal selectivities at 300 K and 270kPa feed pressure with a 138kPa pressure drop were 25, 19, 7.4 and 5.7, respectively, and these selectivities decreased with increasing temperature and increased with increasing pressure. The ideal selectivity of N2/CH4 was 3.4 at the same conditions and decreased with increasing temperature and increasing pressure. The H2/CO2 ideal selectivity was 1.3 at the same conditions and increased with increasing temperature and pressure. At 270kPa feed pressure and 138kPa pressure drop, the CO2/CH4 mixture selectivity was 30 at 300K and 3.4 at 470K.

Synthesis and Permeation Properties of SAPO-34 Tubular Membranes. J.C.Poshusta, V.A.Tuan, J.L.Falconer, R.D.Noble: Industrial and Engineering Chemistry Research, 1998, 37[10], 3924-9