(551e) ALPO-18 Membrane for Gas Separations
CO2 separation property of AEI-type zeolite, a kind of small pore zeolites having 8-membered ring (0.38 × 0.38 nm) was investigated. AlPO4-18 membrane was prepared on a tubular a-alumina support by a secondary growth method using seed crystals. AlPO4-18 seed crystals were supported on a surface of support by a dip coating method. Seeded support was soaked in synthesis gel (1Al2O3 : 1P2O5 : 1.8DIPEA : 100H2O1) and a hydrothermal treatment was carried out at 453 K for 4 h. Gas permeation tests were performed for the mixture of CO2 and CH4. As a result, the AlPO4-18 membrane exhibited high CO2 permselectivity. CO2 permeance of 5 × 10-7 mol m-2 s-1 Pa-1 with separation factor for CO2/CH4 of 39 at 313 K. Kinetic diameters of CO2 and CH4 are 0.33 and 0.38 nm, respectively, suggesting that CO2/CH4 separation by AlPO4-18 membrane is due to a molecular sieving effect.ãIn addition, AlPO4-18 membrane separated hydrogen from the mixture of hydrogen and propane. We will discuss on the possibilities of applying such a type of inorganic membrane to apply to separations of gas mixture containing small molecules like hydroge, CO2 and light hydrocarbons.