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A SAPO-34 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 × 10-8 and 1.9 × 10-10 mol/(m2 s Pa), 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 270 kPa feed pressure with a 138 kPa 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 270 kPa feed pressure and 138 kPa pressure drop, the CO2/CH4 mixture selectivity was 30 at 300 K and 3.4 at 470 K.

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Continuous palladium films were synthesized at controlled depths within porous alumina disks by H 2 reduction of organopalladium compounds dissolved in supercritical CO 2 at 60 °C using an opposing reactants deposition geometry. Film position was controlled by adjusting the relative concentrations of H 2 and the palladium precursor (π-2-methylallyl(cyclopentadienyl)palladium (II) or palladium(II) hexafluoroacetylacetonate) on opposite sides of the alumina substrate. Because of a disparity in the diffusivity of the metal precursor and H 2 in the support, a temporary barrier of poly-4-methyl-1-pentene on the H 2 side of the alumina substrate was used to reduce H 2 flux in a controlled manner. Guided by a simple mass transport model, Pd films between 2 and 80 µm thick were deposited at prescribed depths between 80 and 600 µm as measured from the precursor side. Electron probe microanalysis indicated complete pore filling of the porous alumina at the reaction zone and X-ray diffraction revealed that the structure of the deposit is nanocrystalline. The flux of N 2 through the alumina disk was reduced by over 4 orders of magnitude after deposition and annealing at 500 °C.