CVD modification and vapor gas separation properties of nanoporous alumina membranes

A sol-gel derived 4 nm pore gamma-Al2O3 layer, supported on a macroporous alpha-Al2O3 support, was modified by chemical vapor deposition (CVD), with alternative introduction of trimethylaluminum and water vapor into the reaction chamber, Aluminum oxide was deposited in the pores of the gamma-Al2O3 membrane layer. The modification resulted in a substantial reduction in the permeance of non-condensable gases, but not of condensable vapor. Separation of the mixture of condensable vapor (water) and non-condensable gas (oxygen) was performed on the unmodified and modified membranes at room temperature. The CVD modified membrane exhibits a water/oxygen separation factor as high as 71 at 12% relative humidity with water vapor permeance of 6.9x10(-7) mol/m(2) s Pa. In comparison, the maximum separation factor for the unmodified membranes was about 11 at 80% relative humidity with a water vapor permeance of 2.9x10(-7) mol/m(2) s Pa, (C) 1999 Elsevier Science B.V. All rights reserved.