Experimental investigation on separations of condensable from non-condensable vapors using mesoporous membranes

He/H2O and He/n-C5H12 permeabilities as well as single-component permeabili ties were measured on two mesoporous alumina membranes, in order to determi ne the optimum conditions for separating condensable from non-condensable v apors. The membranes were produced by compaction of non-porous alumina part icles and exhibited similar pore structures but different porosities. The r esults show that, if the relative pressure of the condensable vapor in the condensable/non-condensable mixture is properly selected, very high selecti vity and permeability values can be achieved simultaneously. The optimum re lative pressure of the condensable vapor corresponds, in all cases studied, to the maximum condensable vapor permeability and to a relative gas permea bility of zero. The pressure gradient of the condensable vapor across the m embrane should be kept small, to avoid the formation of low permeability re gions at either end of the membrane. (C) 1999 Elsevier Science B.V. All rig hts reserved.