The conceptual feasibility and the potential of a novel catalytically active supported ionic liquid membrane (SILM) are investigated by means of a mathematical model. Within the SILM, the separation of a propylene/propane vapor mixture is enhanced by selective conversion of propylene to hexenes via a homogeneously catalyzed dimerization reaction. Experimental data from chemically non-reactive vapor separation are used for model evaluation and validation. From prescreening experiments the most promising combination of the ionic liquid [BMIM][BTA] with an asymmetric ceramic support, which displays sufficient permeability, reasonable propylene/propane selectivity and long-term stability, is investigated with respect to the dimerization reaction. (c) 2007 Elsevier Ltd. All rights reserved.