Fundamental and combinatorial approaches in the search for and optimisation of catalytic materials for the oxidative dehydrogenation of propane to propene

An evolutionary approach was applied to create five generations of alpha -Al2O3-supported multi-metal-oxides to be used as catalytic materials for the oxidative dehydrogenation of propane at 773 K. Each generation consisted of 56 differently composed materials, i.e., a total amount of 280 materials. These catalytic materials were tested in parallel. For the best materials propene yields from 7% (Ist generation) to 9% (5th generation) were achieved. Some of these superior catalysts were characterised by XRD, XPS and EPR. A correlation between catalytic performance and the Mg/V ratio on the surface was found. Based on the structural knowledge obtained, from which the requirement of isolated or at least weakly interacting vanadium sites was derived, VOx (2.8 wt. %)/MCM-48 and VOx (2.8 wt. %)/MCM-41 catalysts with a high dispersion of vanadia were used as reference giving a maximal propene yield of 17 and 15%, respectively. (C) 2001 Elsevier Science B.V. All rights reserved.