OXIDATIVE DEHYDROGENATION OF PROPANE OVER NIOBIA SUPPORTED VANADIUM-OXIDE CATALYSTS

Oxidative dehydrogenation (ODH) of propane is examined over a series o f catalysts, which include Nb2O5 supported monolayer V2O5 catalysts, b ulk vanadia-niobia with different vanadium oxide loadings and prepared by four different methods, V2O5 and Nb2O5. The intrinsic activity (TO F) of the samples studied indicates that vanadium containing active si tes are indispensable for catalytic oxidative dehydrogenation of propa ne. Variations in the chemical environment of the vanadium ion do not cause significant changes in activity per site and, hence, all samples show similar TOF when the rates are normalised to the concentration o f V on the surface. Selectivity to propene on the other hand strongly depends on the nature of the catalyst because readsorption and interac tion of propene with the acid sites leads to total oxidation. Optimiza tion of the weak sorption of propene is, therefore, concluded to be th e key factor for the design of selective oxidative dehydrogenation cat alysts.