Performance and Kinetics of Flame-Made Vanadia/Titania Catalyst Nanoparticles in the Partial Oxidation of o-Xylene

Abstract

Vanadia/titania catalyst particles were made by flame-spray pyrolysis and deposited onto ceramic sponge monoliths either by direct deposition of the flame-made particles or by a dip-coating technique. In the partial oxidation of o-xylene, the influence of the coating thickness and porosity on the catalytic performance was investigated. It was found that the highly porous coatings obtained by direct deposition exhibit insufficient heat transfer properties, while dip-coated layers are prone to internal mass transfer limitations if a certain thickness of the coating is exceeded. In the absence of transport limitations, kinetic experiments were carried out to derive a reaction network and to develop a quantitative kinetic model. The resulting model describes well the influences of reactant concentrations and temperature on the product distributions in the oxidation of o-xylene to phthalic anhydride over the novel flame-made catalyst and can be used for reactor simulations.