Abstract: Catalyst particles are prepared by coating a core particle, which is usually catalytically inert with respect to the intended chemical reaction, in a fluidized bed coating apparatus. The coating technique involves repeatedly applying and drying small quantities of an atomized slurry containing the coating material in the form of a colloidal dispersion or in the form of very fine, non-colloidal particles preferably mixed with colloidal particles. In this way, incremental layers are formed to produce a final thin shell which has a highly uniform thickness, which is formed on the surface of the core and which does not penetrate porous cores. Various methods are disclosed for converting the coated particles to the desired catalyst form.

Abstract: The invention relates to a heterogeneous vanadium-phosphorus oxide catalyst system for the selective oxidation of hydrocarbons, which may or may not be saturated, comprising a support based on one or more metal oxides, and vanadium-phosphorus oxide in an amount of from 0.01 to 45 wt. %, based on the weight of the catalyst and calculated as (VO).sub.2 P.sub.2 O.sub.7, to a process for the selective oxidation of an organic compound in the presence of a vanadium-phosphorus oxide catalyst, which process comprises an oxidation and a reduction phase, wherein a hydrocarbon is contacted with said catalyst in the reduction phase and in oxidized or non-oxidized form is adsorbed to the catalyst, whereafter the thus loaded catalyst is brought into the oxidation phase, the desired product is formed in the presence of gaseous oxygen and subsequently separated.