NEW PRECURSORS TO VANADIUM PHOSPHORUS OXIDE CATALYSTS

New precursors to vanadium phosphorus oxide catalysts have been synthe sized based on alteration of the layered structure found in the active VPO catalysts. n-Alkyl amine intercalation compounds of vanadyl hydro en phosphate hemihydrate have been prepared that are transformed into active vanadyl pyrophosphate catalysts. Catalytic performance for sel ective oxidation of n-butane to maleic anhydride improves with length of alkyl chain. Vanadyl phosphonates and vanadyl phosphite have been p repared containing vanadyl dimer structures that are thermally transfo rmed into vanadyl pyrophosphate below 650 K for the phosphonates and 5 50 K for the phosphite. The VPO catalyst from the vanadyl phosphite pr ecursor had a high surface area of 35 m(2)/g, and displayed better sel ectivity for maleic anhydride from n-butane oxidation than the convent ional unpromoted catalyst. Mixed vanadyl phosphite-phosphate materials , which were found to be very reactive for intercalation of amines, we re intercalated with 3-aminopropyltriethoxysilane and calcined to prod uce the first thermally stable pillared VPO catalyst.