| abstract |
Exceptionally reproducible catalysts comprising vanadium and phosphorus are obtained when the catalysts are prepared in an aqueous oxide slurry comprising vanadium, phosphorus and a mineral acid-free, inorganic reducing agent, which is capable of reducing the vanadium in the catalyst to a valence state below +5. Additional promoters may be selected from the group of elements of Group IB through VIB, VIII, lanthanides, actinides, and IA through VIA, excluding the elements H, N, O, C, Fr, Ra, and Po. Catalysts of particular interest consist of the elements vanadium, phosphorus, uranium and oxygen, or vanadium, phosphorus, oxygen and uranium in combination with at least one element selected from the group consisting of Ta, Ce, Cr, Mn, Co, Cu, Sb, Fe, Bi, W, Mo, Hf, Zr, Th, S, an alkali metal and an alkaline earth metal. |