| abstract |
Exceptionally reproducible catalysts comprising vanadium and phosphorus are obtained when 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, is heated at an elevated temperature of at least 120 DEG C. under autogenous pressure so that substantial evaporation of the water in said oxide slurry is prevented. Especially preferred catalysts comprise vanadium, phosphorus, uranium and oxygen. Catalysts prepared in accordance with the invention are especially desirable in the oxidation of n-butane, n-butenes, 1,3-butadiene or mixture thereof. |