Production of maleic anhydride from four-carbon hydrocarbons using catalysts prepared by hydrothermal techniques
AssigneeThe Standard Oil Company (Ohio)
InventorNoel J. Bremer
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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.degree. 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.
Claims24
A process for preparing a catalyst comprising the mixed oxides of vanadium and phosphorus, said process comprising the steps of:
- (a) forming an aqueous oxide slurry of a vanadium compound containing pentavalent vanadium and a mineral acid-free, inorganic reducing agent capable of reducing said pentavalent vanadium to a valence state below +5, wherein said reducing agent is selected from the group consisting of a finely divided metal or a colloidal metal;
- (b) admixing a phosphorus compound containing pentavalent phosphorus with said aqueous slurry of step (a);
- (c) heating said aqueous slurry of step (b) at a temperature of at least 120.degree. C. under autogenous pressure so that substantial evaporation of the water in said slurry is prevented;
- (d) removing the water from the slurry of step (c) to form a dried catalyst;
- and
- (e) calcining the dried catalyst at a temperature of 250.degree. C. to 600.degree. C. in the presence of an oxygen-containing gas.
A process for preparing a catalyst comprising the mixed oxides of vanadium and phosphorus, said process comprising the steps of:
- (a) refluxing an aqueous oxide slurry containing vanadium pentoxide and a mineral acid-free, inorganic reducing agent capable of reducing the vanadium in the vanadium pentoxide to a valence state below +5 to obtain an aqueous slurry containing reduced vanadium, wherein the reducing agent is selected from the group consisting of a finely divided metal or a colloidal metal;
- (b) admixing phosphoric acid with said aqueous slurry containing reduced vanadium;
- (c) autoclaving the aqueous slurry of step (b) at a temperature of 120.degree. C. to 250.degree. C. under autogenous pressure of 15 to 1300 p.s.i.g. so as to retain substantially all of the water content in the slurry;
- (d) removing the water from the slurry of step (c) to form a dried catalyst;
- and
- (e) calcining said dried catalyst at a temperature of 250.degree. C. to 600.degree. C. in the presence of an oxygen-containing gas.
The process for preparing a catalyst comprising the mixed oxides of vanadium, phosphorus, and uranium, said process comprising the steps of:
- (a) forming an aqueous slurry of a vanadium compound containing pentavalent vanadium and a mineral acid-free, inorganic reducing agent capable of reducing said pentavalent vanadium to a valence state below +5, wherein the reducing agent is selected from the group consisting of a finely divided metal or a colloidal metal;
- (b) admixing a phosphorus compound containing pentavalent phosphorus with said aqueous slurry of step (a);
- (c) heating said aqueous slurry of step (b) at a temperature of 120.degree. C. under autogenous pressure so that substantial evaporation of the water in said slurry is prevented;
- (d) removing the water from the slurry of step (c) to form a dried catalyst;
- and
- (e) calcining the dried catalyst at a temperature of 250.degree. C. to 600.degree. C. in the presence of an oxygen-containing gas;
- (f) adding a uranium compound immediately before the addition of the phosphorus compound or after the addition of the phosphorus compound.
Dependencies are inferred from the claim text.