US4222945A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Production of maleic anhydride
Assignee: Imperial Chemical Industries Ltd
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Filing: 1979-01-25
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Granted: 1980-09-16
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Expires: 1999-01-25
Abstract
Abstract Hydrocarbons, particularly n-butane, are oxidized to acid anhydrides, especially maleic anhydride, by contacting them at concentrations above the flammable limit with oxygen in the presence of a vanadium/phosphorus mixed oxide catalyst having a surface area of at least 10 m2/g. The oxygen concentration is greater than 13 molar percent and/or the concentration of inert gas is less than 70 molar percent.
Inventors
- 👤 Raymond Higgins
- 👤 Graham J. Hutchings
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 10:23
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/16; C07C51/21; C07C51/215; B; B01; B01J; B01J23/00; B01J23/16; B01J23/20; B01J23/22; B01J27/00; B01J27/14; B01J27/186; B01J27/195; B01J27/198; B01J35/00; B01J35/60; B01J35/61; B01J35/613; C07C51/255; C07C51/265; B01J2235/00; B01J2235/15; B01J35/70; B01J35/77
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
123 words
A process for producing maleic anhydride comprising oxidising 10 to 50% of a linear C 4 hydrocarbon by contacting it with oxygen, the hydrocarbon concentration being at least 10 molar % and being higher than the flammable limit; the oxygen concentration being greater than 13 molar % of the total material fed to the reaction and the concentration of any inert gas present being less than 70 molar % of the total material fed to the reaction; said oxidation conducted in the presence of a catalyst consisting essentially of a phosphorus/vanadium mixed oxide, the atomic ratio of the vanadium:phosphorus being in the range of about 0.5:1 to about 2:1, the surface area of the catalyst being at least 10 square meters per gram.
Claim 2
Dependent Claim
123 words
A process for producing maleic anhydride comprising oxidising 10 to 50% of a linear C 4 hydrocarbon by contacting it with oxygen, the hydrocarbon concentration being at least 10 molar % and being higher than the flammable limit; the oxygen concentration being greater than 13 molar % of the total material fed to the reaction and the concentration of any inert gas present being less than 70 molar % of the total material fed to the reaction; said oxidation conducted in the presence of a catalyst consisting essentially of a phosphorus/vanadium mixed oxide, the atomic ratio of the vanadium:phosphorus being in the range of about 0.5:1 to about 2:1, the surface area of the catalyst being at least 10 square meters per gram.
Claim 3
Dependent Claim
18 words
A process as claimed in claim 1 in which the oxygen concentration is 14 to 30 molar percent.
Claim 4
Dependent Claim
25 words
A process as claimed in claim 1 in which the temperature is 250° to 600° C. and the pressure is 0.5 to 20 bars absolute.
Claim 5
Dependent Claim
19 words
A process as claimed in claim 1 in which maleic anhydride is produced by oxidising n-butene, butadiene or n-butane.
Claim 6
Dependent Claim
29 words
A process as claimed in claim 1 in which the catalyst has an atomic ratio of vanadium to phosphorus in the range 1:0.8 to 1:1.7 and includes a promoter.
Claim 7
Dependent Claim
22 words
A process as claimed in claim 5 in which the surface area of the catalyst is 30 to 80 m 2 /g.
Claim 8
Dependent Claim
59 words
A process as claimed in claim 5 in which the catalyst is prepared by reacting a vanadium compound with a phosphorus acid in a suitable solvent, precipitating a vanadium/phosphorus mixed oxide catalyst precursor, extracting the precursor with water until substantially only material substantially insoluble in water is left and converting the precursor to a catalytically active form by heating.
Claim 9
Dependent Claim
30 words
A process as claimed in claim 7 in which the extracted catalyst precursor has a mean crystallite size of at most 1000 A before conversion to the catalytically active form.
Claim 10
Dependent Claim
25 words
A process as claimed in claim 8 in which crystallites having a mean size of at most 1000 A are produced by comminuting the precursor.
Claim 11
Dependent Claim
16 words
A process as claimed in claim 1 wherein the phosphorus/vanadium mixed oxide catalyst includes a promoter.
Claim 12
Dependent Claim
19 words
A process as claimed in claim 1 wherein the phosphorus/vanadium mixed oxide catalyst is supported on a catalyst support.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-09-16 | 1984-03-17 | 1984-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-09-16 | 1988-03-17 | 1988-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-09-16 | 1992-03-17 | 1992-09-16 | $7700.00 | Window Closed / Lapsed |