US4094888A
Expired / Lapsed
US
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Maleic anhydride process
Assignee: Chevron USA Inc
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Filing: 1975-05-23
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Granted: 1978-06-13
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Expires: 1995-05-23
Abstract
Abstract A process for the catalytic production of maleic anhydride from n-butane with sustained high activity for the catalyst which comprises contacting the n-butane feed with oxygen gas and a catalyst comprising oxides of vanadium and phosphorus and maintaining between 0.5 and 50 mole percent propane in the feed, based on propane plus n-butane, during the normal onstream time.
Inventors
- 👤 Alan E. Straus
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 17:09
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/16; C07C51/21; C07C51/215
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
58 words
A process for the catalytic production of maleic anhydride from n-butane with sustained high activity for the catalyst which comprises contacting the n-butane feed with oxygen gas and a catalyst comprising oxides of vanadium and phosphorus and maintaining between 3 and 50 mole percent propane in the feed, based on propane plus n-butane, during the normal on-stream time.
Claim 2
Dependent Claim
58 words
A process for the catalytic production of maleic anhydride from n-butane with sustained high activity for the catalyst which comprises contacting the n-butane feed with oxygen gas and a catalyst comprising oxides of vanadium and phosphorus and maintaining between 3 and 50 mole percent propane in the feed, based on propane plus n-butane, during the normal on-stream time.
Claim 3
Dependent Claim
16 words
A process in accordance with claim 1 wherein the propane is at least 10 mole percent.
Claim 4
Dependent Claim
16 words
A process in accordance with claim 1 wherein the temperature is between 300° and 500° C.
Claim 5
Dependent Claim
71 words
A process in accordance with claim 1 wherein said catalyst is a phosphorus-vanadium mixed oxide containing pentavalent phosphorus, vanadium and oxygen, said vanadium having an average valence in the range from about plus 3.9 to plus 4.6, said oxide having a phosphorus to vanadium atomic ratio in the range from about 0.9-1.8 to 1, and an intrinsic surface area in the range from about 7 to 50 square meters per gram.
Claim 6
Dependent Claim
55 words
A process in accordance with claim 4 wherein (a) the average valence of the vanadium is in the range from about 4.1 to 4.4; (b) the phosphorus to vanadium atomic ratio is in the range 1.0-1.5 to 1; and (c) the intrinsic surface area is in the range 10 to 50 square meters per gram.
Claim 7
Dependent Claim
21 words
A process in accordance with claim 4 wherein the catalyst has a B-phase content in excess of about 25 weight percent.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-06-12 | 1981-12-12 | 1982-06-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-06-12 | 1985-12-12 | 1986-06-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-06-12 | 1989-12-12 | 1990-06-13 | $7700.00 | Window Closed / Lapsed |