US4565880A
Expired / Lapsed
US
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Maleic anhydride process
Assignee: Scientific Design LLC
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Filing: 1983-06-29
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Granted: 1986-01-21
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Expires: 2003-06-29
Abstract
Abstract It has been found that phosphoric acid alone and in admixture with phenothiazine and/or methyl-p-benzoquinone reduces residue formed during the fractionation of aqueous crude maleic compositions for the production of maleic anhydride, and in particular, reduces residue due to the presence of small amounts, i.e., less than 10 ppm alkali metal ion. When the alkali metal ion is present at least 9 equivalent acid groups of phosphoric acid per atomic equivalent of alkali metal ion are present.
Inventors
- 👤 Bruno J. Barone
- 👤 William G. Bowman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:58
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/54; C07C51/573
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
130 words
In the process of producing maleic anhydride comprising: (a) oxidizing a hydrocarbon which is a precursor of maleic anhydride to form a reactor effluent comprising maleic anhydride, (b) scrubbing the reactor effluent with water to obtain a crude aqueous composition comprising maleic acid and up to 10 ppm of an alkali metal, and (c) recovering maleic anhydride by fractionation of said crude aqueous composition wherein the improvement comprises having present in said aqueous composition, a combination of phosphoric acid in the range of 100 to 2000 ppm and in a ratio of at least 9 equivalent acid groups of phosphoric acid per atomic equivalent of alkali metal ion present and from 10 to 150 ppm phenothiazine, methyl-p-benzoquinone, or a mixture thereof whereby the loss of said maleic anhydride is reduced.
Claim 2
Dependent Claim
130 words
In the process of producing maleic anhydride comprising: (a) oxidizing a hydrocarbon which is a precursor of maleic anhydride to form a reactor effluent comprising maleic anhydride, (b) scrubbing the reactor effluent with water to obtain a crude aqueous composition comprising maleic acid and up to 10 ppm of an alkali metal, and (c) recovering maleic anhydride by fractionation of said crude aqueous composition wherein the improvement comprises having present in said aqueous composition, a combination of phosphoric acid in the range of 100 to 2000 ppm and in a ratio of at least 9 equivalent acid groups of phosphoric acid per atomic equivalent of alkali metal ion present and from 10 to 150 ppm phenothiazine, methyl-p-benzoquinone, or a mixture thereof whereby the loss of said maleic anhydride is reduced.
Claim 3
Dependent Claim
21 words
The process according to claim 1 wherein a mixture of phosphoric acid and phenothiazine is present in said crude aqueous composition.
Claim 4
Dependent Claim
21 words
The process according to claim 1 wherein a mixture of phosphoric acid and methyl-p-benzoquinone is present in said crude aqueous composition.
Claim 5
Dependent Claim
23 words
The process according to claim 1 wherein a mixture of phosphoric acid, phenothiazene and methyl-p-benzoquinone is present in said crude aqueous maleic composition.
Claim 6
Dependent Claim
11 words
The process according to claim 1 wherein sodium ion is present.
Claim 7
Dependent Claim
11 words
The process according to claim 2 wherein sodium ion is present.
Claim 8
Dependent Claim
11 words
The process according to claim 3 wherein sodium ion is present.
Claim 9
Dependent Claim
16 words
The process according to claim 1 wherein up to 5 ppm alkali metal ion is present.
Claim 10
Dependent Claim
11 words
The process according to claim 8 wherein sodium ion is present.
Claim 11
Dependent Claim
16 words
The process according to claim 8 wherein from about 0.01 ppm alkali metal ion is present.
Claim 12
Dependent Claim
11 words
The process according to claim 10 wherein sodium ion is present.
Claim 13
Dependent Claim
14 words
The process according to claim 1 wherein an entraining agent is present in (c).
Claim 14
Dependent Claim
22 words
The process according to claim 1 wherein the loss of maleic anhydride is characterized by a reduction in residue formed during (c).
Claim 15
Dependent Claim
31 words
The process according to claim 1 wherein the ratio of equivalent acid groups of phosphoric acid per atomic equivalent of alkali metal ion present is in the range up to 140.
Claim 16
Dependent Claim
20 words
The process according to claim 1 wherein said crude aqueous composition contains from 30 to 60 weight % maleic acid.
Claim 17
Dependent Claim
23 words
The process according to claim 12 wherein said entraining agent has a boiling point in the range of 130° C. to 180° C.
Claim 18
Dependent Claim
115 words
In the process of producing maleic anhydride comprising: (a) oxidizing a hydrocarbon which is a precursor of maleic anhydride to form a reactor effluent comprising maleic anhydride, (b) scrubbing the reactor effluent with water to obtain a crude aqueous composition comprising maleic acid and up to 5 ppm of an alkali metal, and (c) recovering maleic anhydride by fractionation of said crude aqueous composition wherein the improvement comprises having present in said aqueous composition, phosphoric acid in the range of 100 to 2000 ppm and in a ratio of 15 to 156 equivalent acid groups of phosphoric acid per atomic equivalent of alkali metal ion present whereby the loss of said maleic anhydride is reduced.
Claim 19
Dependent Claim
115 words
In the process of producing maleic anhydride comprising: (a) oxidizing a hydrocarbon which is a precursor of maleic anhydride to form a reactor effluent comprising maleic anhydride, (b) scrubbing the reactor effluent with water to obtain a crude aqueous composition comprising maleic acid and up to 5 ppm of an alkali metal, and (c) recovering maleic anhydride by fractionation of said crude aqueous composition wherein the improvement comprises having present in said aqueous composition, phosphoric acid in the range of 100 to 2000 ppm and in a ratio of 15 to 156 equivalent acid groups of phosphoric acid per atomic equivalent of alkali metal ion present whereby the loss of said maleic anhydride is reduced.
Claim 20
Dependent Claim
11 words
The process according to claim 17 wherein sodium ion is present.
Claim 21
Dependent Claim
14 words
The process according to claim 17 wherein an entraining agent is present in (c).
Claim 22
Dependent Claim
22 words
The process according to claim 17 wherein the loss of maleic anhydride is characterized by a reduction in residue formed during (c).
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) | 1989-01-20 | 1989-07-22 | 1990-01-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-01-20 | 1993-07-22 | 1994-01-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-01-20 | 1997-07-22 | 1998-01-21 | $7700.00 | Window Closed / Lapsed |