US4163697A
Expired / Lapsed
US
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Process for obtaining isobutylene of a purity higher than 99.5 weight percent
Assignee: Compagnie Francaise de Raffinage SA
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Filing: 1977-02-17
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Granted: 1979-08-07
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Expires: 1997-02-17
Abstract
Abstract An improved process for recovering isobutylene contained in a mixture of hydrocarbons having four carbon atoms by selective extraction with an aqueous solution of sulfuric acid of a concentration of about 50 wt. % followed by separating the isobutylene-rich sulfuric acid extract by a first flash distillation of the extract and by a second physical separation of the isobutylene-enriched extract from said flashing step (which the latter physical separation is preferaby a second flash distillation at a temperature which is higher than the first and is at 75° C. or less, and wherein said first flash distillation is between 10° and 60° C. and both distillations are preferably at a pressure between 0.5 and 1.5 bars absolute to give an isobutylene purity greater than 99.5%).
Inventors
- 👤 Jean-Pierre Michaux
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 20:21
CPC Classifications
C; C07; C07C; C07C7/00; C07C7/148; C07C7/17; C07C7/171
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
109 words
In a process for recovering isobutylene contained in a mixture of hydrocarbons having four carbon atoms, by selective liquid-liquid extraction with an aqueous solution of sulfuric acid of a concentration of about 50 wt. % to give an isobutylene-rich sulfuric acid extract which is then subjected to a flash distillation in a zone to further enrich the isobutylene content of said extract, the improvement for obtaining isobutylene of a purity of greater than 99.5 wt. % comprising removing the bottoms from said flash distillation zone, heating said separated bottoms to an effective distillation temperature and in a separate zone subjecting the heated bottoms to a further independent flashing step.
Claim 2
Dependent Claim
109 words
In a process for recovering isobutylene contained in a mixture of hydrocarbons having four carbon atoms, by selective liquid-liquid extraction with an aqueous solution of sulfuric acid of a concentration of about 50 wt. % to give an isobutylene-rich sulfuric acid extract which is then subjected to a flash distillation in a zone to further enrich the isobutylene content of said extract, the improvement for obtaining isobutylene of a purity of greater than 99.5 wt. % comprising removing the bottoms from said flash distillation zone, heating said separated bottoms to an effective distillation temperature and in a separate zone subjecting the heated bottoms to a further independent flashing step.
Claim 3
Dependent Claim
34 words
A process as defined in claim 1, further comprising carrying out the first flashing step at a temperature comprised between 10° and 60° C. and at a pressure between 0.5 and 4 bars absolute.
Claim 4
Dependent Claim
17 words
A process as defined in claim 2, wherein said pressure is between 0.5 and 1.5 bars absolute.
Claim 5
Dependent Claim
52 words
A process as defined in claim 2, further comprising carrying out the second step of the separation stage at a pressure between 0.5 and 1.5 bars absolute and at a temperature that is higher than that at which the first flashing step is carried out and is at 75° C. or less.
Claim 6
Dependent Claim
26 words
A process as defined in claim 2, further comprising simultaneously stripping the gases dissolved in the bottoms from the first flashing step with a stripping gas.
Claim 7
Dependent Claim
30 words
A process as defined in claim 4, wherein during the second flashing step the gases dissolved in the bottoms from the first flashing step are stripped with a stripping gas.
Claim 8
Dependent Claim
25 words
A process as defined in claim 5, wherein the stripping gas is selected from the group consisting of hydrogen, nitrogen, methane and a refinery gas.
Claim 9
Dependent Claim
25 words
A process as defined in claim 6, wherein the stripping gas is selected from the group consisting of hydrogen, nitrogen, methane and a refinery gas.
Claim 10
Dependent Claim
24 words
In the process defined in claim 1 said mixture of hydrocarbons having four carbon atoms comprising from 10 to 60 wt. % of isobutylene.
Claim 11
Dependent Claim
28 words
In the process defined in claim 4, to the treatment of a charge of hydrocarbons having four carbon atoms comprising from 10 to 60 wt. % of isobutylene.
Claim 12
Dependent Claim
28 words
In the process defined in claim 5 to the treatment of a charge of hydrocarbons having four carbon atoms comprising from 10 to 60 wt. % of isobutylene.
Claim 13
Dependent Claim
38 words
In the process defined in claim 5 to the treatment of a charge of hydrocarbons having four carbon atoms comprising from 10 to 60 wt. % of isobutylene and from 20 to 50 wt. % of normal butenes.
Claim 14
Dependent Claim
38 words
In the process defined in claim 4 to the treatment of a charge of hydrocarbons having four carbon atoms comprising from 10 to 60 wt. % of isobutylene and from 20 to 50 wt. % of normal butenes.
Claim 15
Dependent Claim
103 words
In a process for recovering isobutylene contained in a mixture of hydrocarbons having four carbon atoms, by selective liquid-liquid extraction with an aqueous solution of sulfuric acid of a concentration of about 50 wt. % to give an isobutylene-rich sulfuric acid extract which is then subjected to a flash distillation in a zone to further enrich the isobutylene content of said extract, the improvement for obtaining isobutylene of a purity of greater than 99.5 wt. % comprising removing the bottoms from said flash distillation zone, and independently stripping the gases dissolved in the bottoms from the first flashing step with a stripping gas.
Claim 16
Dependent Claim
103 words
In a process for recovering isobutylene contained in a mixture of hydrocarbons having four carbon atoms, by selective liquid-liquid extraction with an aqueous solution of sulfuric acid of a concentration of about 50 wt. % to give an isobutylene-rich sulfuric acid extract which is then subjected to a flash distillation in a zone to further enrich the isobutylene content of said extract, the improvement for obtaining isobutylene of a purity of greater than 99.5 wt. % comprising removing the bottoms from said flash distillation zone, and independently stripping the gases dissolved in the bottoms from the first flashing step with a stripping gas.
Claim 17
Dependent Claim
34 words
A process as defined in claim 14, further comprising carrying out the first flashing step at a temperature comprised between 10° and 60° C. and at a pressure between 0.5 and 4 bars absolute.
Claim 18
Dependent Claim
38 words
In the process defined in claim 15 to the treatment of a charge of hydrocarbons having four carbon atoms comprising from 10 to 60 wt. % of isobutylene and from 20 to 50 wt. % of normal butenes.
Claim 19
Dependent Claim
28 words
In the process defined in claim 16, to the treatment of a charge of hydrocarbons having four carbon atoms comprising from 10 to 60 wt. % of isobutylene.
Claim 20
Dependent Claim
25 words
A process as defined in claim 13, wherein the stripping gas is selected from the group consisting of hydrogen, nitrogen, methane and a refinery gas.
Claim 21
Dependent Claim
32 words
In the process defined in claim 18, the feed rate of the stripping gas is between 2 and 10 normal liters (at standard temperature and pressure) per liter of sulfuric acid extract.
Claim 22
Dependent Claim
25 words
A process as defined in claim 16, wherein the stripping gas is selected from the group consisting of hydrogen, nitrogen, methane and a refinery gas.
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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) | 1982-08-06 | 1983-02-05 | 1983-08-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-08-06 | 1987-02-05 | 1987-08-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-08-06 | 1991-02-05 | 1991-08-07 | $7700.00 | Window Closed / Lapsed |