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Patent US4062903A successfully refreshed from Google Patents.
US4062903A
Expired / Lapsed
US
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Process for isomerizing alkylaromatics
Assignee: Chevron USA Inc
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Filing: 1976-09-24
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Granted: 1977-12-13
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Expires: 1996-09-24
Abstract
Abstract A process is disclosed for producing a selected C 8 alkylaromatic isomer from a feedstock containing a less than equilibrium concentration of the selected isomer and a low C 8 naphthenes concentration, in which the feedstock is first contacted with a platinum-halogen catalyst at low temperature isomerization conditions to form an intermediate reaction mixture containing a substantial amount of C 8 naphthenes and a partially isomerized mixture of C 8 alkylaromatics; the intermediate mixture is then contacted with another platinum-halogen catalyst at higher temperature dehydrogenation conditions to form a final product mixture with a very low naphthenes content and a substantially equilibrium concentration of the selected isomer; and the selected xylene isomer is recovered from the final product mixture.
Inventors
- 👤 Robert L. Jacobson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 10:17
CPC Classifications
C; C07; C07C; C07C15/00; C07C15/02; C07C15/067; C07C15/08; C07C5/00; C07C5/02; C07C5/13; C07C5/32; C07C5/367; C07C2521/00; C07C2521/02; C07C2521/04; C07C2523/00; C07C2523/16; C07C2523/32; C07C2523/36; C07C2523/38; C07C2523/40; C07C2523/42; C07C2523/54; C07C2523/56; C07C2523/64; C07C2523/656; Y; Y02; Y02P; Y02P20/00; Y02P20/50; Y02P20/52
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
249 words
A process for producing a first selected xylene isomer from a feedstock including a substantially greater than equilibrium concentration of ethylbenzene, a substantially less than equilibrium concentration of said selected isomer, and a weight ratio of C 8 naphthenes to C 8 alkylaromatics of less than 1:50, comprising the steps of: a. forming an intermediate reaction mixture having a weight ratio of C 8 naphthenes to C 8 alkylaromatics of greater than 1:50 and less than 1:10 by contacting said feedstock and hydrogen with a first catalyst comprising 0.1-3 weight percent platinum, 0.1-3 weight percent rhenium and 1.25-2.0 weight percent chloride on an alumina carrier at isomerization conditions including an isomerization temperature between about 750° F and 900° F and an isomerization hydrogen pressure of about 100 psia to 250 psia; b. forming a final hydrocarbon product mixture including a substantially equilibrium concentration of said first isomer and having a weight ratio of C 8 naphthenes to C 8 alkylaromatics of less than 1:50 by contacting said intermediate reaction mixture with a second catalyst having essentially the same composition as said first catalyst and comprising 0.1-3 weight percent platinum, 0.1-3 weight percent rhenium, and 1.25-2.0 weight percent chloride on an alumina carrier at dehydrogenation conditions including a temperature at least 25° F above said isomerization hydrogen temperature and in the range from about 775° F to 950° F and a pressure not higher than said isomerization hydrogen pressure; and c. recovering said first isomer from said final product mixture.
Claim 2
Dependent Claim
249 words
A process for producing a first selected xylene isomer from a feedstock including a substantially greater than equilibrium concentration of ethylbenzene, a substantially less than equilibrium concentration of said selected isomer, and a weight ratio of C 8 naphthenes to C 8 alkylaromatics of less than 1:50, comprising the steps of: a. forming an intermediate reaction mixture having a weight ratio of C 8 naphthenes to C 8 alkylaromatics of greater than 1:50 and less than 1:10 by contacting said feedstock and hydrogen with a first catalyst comprising 0.1-3 weight percent platinum, 0.1-3 weight percent rhenium and 1.25-2.0 weight percent chloride on an alumina carrier at isomerization conditions including an isomerization temperature between about 750° F and 900° F and an isomerization hydrogen pressure of about 100 psia to 250 psia; b. forming a final hydrocarbon product mixture including a substantially equilibrium concentration of said first isomer and having a weight ratio of C 8 naphthenes to C 8 alkylaromatics of less than 1:50 by contacting said intermediate reaction mixture with a second catalyst having essentially the same composition as said first catalyst and comprising 0.1-3 weight percent platinum, 0.1-3 weight percent rhenium, and 1.25-2.0 weight percent chloride on an alumina carrier at dehydrogenation conditions including a temperature at least 25° F above said isomerization hydrogen temperature and in the range from about 775° F to 950° F and a pressure not higher than said isomerization hydrogen pressure; and c. recovering said first isomer from said final product mixture.
Claim 3
Dependent Claim
13 words
A process according to claim 1 wherein said selected xylene isomer is paraxylene.
Claim 4
Dependent Claim
28 words
A process according to claim 1 wherein the weight ratio of C 8 naphthenes to C 8 alkylaromatics in said intermediate reaction mixture is between 1:33 and 1:20.
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) | 1980-12-12 | 1981-06-13 | 1981-12-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-12-12 | 1985-06-13 | 1985-12-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-12-12 | 1989-06-13 | 1989-12-13 | $7700.00 | Window Closed / Lapsed |