Patent US4236996A successfully refreshed from Google Patents.
US4236996A
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US
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Xylene isomerization
Assignee: Mobil Oil AS
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Filing: 1979-05-25
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Granted: 1980-12-02
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Expires: 1999-05-25
Abstract
Abstract Isomerization of xylenes in admixture with ethylbenzene by contact with a zeolite catalyst such as ZSM-5 is improved by use of zeolite which has been steamed at high temperature to reduce activity, the reaction being at a temperature above about 700 DEG F. At these conditions, conversion of ethylbenzene follows a different reaction path which permits high conversion of ethylbenzene to benzene without loss of xylenes of disproportionation.
Inventors
- 👤 Samuel A. Tabak
- 👤 Roger A. Morrison
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 13:16
CPC Classifications
B; B01; B01J; B01J29/00; B01J29/04; B01J29/06; B01J29/40; C; C07; C07C; C07C5/00; C07C5/22; C07C5/27; C07C5/2729; C07C5/2732; C07C5/2737; B01J2229/00; B01J2229/30; B01J2229/42; Y; Y02; Y02P; Y02P20/00; Y02P20/50; Y02P20/52
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
119 words
In a process for isomerizing the xylene content of a charge mixture of eight carbon atom aromatic hydrocarbon compounds which mixture contains xylene and ethylbenzene by contact at conversion conditions with a catalyst comprising a zeolite having a silica/alumina ratio greater than 12 and a constraint index of 1 to 12, the improvement which comprises using as said catalyst a steamed zeolite and maintaining a conversion temperature of about 700° F. to about 1000° F.; said zeolite having been steamed prior to said contact under a temperature and pressure and for a period of time such that the steamed zeolite requires an increased reaction temperature of at least 50° F. to equal the ethylbenzene conversion by the unsteamed zeolite.
Claim 2
Dependent Claim
119 words
In a process for isomerizing the xylene content of a charge mixture of eight carbon atom aromatic hydrocarbon compounds which mixture contains xylene and ethylbenzene by contact at conversion conditions with a catalyst comprising a zeolite having a silica/alumina ratio greater than 12 and a constraint index of 1 to 12, the improvement which comprises using as said catalyst a steamed zeolite and maintaining a conversion temperature of about 700° F. to about 1000° F.; said zeolite having been steamed prior to said contact under a temperature and pressure and for a period of time such that the steamed zeolite requires an increased reaction temperature of at least 50° F. to equal the ethylbenzene conversion by the unsteamed zeolite.
Claim 3
Dependent Claim
11 words
A process according to claim 1 wherein said zeolite is ZSM-5.
Claim 4
Dependent Claim
20 words
A process according to claim 1 wherein said catalyst also comprises a metal of Group VIII of the Periodic Table.
Claim 5
Dependent Claim
11 words
A process according to claim 3 wherein said zeolite is ZSM-5.
Claim 6
Dependent Claim
14 words
A process according to claim 3 wherein said charge mixture is admixed with hydrogen.
Claim 7
Dependent Claim
11 words
A process according to claim 5 wherein said zeolite is ZSM-5.
Claim 8
Dependent Claim
13 words
A process according to claim 1 wherein the reaction temperature is 700°-800° F.
Claim 9
Dependent Claim
27 words
A process according to claim 7 resulting in conversion of ethylbenzene to benzene at substantially no loss of xylene in the product as compared to the charge.
Claim 10
Dependent Claim
14 words
A process according to claim 7 wherein the said charge mixture contains paraffin hydrocarbons.
Claim 11
Dependent Claim
16 words
A process according to claim 1 wherein the said charge mixture consists essentially of aromatic hydrocarbons.
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) | 1983-12-02 | 1984-06-02 | 1984-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-02 | 1988-06-02 | 1988-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-02 | 1992-06-02 | 1992-12-02 | $7700.00 | Window Closed / Lapsed |