US3856874A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Xylene isomerization
Assignee: Mobil Oil AS
•
Filing: 1973-09-13
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Granted: 1974-12-24
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Expires: 1993-09-13
Abstract
Abstract Costs for commercial application of Low Temperature Isomerization (LTI) of xylenes contained in C8 aromatic fractions are greatly reduced by diverting a portion of p-xylene separator effluent through Octafining or an equivalent isomerization over such zeolites as ZSM-5.
Inventors
- 👤 C Hayward
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 03:11
CPC Classifications
C; C07; C07C; C07C15/00; C07C15/02; C07C15/067; C07C15/073; C07C5/00; C07C5/22; C07C5/27; C07C5/2702; C07C5/2708; C07C5/2724; C07C7/00; C07C7/148
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
121 words
IN A PROCESS OF SELECTIVELY RECOVERING ONE OR MORE EIGHT CARBON ATOM AROMATIC ISOMER FROM A MIXTURE OF SUCH ISOMERS ISOMERIZING A MIXTURE OF UNRECOVERED ISOMERS AND RECYCLING ISOMERIZATE TO THE SELEDTED RECOVERY STEP; THE IMPROVEMENT WHICH COMPRISES CONTACTING A PORTION OF SAID UNRECOVERED ISOMERS GREATER THAN HALF BUT LESS THAN 90 PERCENT OF THE TOTAL WITH A CRYSTALLINE ALUMINOSILICATE CATALYST UNDER ISOMERIZING CONDITIONS AT A TEMPERATURE LESS THAN 600*F. AND UNDER PRESSURE SUFFICIENT TO MAINTAIN SAID UNRECOVERED ISOMERS IN THE LIQUID PHASE AND CONTACTING HYDROGEN AND THE REMAINDER OF SAID UNRECOVERED ISOMERS IN VAPOR PHASE WITH PLATINUM ON SILICA-ALUMINA, A ZEOLITE OF THE ZSM-5 TYPE, ZEOLITE-12 OR ZEOLITE 21 AT A TEMPERATURE OF 500 TO 900*F. AND A PRESSURE OF
Claim 2
Dependent Claim
121 words
IN A PROCESS OF SELECTIVELY RECOVERING ONE OR MORE EIGHT CARBON ATOM AROMATIC ISOMER FROM A MIXTURE OF SUCH ISOMERS ISOMERIZING A MIXTURE OF UNRECOVERED ISOMERS AND RECYCLING ISOMERIZATE TO THE SELEDTED RECOVERY STEP; THE IMPROVEMENT WHICH COMPRISES CONTACTING A PORTION OF SAID UNRECOVERED ISOMERS GREATER THAN HALF BUT LESS THAN 90 PERCENT OF THE TOTAL WITH A CRYSTALLINE ALUMINOSILICATE CATALYST UNDER ISOMERIZING CONDITIONS AT A TEMPERATURE LESS THAN 600*F. AND UNDER PRESSURE SUFFICIENT TO MAINTAIN SAID UNRECOVERED ISOMERS IN THE LIQUID PHASE AND CONTACTING HYDROGEN AND THE REMAINDER OF SAID UNRECOVERED ISOMERS IN VAPOR PHASE WITH PLATINUM ON SILICA-ALUMINA, A ZEOLITE OF THE ZSM-5 TYPE, ZEOLITE-12 OR ZEOLITE 21 AT A TEMPERATURE OF 500 TO 900*F. AND A PRESSURE OF
Claim 3
Dependent Claim
12 words
A process as defined in claim 1 wherein p-xylene is selectively recovered.
References Cited (Backward Citations)
US3538173A
Cited
US3790471A
Cited
US3766287A
Cited
US3751504A
Cited
US3756942A
Cited
US3761389A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-23 | 1978-06-24 | 1978-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-23 | 1982-06-24 | 1982-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-23 | 1986-06-24 | 1986-12-24 | $7700.00 | Window Closed / Lapsed |