Patent US2837581A successfully refreshed from Google Patents.
US2837581A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Isomerization of xylene
Assignee: California Research LLC
•
Filing: 1954-05-03
•
Granted: 1958-06-03
•
Expires: 1974-05-03
Abstract
No abstract record available.
Inventors
- 👤 Roger W Hill
- 👤 Raymond V Luthy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 22:28
CPC Classifications
C; C07; C07C; C07C15/00; C07C15/02; C07C15/067; C07C15/08; C07C5/00; C07C5/22; C07C5/27; C07C5/2729; C07C5/2732; C07C5/2735; C07C7/00; C07C7/005; C07C7/14
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
148 words
A PROCESS FOR PRODUCTING PARA-XYLENE WHICH COMPRISES COOLING A XYLENE FEED TO A TEMPERATURE IN THE RANGE -75*F. TO -120*F. TO CAUSE CRYSTALLIZATION OF A PORTION OF THE PARA-XYLENE, SEPARATING THE PARA-XYLENE CRYSTALS AND A MOTHER LIQUOR, FRACTIONALLY DISTILLING THE MOTHER LIQUOR TO SEPARATE AN OVERHEAD FRACTION COMPRISING METAXYLENE AND PARA-XYLENE AND HAVING AN ORTHO-XYLENE CONTENT SUBSTANTIALLY LES THAN THAT OF THE MOTHER LIQUOR AND A BOTTOMS FRACTION HAVING AN ORTHO-XYLENE CONTENT SUBSTANTIALLY HIGHER THAN THAT OF THE MOTHER LIQUOR, ISOMERIZING THE OVERHEAD FRACTION BY CONTACTING IT WITH A SILICAALUMINA CATALYST AT 700*F. TO 1000*F. AND AT A SPACE VELOCITY IN THE RANGE FROM 0.5 TO 5.0 V./V./HR., SEPARATELY ISOMERIZING THE BOTTOMS FRACTION BY CONTACTING IT WITH A SILICA-ALUMINA CATALYST AT CONDITIONS OF TEMPERATURE AND SPACE VELOCITY SUBSTANTIALLY MORE SEVERE THAN THOSE EMPLOYED IN ISOMERIZING THE OVERHEAD FRACTIONS, THE TEMPERATURE BEING IN THE RANGE FROM 900*F. TO 1050*F.
Claim 2
Dependent Claim
148 words
A PROCESS FOR PRODUCTING PARA-XYLENE WHICH COMPRISES COOLING A XYLENE FEED TO A TEMPERATURE IN THE RANGE -75*F. TO -120*F. TO CAUSE CRYSTALLIZATION OF A PORTION OF THE PARA-XYLENE, SEPARATING THE PARA-XYLENE CRYSTALS AND A MOTHER LIQUOR, FRACTIONALLY DISTILLING THE MOTHER LIQUOR TO SEPARATE AN OVERHEAD FRACTION COMPRISING METAXYLENE AND PARA-XYLENE AND HAVING AN ORTHO-XYLENE CONTENT SUBSTANTIALLY LES THAN THAT OF THE MOTHER LIQUOR AND A BOTTOMS FRACTION HAVING AN ORTHO-XYLENE CONTENT SUBSTANTIALLY HIGHER THAN THAT OF THE MOTHER LIQUOR, ISOMERIZING THE OVERHEAD FRACTION BY CONTACTING IT WITH A SILICAALUMINA CATALYST AT 700*F. TO 1000*F. AND AT A SPACE VELOCITY IN THE RANGE FROM 0.5 TO 5.0 V./V./HR., SEPARATELY ISOMERIZING THE BOTTOMS FRACTION BY CONTACTING IT WITH A SILICA-ALUMINA CATALYST AT CONDITIONS OF TEMPERATURE AND SPACE VELOCITY SUBSTANTIALLY MORE SEVERE THAN THOSE EMPLOYED IN ISOMERIZING THE OVERHEAD FRACTIONS, THE TEMPERATURE BEING IN THE RANGE FROM 900*F. TO 1050*F.
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) | 1961-06-02 | 1961-12-02 | 1962-06-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1965-06-02 | 1965-12-02 | 1966-06-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1969-06-02 | 1969-12-02 | 1970-06-03 | $7700.00 | Window Closed / Lapsed |