Claims
- 1. A method of controlling the stability of an isomerization dewaxing process in which a waxy hydrocarbon fraction is contacted under dewaxing conditions with a zeolitic dewaxing catalyst comprising zeolite beta and from 0.01 to 2 wt % noble metal in a dewaxing reactor having an inlet and an outlet, the method comprising injecting ammonia vapor into the reactor to contact the catalyst in amounts sufficient to maintain operating temperatures in said dewaxing reactor below 900° F.
- 2. The method according to claim 1 wherein said zeolitic dewaxing catalyst comprises from 0.1 to 1% wt platinum.
- 3. A method of controlling the stability of an isomerization dewaxing process in which a waxy hydrocarbon fraction is contacted under dewaxing conditions with a zeolitic dewaxing catalyst comprising zeolite beta in a dewaxing reactor having an inlet and an outlet, the method comprising injecting ammonia vapor at at least one point along the length of the dewaxing reactor to contact the catalyst in amounts sufficient to maintain operating temperatures in said dewaxing reactor below 900° F.
- 4. The method according to claim 3 wherein said injection of ammonia is made at at least three points along the length of the dewaxer reactor.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a division of application Ser. No. 08/102,675, filed Aug. 5, 1993, now U.S. Pat. No. 5,419,830, which is a continuation of application Ser. No. 07/738,991, filed Aug. 1, 1991, now abandoned which is a continuation-in-part of application Ser. No. 07/279,748 filed Dec. 5, 1988, U.S. Pat. No. 5,100,535 now allowed which is a continuation-in-part of application Ser. No. 07/129,951 filed Dec. 3, 1987 abandoned of N. Y. Chen and S. S. Wong which was, in turn, a continuation of application Ser. No. 06/759,387, filed Jul. 26, 1985. The complete disclosures of Ser. Nos. 279,748 and 129,951 are incorporated in the present application by reference.
US Referenced Citations (16)
Foreign Referenced Citations (2)
Number |
Date |
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209208 |
Apr 1984 |
DE |
1429291 |
Mar 1976 |
GB |
Continuations (2)
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Number |
Date |
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Parent |
07/738991 |
Aug 1991 |
US |
Child |
08/102675 |
|
US |
Parent |
06/759387 |
Jul 1985 |
US |
Child |
07/129951 |
|
US |
Continuation in Parts (2)
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Number |
Date |
Country |
Parent |
07/279748 |
Dec 1998 |
US |
Child |
07/738991 |
|
US |
Parent |
07/129951 |
Dec 1987 |
US |
Child |
07/279748 |
|
US |