Claims
- 1. A process for improving the activity of an existing catalyst comprising:(1) wetting an existing catalyst, said catalyst comprising gamma alumina, amorphous alumina, and one or more catalytically active metals and/or compounds of such metals, with a chelating agent in a carrier liquid; (2) aging the wetted catalyst while wet; (3) drying the so-aged catalyst at a temperature and under conditions to substantially volatilize the carrier liquid; and (4) calcining the so-dried catalyst.
- 2. The process of claim 1, wherein the chelating agent possesses a high stability constant with respect to the one or more catalytically active metals and/or compounds of such metals.
- 3. The process of claim 1, wherein the chelating agent is ethylenediaminetetraacetic acid or a derivative thereof.
- 4. The process of claim 1, wherein the chelating agent is selected from the group consisting of diammonium ethylenediaminetetraacetic acid, tris(2-aminoethyl)amine and triethylenetetraamine.
- 5. The process of claim 1, wherein the so-aged catalyst is dried at a temperature in the range of 100° C. to 250° C.
- 6. The process of claim 1, wherein the so-aged catalyst is dried with the aid of a forced air heater.
- 7. The process of claim 1, wherein the so-dried catalyst is calcined in a first stage at a temperature which is sufficiently high to drive off or decompose the chelating agent, but which is not so high that the chelating agent combusts to form carbonaceous deposits, and in a second stage at normal calcining conditions.
CROSS REFERENCE TO RELATED APPLICATION
This is a continuation of application Ser. No. 09/434,417, filed Nov. 4, 1999, now U.S. Pat. No. 6,200,927, which is a division of application Ser. No. 08/433,381, filed Sep. 25, 1995, now U.S. Pat. No. 6,015,485 which is a 371 of PCT/US94/05293 filed May 13, 1994.
US Referenced Citations (5)
Continuations (1)
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Number |
Date |
Country |
Parent |
09/434417 |
Nov 1999 |
US |
Child |
09/576564 |
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US |