Claims
- 1. In a catalytic cracking process for converting a metals contaminated hydrocarbon feedstock to more valuable, lower boiling hydrocarbon products in a cracking reaction zone wherein the cracking catalyst is poisoned and contaminated by metals present in the feedstock, the improvement which comprises
- (i) withdrawing at least a portion of said metal contaminated catalyst from the cracking reaction zone;
- (ii) contacting at least a portion of said metal contaminated catalyst with at least one sulfur containing compound to provide a catalyst containing sulfur and metal compounds;
- (iii) contacting said catalyst containing sulfur and metal compounds with an oxygen-containing gas at a temperature maintained within the range of from 550.degree. C. to 725.degree. C. for a time sufficient to promote subsequent metal compounds removal by converting at least a portion of said metal compounds on a promoted catalyst to a dispersible form;
- (iv) removing at least a portion of the metal compounds from the promoted catalyst;
- (v) recovering a catalyst of reduced metal content and improved catalytic activity; and
- (vi) returning at least a portion of said catalyst of reduced metal content and improved catalytic activity to the catalytic cracking reaction zone.
- 2. A process as in claim 1 wherein the temperature of (iii) is within the range of from about 600.degree. F. to about 700.degree. F.
- 3. A process as in claim 1 wherein the temperature of (iii) is within the range of from about 620.degree. F. to about 680.degree. F.
- 4. A process as in claim 1 which includes the presence of steam while contacting said catalyst containing sulfur and metal compounds with an oxygen-containing gas.
- 5. A process as in claim 1 wherein the metal compounds on the promoted catalyst are removed therefrom by contact with a wash medium.
- 6. A process as in claim 1 wherein the wash medium is an aqueous reductive wash medium and provides a reductively washed catalyst.
- 7. A process as in claim 6 wherein the reductive aqueous wash medium is a solution of SO.sub.2 in water.
- 8. A process as in claim 6 wherein the solution is a saturated SO.sub.2 solution.
- 9. A process as in claim 8 wherein said reductive aqueous wash medium is at a temperature of about 65.degree.-80.degree. C. and contacts said promoted catalyst for a contact time of about 0.5-10 minutes.
- 10. A process as in claim 9 where said contact time is about 1-5 minutes.
- 11. A process as in claim 6 wherein the reductively washed catalyst is subjected to an oxidative wash medium.
- 12. A process as in claim 11 wherein the oxidative wash medium is an aqueous solution of hydrogen peroxide.
- 13. A process as in claim 12 wherein said oxidative wash medium is at a temperature of about 60.degree.-85.degree. C. and contacts said reductively washed catalyst for a contact time of about 1-5 minutes.
- 14. A process as in claim 13 wherein said aqueous solution of hydrogen peroxide comprises about 2 to 30 weight % hydrogen peroxide.
- 15. A process as in claim 1 wherein removing at least a portion of the metal compounds from the promoted catalyst comprises alternate reductive and oxidative washes, the last wash comprising an oxidative wash.
- 16. A process as in claim 1 wherein the cracking catalyst comprises a zeolitic molecular sieve.
- 17. A process as in claim 16 wherein said zeolitic molecular sieve comprises a decationized zeolitic molecular sieve having less than 90% of the aluminum atoms associated with cations, a crystalline structure capable of internally absorbing benzene and a SiO.sub.2 to Al.sub.2 O.sub.3 molar ratio greater than 3.
Parent Case Info
This is a division of application Ser. No. 695,687, filed June 14, 1976, now U.S. Pat. No. 4,102,811.
US Referenced Citations (8)
Divisions (1)
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Number |
Date |
Country |
Parent |
695687 |
Jun 1976 |
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