Methods of regenerating aromatization catalysts

1. A method of treating a spent catalyst comprising a transition metal and a catalyst support, the method comprising:

(1) contacting the spent catalyst with a halogen-containing stream comprising chlorine and fluorine to produce a halogenated spent catalyst;

(2) contacting the halogenated spent catalyst with a purging stream consisting essentially of an inert gas; and

(3) contacting the halogenated spent catalyst with a decoking gas stream comprising oxygen; wherein the decoking gas stream contains less than 50 ppmw of halogen-containing compounds.

2. The method of claim 1 , wherein:

step (1) is conducted at a halogenation temperature in a range from about 120° C. to about 320° C.; and

a molar ratio of Cl:F in the halogen-containing stream is in a range from about 0.2:1 to about 10:1.

3. The method of claim 2 , wherein the halogen-containing stream is substantially free of oxygen-containing compounds.

4. The method of claim 1 , wherein the halogen-containing stream comprises Cl 2 , F 2 , and nitrogen.

5. The method of claim 1 , wherein the halogen-containing stream comprises a chlorofluorocarbon.

6. The method of claim 1 , wherein:

step (2) is conducted at a purging temperature in a range from about 150° C. to about 400° C.; and

the purging stream consists essentially of nitrogen.

7. The method of claim 1 , wherein:

step (3) is conducted at a peak decoking temperature in a range from about 300° C. to about 500° C.; and

the decoking gas stream in step (3) comprises air or a mixture of nitrogen and oxygen.

8. The method of claim 1 , wherein the spent catalyst comprises:

platinum on a KL-zeolite;

a support matrix comprising alumina, silica, a mixed oxide thereof, or a mixture thereof;

from about 0.025 wt. % to about 5 wt. % chlorine; and

from about 0.025 wt. % to about 5 wt. % fluorine.

9. The method of claim 1 , further comprising a pre-drying step prior to step (1), the pre-drying step comprising contacting the spent catalyst with a pre-drying gas stream consisting essentially of an inert gas.

10. The method of claim 1 , further comprising a re-coking pretreatment step prior to step (1), the re-coking pretreatment step comprising contacting the spent catalyst with a pretreatment stream comprising molecular hydrogen and a hydrocarbon feed comprising C 6 -C 8 alkanes and/or cycloalkanes.

11. The method of claim 1 , further comprising a partial decoking step prior to step (1), the partial decoking step comprising contacting the spent catalyst with a partial decoking gas stream comprising oxygen at a partial decoking temperature in a range from about 150° C. to about 250° C.

12. The method of claim 1 , further comprising a reducing step after step (3), the reducing step comprising contacting the de-coked catalyst with a reducing gas stream comprising molecular hydrogen.

13. The method of claim 12 , wherein the reducing gas stream comprises at least about 25 mole % molecular hydrogen.

14. A method of treating a spent catalyst comprising a transition metal and a catalyst support, the method comprising:

(i) contacting the spent catalyst with a halogen-containing stream comprising chlorine and fluorine to produce a halogenated spent catalyst; and

(ii) contacting the halogenated spent catalyst with a decoking gas stream comprising oxygen;

wherein the decoking gas stream contains less than 50 ppmw of halogen-containing compounds.

15. The method of claim 14 , wherein:

the transition metal comprises a Group VIII transition metal; and

the catalyst support comprises a potassium L-zeolite or a barium ion-exchanged L-zeolite.

16. The method of claim 14 , further comprising a hydrocarbon treatment step prior to step (ii), the hydrocarbon treatment step comprising contacting the halogenated spent catalyst with a hydrocarbon treatment stream comprising a hydrocarbon feed comprising C 6 -C 8 alkanes and/or cycloalkanes.

17. A reforming process comprising:

(a) contacting a hydrocarbon feed with an aromatization catalyst comprising a transition metal and a catalyst support under reforming conditions in a reactor system to produce an aromatic product;

(b) performing step (a) for a time period sufficient to form a spent aromatization catalyst;

(c) contacting the spent aromatization catalyst with a halogen-containing stream comprising chlorine and fluorine to produce a halogenated spent catalyst;

(d) contacting the halogenated spent catalyst with a purging stream consisting essentially of an inert gas; and

(e) contacting the halogenated spent catalyst with a decoking gas stream comprising oxygen; wherein the decoking gas stream contains less than 50 ppmw of halogen-containing compounds.

18. The process of claim 17 , wherein the reforming process is an in situ process.

19. The process of claim 17 , wherein steps (c)-(e) are performed in a vessel external to the reactor system.

20. The method of claim 14 , wherein the spent catalyst comprises:

platinum on a KL-zeolite;

from about 0.1 wt. % to about 10 wt. % platinum;

a support matrix comprising alumina, silica, a mixed oxide thereof, or a mixture thereof;

from about 0.025 wt. % to about 5 wt. % chlorine; and

from about 0.025 wt. % to about 5 wt. % fluorine.

21. The method of claim 20 , wherein:

the halogen-containing stream comprises Cl 2 , F 2 , and nitrogen, and is substantially free of oxygen-containing compounds; and

the decoking gas stream comprises nitrogen and oxygen.

22. The method of claim 14 , wherein:

the transition metal comprises platinum; and

a molar ratio of Cl:F in the halogen-containing stream is in a range from about 0.1:1 to about 15:1.

23. The method of claim 22 , wherein:

step (i) is conducted at a halogenation temperature in a range from about 100° C. to about 500° C.; and

step (ii) is conducted at a peak decoking temperature in a range from about 300° C. to about 600° C.

24. A reforming process comprising:

(a) contacting a hydrocarbon feed with an aromatization catalyst comprising a transition metal and a catalyst support under reforming conditions in a reactor system to produce an aromatic product;

(b) performing step (a) for a time period sufficient to form a spent aromatization catalyst;

(c) contacting the spent aromatization catalyst with a halogen-containing stream comprising chlorine and fluorine to produce a halogenated spent catalyst; and

(d) contacting the halogenated spent catalyst with a decoking gas stream comprising oxygen; wherein the decoking gas stream contains less than 50 ppmw of halogen-containing compounds.

25. The process of claim 24 , wherein the reforming process is an in situ process.

26. The process of claim 24 , wherein steps (c)-(d) are performed in a vessel external to the reactor system.