Methods of regenerating aromatization catalysts with a decoking step between chlorine and fluorine addition
Methods for regenerating a spent catalyst in a metal reactor are disclosed. Such methods may employ a step of chlorinating the spent catalyst, followed by decoking the chlorinated spent catalyst, and then fluorinating the de-coked catalyst.
1. A method of regenerating a spent catalyst comprising a transition metal and a catalyst support in a metal reactor, the method comprising:
(1) contacting the spent catalyst with a chlorine-containing stream comprising a chlorine-containing compound to produce a chlorinated spent catalyst;
(2) contacting the chlorinated spent catalyst with a decoking gas stream comprising oxygen to produce a de-coked catalyst; and
(3) contacting the de-coked catalyst with a fluorine-containing stream comprising a fluorine-containing compound to form a regenerated catalyst containing less than about 1 wt. % of carbon; wherein:
the transition metal comprises a Group 8-11 transition metal;
the catalyst support comprises a large pore zeolite having an average pore diameter in a range of from about 7 Å to about 12 Å; and
the spent catalyst further comprises chlorine and/or fluorine.
2. The method of claim 1 , wherein step (1) is conducted at a chlorination temperature in a range from about 20° C. to about 300° C.
3. The method of claim 1 , wherein an amount of the chlorine-containing compound in the chlorine-containing stream is controlled to give a concentration of chlorine (Cl) in the chlorine-containing stream in a range from about 5,000 to about 50,000 ppm by volume.
4. The method of claim 3 , wherein the chlorine-containing stream is substantially free of an oxygen-containing compound.
5. The method of claim 1 , wherein the chlorine-containing stream comprises Cl 2 and nitrogen.
6. The method of claim 1 , further comprising a chlorine purging step prior to step (2), the chlorine purging step comprising contacting the chlorinated spent catalyst with a chlorine purging stream consisting essentially of an inert gas.
7. The method of claim 1 , wherein:
step (2) is conducted at a peak decoking temperature in a range from about 300° C. to about 500° C.;
the decoking gas stream comprises nitrogen and oxygen; and
the decoking gas stream is substantially free of halogen-containing compounds.
8. The method of claim 1 , wherein step (3) is conducted at a fluorination temperature in a range from about 20° C. to about 250° C.
9. The method of claim 1 , wherein an amount of the fluorine-containing compound in the fluorine-containing stream is controlled to give a concentration of fluorine (F) in the fluorine-containing stream is in a range from about 5,000 to about 100,000 ppm by volume.
10. The method of claim 9 , wherein the fluorine-containing stream is substantially free of oxygen-containing compounds.
11. The method of claim 1 , wherein the fluorine-containing stream comprises F 2 and nitrogen.
12. The method of claim 1 , further comprising a fluorine purging step after step (3), the fluorine purging step comprising contacting the regenerated catalyst with a fluorine purging stream consisting essentially of an inert gas.
13. The method of claim 1 , wherein the spent catalyst comprises:
platinum on the catalyst support, wherein the catalyst support comprises a KL-zeolite and a binder comprising alumina, silica, a mixed oxide thereof, or a mixture thereof;
from about 0.01 wt. % to about 5 wt. % chlorine; and
from about 0.01 wt. % to about 5 wt. % fluorine.
14. The method of claim 1 , further comprising a reducing step after step (3), the reducing step comprising contacting the regenerated catalyst with a reducing gas stream comprising molecular hydrogen.
15. The method of claim 1 , wherein the metal reactor comprises a stainless steel, and the regenerated catalyst contains less than about 250 ppmw of iron and less than about 0.5 wt. % of carbon.
16. The method of claim 15 , wherein the regenerated catalyst is characterized by:
a TEOR (end of run temperature) within about 40° F. of the TEOR of a fresh reference catalyst;
a FR (fouling rate) in a range from about 0.02° F./hr to about 0.2° F./hr; and
a benzene+toluene selectivity in a range from about 0.88 to about 0.95.
17. A method of regenerating a spent catalyst comprising a transition metal and a catalyst support in a metal reactor, the method comprising:
(i) contacting the spent catalyst with a chlorine-containing stream comprising a chlorine-containing compound to produce a chlorinated spent catalyst;
(ii) contacting the chlorinated spent catalyst with a chlorine purging stream comprising an inert gas;
(iii) contacting the chlorinated spent catalyst with a decoking gas stream comprising oxygen to produce a de-coked catalyst;
(iv) contacting the de-coked catalyst with a fluorine-containing stream comprising a fluorine-containing compound to produce a de-coked and fluorinated catalyst; and
(v) contacting the de-coked and fluorinated catalyst with a fluorine purging stream comprising an inert gas to form a regenerated catalyst containing less than about 1 wt. % of carbon; wherein:
the transition metal comprises a Group 8-11 transition metal;
the catalyst support comprises a large pore zeolite having an average pore diameter in a range of from about 7 Å to about 12 Å; and
the spent catalyst further comprises chlorine and/or fluorine.
18. The method of claim 17 , wherein:
the chlorine-containing stream comprises Cl 2 and nitrogen;
the chlorine purging stream consists essentially of nitrogen;
the decoking gas stream comprises nitrogen and oxygen;
the fluorine-containing stream comprises F 2 and nitrogen; and
the fluorine purging stream consists essentially of nitrogen.
19. The method of claim 17 , further comprising an oxygen purging step after step (iii) and before step (iv), the oxygen purging step comprising contacting the de-coked catalyst with an oxygen purging stream consisting essentially of an inert gas.
20. The method of claim 17 , further comprising a reducing step after step (v), the reducing step comprising contacting the regenerated catalyst with a reducing gas stream comprising molecular hydrogen to produce a reactivated catalyst.
21. The method of claim 20 , wherein the reactivated catalyst contains less than about 300 ppmw of iron and less than about 0.5 wt. % of carbon, and is characterized by:
a TEOR (end of run temperature) within about 40° F. of the TEOR of a fresh reference catalyst;
a FR (fouling rate) in a range from about 0.02° F./hr to about 0.2° F./hr; and
a benzene +toluene selectivity in a range from about 0.88 to about 0.95.
22. 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 metal reactor system to produce an aromatic product;
(B) performing step (A) for a time period sufficient to form a spent catalyst;
(C) contacting the spent catalyst with a chlorine-containing stream comprising a chlorine-containing compound to produce a chlorinated spent catalyst;
(D) contacting the chlorinated spent catalyst with a decoking gas stream comprising oxygen to produce a de-coked catalyst; and
(E) contacting the de-coked catalyst with a fluorine-containing stream comprising a fluorine-containing compound to form a regenerated catalyst containing less than about 1 wt. % of carbon; wherein:
the transition metal comprises a Group 8-11 transition metal;
the catalyst support comprises a large pore zeolite having an average pore diameter in a range of from about 7 Å to about 12 Å;
the aromatization catalyst further comprises chlorine and/or fluorine, and wherein steps (C)-(E) are performed in a metal reactor.
23. The process of claim 22 , wherein the reforming process is an in situ process.
24. The process of claim 22 , wherein steps (C)-(E) are performed in a metal reactor external to the metal reactor system.