Methods for chromium catalyst activation using oxygen-enriched fluidization gas

Patent metadata

Field	Value
Publication number	US-12297310-B2
Application number	US-202318159119-A
Country	US
Kind code	B2
Filing date	Jan 25, 2023
Priority date	Feb 19, 2021
Publication date	May 13, 2025
Grant date	May 13, 2025

Abstract

Processes for producing an activated chromium catalyst are disclosed, and these processes comprise contacting a supported chromium catalyst with a gas stream containing from 25-60 vol % oxygen at a peak activation temperature of 550-900° C. to produce the activated chromium catalyst. The linear velocity of the gas stream is 0.18-0.4 ft/sec, and the oxygen linear velocity of the gas stream is 0.05-0.15 ft/sec. The resultant activated chromium catalyst and an optional co-catalyst can be contacted with an olefin monomer and an optional olefin comonomer in a polymerization reactor system under polymerization conditions to produce an olefin polymer.

First claim

We claim:

1. A process to produce an activated chromium catalyst, the process comprising:
contacting a supported chromium catalyst with a gas stream comprising from 25 to 50 vol % oxygen at a peak activation temperature of from 550° C. to 900° C. to produce the activated chromium catalyst; wherein:
the supported chromium catalyst contains from 0.5 to 2 wt % of chromium, based on a weight of the supported chromium catalyst;
a linear velocity of the gas stream is in a range from 0.18 to 0.4 ft/sec; and
an oxygen linear velocity of the gas stream is in a range from 0.05 to 0.15 ft/sec.

2. The process of claim 1 , wherein the supported chromium catalyst and the activated chromium catalyst comprise silica.

3. The process of claim 1 , wherein the supported chromium catalyst and the activated chromium catalyst comprise chromium/silica, chromium/silica-titania, or a combination thereof.

4. The process of claim 1 , wherein the peak activation temperature is in a range from 600° C. to 871° C.

5. The process of claim 1 , wherein the linear velocity of the gas stream is in a range from 0.18 to 0.33 ft/sec.

6. The process of claim 1 , wherein the oxygen linear velocity of the gas stream is in a range from 0.07 to 0.13 ft/sec.

7. The process of claim 1 , wherein, in a ramp up to the peak activation temperature, a rate of temperature increase is in a range from 0.25° C./min to 5° C./min.

8. The process of claim 1 , wherein the process further comprises, in a cool down from the peak activation temperature, contacting the activated chromium catalyst with a gas stream comprising from 20 to 60 vol % oxygen to a temperature T 1 in a range from 260° C. to 480° C.

9. The process of claim 8 , wherein the process further comprises, in the cool down from the peak activation temperature, contacting the activated chromium catalyst with a gas stream consisting essentially of an inert gas from the temperature T 1 to ambient temperature.

10. The process of claim 9 , wherein the inert gas is nitrogen.

11. An olefin polymerization process, the process comprising:
(i) contacting a supported chromium catalyst with a gas stream comprising from 25 to 50 vol % oxygen at a peak activation temperature of from 550° C. to 900° C. to produce an activated chromium catalyst; wherein:
the supported chromium catalyst contains from 0.5 to 2 wt % of chromium, based on a weight of the supported chromium catalyst;
a linear velocity of the gas stream is in a range from 0.18 to 0.4 ft/sec; and
an oxygen linear velocity of the gas stream is in a range from 0.05 to 0.15 ft/sec; and
(ii) contacting the activated chromium catalyst and an optional co-catalyst with an olefin monomer and an optional olefin comonomer in a polymerization reactor system under polymerization conditions to produce an olefin polymer.

12. The process of claim 11 , wherein the olefin monomer comprises ethylene.

13. The process of claim 11 , wherein the activated chromium catalyst is contacted with ethylene and an olefin comonomer comprising 1-butene, 1-hexene, 1-octene, or a mixture thereof.

14. The process of claim 11 , wherein the olefin polymer comprises an ethylene homopolymer, an ethylene/1-butene copolymer, an ethylene/1-hexene copolymer, and/or an ethylene/1-octene copolymer.

15. The process of claim 14 , wherein the polymerization reactor system comprises a slurry reactor, a gas-phase reactor, a solution reactor, or a combination thereof.

16. The process of claim 14 , wherein the polymerization reactor system comprises a loop slurry reactor.

17. The process of claim 14 , wherein the activated chromium catalyst comprises chromium/silica.

18. The process of claim 14 , wherein the activated chromium catalyst comprises chromium/silica-titania.

19. The process of claim 14 , wherein:
the peak activation temperature is in a range from 600° C. to 871° C.; and
in a ramp up to the peak activation temperature, a rate of temperature increase is in a range from 0.25° C./min to 5° C./min.

20. The process of claim 14 , wherein the linear velocity of the gas stream is in a range from 0.18 to 0.33 ft/sec.

21. The process of claim 14 , wherein the oxygen linear velocity of the gas stream is in a range from 0.07 to 0.13 ft/sec.

Assignees

• Chevron Phillips Chemical Co Lp

Inventors

• Romig Ralph W
• Hein James E
• Bretz Troy
• Gu Zhihui

Classifications

• B01J31/34

  of chromium, molybdenum or tungsten · CPC title

• C08F210/16

  Copolymers of ethene with alpha-alkenes, e.g. EP rubbers · CPC title

• B01J21/08

  Silica · CPC title

• C08F4/78

  selected from chromium, molybdenum or tungsten · CPC title

• C08F10/02

  Ethene · CPC title