Chromium (III) catalyst systems with activator-supports

Patent metadata

Field	Value
Publication number	US-10246528-B2
Application number	US-201414151032-A
Country	US
Kind code	B2
Filing date	Jan 9, 2014
Priority date	Jan 9, 2014
Publication date	Apr 2, 2019
Grant date	Apr 2, 2019

Abstract

Methods for preparing supported chromium catalysts containing a chromium (III) compound and an activator-support are disclosed. These supported chromium catalysts can be used in catalyst compositions for the polymerization of olefins to produce polymers having low levels of long chain branching, and with greater sensitivity to the presence of hydrogen during polymerization.

First claim

We claim:

1. An olefin polymerization process, the process comprising:
(i) combining a chromium (III) compound with an activator-support comprising a solid oxide treated with an electron-withdrawing anion to form a mixture;
(ii) subjecting the mixture to a non-oxidizing atmosphere at a peak temperature to produce a supported chromium catalyst; and
(iii) contacting the supported chromium catalyst and a co-catalyst with ethylene and an optional olefin comonomer in a polymerization reactor system under polymerization conditions to produce an ethylene polymer, wherein a molar ratio of co-catalyst:chromium is in a range from about 50:1 to about 500:1; and
wherein the ethylene polymer has a melt index in a range from 0 to about 0.5 g/10 min, and a Mw in a range from about 400,000 to about 900,000 g/mol.

2. The process of claim 1 , wherein:
an increase in melt index of the ethylene polymer produced by the process with the addition of hydrogen from 0 to 1 mol %, based on ethylene, is greater than an increase in melt index of an ethylene polymer obtained using a Cr(VI)/silica catalyst system, under the same polymerization conditions; or
a melt index of an ethylene polymer produced by the process in the presence of 0.5 mol % hydrogen, based on ethylene, is greater than a melt index of an ethylene polymer obtained using a Cr(VI)/silica catalyst system, under the same polymerization conditions; or both.

3. The process of claim 1 , wherein:
the polymerization reactor system comprises a slurry reactor, gas-phase reactor, solution reactor, or a combination thereof; and
the supported chromium catalyst and the co-catalyst are contacted with ethylene and an olefin comonomer comprising 1-butene, 1-hexene, 1-octene, or a mixture thereof.

4. The process of claim 1 , wherein the ethylene polymer is an ethylene/α-olefin copolymer characterized by a number of short chain branches (SCB) per 1000 total carbon atoms at Mn that is greater than at Mw.

5. The process of claim 1 , wherein the ethylene polymer is characterized by:
a ratio of Mw/Mn in a range from about 90 to about 200; and/or
a HLMI of less than or equal to about 1 g/10 min; and
wherein the ethylene polymer is an ethylene homopolymer, an ethylene/1-butene copolymer, an ethylene/1-hexene copolymer, or an ethylene/1-octene copolymer.

6. The process of claim 1 , wherein the peak temperature is in a range from about 25° C. to about 600° C.

7. The process of claim 1 , wherein the non-oxidizing atmosphere is an inert atmosphere.

8. The process of claim 1 , wherein step (i) comprises dry mixing the activator-support with the chromium (III) compound, and step (ii) comprises subjecting the mixture to the non-oxidizing atmosphere at a peak temperature sufficient for at least a portion of the chromium (III) compound to sublime or vaporize and impregnate the activator-support.

9. The process of claim 1 , wherein step (i) comprises mixing the activator-support with the chromium (III) compound in a solvent, and step (ii) comprises subjecting the mixture to the non-oxidizing atmosphere at a peak temperature sufficient to remove the solvent.

10. The process of claim 1 , wherein:
the chromium (III) compound comprises chromium (III) formate, chromium (III) acetate, chromium (III) propionate, chromium (III) butyrate, chromium (III) pentanoate, chromium (III) neopentanoate, chromium (III) hexanoate, chromium (III) 2-ethylhexanoate, chromium (III) benzoate, chromium (III) naphthenate, chromium (III) oleate, chromium (III) oxalate, chromium (III) acetylacetonate, chromium (III) stearate, chromium (III) laurate, or any combination thereof; and
the activator-support comprises fluorided alumina, chlorided alumina, bromided alumina, sulfated alumina, fluorided silica-alumina, chlorided silica-alumina, bromided silica-alumina, sulfated silica-alumina, fluorided silica-zirconia, chlorided silica-zirconia, bromided silica-zirconia, sulfated silica-zirconia, fluorided silica-titania, fluorided silica-coated alumina, sulfated silica-coated alumina, phosphated silica-coated alumina, or any combination thereof.

11. The process of claim 1 , wherein:
the chromium (III) compound comprises chromium (III) acetylacetonate; and
the activator-support comprises a fluorided solid oxide and/or a sulfated solid oxide.

12. The process of claim 1 , wherein:
a weight percentage of chromium, based on the weight of the activator-support, is in a range from about 0.25 to about 5 wt %; and
a weight percentage of the electron-withdrawing anion, based on the weight of the activator-support, is in a range from about 2 to about 15 wt %.

13. The process of claim 1 , wherein the co-catalyst comprises an aluminoxane co-catalyst.

14. The process of claim 1 , wherein the co-catalyst comprises an organoaluminum co-catalyst.

15. The process of claim 1 , wherein:
the chromium (III) compound comprises chromium (III) formate, chromium (III) acetate, chromium (III) propionate, chromium (III) butyrate, chromium (III) pentanoate, chromium (III) neopentanoate, chromium (III) hexanoate, chromium (III) 2-ethylhexanoate, chromium (III) benzoate, chromium (III) naphthenate, chromium (III) oleate, chromium (III) oxalate, chromium (III) acetylacetonate, chromium (III) stearate, chromium (III) laurate, a derivative thereof, or any combination thereof;
the activator-support comprises sulfated alumina, fluorided silica-alumina, fluorided silica-coated alumina, or any combination thereof; and
the co-catalyst comprises trimethylaluminum, triethylaluminum, tri-n-propylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, diisobutylaluminum hydride, diethylaluminum ethoxide, diethylaluminum chloride, or any combination thereof.

16. The process of claim 15 , wherein the ethylene polymer is characterized by:
a ratio of Mw/Mn in a range from about 90 to about 200; and/or
a HLMI of less than or equal to about 1 g/10 min; and
wherein the ethylene polymer is an ethylene homopolymer, an ethylene/1-butene copolymer, an ethylene/1-hexene copolymer, or an ethylene/1-octene copolymer.

17. The process of claim 16 , wherein greater than 500 grams of the ethylene polymer per gram of the supported chromium catalyst are produced per hour, under slurry polymerization conditions, using isobutane as a diluent, with an organoaluminum:chromium molar ratio of 100:1, and with a polymerization temperature of 100° C. and a reactor pressure of 550 psig.

18. An olefin polymerization process, the process comprising:
(i) combining a chromium (III) compound with an activator-support comprising a solid oxide treated with an electron-withdrawing anion to form a mixture;
(ii) subjecting the mixture to a non-oxidizing atmosphere at a peak temperature in a range from about 25° C. to about 250° C. to produce a supported chromium catalyst; and
(iii) contacting the supported chromium catalyst and a co-catalyst with ethylene and an optional olefin comonomer in a polymerization reactor system under polymerization conditions to produce from about 2000 to about 10,000 grams of the ethylene polymer per gram of the supported chromium catalyst per hour;
wherein the ethylene polymer has a melt index in a range from 0 to about 0.5 g/10 min.

19. The process of claim 18 , wherein:
the non-oxidizing atmosphere is an inert atmosphere;
the polymerization reactor system comprises a slurry reactor, gas-phase reactor, solution reactor, or a combination thereof; and
the supported chromium catalyst and the co-catalyst are contacted with ethylene and an olefin

Assignees

• Chevron Phillips Chemical Co Lp

Inventors

• Mcdaniel Max P
• Hlavinka Mark L
• Collins Kathy S

Classifications

• C08F10/02 Primary

  Ethene · CPC title

• C08F4/63927

  two cyclopentadienyl rings being mutually bridged · CPC title

• C08F4/63904

  in combination with another component of C08F4/62 · CPC title

• C08F4/63916

  supported on a carrier, e.g. silica, MgCl2, polymer · CPC title

• C08F4/63912

  in combination with an organoaluminium compound · CPC title