Methods for restoring metallocene solids exposed to air

Patent metadata

Field	Value
Publication number	US-10221258-B2
Application number	US-201715461523-A
Country	US
Kind code	B2
Filing date	Mar 17, 2017
Priority date	Mar 17, 2017
Publication date	Mar 5, 2019
Grant date	Mar 5, 2019

Abstract

Methods for treating solid metallocene compounds that are exposed to air are disclosed. These methods include a step of contacting the exposed solid metallocene compound with a purging gas stream containing an inert gas, and optionally, subjecting the exposed solid metallocene compound to a sub-atmospheric pressure.

First claim

We claim:

1. A method for treating an exposed solid metallocene compound, the method comprising, in any order:
contacting the exposed solid metallocene compound with a purging gas stream comprising an inert gas; and
subjecting the exposed solid metallocene compound to a sub-atmospheric pressure;
to form a treated solid metallocene compound.

2. The method of claim 1 , wherein subjecting the exposed solid metallocene compound to a sub-atmospheric pressure comprises:
a pressure in a range from about 100 torr to about 0.01 torr; and
a temperature in a range from about 10° C. to about 75° C.

3. The method of claim 1 , wherein the method comprises at least two contacting steps and at least two subjecting steps, performed in any order.

4. The method of claim 1 , wherein a 1 mg/mL solution of the treated solid metallocene compound in toluene has a moisture content of less than 10 ppmw.

5. The method of claim 1 , wherein a color of a 1 mg/mL solution of the treated solid metallocene compound in toluene is unchanged for a time period of 24 hours at 25° C.

6. The method of claim 1 , wherein a catalyst activity of a 1 mg/mL solution of the treated solid metallocene compound in toluene is at least 85% of the catalyst activity obtained by using a 1 mg/mL solution of a fresh solid metallocene compound in toluene, after a time period of 24 hours at 25° C., under the same catalyst preparation and polymerization conditions.

7. A method for treating an exposed solid metallocene compound, the method comprising:
contacting the exposed solid metallocene compound with a purging gas stream comprising an inert gas to form a treated solid metallocene compound.

8. The method of claim 7 , wherein:
the inert gas comprises nitrogen;
the purging gas stream comprises less than 25 ppmw of water; and
the purging gas stream comprises less than 25 ppmw of oxygen-containing compounds.

9. The method of claim 7 , wherein the method does not comprise a recrystallization step.

10. The method of claim 7 , wherein the treated solid metallocene compound comprises an unbridged zirconium or hafnium based metallocene compound containing two cyclopentadienyl groups, two indenyl groups, or a cyclopentadienyl and an indenyl group.

11. The method of claim 7 , wherein:
a 1 mg/mL solution of the treated solid metallocene compound in toluene has a moisture content of less than 5 ppmw;
a color of a 1 mg/mL solution of the treated solid metallocene compound in toluene is unchanged for a time period of 36 hours at 25° C.; and
a catalyst activity of a 1 mg/mL solution of the treated solid metallocene compound in toluene is at least 80% of the catalyst activity obtained by using a 1 mg/mL solution of a fresh solid metallocene compound in toluene, after a time period of 24 hours at 25° C., under the same catalyst preparation and polymerization conditions.

12. The method of claim 1 , wherein:
the treated solid metallocene compound comprises titanium, zirconium, hafnium, or a combination thereof; and
the method does not comprise a recrystallization step.

13. The method of claim 12 , wherein:
subjecting the exposed solid metallocene compound to a sub-atmospheric pressure comprises a pressure of less than 10 torr; and
a 1 mg/mL solution of the treated solid metallocene compound in toluene has a moisture content of less than 5 ppmw.

14. The method of claim 1 , wherein the treated solid metallocene compound comprises a bridged zirconium or hafnium based metallocene compound with a cyclopentadienyl group and a fluorenyl group.

15. The method of claim 14 , wherein a catalyst activity of a 1 mg/mL solution of the treated solid metallocene compound in toluene is at least 80% of the catalyst activity obtained by using a 1 mg/mL solution of a fresh solid metallocene compound in toluene, after a time period of 24 hours at 25° C., under the same catalyst preparation and polymerization conditions.

16. The method of claim 1 , wherein the treated solid metallocene compound comprises an unbridged zirconium or hafnium based metallocene compound containing two cyclopentadienyl groups, two indenyl groups, or a cyclopentadienyl and an indenyl group.

17. The method of claim 16 , wherein:
the purging gas stream is a nitrogen gas stream comprising less than 10 ppmw of water and less than 10 ppmw of oxygen-containing compounds; and
a catalyst activity of a 1 mg/mL solution of the treated solid metallocene compound in toluene is at least 80% of the catalyst activity obtained by using a 1 mg/mL solution of a fresh solid metallocene compound in toluene, after a time period of 24 hours at 25° C., under the same catalyst preparation and polymerization conditions.

18. The method of claim 7 , wherein:
the method comprises fluidizing the exposed solid metallocene compound with the purging gas stream; and
the treated solid metallocene compound comprises titanium, zirconium, hafnium, or a combination thereof.

19. The method of claim 7 , wherein:
the treated solid metallocene compound comprises a bridged zirconium or hafnium based metallocene compound with a cyclopentadienyl group and a fluorenyl group; and
a catalyst activity of a 1 mg/mL solution of the treated solid metallocene compound in toluene is at least 85% of the catalyst activity obtained by using a 1 mg/mL solution of a fresh solid metallocene compound in toluene, after a time period of 24 hours at 25° C., under the same catalyst preparation and polymerization conditions.

20. The method of claim 7 , wherein the purging gas stream is a nitrogen gas stream comprising less than 10 ppmw of water and less than 10 ppmw of oxygen-containing compounds.

Assignees

• Chevron Phillips Chemical Co Lp

Inventors

• Yang Qing
• Crain Tony R
• Rajaendran George R

Classifications

• C08F4/65916

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

• C08F2420/01

  Cp or analog bridged to a non-Cp X neutral donor · CPC title

• C08F10/02 Primary

  Ethene · CPC title

• C08F4/65927

  two cyclopentadienyl rings being mutually bridged · CPC title

• C08F4/63925

  two cyclopentadienyl rings being mutually non-bridged · CPC title