Claims
- 1. A polymerization process comprising contacting an ethylene feedstream with a catalyst system made by a process comprising
- (a) forming a chromium catalyst component on a predominantly silica support;
- (b) subjecting the composition of (a) to activation in an oxygen-containing ambient at an elevated temperature sufficient to convert at least a portion of any chromium in a lower valent state to the hexavalent state;
- (c) thereafter subjecting the activated catalyst composition of (b) to carbon monoxide under reducing conditions; and
- (d) thereafter contacting the thus reduced supported catalyst composition of (c) with a cocatalyst selected from trialkyl boron compounds and dialkyl aluminum alkoxide compounds.
- 2. A process according to claim 1 wherein said feedstream consists essentially of pure polymerization grade ethylene.
- 3. A process according to claim 2 carried out under slurry conditions.
- 4. A process according to claim 2 carried out in a reactor connected in series with a second reactor utilizing a different supported chromium oxide olefin polymerization catalyst.
- 5. A process according to claim 1 wherein said polymer product has a density within the range of 0.920 to 0.960.
- 6. A method according to claim 1 wherein said ethylene feedstream consists essentially of pure polymerization grade ethylene, said support is selected from pure silica and a composition comprising 95 to 98 weight percent silica the remainder being a titania component, wherein said activation is carried out in air at a temperature within the range of 400.degree. to 900.degree. C., wherein said carbon monoxide reduction is carried out at a temperature within the range of 300.degree. to 500.degree. C. and wherein the reduced supported chromium catalyst component is contacted with triethyl borane in a stirred mixing vessel.
- 7. A process in accordance with claim 1 wherein said feedstream consists essentially of polymerization grade ethylene, said process comprising in addition recovering a copolymer as a product of the process.
- 8. A process according to claim 7 wherein said copolymer has a density within the range of 0.930 to 0.955.
- 9. A process according to claim 7 wherein said support is selected from pure silica and a composition comprising 95 to 98 weight percent silica the remainder being a titania component, wherein said activation is carried out in air at a temperature within the range of 400.degree. to 900.degree. C., wherein said carbon monoxide reduction is carried out at a temperature within the range of 300.degree. to 500.degree. C. and wherein the reduced supported chromium catalyst component is contacted with triethyl borane is a stirred mixing vessel.
- 10. A process according to claim 1 wherein said predominantly silica support is a cogel of at least 90% silica the remainder being titania.
- 11. A method according to claim 1 wherein said predominantly silica support is essentially pure silica.
- 12. A method according to claim 1 wherein said activation is carried out in air at a temperature within the range of 400.degree. to 900.degree. C.
- 13. A method according to claim 1 wherein said carbon monoxide reduction is carried out at a temperature within the range of 300.degree. to 500.degree. C.
- 14. A method according to claim 1 wherein the reduced supported catalyst component of (c) is contacted in a mixing vessel with a hydrocarbon solution of said cocatalyst.
- 15. A method according to claim 1 wherein said cocatalyst is triethyl borane.
- 16. A method according to claim 1 wherein said thus reduced activated catalyst of (c) is precontacted with said cocatalyst prior to contact with said monomer.
Parent Case Info
This is a divisional of copending application Ser. No. 874,977, filed June 16, 1986 now U.S. Pat. No. 4,735,931 issued Apr. 5, 1988.
US Referenced Citations (8)
Foreign Referenced Citations (1)
Number |
Date |
Country |
1415648 |
Nov 1975 |
GBX |
Divisions (1)
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Number |
Date |
Country |
Parent |
874977 |
Jun 1986 |
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