Process for the starting of the polymerization of ethylene or copolymerization of ethylene and at least one other alpha-olefin in the gas phase in the presence of a catalyst based on chromium oxide
US5075395A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 11, 1988 |
| Grant date | Dec 24, 1991 |
| Priority date | — |
| Expiry date | Feb 11, 2008 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S526/904
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
The present invention relates to a process for starting up the polymerization of ethylene or copolymerization of ethylene and at least one other alpha-olefin by bringing ethylene and optionally at least one other alpha-olefin in contact under fluidized-bed polymerization or copolymerization conditions and/or stirred mechanically, with a charge powder in the presence of a catalyst comprising a chromium oxide compound associated with a granular support and activated by thermal treatment, this catalyst being used in the form of a prepolymer, this process being characterized in that the charge powder employed is previously subjected to a treatment by contacting the said charge powder with an organo-aluminium compound, in such a way that the polymerization or copolymerization starts up immediately after the contacting of the ethylene and optionally one other alpha-olefin with the charge powder in the presence of the prepolymer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.