Processes for transitioning between chrome-based and mixed polymerization catalysts
US6833417B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 29, 2004 |
| Grant date | Dec 21, 2004 |
| Priority date | — |
| Expiry date | Apr 29, 2024 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S526/901
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
A process of transitioning from a first polymerization reaction conducted in the presence of a mixed catalyst system to a second polymerization reaction conducted in the presence of a chrome-based catalyst system is disclosed, the polymerization reactions being conducted in one embodiment in a polymerization zone of a gas phase fluidized bed reactor which contains a fluidized bed of polymer particles by the essentially continuous passage of monomer gases through the polymerization zone, comprising:a) discontinuing the introduction of the mixed catalyst system into the reactor;b) maintaining polymerization conditions in the reactor and permitting polymerization to continue for a period of time to allow the components of the mixed catalyst system present in the reactor to produce additional polymer particles;c) introducing a deactivating agent into the fluidized bed in an amount sufficient to deactivate the mixed catalyst system;d) establishing optimal conditions within the reactor for the chrome-based catalyst system; ande) introducing the chrome-based catalyst system into the reactorcharacterized in that the amount of polymer particles in the fluidized bed is substantially maintain…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.