| abstract |
A method for transitioning between two different catalysts during a continuous olefin polymerizations, more specifically in the production of polypropylene homo- or copolymers in a continuous slurry/gas phase polymerization reaction with a prior pre-polymerization reaction, said method comprises the steps of: a) discontinuing the feed of the first catalyst into the pre-polymerization reactor and then b) introducing the second catalyst into the prepolymerization reactor, c) adapting the reaction conditions in the prepolymerization reactor, the slurry reactor as well as in the subsequent gas phase reactor, wherein the transition is performed between a Ziegler-Natta catalyst and an self-supported, solid metallocene catalyst, prepared by using an emulsion/solidification technology or vice versa and, whereby the transition is performed in the absence of any additional agent which deactivates or kills the catalyst. |