Patent ID: 9085650
Filing Date: 2015-07-21
Classification: C08F

Abstract:
1. A method for optimizing sequential use of at least two ethylene polymerization catalysts in an ethylene polymerization loop reactor, comprising: transferring to a mixing vessel a first ethylene polymerization catalyst and a first diluent, thereby providing a first catalyst slurry, transferring said first catalyst slurry from said mixing vessel to an ethylene polymerization loop reactor at a concentration suitable for polymerizing ethylene, increasing a ratio of said first diluent to said first ethylene polymerization catalyst in said first catalyst slurry, stopping a supply of said first catalyst slurry to said mixing vessel, stopping a supply of said first catalyst slurry to said ethylene polymerization loop reactor, stopping a supply of ethylene to said ethylene polymerization loop reactor, removing said first catalyst slurry from said ethylene polymerization loop reactor, emptying said mixing vessel, optionally rinsing said mixing vessel with fresh diluent, transferring to said mixing vessel a second ethylene polymerization catalyst and a second diluent, thereby providing a second catalyst slurry, decreasing a ratio of said second diluent to said second ethylene polymerization catalyst in said mixing vessel to obtain a concentration of said second ethylene polymerization catalyst in said second diluent suitable for polymerizing ethylene, transferring said second ethylene polymerization catalyst slurry from said mixing vessel to said ethylene polymerization loop reactor, restoring the supply of ethylene to said ethylene polymerization loop reactor, restarting ethylene polymerization in said ethylene polymerization loop reactor.