Polymerisation of ethylene

摘要

A process for producing polyethylene in a two step polymerisation process that comprises the steps of: (a) homopolymerising ethylene in the presence of a first catalyst comprising an activated chromium catalyst in a first reactor to produce a first polyethylene fraction; (b) transferring the first polyethylene fraction produced in the first reactor and at least a portion of the first catalyst to a second reactor; (c) in the second reactor homopolymerising ethylene or copolymerising ethylene and an alpha-olefinic comonomer having from 3 to 10 carbon atoms in the presence of a second catalyst under conditions which suppress residual activity in the first catalyst to produce a second polyethylene fraction; and (d) retrieving from the second reactor polyethylene comprising a blend of the first and second polyethylene fractions.