Process for the preparation of ethylene polymers using a number of reactors arranged in series

摘要

The present invention relates to a process for the preparation of ethylene polymers using a number of reactors arranged in series comprising the steps in whicha) ethylene, a diluent, a catalyst, a co-catalyst and optionally comonomers and hydrogen are introduced into a first reactor,b) polymerization of ethylene and optionally comonomers is carried out in the reaction mixture of said first reactor to make ethylene polymers,c) reaction mixture is discharged from said first reactor,d) said reaction mixture and fresh ethylene and optionally comonomers and hydrogen are introduced into the consecutive reactor to make additional ethylene polymers,e) said reaction mixture is discharged from said consecutive reactor and introduced into the further consecutive reactor, if any, with fresh ethylene and optionally comonomers and hydrogen to make additional ethylene polymers, steps c) and d) are repeated until the last reactor of the series,f) reaction mixture is discharged from last reactor of the series and ethylene polymers are recovered,wherein,additional co-catalyst is injected in at least a subsequent reactor of the series.;Advantage of the process of the present invention is mainly to decrease catalyst consumption for the same polyethylene production, in other words to increase the productivity. In a most preferred embodiment the process of the present invention is carried out in two loop reactors under slurry conditions.