The present invention relates to a gas phase process for the (co-)polymerization of alpha-olefins in a fluidized bed, by means of a catalyst system of the Ziegler-Natta type consisting of a catalyst (a) comprising magnesium, halogen and transition metal atoms and a cocatalyst (b) consisting of an organometallic compound. The catalyst system is (i) prepared in a granular form, either fixed on a granular support or converted into a prepolymer, (ii) then subjected to a treatment by a polymerization inhibiting agent in the absence of alpha-olefins, and then (iii) brought into contact with alpha-olefins under (co-)polymerization conditions in the fluidized bed, in the presence of a cocatalyst (c) consisting of an organometallic compound, identical or different from the cocatalyst (b).
展开▼
