| abstract |
In a process for polymerizing olefins in the gaseous phase in a first gas-phase polymerization zone and a second gas-phase polymerization zone, which are provided independently from each other, in the presence of a catalyst composed of a transition metal catalyst component and an organometallic compound of a metal of Groups I to III of the periodic table and in the co-presence of hydrogen gas while feeding the catalyst-containing polymer formed in the first zone to the second zone; the improvement wherein (i) a dilution zone for diluting a feed flow from the first gas-phase polymerization zone which comprises a mixture of the polymer, the catalyst, the olefin gas and hydrogen gas by feeding a fresh supply of olefin gas thereto is provided in a feed passage for feeding said flow from the first gas-phase polymerization zone to the second gas-phase polymerization zone, (ii) a part of the gas phase in said feed flow diluted in the dilution zone is recycled to the first gas-phase polymerization zone, and remainder is fed into the second gas-phase polymerization zone, and (iii) in the second gas-phase polymerization zone, the hydrogen to olefin mole ratio is maintained lower than that in the first gas-phase polymerization zone. |