Patent ID: 6936666

Claim:
A continuous gas phase polymerization process for preparing ethylene and propene homopolymers and copolymers, in which ethylene, propene or mixtures comprising ethylene and propene and C 3 -C 8 -α-monoolefins are polymerized in the polymerization zone of a gas-phase polymerization reactor at from 30 to 125° C. and pressures of from 1 to 100 bar in the gas phase in a bed comprising finely divided polymer in the presence of a catalyst, with the reactor gas being circulated to remove the heat of polymerization and the circulated reactor gas being firstly passed through a cyclone after leaving the reactor, wherein a catalyst poison having a boiling point above the maximum temperature within the circulating gas system is fed into this circulating gas system at a position between the reactor and the cyclone to prevent polymer deposits in the circulating gas system.