| abstract |
Processes are disclosed for the vapor phase polymerization of gaseous monomers, particularly olefins such as propylene and ethylene. A gaseous stream containing at least one gaseous monomer is passed upwardly through a series of fluidized bed reaction zones of successively smaller diameter. A polymerization catalyst is introduced into an uppermost one of said zones. The gaseous monomer is polymerized to form solid polymer particles which are a part of a fluidized bed in each zone, and which flow downwardly through the series of reaction zones, thereby decreasing a volumetric flow rate of the upwardly flowing gaseous stream as the stream moves upward. A velocity of the upwardly flowing gaseous stream is maintained at a sufficient level to fluidize the fluidized bed in each successive zone at least partially by means of the smaller diameter of each successive zone. Techniques are disclosed for dividing zones into subzones thus multiplying the effective number of stages of the reactor. |