Abstract: The method of forming a catalytic component for use in the polymerization of ethylene or a copolymer of ethylene and a C.sub.3 to C.sub.12 alpha olefin in a gas-phase comprising impregnating a porous metal oxide support with at least one titanium compound, magnesium compound, and chlorine compound, and prepolymerizing ethylene or a copolymer of ethylene and a C.sub.3 to C.sub.12 alpha olefin, a least partially in suspension, in the presence of said porous metal oxide support and at least one alkylaluminum compound until a degree of prepolymerization is reached which is suitable for the subsequent gas-phase of fluidized bed polymerization, and the method of polymerizing olefins utilizing the catalysts formed by the prepolymerization.

Abstract: The method of forming a catalytic component for use in the polymerization of ethylene or a copolymer of ethylene and a C.sub.3 to C.sub.12 alpha olefin in a gas-phase comprising impregnating a porous metal oxide support with at least one titanium compound, magnesium compound, and chlorine compound, and prepolymerizing ethylene or a copolymer of ethylene and a C.sub.3 to C.sub.12 alpha olefin, a least partially in suspension, in the presence of said porous metal oxide support and at least one alkylaluminum compound until a degree of prepolymerization is reached which is suitable for the subsequent gas-phase of fluidized bed polymerization, and the method of polymerizing olefins utilizing the catalysts formed by the prepolymerization.

Abstract: A process is provided for the polymerization of olefins in the gas phase wherein olefins are contacted with a catalyst system consisting of an active solid hydrocarbon having been prepared by forming a pulverulent composition by mixing a transition metal component, a porous organic or inorganic solid support and an organometallic compound of the organo-Al, organo-Mg or organo-Zn type, and polymerizing a controlled amount of one or more C.sub.2 to C.sub.12 olefins in the gas phase in contact with the pulverulent composition with a specific hourly conversion of the olefins to produce the active solid hydrocarbon.

Abstract: Process for the preparation of an active solid hydrocarbon which can be used to polymerize olefines.This process comprises forming a pulverulent composition by mixing a transition metal component, a porous organic or inorganic solid support and an organometallic compound of the organo-Al, organo-Mg or organo-Zn type, and polymerizing a controlled amount of one or more C.sub.2 to C.sub.12 olefines in the gas phase in contact with the pulverulent composition with a specific hourly conversion of the olefines to produce the active solid hydrocarbon.The above active solid hydrocarbon can be used, by itself or together with an organometallic cocatalyst, as a catalytic system for polymerization of olefines, in particular in the gas phase.