Abstract: A Ziegler-Natta procatalyst composition in the form of solid particles and comprising magnesium, halide and transition metal moieties, said particles having an average size (D50) of from 10 to 70 ?m, characterized in that at least 5 percent of the particles have internal void volume substantially or fully enclosed by a monolithic surface layer (shell), said layer being characterized by an average shell thickness/particle size ratio (Thickness Ratio) determined by SEM techniques for particles having particle size greater than 30 ?m of greater than 0.2.

Abstract: A process for polymerizing polyethylene with chromium-based catalysts wherein one or more supported chromium-based catalysts is mixed with mineral oil to form a slurry and the slurry is then introduced into a polymerization reactor, especially a gas-phase polymerization reactor.

Abstract: A process for producing polyethylene having a broad molecular weight distribution is provided, in which ethylene and optionally a comonomer are contacted in two reactors connected in series, one reactor containing a titanium-based catalyst and the other reactor containing a vanadium-based catalyst and a halohydrocarbon promoter, or alternatively, both reactors containing a mixed metal catalyst comprising both titanium and vanadium. In the latter case, the halohydrocarbon promoter is present in only one of the reactors to activate the vanadium sites of the catalyst and deactivate the titanium sites of the catalyst simultaneously.

Abstract: A gas phase process for the production of a polyethylene blend comprising contacting ethylene and at least one alpha-olefin comonomer having 3 to 8 carbon atoms with a magnesium/titanium based catalyst system including an activator and a cocatalyst in each of two fluidized bed reactors connected in series, under polymerization conditions, with the provisos that:(a) the mixture of ethylene copolymer matrix and active catalyst formed in the first reactor in the series is transferred to the second reactor in the series;(b) other than the active catalyst referred to in proviso (a) and the cocatalyst referred to in proviso (e), no additional catalyst is introduced into the second reactor;(c) in the first reactor in which a low melt index copolymer is made:(1) the alpha-olefin is present in a ratio of about 0.01 to about 0.4 mole of alpha-olefin per mole of ethylene;(2) optionally, hydrogen is present in a ratio of about 0.001 to about 0.

Abstract: A process comprising continuously contacting with a catalyst, under polymerization conditions, ethylene or a mixture comprising ethylene and one or more alpha-olefins in a first fluidized bed reactor and a mixture comprising ethylene and one or more alpha-olefins in a second fluidized bed reactor, the first and second reactors being connected in series, said catalyst comprising:(A) a catalyst precursor comprising:(i) a vanadium compound, which is the reaction product of(a) VX.sub.3 wherein each X is independently chlorine, bromine, or iodine; and(b) an electron donor, which is a liquid, organic Lewis base in which VX.sub.3 is soluble;(ii) a modifier having the formula BX.sub.3 or AlR.sub.(3-a) wherein each X is as defined above; each R is independently alkyl having 1 to 14 carbon atoms; and a is 1 or 2; and(iii) a silica or alumina support for said vanadium compound and modifier;(B) a cocatalyst having the formula AlR.sub.3 wherein R is as defined above; and(C) a promoter having the formula R'.sub.b CX'.sub.

Abstract: A process for the simultaneous trimerization of ethylene and the copolymerization of the trimer with ethylene comprising continuously contacting ethylene, the 1-hexene which is formed, and, optionally, hydrogen in a reaction zone, under trimerization and polymerization conditions, with the supported reaction product of one or more bis-triarylsilyl chromates and one or more trihydrocarbylaluminum compounds wherein the atomic ratio of aluminum to chromium is at least about 3 to 1.

Abstract: A method for reducing sheeting during polymerization of alpha-olefins by feeding either a positive charge generating or negative charge generating chemical additive to the reactor responsive to particular static levels in the reactor. The chemical additive is added in amounts which neutralize the charges in the reactor.