Abstract: A process for the preparation of ethylene polymers comprising polymerizing ethylene, optionally with one or more ?-olefin comonomers, in the presence of: (i) a solid catalyst component comprising titanium, magnesium, halogen and optionally an internal electron-donor compound, (ii) an aluminum alkyl compound, and (iii) an antistatic compound selected among the hydroxyesters with at least two free hydroxyl groups, wherein the weight ratio of aluminum alkyl compound to solid catalyst component is higher than 0.80 and the weight ratio of antistatic compound to aluminum alkyl compound is higher than 0.10.

Abstract: Process for transferring polyolefin particles from a first gas-phase polymerization reactor to a second gas-phase polymerization reactor in a multistage polymerization of olefins carried out in at least two serially connected gas-phase polymerization reactors, wherein the first gas-phase reactor is a fluidized-bed reactor comprising a gas distribution grid and a settling pipe, which is integrated with its upper opening into the distribution grid and contains a bed of polyolefin particles which moves from top to bottom of the settling pipe, the process comprising the steps of introducing a fluid into the settling pipe in an amount that an upward stream of the fluid is induced in the bed of polyolefin particles above the fluid introduction point; withdrawing polyolefin particles from the lower end of the settling pipe; and transferring the withdrawn polyolefin particles into the second gas-phase polymerization reactor, process for polymerizing olefins comprising such a process for transferring polyolefin p

Abstract: A two steps polymerization process for obtaining a polyolefin composition comprising: a) from 25 wt % to 70 wt % of a propylene homopolymer or a propylene-ethylene copolymer containing from 0.1 wt % to 10 wt % of ethylene derived units; b) from 27 wt % to 70 wt % of a copolymer of ethylene and at least one C3-C20 alpha olefins, wherein the ethylene derived units content ranges from 15 wt % to 70 wt %; c) from 3 wt % to 20 wt % of polyethylene homopolymer or an ethylene and at least one C3-C20 alpha olefins copolymer; the sum a)+b)+c) being 100, wherein said process comprises: step a) contacting under polymerization conditions propylene, optionally ethylene and the catalyst system in order to obtain component a), step b) contacting under polymerization conditions ethylene and at least one C3-C20 alpha-olefins and the catalyst system in order to obtain components b) and c); wherein the catalyst system comprises a metallocene compound and an iron complex.

Abstract: Process for transferring polyolefin particles from a first gas-phase polymerization reactor to a second gas-phase polymerization reactor in a multistage polymerization of olefins carried out in at least two serially connected gas-phase polymerization reactors, wherein the first gas-phase reactor is a fluidized-bed reactor comprising a gas distribution grid and a settling pipe, which is integrated with its upper opening into the distribution grid and contains a bed of polyolefin particles which moves from top to bottom of the settling pipe, the process comprising the steps of introducing a fluid into the settling pipe in an amount that an upward stream of the fluid is induced in the bed of polyolefin particles above the fluid introduction point; withdrawing polyolefin particles from the lower end of the settling pipe; and transferring the withdrawn polyolefin particles into the second gas-phase polymerization reactor, process for polymerizing olefins comprising such a process for transferring polyolefin partic

Abstract: A method for transitioning from a first to a second catalyst system for the olefin polymerization reaction in one reactor, wherein the first catalyst system is incompatible with the second catalyst system, is described. The method comprises the steps of a) discontinuing a first olefin polymerization reaction performed in the presence of the first catalyst system; and b) performing a second olefin polymerization reaction in the presence of the second catalyst system comprising catalyst components (A) and (B) producing, respectively, a first and a second polyolefin fraction, wherein the Mw of the first polyolefin fraction is less than the Mw of the second polyolefin fraction and the initial activity of catalyst component (A) exceeds the initial activity of catalyst component (B).

Abstract: A method for transitioning from a first to a second catalyst system for the olefin polymerization reaction in one reactor, wherein the first catalyst system is incompatible with the second catalyst system, is described. The method comprises the steps of a) discontinuing a first olefin polymerization reaction performed in the presence of the first catalyst system; and b) performing a second olefin polymerization reaction in the presence of the second catalyst system comprising catalyst components (A) and (B) producing, respectively, a first and a second polyolefin fraction, wherein the Mw of the first polyolefin fraction is less than the Mw of the second polyolefin fraction and the initial activity of catalyst component (A) exceeds the initial activity of catalyst component (B).

Abstract: A process for preparing a broad molecular weight polyethylene carried out in the presence of a catalyst system comprising (i) a solid catalyst component comprising Mg, Ti, halogen, and optionally an internal electron donor compound, and (ii) an Al-alkyl cocatalyst said process comprising at least two step of polymerization (a) and (b), in which: in a first step (a) ethylene is polymerized in the presence of a molecular weight regulator in order to produce a ethylene (co)polymer, and in a further step (b), which is carried out in the presence of an external electron donor compound added to this polymerization step as a fresh reactant, ethylene is copolymerized with an alpha olefin of formula CH2?CHR, in which R is a C1-C20 hydrocarbon group, to produce an ethylene copolymer having a molecular weight higher than that of the copolymer produced in step (b).

Abstract: Process for the gas-phase polymerization of one or more alpha-olefins in the presence of a catalyst system, the process comprising: contacting in a continuous way one or more of said alpha-olefins with said catalyst system in a prepolymerization reactor, wherein the reaction is carried out in a liquid medium at a temperature ranging from 23° to 50° C.; feeding in continuous the prepolymer obtained in step a) into a gas-phase reactor having interconnected polymerization zones, where the growing polymer particles flow upward through a first polymerization zone (riser) under fast fluidization or transport conditions, leave said riser and enter a second polymerization zone (downcomer) through which they flow downward under the action of gravity, leave said downcomer and are reintroduced into said riser; wherein the prepolymer obtained from step a) is continuously fed at a section of said riser characterized by an upwardly gas velocity higher than 3.0 m/s.

Abstract: Process for preparing a broad molecular weight polyethylene by polymerizing ethylene in the presence of a polymerization catalyst, the process comprising the following steps, in any mutual order: a) polymerizing ethylene, optionally together with one or more ?-olefinic comonomers having from 3 to 12 carbon atoms, in a gas-phase reactor in the presence of hydrogen, b) copolymerizing ethylene with one or more ?-olefinic comonomers having from 3 to 12 carbon atoms in another gas-phase reactor in the presence of an amount of hydrogen less than step a), where in at least one of said gas-phase reactors the growing polymer particles flow upward through a first polymerization zone under fast fluidization or transport conditions, leave said first polymerization zone and enter a second polymerization zone through which they flow downward under the action of gravity.

Abstract: Process for the gas-phase polymerization of one or more alpha-olefins in the presence of a catalyst system, the process comprising: contacting in a continuous way one or more of said alpha-olefins with said catalyst system in a prepolymerization reactor, wherein the reaction is carried out in a liquid medium at a temperature ranging from 23° to 50° C.; feeding in continuous the prepolymer obtained in step a) into a gas-phase reactor having interconnected polymerization zones, where the growing polymer particles flow upward through a first polymerization zone (riser) under fast fluidization or transport conditions, leave said riser and enter a second polymerization zone (downcomer) through which they flow downward under the action of gravity, leave said downcomer and are reintroduced into said riser; wherein the prepolymer obtained from step a) is continuously fed at a section of said riser characterized by an upwardly gas velocity higher than 3.0 m/s.

Abstract: A solution process for polymerizing one or more ?-olefins of the formula CH2?CHR, where R is H or an alkyl radical C1-C18, to produce a polymer that is soluble in the reaction medium, comprising the steps of: continuously polymerizing in a liquid phase the ?-olefin in the presence of a catalyst system based on a transition metal compound to obtain a solution of polymer in the reaction medium; the polymeric solution obtained from step a) is then mixed in one or more mixing stages with an aqueous mixture comprising one or more organic compounds having at least a hydroxy or epoxy group, said aqueous mixture having a dynamic viscosity at 30° C. higher than 50 cP (centiPoise).

Abstract: Process for the gas-phase catalytic polymerization of olefins carried out in a plurality of interconnected polymerization zones, the process comprising feeding one or more monomers to said polymerization zones in the presence of a catalyst under reaction conditions and collecting the polymer product from said polymerization zones, in which process the polymer particles grow within a first polymerization zone where a fluidized bed is formed, at least a part of said polymer particles leave said first polymerization zone to enter a second polymerization zone through which they flow downward, leave said second polymerization zone and enter a third polymerization zone through which they flow upward under fast fluidization or transport conditions, leave said third polymerization zone and are reintroduced into the first polymerization zone, thus establishing a circulation of polymer between the different polymerization zones.

Abstract: A process for preparing a broad molecular weight polyethylene carried out in the presence of a catalyst system comprising (i) a solid catalyst component comprising Mg, Ti, halogen, and optionally an internal electron donor compound, and (ii) an Al-alkyl cocatalyst said process comprising at least two step of polymerization (a) and (b), in which: in a first step (a) ethylene is polymerized in the presence of a molecular weight regulator in order to produce a ethylene (co)polymer, and in a further step (b), which is carried out in the presence of an external electron donor compound added to this polymerization step as a fresh reactant, ethylene is copolymerized with an alpha olefin of formula CH2?CHR, in which R is a C1-C20 hydrocarbon group, to produce an ethylene copolymer having a molecular weight higher than that of the copolymer produced in step (b).

Abstract: A solution process for polymerizing one or more ?-olefins of the formula CH2?CHR, where R is H or an alkyl radical C1-C18, to produce a polymer that is soluble in the reaction medium, comprising the steps of: continuously polymerizing in a liquid phase the ?-olefin in the presence of a catalyst system based on a transition metal compound to obtain a solution of polymer in the reaction medium; the polymeric solution obtained from step a) is then mixed in one or more mixing stages with an aqueous mixture comprising one or more organic compounds having at least a hydroxy or epoxy group, said aqueous mixture having a dynamic viscosity at 30° C. higher than 50 cP (centiPoise).

Abstract: Process for preparing a broad molecular weight polyethylene by polymerizing ethylene in the presence of a polymerization catalyst, the process comprising the following steps, in any mutual order: a) polymerizing ethylene, optionally together with one or more ?-olefinic comonomers having from 3 to 12 carbon atoms, in a gas-phase reactor in the presence of hydrogen, b) copolymerizing ethylene with one or more ?-olefinic comonomers having from 3 to 12 carbon atoms in another gas-phase reactor in the presence of an amount of hydrogen less than step a), where in at least one of said gas-phase reactors the growing polymer particles flow upward through a first polymerization zone under fast fluidization or transport conditions, leave said first polymerization zone and enter a second polymerization zone through which they flow downward under the action of gravity.

Abstract: Method for continuously removing the unreacted butene-1, and optionally other volatile components, from a polymeric solution obtained by liquid phase (co)polymerization of butene-1, the method comprising the steps of: subjecting the polymeric solution to heating and mixing conditions such that a mixture is formed consisting substantially of: (1) a polybutene melt containing entrapped butene-1 and (2) supercritical gaseous butene-1; subjecting the above mixture to a sequence of devolatilization steps operating at decreasing pressures.

Abstract: A liquid-phase process for polymerizing ?-olefins of the formula CH2?CHR, where R is H or an alkyl radical C1–C6, to produce a polymer that is soluble in the reaction medium, comprising the steps of: a) continuously polymerizing in liquid phase the ?-olefin in the presence of a catalyst system based on a transition metal compound; b) continuously withdrawing from step a) a solution of polymer in the liquid reaction medium; c) mixing in one or more mixing stages said solution of polymer in the reaction medium with an organic deactivator having: at least a hydroxy group, a boiling point higher than 150° C., and a ratio between the molecular weight (MW) and the number of hydroxy groups (OH) comprised between 20 and 100.

Abstract: A process to support a homogeneous catalyst on a porous solid support is performed in two separate zones. In the first zone the solid is contacted, under stirring, with an amount of a catalyst solution lower than the total pore volume of the solid. In the second zone the solid is dried from the solvent while flowing under pneumatic conveying. A loop circulation of solid is established between the two zones, so that the solid is subject to more contacting steps. The process is particularly suitable to support a metallocene-alumoxane polymerization catalyst on a porous prepolymer. The process can be advantageously performed in continuous, thus fitting the needs of an industrial scale production process.

Abstract: Process for the gas-phase catalytic polymerization of olefins carried out in a plurality of interconnected polymerization zones, the process comprising feeding one or more monomers to said polymerization zones in the presence of a catalyst under reaction conditions and collecting the polymer product from said polymerization zones, in which process the polymer particles grow within a first polymerization zone where a fluidized bed is formed, at least a part of said polymer particles leave said first polymerization zone to enter a second polymerization zone through which they flow downward, leave said second polymerization zone and enter a third polymerization zone through which they flow upward under fast fluidization or transport conditions, leave said third polymerization zone and are reintroduced into the first polymerization zone, thus establishing a circulation of polymer between the different polymerization zones.

Abstract: A liquid-phase process for polymerizing ?-olefins of the formula CH2?CHR, where R is H or an alkyl radical C1-C6, to produce a polymer that is soluble in the reaction medium, comprising the steps of: a) continuously polymerizing in liquid phase the ?-olefin in the presence of a catalyst system based on a transition metal compound; b) continuously withdrawing from step a) a solution of polymer in the liquid reaction medium; c) mixing in one or more mixing stages said solution of polymer in the reaction medium with an organic deactivator having: at least a hydroxy group, a boiling point higher than 150° C., and a ratio between the molecular weight (MW) and the number of hydroxy groups (OH) comprised between 20 and 100.