Abstract: The present invention relates to a solid catalyst suitable for polymerizing olefins in a heterogeneous process, the catalyst consisting of spheroidal particles having a narrow particle size distribution and comprising (i) a support containing magnesium dichloride and an electron-donor free from labile hydrogene, (ii) a zirconium metallocene, and (iii) optionally an organoaluminium compound which is an aluminoxane preferably. The solid catalyst may be used in the form of a prepolymer comprising a polyethylene or a copolymer of ethylene and an active zirconium metallocene catalyst essentially consisting of atoms of Zr, Mg, Cl and Al, preferably in the form of spheriodal particles. The solid catalyst or the prepolymer may be used for producing polyethylene or copolymer of ethylene having from 0.5 to 20 ppm of Zr and a molecular weight distribution from 2 to 5, in the form of a powder having a bulk density from 0.3 to 0.55 g/cm.sup.3, preferably consisting of spheroidal particles.

Abstract: The present invention relates to a process for preparing a Ziegler-Natta type catalyst based on a vanadium compound. The process comprises sequentially contacting within a liquid hydrocarbon a spheroidal support comprising (i) MgCl.sub.2 free from any Mg-C bond and (ii) an electron-donor D1 free from labile hydrogen, an electron-donor D2 containing labile hydrogen and an organometallic compound capable of reducing a vanadium compound, (2) washing the solid product with a liquid hydrocarbon resulting from the contacting, and (3) contacting the washed solid product with one or more vanadium compounds soluble in the liquid hydrocarbon, comprising halogen atoms and alkoxy radical, both being bonded to the same or different vanadium atoms. The catalyst which consists of spheroidal particles without fines, is very active in olefin polymerization and is particularly suitable for producing elastomeric copolymers of propylene.

Abstract: A process for (co)polymerizing alpha-olefins in the gas phase in a fluidized bed or mechanically stirred bed reactor using a Ziegler-Natta type catalyst or a heat activated chromium oxide/refractory oxide catalyst wherein the (co)polymerization is carried out in the presence of 0.005 to 0.2 weight %, based on the weight of the (co)polymer bed, of an inert pulverulent inorganic substance (e.g. silica) having a mean particle diameter between 0.5 and 20 microns. The process is capable of being operated at temperatures closer to the softening point of the produced polyolefin than in the absence of the pulverulent solid.

Abstract: The present invention relates to a process for preparing a Ziegler-Natta type catalyst based on a vanadium compound precipitated on a MgCl.sub.2 spherical support. The catalyst preparation consists of contacting within a liquid hydrocarbon a vanadium-reducing agent chosen from organometallic compound with a vanadium compound soluble in the liquid hydrocarbon at least one halogen and one alkoxy group, and with a support containing (i) MgCl.sub.2 free from Mg--C bond and (ii) an organic electron donor compound free from labile hydrogen. The support consists of spherical particles having a well-defined diameter and a narrow particle size distribution. The catalyst is particularly suitable for manufacturing in a gas process elastomeric copolymers of propylene.

Abstract: The present invention relates to a process for the polymerization of ethylene or copolymerization of ethylene and at least one other alpha-olefin, in the gas phase in a fluidized bed reactor, in the presence of a catalyst comprising chromium compounds associated with a granular support comprising a refractory oxide and activated by thermal treatment, which process is characterized in that the catalyst is used in the form of active particles of prepolymer, obtained by bringing the said catalyst in contact with ethylene, alone, or in a mixture with at least one higher alpha-olefin, in such a way that the prepolymer contains from 4.times.10.sup.-5 to 3 milligram atoms of chromium in the catalyst per gram.

Abstract: A Zeigler-Natta type catalyst suitable for polymerizing propylene comprising a preactivated support coated with 0.1 to 10 g of homopolymer or copolymer of propylene. The preactivated support which comprises magnesium chloride and 1 to 20% by mol of an electron donor free from labile hydrogen and from ester function, is in the form of spherical particles having a mean diameter by mass of 10 to 100 microns and a ratio of the mean diameter by mass to the mean diameter by number of less than 2.0. The preactivated support is treated with at least one internal electron donor compound and coated by contacting the treated support with an alkyl aluminium halide and propylene, optionally together with ethylene and/or a C.sub.4-8 alpha-olefin, in the absence of an external electron donor compound.

Abstract: The present invention relates to a solid catalyst suitable for polymerizing olefins in a heterogeneous process, the catalyst consisting of spheroidal particles having a narrow particle size distribution and comprising (i) a support containing magnesium dichloride and an electron-donor free from labile hydrogen, (ii) a zirconium metallocene, and (iii) optionally an organoaluminium compound which is an aluminoxane preferably. The solid catalyst may be used in the form of a prepolymer comprising a polyethylene or a copolymer of ethylene and an active zirconium metallocene catalyst essentially consisting of atoms of Zr, Mg, Cl and Al, preferably in the form of spheriodal particles. The solid catalyst or the prepolymer may be used for producing polyethylene or copolymer of ethylene having from 0.5 to 20 ppm of zr and a molecular weight distribution from 2 to 5, in the form of a powder having a bulk density from 0.3 to 0.55 g/cm.sup.3, preferably consisting of spheroidal particles.

Abstract: The present invention relates to a process for preparing a Ziegler-Natta type catalyst based on a vanadium compound. The process comprises sequentially contacting within a liquid hydrocarbon a spheroidal support comprising (i) MgCl.sub.2 free from any Mg-C bond and (ii) an electron-donor D1 free from labile hydrogen, an electron-donor D2 containing labile hydrogen and an organometallic compound capable of reducing a vanadium compound, (2) washing the solid product with a liquid hydrocarbon resulting from the contacting, and (3) contacting the washed solid product with one or more vanadium compounds soluble in the liquid hydrocarbon, comprising halogen atoms and alkoxy radical, both being bonded to the same or different vanadium atoms. The catalyst which consists of spheroidal particles without fines, is very active in olefin polymerization and is particularly suitable for producing elastomeric copolymers of propylene.

Abstract: The present invention relates to a process for preparing a Ziegler-Natta type catalyst based on a vanadium compound precipitated on a MgCl.sub.2 spherical support. The catalyst preparation consists of contacting within a liquid hydrocarbon a vanadium-reducing agent chosen from organometallic compounds with a vanadium compound soluble in the liquid hydrocarbon containing at least one halogen and one alkoxy group, and with a support containing (i) MgCl.sub.2 free from Mg-C bond and (ii) an organic electron donor compound free from labile hydrogen. The support consists of spherical particles having a well-defined diameter and a narrow particle size distribution. The catalyst is particularly suitable for manufacturing in a gas phase process elastomeric copolymers of propylene.

Abstract: A process for (co)polymerizing alpha-olefins in the gas phase in a fluidized bed or mechanically stirred bed reactor using a Ziegler-Natta type catalyst or a heat activated chromium oxide/refractory oxide catalyst wherein the (co)polymerization is carried out in the presence of 0.005 to 0.2 weight %, based on the weight of the (co)polymer bed, of an inert pulverulent inorganic substance (e.g. silica) having a mean particle diameter between 0.5 and 20 microns. The process is capable of being operated at temperatures closer to the softening point of the produced polyolefin than in the absence of the pulverulent solid.

Abstract: The present invention relates to a process for preparing a Ziegler-Natta type catalyst based on vanadium and titanium compounds precipitated on a MgCl.sub.2 spherical support. The catalyst preparation consists of contacting within a liquid hydrocarbon a vanadium- and titanium-reducing agent chosen from organometallic compounds with a vanadium compound and a titanium compound, both soluble in the liquid hydrocarbon, in a molar ratio V/Ti from 70/30 to 99.5/0.5 and a support containing (i) MgCl.sub.2 free from Mg-C bond and (ii) an organic electron donor compound free from labile hydrogen. The support consists of spherical particles having a well-defined diameter and a narrow particle size distribution. The catalyst is particularly suitable for manufacturing in a gas phase process elastomeric copolymers of propylene.

Abstract: A Zeigler-Natta type catalyst suitable for polmerizing propylene comprising a preactivated support coated with 0.1 to 10 g of homopolymer or copolymer of propylene. The preactivated support which comprises magnesium chloride and 1 to 20% by mol of an electron donor free from labile hydrogen and from ester function, is in the form of spherical particles having a mean diameter by mass of 10 to 100 microns and a ratio of the means diameter by mass to the mean diameter by number of less than 2.0. The preactivated support is treated with at least one internal electron donor compound and coated by contacting the treated support with an alkyl aluminium halide and propylene, optionally together with ethylene and/or a C.sub.4-8 alpha-olefin, in the absence of an external electron donor compound.

Abstract: A process for (co)polymerizing alpha-olefins in the gas phase in a fluidized bed or mechanically stirred bed reactor using a Ziegler-Natta type catalyst or a heat activated chromium oxide/refractory oxide catalyst wherein the (co)polymerization is carried out in the presence of 0.005 to 0.2 weight %, based on the weight of the (co)polymer bed, of an inert pulverulent inorganic substance (e.g. silica) having a mean particle diameter between 0.5 and 20 microns. The process is capable of being operated at temperatures closer to the softening point of the produced polyolefin than in the absence of the pulverulent solid.

Abstract: A process of the Ziegler-Natta type is prepared using a preactivated support containing (A) from 80 to 95 mol % of magnesium chloride and (B) 5 to 20 mol % of at least one electron donor compound which contains no labile hydrogen and no ester function; the preactivated support consisting of spherical particles having a mass average diameter, Dm of 10 to 100 microns and a particle size distribution Dm/Dn of less than 2. The catalyst is prepared by (i) treating the preactivated support with at least one electron donor compound containing labile hydrogen, (ii) treating the resulting activated support with at least one ester of an aromatic acid, (iii) impregnating the treated support with titanium tetrachloride and (iv) after washing the impregnated catalyst activating it with titanium tetrachloride. The catalyst has a high titanium content and a high activity when used to polymerize olefins.

Abstract: The present invention relates to a process for the polymerisation of ethylene or copolymerisation of ethylene and at least one other alpha-olefin, in the gas phase in a fluidised bed reactor, in the presence of a catalyst comprising chromium compounds associated with a granular support comprising a refractory oxide and activated by thermal treatment, which process is characterised in that the catalyst is used in the form of active particles of prepolymer, obtained by bringing the said catalyst in contact with ethylene, alone, or in a mixture with at least one higher alpha-olefin, in such a way that the prepolymer contains from 4.times.10.sup.-5 to 3 milligram atoms of chromium in the catalyst per gram.

Abstract: Atactic waxes and method for preparing same by polymerization of polyolefin alone or in combination with other monoolefins of the formula CH.sub.2 = CHR in which R is hydrogen or an alkyl radical having from 2 to 8 carbon atoms in which the polymerization is carried out at low pressure and in a hydrocarbon solvent in the presence of a catalyst formed of the product of the reaction of magnesium or a compound thereof, a compound of a transition metal selected from the sub-groups IVa, Va and VIa of the periodic classification of elements and an alkyl halide, and a co-catalyst in the form of an organometallic compound of a metal selected of groups II and III of the periodic classification of elements.

Abstract: The present invention relates to a process for the polymerization of ethylene or copolymerization of ethylene and at least one other alpha-olefin, in the gas phase in a fluidized bed reactor, in the presence of a catalyst comprising chromium compounds associated with a granular support comprising a refractory oxide and activated by thermal treatment, which process is characterized in that the catalyst is used in the form of active particles of prepolymer, obtained by bringing the said catalyst in contact with ethylene, alone, or in a mixture with at least one higher alpha-olefin, in such a way that the prepolymer contains from 4.times.10.sup.-5 to 3 milligram atoms of chromium in the catalyst per gram.

Abstract: The present invention relates to a process for the polymerisation of ethylene or copolymerisation of ethylene and at least one other alpha-olefin, in the gas phase in a fluidised bed reactor, in the presence of a catalyst comprising chromium compounds associated with a granular support comprising a refractory oxide and activated by thermal treatment, which process is characterised in that the catalyst is used in the form of active particles of prepolymer, obtained by bringing the said catalyst in contact with ethylene, alone, or in a mixture with at least one higher alpha-olefin, in such a way that the prepolymer contains from 4.times.10.sup.-5 to 3 milligram atoms of chromium in the catalyst per gram.