Abstract: A solid component of catalyst for the (co)polymerization of ethylene and &agr;-olefins contains magnesium-carboxylate bonds and transition metal-carboxylate and can be represented by the formula: M1Mg(0.3-20)X(2-60)Al(0-6)(R—COO)(0.1-3)  (I) wherein: M is at least one metal selected from titanium, vanadium, zirconium and hafnium, X is a halogen excluding iodine, and R is an aliphatic, cycloaliphatic or aromatic hydrocarbon radical, containing at least 4 carbon atoms. A description follows of the preparation of a solid component of catalyst (I) and its use in procedures for the (co)polymerization of ethylene and &agr;-olefins.

Abstract: Bimetal catalyst for the (co)polymerization of &agr;-olefins comprising a co-catalyst consisting of a hydride or an organometallic compound of an element of groups 1, 2 or 13 of the periodic table, and a solid component consisting of at least 95% by weight of titanium, magnesium, hafnium, aluminum, chlorine and R—COO carboxylate groups, wherein R is an aliphatic, cycloaliphatic or aromatic hydrocarbon, containing from 1 to 30 carbon atoms, wherein at least 80% of the titanium is in oxidation state +3, and at least 1% of said titanium in oxidation state +3 has a tetrahedral coordination geometry. Said catalyst allows the production of olefinic polymers, particular polyethylene, with a high molecular weight by means of solution polymerization processes at temperatures exceeding 200° C.

Abstract: A solid component of catalyst highly active in the (co)polymerization of ethylene containing titanium, magnesium, aluminum, chlorine and alkoxy groups, and obtained by means of a procedure wherein:(i) a solid, granular support of magnesium chloride, obtained by spray-drying an alcohol solution of magnesium chloride, is suspended in a liquid hydrocarbon solvent and an aliphatic alcohol and a titanium tetraalkoxide are added to the suspension thus obtained,(ii) the suspension of step (i) is heated until a homogeneous solution is obtained and the solution is cooled to precipitate a granular solid in a relative suspension,(iii) the granular solid obtained in step (ii), in the relative suspension, is put in contact and reacted with an aluminum alkyl halide, and(iv) the solid component catalyst is recovered from the reaction products of step (iii).

Abstract: A procedure is described for the preparation of a vanadium bis-arene, [V(arene).sub.2 ], starting from vanadium oxychloride, aluminium metal, aluminium trichloride and an arene, wherein:(a) vanadium oxychloride (VOCl.sub.3), active aluminium metal, and aluminium trichloride are put in contact with each other, in a liquid arene, to transform the vanadium oxychloride into the complex compound [V(arene).sub.2 ].sup.+ [AlCl.sub.4 ].sup.- ;(b) a liquid cyclic or acyclic or acyclic ether is added to the reaction product of step (a) to reduce [V(arene).sub.2 ].sup.+ to [V(arene).sub.2 ]; and(c) the vanadium bis-arene [V(arene).sub.2 ] is recovered from the reacton product of step (b).The vanadium bis-arenes thus obtained are use in the preparation of catalysts for the polymerization of olefins.

Abstract: A supported catalyst for the polymerization and copolymerization of olefinically unsaturated compounds is described, comprising an organometallic compound of aluminium and a second component obtained by bringing a titanium, vanadium or chromium compound, at least one compound of a second metal chosen from V, Al, Zr, Hf, Mo and Nd and optionally a magnesium compound into contact with a porous support consisting of microbeads of aerogels of one or more inorganic oxides distinguished by low density, high porosity and the fact that at least 90% of the pores have a diameter lying within a very narrow range of values. The process for the polymerization or copolymerization of olefinically unsaturated compounds based on the use of said catalyst is also described.

Abstract: Vanadium-arenes[V(arene).sub.2 ]wherein "arene" means benzene or mono-, di- or poly-(C.sub.1 -C.sub.5)-alkyl-substituted benzene, are prepared by means of a process which comprises:(a) forming a complex:[V(arene).sub.2 ](+).AlCl.sub.4 (-)by reacting vanadium trichloride, aluminum metal and aluminum trichloride with one another, by operating in the presence of the selected arene;(b) treating the so obtained complex with an either cyclic or acyclic, liquid aliphatic ether to obtain the reduction of [V(arene).sub.2 ](+) to [V(arene).sub.2 ]; and(c) recovering the so separated vanadium-arene.The vanadium-arenes are useful in the preparation of catalysts for olefin polymerization.

Abstract: Ethylene homopolymers and ethylene copolymers with alpha-(C.sub.3 -C.sub.10)-olefins are obtained by polymerizing the monomers with a polymerization catalyst formed by:a) an alkyl-aluminum; andb) a modified solid catalyst component obtained by treating with a Lewis' base a non-modified solid component to be defined by means of the following formula, expressed as atomic proportions:Ti(1), hf(0.5-3), Si (1-6), Mg (0.5-15) Al (0.5-15),X (20-60, ROH (1-10)wherein:X represents either chlorine and bromine, andR represents either a linear or branched alkyl radical of from 1 to 6 carbon atoms.The catalyst is particularly useful for controlling the molecular weight and the molecular weight distribution of ethylene hompolymers and copolymers.

Abstract: A solid catalyst component for the low-pressure polymerization of ethylene and C.sub.3 -C.sub.10 alpha-olefins into very high molecular weight polyolefins is in the form of a spherical granular solid having a surface area of between 20 and 40 m.sup.2 /g, a mean pore radius of between 5,000 and 40,000 .ANG. and a porosity of between 40 and 90 vol %, and is definable by the following formula (in atomic proportions:X (1), Mg (1-8), Al (0.2-0.8), Cl (5-20), (Et+OEt+OR) (1-3);where: X=Hf or Zr; Et=ethyl group; OEt=ethoxy group; and OR=alkoxy group containing from 2 to 8 carbon atoms in the linear or branched alkyl portion.Such a catalyst component is obtained by preparing a solid spherical granular support by spray-drying an ethanolic solution of magnesium chloride, reacting said support with a hafnium or zirconium alkoxide or halogenalkoxide, and finally reacting the thus treated support with an alkyl aluminum chloride.

Abstract: A solid catalyst component for the polymerization of ethylene and the copolymerization of ethylene with C.sub.3 -C.sub.10 alpha-olefins, contains titanium, vanadium and chlorine, is substantially definable by the formula (in atomic proportions):V (1), Ti (n), Cl (4n)where n varies from 1 to 3, and is prepared by reacting titanium tetrachloride with a vanadium arene [V.degree.(arene).sub.2 ] (arene=benzene or mono-, di- or tri-alkyl substituted benzene) in accordance with the equation:V.degree.(arene).sub.2 +nTiCl.sub.4 .fwdarw.VTi.sub.n Cl.sub.4n +2 arenepossibly followed by treatment with an alkyl aluminum chloride. This catalyst component, when associated with a trialkyl aluminium, is highly active in the production of ethylene polymers and copolymers by low temperature, low pressure methods in suspension, or by high temperature, high pressure methods conducted in a tubular reactor or pressure vessel, or by high temperature methods conducted in solution.

Abstract: Vanadium-arenes [V(arene).sub.2 ] (arene=benzene or mono-, di-, or poly-alkyl-substituted benzene) are obtained, with a high yield, by means of the reduction of a vanadium-arene iodide with zinc, manganese or iron in metal form, or with cobalt di-(cyclopentadienyl).Vanadium-arenes are useful in the preparation of catalyst components active in ethylene polymerization, or in the copolymerization of ethylene in an alpha-olefin.

Abstract: A catalyst component is in the form of a granular spherical solid with at least 80% of the granules between 30 and 40 microns in size, a service area of 15 to 30 m.sup.2 /g and a porosity of 40 to 80 volumes % and definable (in atomic proportions) by the formula: ##STR1## where Et denotes the ethyl group; OEt denotes the ethoxy group and OR' is an alkoxy group containing from 1 to 8 carbon atoms in the alkyl portion, and in which the ratio of trivalent titanium to the sum of trivalent and tetravelent titanium is in the range from 0.8/1 to 1/1.