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: Low or medium-density straight-chain ethylene polymers are prepared by copolymerising ethylene with a C.sub.4 -C.sub.6 alpha-olefin at elevated temperature and pressure in a tubular reactor and in the presence of a Ziegler-type catalyst comprising a trialkyl aluminium as co-catalyst and a solid component, the solid component being obtained:by spray-drying an ethanolic solution of magnesium chloride to obtain a solid substrate of magnesium chloride particles containing alcoholic hydroxyls,by reacting the substrate with titanium tetrachloride to form an activated substrate, andby reacting the activated substrate with an alkyl aluminium chloride to chlorinate the titanium and partially or completely reduce the titanium from the tetravalent to the trivalent state.

Abstract: A solid component of catalyst for the (co)polymerization of ethylene is composed of a silica carrier and a catalytically active part including titanium, magnesium, chlorine and alkoxylic groups and is obtained: by suspending an activated silica in a solution of magnesium chloride and titanium tetraalcoholate in a liquid aliphatic acid ester; eliminating the aliphatic acid ester from the resulting suspension to recover a solid; and making this solid react with an aluminium alkyl chloride. It is preferable to add also some measured quantities of a silicon halide to the solution in aliphatic acid ester.

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 catalyst for the polymerization of olefins, containing magnesium, chlorine, aluminium and at least one transition metal, in a dispersed or emulsified form within an inert diluent, is obtained by:contacting, in an inert diluent, a magnesium dialkyl and aluminium trichloride, in a molar ratio equal or almost equal to 2/1, at a temperature lower than 105.degree. C. to obtain a catalyst precursor in a suspended form, or at a temperature higher than 105.degree. C. to form a catalyst precursor in the form of a colloidal emulsion, in the diluent used; andcontacting said suspended or emulsified precursor with at least one compound of a transition metal to form a catalyst in the form of a suspension or emulsion respectively.

Abstract: A supported solid component of catalyst, for the stereospecific polymerization of propylene and other .alpha.-olefins, is obtained by making a non-activated silica interact in succession with: (i) a magnesium dialkyl or halide of magnesium alkyl; (ii) a halogenating agent selected from silicon, tin and antimony halides; (iii) a titanium tetrahalide; and (iv) a Lewis base. A catalyst for the stereospecific polymerization of propylene and other .alpha.-olefins is composed of: (A) the solid component of catalyst; (B) an aluminium trialkyl or aluminium alkyl halide; and (C) an electron donor compound, capable of forming a complex compound with component (B).

Abstract: A solid component of catalyst for the (co)polymerization of ethylene is composed of a silica support and of a catalytically active part containing titanium, magnesium, chlorine and alkoxy groups, and is obtained by:(i) activating a silica support by contact with a solution of magnesium dialkyl, or magnesium alkyl chloride, in a liquid, aliphatic hydrocarbon solvent;(ii) impregnating the activated silica with a solution, in a liquid aliphatic or aromatic ester, of titanium tetrachloride and tetra-alkoxide in equimolecular or almost equimolecular quantities, and magnesium chloride; and(iii) treating the solid obtained in step (ii) with a proportioned quantity of aluminium alkyl sesquichloride.

Abstract: A supported Ziegler-Natta catalyst active in ethylene polymerization and in the copolymerization of ethylene with alpha-olefins consists of:(A) a cocatalyst in the form of an organometallic compound of aluminium, and(B) a solid catalyst component obtained by:(i) impregnating a granular solid support with a solution of a titanium alcoholate and magnesium chloride in a liquid aliphatic hydrocarbon, followed by evaporation of the hydrocarbon solvent;(ii) impregnating the support treated in (i) with a solution of magnesium chloride in a liquid aliphatic ester, followed by evaporation of the ester solvent; and(iii) activating the support treated in (ii) by contact with an alkyl aluminium halide.In a preferred embodiment, measured quantities of a silicon halide are introduced in stage (i) and/or (ii), this considerably improving catalytic activity.

Abstract: A solid component of catalyst for the (co)polymerization of ethylene, including magnesium, halogen and titanium, is prepared:(i) by dissolving a magnesium dialkyl, a silicon halide and at times also an alkyl halide, in an inert organic solvent and maintaining contact until a granular solid precipitates;(ii) putting this granular solid in contact and making it react with a titanium halide, alkoxide or halogen-alkoxide, to produce a solid component of catalyst; and(iii) activating this solid component of catalyst by contact with aluminium alkyl halide, if a titanium alkoxide or halogen-alkoxide has been used in phase (ii).

Abstract: A process for the preparation of a solid component of a catalyst active in the (co)polymerization of ethylene and able to form (co)polymers of ethylene having from middle to wide distribution of molecular weight and monomodal distribution of molecular weights, in processes operating in a single step, in suspension or in the gaseous phase. Said solid component of a catalyst contains magnesium, chlorine, silicon, titanium and at least another transition metal on a solid, granular and porous carrier and is obtained by treating the carrier, in succession, with: a compound of a metal selected from hafnium, zirconium or vanadium; a magnesium dialkyl or magnesium alkyl halide; a silicon chloride; and a titanium compound.

Abstract: A solid component of catalyst for the (co)polymerization of ethylene is composed of a silica carrier and a catalytically active part which includes titanium, magnesium, chlorine and also alkoxy groups, and is obtained: by suspending an activated silica in an ethanolic solution of magnesium chloride; by contact of the suspension with an alkoxy or halogen alkoxyde of titanium and with a silicon halide; by eliminating the ethanol from the resulting suspension in order to recover a solid matter; and by making this solid react with an aluminium alkyl chloride.

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 solid component of a catalyst for the (co)polymerization of ethylene is composed of a silica carrier and a catalytically active part which includes titanium, magnesium, chlorine and also alkoxy groups, and is obtained: by suspending an activated silica in an ethanolic solution of magnesium chloride; by contact of the suspension with an alkoxy or halogen alkoxyde of titanium and with a silicon halide; by eliminating the ethanol from the resulting suspension in order to recover a solid matter; and by making this solid react with an aluminum alkyl chloride.

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: A solid catalyst component for ethylene (co)polymerization, consisting of a particulate silica support and a catalytically active part containing titanium, magnesium, chlorine and alkoxy groups is obtained by a) preparing a solution of magnesium chloride in ethanol; b) impregnating particulate silica with said solution; c) eliminating the unabsorbed ethanol from the suspension; d) eliminating absorbed ethanol from the solid; e) interacting the resultant solid with a titanium chloride, alkoxide or chloroalkoxide; and possibly interacting with an alkylaluminium chloride. In a preferred embodiment in stage e), a silicon halide is added to improve the catalyst activity.

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.