Abstract: This invention is directed to reduced oxidation state Group 4-6 metal compounds, preferably the first row metals in those groups, suitable for activation as polymerization catalysts and characterized by comprising a substituted hydrotris(pyrazolyl)borate ancillary ligand and a plurality of single or multidentate uninegative ligands, excluding cyclopentadienyl ligands. The invention includes a polymerization process characterized by comprising contacting one or more monomers polymerizable by coordination or insertion polymerization under suitable polymerization conditions with these catalyst compositions.

Abstract: Calcined ammonium salts of phosphotungstic acid salts are used to polymerize C2-C30 &agr;-olefins and derivatives thereof to form highly reactive products having a high content of terminal vinylidene groups and &bgr;-isomers in resonance therewith.

Abstract: A process for producing an olefin polymer using a catalyst in which (A) is a solid catalyst component which includes magnesium, titanium, halogen and an electron donative compound as essential constituents; (B) is an organoaluminum component; and (C) is at least two electron donative compounds (&agr;) and (&bgr;), wherein the pentad stereoregularity of a xylene insoluble fraction of a homopolyproylene is 0<mmrr/mmmm≦0.0068 when electron donative compound (&agr;) is used in combination with (A) and (B), and the pentad stereoregularity of a xylene insoluble fraction homoproplyene of a is 0.0068<mmrr/mmmm ≦0.0320 when electron donative compound (&bgr;) is used in combination with (A) and (B). A polypropylene produced in the process can be used to obtain a biaxially oriented film. (A) and (B). A polypropylene produced in the process can be used to obtain a biaxially oriented film.

Abstract: Copolymer of ethylene and of at least one alpha-olefin obtained by means of a catalytic solid base on chromium oxide deposited on an inorganic support, the said copolymer having a melt flow index HLMI, measured in g/10 min, an amount of alpha-olefin Q, pressed in g of alpha-olefin per kg of copolymer, a standard density SD, measured in kg/m3, at least equal to (952.75+5.40×log HLMI−0.79×Q) and a relatively broad molecular mass distribution, characterized by a ratio of the dynamic viscosities &mgr;0/&mgr;2 at least equal to (23.67−6.67×log HLMI).

Abstract: This invention relates to a method of making polymer compositions, e.g. EPDM compositions, in a multistage reactor with monomers chosen from ethylene, C3-C8 alpha olefins, and a non conjugated diene. In particular, the invention relates to a process for improving diene conversion during the manufacture of the aforementioned polymer compositions by use of a multistage reactor and a metallocene catalyst system.

Abstract: A process comprising polymerizing ethylene with at least one olefin to produce a polymer, and said polymer are provided.

Abstract: A process for preparing polyolefins having at least 0.01 long chain branches (LCB)/1000 carbon atoms along the polymer backbone as measured by flow activation and a molecular weight distribution greater than 2.5 comprises polymerization in the presence of a metallocene complex having the formula: wherein Cp1, Cp2 are independently a substituted or unsubstituted indenyl or hydrogenated indenyl group, Y is a univalent anionic ligand, M is zirconium, titanium or hafnium, and Z is a bridging group comprising an alkylene group having 1 to 20 carbon atoms or a dialkyl silyl- or germyl- group, or alkyl phophine or amine radical. Polyolefins prepared from such a process show specific flow activation energy/LCB relationships.

Abstract: Ethylene polymer having a blow-up ratio (RB) of at least 1.4, a resistance to crazing under stress (ESCR) of at least 55 h and a melt index (MI5) of at least 0.2 g/10 min. Processes for obtaining this ethylene polymer using different catalytic systems, the first based on titanium and zirconium used in a polymerization in two reactors; the second consisting of a mixture of a titanium catalyst and a titanium and zirconium catalyst, used in a polymerization in two reactors; the third based on chromium on a support comprising at least two constituents chosen from silica, alumina and aluminium phosphates, used in a polymerization in a single or in two reactors.

Abstract: A process for polymerizing ethylene feedstock to produce branched polymer of ethylene suitable for blow molding applications and having improved environmental stress crack resistance (ESCR). For example, a catalyst comprising chromium on silica is (1) calcined in air and (2) reduced in carbon monoxide and then used with hydrogen to polymerize ethylene feedstock.

Abstract: The present invention provides a new type of supported metallocene catalyst system. In one aspect of the invention, an inorganic oxide support, such as silica, is impregnated with a Group XIII element such as B, Al or GA. The support is then contacted with a liquid catalyst system prepared by combining in a liquid an organo aluminoxane and a metallocene having two cyclopetadienyl-type ligands selected from substituted or unsubstituted cyclopentadienyl, indenyl, benzoindenyl, tetrahdroindenyl, benzofluorenyl, octahydrofluorenyl, and fluorenyl ligands to form a supported metallocene catalyst system. In preferred embodiments the process further includes conducting prepolymerization of at least one olefin in the presence of the supported metallocene catalyst system to produce a prepolymerized metallocene catalyst system. The prepolymerized metallocene catalyst system prepared in this manner yields substantially increased activity for the polymerization of olefins.

Abstract: Random copolymers of propylene with ethylene and at least one C4-C10-alk-1-ene, having a melting point, determined by the DSC method, of less than or equal to 135° C., are obtainable by polymerization of propylene, ethylene and at least one C4-C10-alk-1-ene in the absence of a liquid reaction medium from the gas phase at from 50 to 100° C. and a pressure of from 15 to 40 bar in the presence of a Ziegler-Natta catalyst system comprising a) a titanium-containing solid component comprising at least one halogen-containing magnesium compound, an electron donor and an inorganic oxide as support, b) an aluminum compound and c) a further electron donor compound, wherein the ratio of the partial pressures of propylene and ethylene is set to from 20:1 to 100:1 and the ratio of the partial pressures of the C4-C10-alk-1-ene(s) and ethylene is set to from 2.5:1 to 20:1. A process for preparing such random copolymers is also provided, and they can be used in films, fibers or moldings.

Abstract: An olefin polymerization process is described. The process comprises polymerizing an olefin in the presence of a supported single-site catalyst, an optional activator, and a fatty amine. The fatty amine is added at a concentration in the range from about 10 to about 75 weight percent based on the weight of the supported catalyst. The fatty amine helps to reduce fouling and sheeting during the polymerization process and enhances catalyst activity.

Abstract: A process for producing polyethylene having impact resistance, the process comprising polymerizing ethylene, or copolymerizing ethylene and an alpha-olefinic comonomer comprising from 3 to 10 carbon atoms, in the presence of a chemically reduced chromium-based catalyst containing in a support thereof from 2 to 3 wt % of titanium, based on the weight of the catalyst. The invention also provides a chromium-based catalyst for the production of polyethylene by polymerizing ethylene or copolymerizing ethylene and an alpha-olefinic comonomer comprising from 3 to 10 carbon atoms, the catalyst being chemically reduced and containing in a support from 2 to 3 wt % of titanium, based on the weight of the catalyst.

Abstract: A novel process for producing homopolymers and interpolymers of olefins which involves contacting an olefin and/or an olefin and at least one or more other olefin(s) under polymerization conditions with an olefin polymerization catalyst and dinitrogen monoxide in an amount sufficient to reduce the electrostatic charge in the polymerization medium. Also provided is a process for reducing electrostatic charge in the polymerization of an olefin by adding dinitrogen monoxide.

Abstract: A method for producing a low density copolymer of ethylene and 1-hexene having a density in the range of about 0.915 to about 0.930 grams/cc in a continuous loop reactor under slurry phase reactor conditions in the presence of a liquid diluent comprising (a) using a prepolymerized solid particulate metallocene catalyst system, (b) combining the catalyst system with a liquid diluent, and (c) agitating the mixture of (b) to form a liquid mixture containing catalyst system particles that are substantially uniform in size, (d) passing this liquid mixture into the loop reactor, (e) not adding any hydrogen, (f) employing the temperature in the range of about 170.degree. F. to about 180.degree. F., (g) employing ethylene in an amount equal to about 5 to about 6 weight % of the liquid diluent and the loop reactor, and (h) employing 1-hexene in an amount equal to about 1.5 to about 2.5 weight % of the liquid diluent in the loop reactor.

Abstract: Propylene may be polymerized by contacting it with certain iron complexes of selected 2,6-pyridinecarboxaldehydebis(imines) and 2,6-diacylpyridinebis(imines). The polymers produced are useful as molding resins.

Abstract: This invention is directed to a process for the preparation of polyolefins from one or more olefinic monomers comprising combining said olefins under olefin polymerization conditions with an organometallic catalyst compound that is activated for olefin polymerization by reaction with at least one Lewis acid aluminum compound of the formula R.sub.n Al(ArHal).sub.3-n, where "ArHal" is a halogenated aryl group, n=1 or 2, and R is a monoanionic group other than a halogenated aryl group. The invention also relates to a polymer produced using the process and to the polymer itself.

Abstract: Provided are heterogeneous catalysts for homo- and copolymerization of olefins as well as a method for preparing these catalysts, which comprise at least one metallocene compound of a Group 4A, 5A or 6A (Hubbard) transition metal on a solid inorganic support. The method comprises the steps of vaporizing the metallocene compound, treating the support material with the vaporized metallocene compound at a temperature which is sufficiently high to keep the metallocene compound in the vaporous state, contacting the support material with an amount of the vaporized metallocene compound which is sufficient to allow for a reaction between the metallocene compound and at least a substantial part of the available surface sites capable of reacting therewith, removing the rest of the metallocene compound not bound to the support, and optionally treating the product thus obtained with an activating agent. The catalysts are active even if very low amounts of activator agents, such as alumoxane, are used.

Abstract: This invention is generally directed toward a supported catalyst system useful for polymerizing olefins. The method for supporting the catalyst of the invention provides for a supported metallocene catalyst which when utilized in a polymerization process substantially reduces reactor fouling and sheeting in a gas or slurry polymerization process.

Abstract: Metal oxide solid acids are used as catalysts for the polymerization of a feed stream containing at least one of pure monomer (e.g., styrene based monomers), C5 monomers, and C9 monomers to produce hydrocarbon resins. Freely-associated water may be removed from the solid acid catalyst prior to use. Resins with softening points (Ring and Ball) in the range of about 5.degree. C. to 170.degree. C. can be prepared. These catalysts offer advantages over the traditional Friedel-Crafts polymerization catalysts since the acid sites are an integral part of the solid. The solid acid catalysts are relatively nonhazardous, reusable catalysts which eliminate or at least reduce contamination of the resulting resin products with acid residues or by-products.

Abstract: This invention is generally directed toward a supported catalyst system useful for polymerizing olefins. The method for supporting the catalyst of the invention provides for a supported metallocene catalyst which when utilized in a polymerization process substantially reduces reactor fouling and sheeting in a gas or slurry polymerization process.

Abstract: In catalyst systems of the Ziegler-Natta type comprising as active constituentsa) a titanium-containing solid component which is obtained by reacting a compound of titanium with a compound of magnesium, a halogen, an inorganic oxide as support, a C.sub.1 -C.sub.8 -alkanol and a carboxylic ester as electron donor compound,and also as cocatalyst,b) an aluminum compound andc) if desired, a further electron donor compound,the reaction of the individual components for preparing the titanium-containing solid component a) is carried out in the presence of an aromatic hydrocarbon as solvent.

Abstract: A support for use in preparing supported catalysts for addition polymerizations comprising the reaction product of: (A) an inorganic oxide material comprising reactive surface hydroxyl groups, at least some of said hydroxyl groups optionally having been functionalized an converted to a reactive silano moiety corresponding to the formula: --OSiR.sub.2 H, wherein R, independently each occurrence, is hydrogen C.sub.1-20 hydrocarbyl, or C.sub.1-20 hydrocarbyloxy, said inorganic oxide or functionalized derivative thereof comprising less than 1.0 mmol of reactive surface hydroxyl functionality per gram, and (B) an activator compound comprising: b.sub.1) a cation which is capable of reacting with a transition metal compound to form a catalytically active transition metal complex, and b.sub.

Abstract: An ethylene base polymer and a preparation method of an ethylene base polymer characterized in use of a catalyst comprising a chromium amide compound, a solid inroganic oxide calcined at 100 to 500.degree. C. and alumoxane. According to the present invention, an ethylene base polymer with a wide molecular weight distribution, excellent shock and environmental stress cracking resistances, causing no melt fracture, and suitable for film forming and blow molding can be effectively prepared.

Abstract: A novel loop/slurry olefin polymerization process is provided which produces ultra high molecular weight ethylene homopolymer.

Abstract: Procedure for the preparation of a solid catalyst component which is active in the polymerization of olefins, comprising the steps:a) contacting a silylated silica support with a solution of Mg-halide or Mg-alkyl-halide or a mixture of both and Ti-alkoxide or Ti-halogen-alkoxide or a mixture of both, optionally in the presence of Ti-tetrahalide,b) contacting the catalyst-precursor obtained in (a) with Mg-alkyl or Mg-alkyl-halide or a mixture of both, optionally in presence of Lewis base,c) halogenating the catalyst-precursor obtained in (b) by contact of said activated support with halogenating agents,d) titanating the catalyst-precursor obtained in (c) with Ti-tetrahalide in the presence of electron-donors,e) recovering the solid catalyst-component from the reaction products of step (d).The catalyst component, which is obtained according to the above procedure, may also be used together with Al-trialkyl or Al-alkyl-halides and a Lewis base, as a catalyst for the polymerization of olefins.

Abstract: Group 4 metal complexes comprising an indenyl group substituted in the 2 or 3 position with at least one group selected from hydrocarbyl, fluoro-substituted hydrocarbyl, hydrocarbyloxy-substituted hydrocarbyl, dialkylamino-substituted hydroacrbyl, silyl, germyl and mixtures thereof, said indenyl group further being covalently bonded to the metal by means of a divalent ligand group, catalytic derivatives thereof and their use as olefin polymerization catalysts are disclosed.

Abstract: There is provided process for producing an ethylene-alpha-olefin polymer at a polymerization reaction temperature in excess of the softening temperature of the polymer in a gas-phase fluidized-bed reactor in the presence of a polymerization catalyst and wherein the polymerization reaction is conducted in the presence of an inert particulate material, the improvement comprising: commencing polymerization by polymerizing an ethylene propylene rubber having a crystallinity ranging from about 4 to 18 percent as measured by differential scanning calorimetry.

Abstract: Catalyst component for the polymerization of alpha-olefins of general formula (I) ##STR1## wherein: M is a transition metal of groups 3, 4-10, lanthanide or actinide of the periodic table of the elements; A is a ring with delocalized .pi. electrons, L is a neutral Lewis base; m is an integer whose value can be: 0 or 1; E is selected from the group comprising: BR.sup.II, CR.sup.II.sub.2, SiR.sup.II.sub.2, GeR.sup.II.sub.2 ; Hal is selected from the group comprising iodine, bromine or chlorine; R.sup.III has the same meaning of R.sup.II ; Si is a silicon atom; D is selected from the group comprising: O, S, NR.sup.IV, PR.sup.IV, OR.sup.IV, SR.sup.IV, NR.sup.IV.sub.2, PR.sup.IV.sub.2 ; each X group equal to or different from each other is selected from the group comprising hydrogen, halide, alkyl, cycloalkyl, aryl, alkenyl, arylallyl, arylalkenyl or alkylaryl with 1 to 20 carbon atoms, n is a number whose value can be: 0, 1, 2 or 3, in order to full the remaining valences of metal M.

Abstract: Ethylene may be polymerized by contacting it with certain iron or cobalt complexes of selected 2,6-pyridinecarboxaldehydebis(imines) and 2,6-diacylpyridinebis(imines). The polymers produced are useful as molding resins. Novel 2,6-pyridinecarboxaldehydebis(imines) and 2,6-diacylpyridinebis(imines), and novel complexes of 2,6-pyridinecarboxaldehydebis(imines) and 2,6-diacylpyridinebis(imines) with iron and cobalt are also disclosed.

Abstract: A supported polyolefin catalyst activator, comprising a four coordinate anion having a direct chemical bond to a catalyst carrier, wherein said anion is comprised of a neutral, three coordinate compound, MR.sub.3, and a carrier having oxygen containing functionalities, wherein M is selected from the group comprising boron, tellurium, aluminum, gallium, indium and mixtures thereof, and R's can be the same or different and are selected from the group comprising alkyls, alkoxys, alkenyls, halogen substituted alkyls, alkoxys, and alkenyls, aryls, aryl halides, halides and mixtures thereof; and a cation counter ion to said anion, wherein said cation is a protonated base or a Lewis Acid capable of protonating or abstracting a moiety, such as an alkyl or aryl, from a transition metal containing catalyst precursor resulting in a cationic transition metal species.

Abstract: Metallocene complexes of a metal M selected from titanium, zirconium and hafnium, comprising at least one anionic group A containing an .eta..sup.5 -cyclopentadienyl ring co-ordinated with the metal M, wherein the anionic group is substituted in at least one position of the cyclopentadienyl ring with a radical having the formula:Ph*--(CR.sup.6 R.sup.7).sub.nwherein: R.sup.6 and R.sup.7 are independently hydrogen, halogen or a C.sub.1 -C.sub.4 alkyl group, preferably hydrogen, "n" is 0 or 1, preferably 1, Ph* is a C.sub.6 -C.sub.14 group comprising an aromatic ring linked to --CR.sup.6 R.sup.7 -- or to A and substituted with at least one and up to a maximum of three electron-attractor groups, on the condition that, when A is an .eta..sup.5 -indenyl group and "n" is 0, at least one Ph group is linked to A in position 1 or 3 of indenyl.These complexes can be used in (co)polymerization processes of .alpha.

Abstract: Group 4 metal constrained geometry complexes comprising a 3-aryl- substituted indenyl ligand, catalytic derivatives thereof and their use as olefin polymerization catalysts, especially for preparing interpolymers comprising ethylene and a monovinyl aromatic monomer are disclosed.

Abstract: Metal complexes corresponding to the formula: ##STR1## wherein: L independently each occurrence is a delocalized, .pi.-bonded group that is bound to M, containing up to 50 nonhydrogen atoms;M is a metal of Group 3, 4 or the Lanthanide series of the Periodic Table of the Elements;Z is a covalently bound, divalent substituent of up to 50 non-hydrogen atoms having the formula, --(ER.sub.2).sub.m --, wherein E independently each occurrence is carbon, silicon or germanium, R independently each occurrence is selected from the group consisting of C.sub.1-20 hydrocarbyl, and C.sub.1-20 hydrocarbyloxy, with the proviso that in at least one occurrence R is C.sub.

Abstract: Catalyst compositions are provided that comprise (a) discrete silica particles; (b) chromium; and (c) a support comprising silica. These composition are useful in polymerizing ethylene or copolymerizing ethylene with a comonomer and provide better control over the molecular weight and the molecular weight distribution of a resulting polymer.

Abstract: Support for catalysts, containing at least two constituents chosen from silica, alumina and aluminium phosphate, having a specific surface of 100 to 800 m.sup.2 /g, a crystallization temperature greater than or equal to 700.degree. C. and a pore volume of 1.5 to 4 cm.sup.3 /g, the specific surface (SS) and the pore volume (PV) corresponding to the relationship:SS<(PV.times.564-358).Process for the manufacture of such a support, according to which an alcohol, water, a silicon alkoxide and an acid are mixed under conditions such that gelling or precipitation of silica is prevented, an acidic solution of an aluminium compound and/or a solution of a source of phosphate ions are added thereto, a gelling agent is added thereto, a gel is recovered which is washed with water and then by means of an organic liquid, the gel is then dried until a powder is obtained, and the powder is calcined. Polymerization of olefins in the presence of a catalyst containing chromium on a support as described above.

Abstract: A supported Lewis acid catalyst system for catalyzing hydrocarbon conversion reactions including cationic polymerization, alkylation, isomerization and cracking reactions is disclosed, wherein the catalyst system comprises an inorganic oxide support having immobilized thereon a least one strong Lewis acid comprising at least one metal salt of a strong Bronsted acid wherein the metal is selected from the group consisting of aluminum, boron gallium, antimony, tantalum, niobium, yttrium, cobalt, nickel, iron, tin, zinc, magnesium barium strontium, calcium, tungsten, molybdenum and the metals of the lanthanide series and wherein the strong Bronsted acid is selected from the group consisting of mineral and organic acids stronger than 100% sulfuric acid.

Abstract: A supported catalyst composition comprising a complex of a Group 4 metal cyclopentadienyl derivative reacted with silica treated with an aluminoxane demonstrates improved reactivity, especially for incorporating long chain alpha-olefins and also shows improved resistance to catalyst poisoning. The supported catalyst composition is adapted to produce homogeneous polymers, copolymers, terpolymers, etc., for example, homogeneous polyethylene, homogeneous poly(ethylene-octene) copolymers and the like. The invention further includes the process of preparing the supported catalyst compositions and a process for preparing olefinic polymers using these catalyst compositions.

Abstract: The solid catalytic component according to the invention is obtained bya) treatment of a catalytic component support with ZrCl.sub.4 or HfCl.sub.4 in the gas phase, followed by ab) treatment with a solution or suspension of a compound capable of grafting a group containing the cycloalkadienyl skeleton to the Zr or Hf contained in the support. Polymerization of olefins in the presence of such a catalytic component results in polymers with low polydispersities, which polymers are obtained with high productivities.

Abstract: Metal complexes useful as olefin polymerization catalysts corresponding to the formula: ##STR1## wherein: L is a delocalized, .pi.-bonded group that is bound to M, containing up to 50 nonhydrogen atoms;M is a metal of Group 3, 4 or the Lanthanide series of the Periodic Table of the Elements;Z is a covalently bound, divalent substituent of up to 50 non-hydrogen atoms having the formula, --(ER.sub.2).sub.m --, wherein E independently each occurrence is carbon, silicon or germanium, R independently each occurrence is selected from the group consisting of C.sub.1-20 hydrocarbyl, and C.sub.1-20 hydrocarbyloxy, with the proviso that in at least one occurrence R is C.sub.

Abstract: A process is provided comprising copolymerizing, under copolymerizing conditions, ethylene with one or more alpha-olefins, using a catalyst system, where said catalyst system has been sized, to produce a lower-density-copolymer, where said lower-density-copolymer has a density lower than a similar copolymer produced by copolymerizing, under said copolymerizing conditions, ethylene with said one or more alpha-olefins, using said catalyst system, where said catalyst system has not been sized, where said catalyst system that has been sized has had substantially all particles removed that produce, under said copolymerizing conditions, a higher-density-copolymer, where said higher-density-copolymer has a density higher than said similar copolymer.

Abstract: This invention is generally directed toward a supported catalyst system useful for polymerizing olefins. The invention particularly relates to a supported metallocene catalyst system that does not require an activator or cocatalyst for the polymerization of olefins.

Abstract: A process for the preparation of a supported catalyst for the polymerization of .alpha.-olefins, in which(1) a silicon dioxide-containing support gel is prepared by(1.1) introducing a sodium water glass or potassium water glass solution into a swirling stream of an aqueous mineral acid longitudinally and tangentially to the stream, spraying the resultant silica hydrosol in drop form into a gaseous medium and allowing it to solidify to form a hydrogel, and freeing the resultant hydrogel from salts by washing without prior ageing,(1.2) drying the hydrogel resulting from (1.1) to form the support gel,(2) the support gel (1) is charged with chromium trioxide or a chromium compound which can be converted into chromium trioxide under the conditions of process step (3), giving a chromium-containing support gel, and(3) the chromium-containing support gel (2) is heated at from 400.degree. to 1100.degree. C.

Abstract: Disclosed is a catalyst system for the homopolymerization of alpha-olefins having 2-8 carbon atoms, said catalyst system comprising a mixed-valent dimeric Group 6b metal compound catalyst precursor wherein one atom of said Group 6b metal is a cyclopentadienyl Group 6b metal hydrocarbyl complex in which the Group 6b metal has an oxidation state +3 and wherein one atom of said Group 6b metal is a cyclopentadienyl alkaryl complex in which the Group 6b metal has an oxidation state +1, said dimeric Group 6b metal compound being supported on an inorganic support. The catalyst system can contain, in addition, a Group 2 or Group 3 metal-alkyl compound.

Abstract: A catalyst system comprising a bridged fluorenyl-containing metallocene, an unbridged metallocene, and a suitable cocatalyst and the use of such catalyst systems to produce olefin polymers. Also novel olefin polymers produced by those processes.

Abstract: Chromium catalyst compositions are provided. These chromium catalyst compositions comprise at least two chromium catalyst systems that have a certain amount of chromium and a support that comprises silica and titania. the supports have certain pore volumes and surface areas. These catalyst compositions are useful for homopolymerizing ethylene or copolymerizing ethylene with a comonomer. The resins produced are useful in film applications.

Abstract: A hydrocarbon soluble drag reducing suspension is described as well as a process for obtaining the same. Process is directed toward producing a drag reducing product which is easily transportable, non-hazardous, easily handled and while providing a significant increase in drag reduction capability over existing commercial products. The suspension is preferably substantially solvent-free.

Abstract: Disclosed is a mono- or di-amido siladiyl bridged composition of matter useful as a catalyst component for the homo or copolymerization of olefins.

Abstract: Chromium catalyst compositions are provided. Theses chromium catalyst compositions can be used to polymerized olefins. The resulting polymerization product can have improved properties.

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.