Abstract: A method is provided for forming a supported cyclopentadiene-type compound comprising contacting a cyclopentadiene-type compound containing an active halogen with an inorganic support having surface hydroxyl group. Also there is provided a method of preparing a supported metallocene comprising reacting the supported cyclopentadiene-type compound with a transition metal compound under suitable conditions. There is also provided a process for producing bridged cyclopentadiene-type ligands having a bridge having branch that has a terminal vinyl group. Also metallocenes of these ligands are provided. Still further there is provided a process for producing bridged cyclopentadiene-type ligands having a bridge having a branch that has a terminal active halogen. The resulting new ligands and supported metallocenes produced therefrom are also provided.

Abstract: Catalytic compositions and catalytic processes are provided. The catalytic compositions are produced by the process that comprises contacting an organonickel compound with a cyclicazacarbyl compound. Optionally, one or more catalytic promoters can be present in the catalytic compositions. Additionally, one or more olefins can be contacted with one or more of these catalytic compositions to form oligomerization products and/or polymerization products.

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: Olefin polymerization is carried out in the presence of a catalyst comprising, as main components, the following Compounds (A) and (B):(A) a transition metal compound containing a transition metal selected from the IVB Group of the Periodic Table having the formula:M.sup.1 R.sup.1.sub.a R.sup.2.sub.b R.sup.3.sub.c R.sup.4.sub.dwherein M.sup.1 is a Ti, Zr, or Hf atom; a, b, c, and d are independently an integer of 0 to 4; and R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are selected from the group consisting of hydrogen atom, oxygen atom, halogen atom, C.sub.1-20 alkyl, C.sub.1-2 alkoxy, C.sub.6-20 aryl, tolyl, xylyl, benzyl, C.sub.

Abstract: Disclosed is a catalyst system for the homopolymerization and copolymerization of alpha-olefins having 2-8 carbon atoms, said catalyst system comprising a cyclopentadienyl Group 6b metal hydrocarbyl compound in which the metal has an oxidation state of +3, said Group 6b metal compound being supported on an inorganic support. The catalyst system may also contain a Group 2 or Group 3 metal alkyl compound.

Abstract: In one embodiment of this invention a surface silicated alumina composition, as opposed to conventional silica alumina, is provided. Such composition may also be fluorided and/or phosphated or phosphited. The resulting compositions are broadly useful but are of particular applicability as supports for chromium olefin polymerization catalysts. In another aspect alumina is fluorided and used with hexavalent chromium catalyst and a co-catalyst or in the alternative with an organochromium catalyst. If desired the support in this embodiment can also be phosphated or phosphited. In another embodiment, aluminum phosphate is formed in the pores of alumina. In contrast with alumina catalyst supports of the prior art, the supports of this invention allow for the production of olefin polymers at high rates of productivity. Also novel high density ultrahigh molecular weight polymers are produced.

Abstract: A composition is provided comprising a metallocene having the formula of: ##STR1## wherein each Z can be the same or different hydrocarbyl radical selected from the group consisting of cyclopentadienyl, indenyl, tetrahydroindenyl, fluorenyl, and mixtures thereof; each X can be the same or different and is selected from the group consisting of hydrogen, fluorine, chlorine, bromine, iodine, R, OR, NR.sub.2, PR.sub.2, or OQ, or mixtures thereof wherein the R is a C.sub.1 -C.sub.20 hydrocarbyl radical and Q is an inorganic moiety selected from the group consisting of silica, alumina, clay, phosphated alumina, and mixtures thereof; each Y can be the same or different and is an alkyl group, hydrogen, fluorine, chlorine, bromine, iodine, or mixtures thereof; E is selected from C, Sn, Si, Ge, B, Al, N, or P; M is a metal selected from Ti, Zr, Hf, Sc, Y, V, or La; m is a number sufficient to fill out the valences of metal M; and n is 1 or 2.

Abstract: A novel polymerization catalyst system comprising a diluent, a substrate, a nickel compound wherein the nickel is in a zero oxidation state and picolinic acid and a method for making such catalyst system is described. The polymerization catalyst system can be used in a process for the polymerization of polymerizable olefins.

Abstract: Olefins are polymerized with a catalyst system composition comprising a nickel compound and an aromatic carboxylic acid wherein there is a heteroatom linkage between the aromatic moiety and the carboxylic acid functional group. The novel catalyst system composition can be heterogeneous or homogeneous. This composition allows the production of one or more olefin polymers which have a very high molecular weight.

Abstract: A bimodal silica gel particle, its method of preparation and its use as a catalyst support in the polymerization of olefins is disclosed. The bimodal silica gel particle exhibits a bimodal pore radius distribution, wherein the silica gel particle has a first average pore radius and a second average pore radius differing by at least about 20 .ANG.. The bimodal silica gel particle is useful as a support for a transition metal-based catalyst to provide a polyolefin having a broad or bimodal molecular weight distribution.

Abstract: In a novel process for the preparation of a supported catalyst for the polymerization of .alpha.-olefins, a carrier gel (1) is first prepared by a method in which a sodium or potassium waterglass solution is introduced into a stream of an aqueous mineral acid which is subjected to angular momentum and may contain aluminum ions, longitudinally and tangentially to the stream, the resulting silica hydrosol sprayed in the form of drops into a gaseous medium and allowed to solidify into a hydrogel, and the resulting hydrogel is freed from salts by washing without prior aging and, if necessary, freed from some of the water by extraction with alcohols and/or ketones and is then dried. This gives the carrier gel (1), which is milled and is fractionated according to particle size. In a second process step, the carrier gel (1) is laden with chromium trioxide or with a chromium compound which can be converted into chromium trioxide, after which the resulting chromium-containing carrier gel (2) is heated at from 400.

Abstract: Process for the polymerization of alpha-olefins in the presence of a catalyst, including providing monodisperse microspheroidal particles by spraying an electrostatically charged gellable liquid material (L) through a spraying orifice and into a chamber, so as to produce macrodrops which break up into microdrops which fall in the chamber and within which gelling is produced after spraying; providing a catalyst for the polymerization of alpha-olefins which contains chromium and which is supported on the monodisperse microspheroidal particles; and polymerizing alpha-olefins in the presence of the catalyst.

Abstract: A copolymer of ethylene and a higher alpha-olefin, preferably 1-butene and/or 1-hexene, can be produced using an activated and subsequently carbon monoxide reduced chromium containing catalyst system and an alkylaluminum or alkylboron cocatalyst. The polymerization process must be carefully controlled to produce a copolymer resin that can be made into a tough product, with an increased melt index and a broad molecular weight distribution.

Abstract: A process for producing sticky polymers at polymerization reaction temperatures in excess of the softening temperatures of the sticky polymers in a fluidized bed reactor in the presence of an inert particulate material which comprises utilizing as a support material for the catalyst, a support which includes silica having an average particle size of from about 60 to about 200 microns.

Abstract: A composition of matter is provided comprising a catalytic mixture resulting from contacting at least one of each of the following compounds, an pyridine compound, a clay compound, and an organo-nickel compound. Additionally, a process is provided comprising contacting, under polymerization conditions, at least one alpha-olefin, wih a catalytic mixture resulting from contacting at least one of each of the following compounds, an pyridine compound, a clay compound, and an organo-nickel compound.

Abstract: The present invention relates to a novel catalyst for the preparation of high molecular weight homopolymers and copolymers of ethene, which catalyst is obtainable by(1) loading a support based on silicon dioxide with(2) either chromium trioxide or a chromium compound capable of being converted to chromium trioxide under the conditions of stage (3) below and then(3) heating the resulting intermediate in a gas stream containing oxygen.the support (1) being a special silica xerogel obtained by extracting not more than 30% of the water from a silica hydrogel by means of an alkanol, an alkanone or a mixture thereof followed by drying, comminution and fractional screening.

Abstract: Olefin polymerization catalysts, processes for preparing the catalysts and processes for producing polyolefins utilizing the catalysts are provided. The catalysts are basically comprised of a pentadienyl derivative-transition metal complex adsorbed on an activated inorganic refractory compound.

Abstract: A process for preparing syndiotactic vinyl aromatic polymers comprising contacting one or more aromatic monomers under polymerization conditions with a catalyst corresponding to the formula:[Cp.sub.m MX.sub.n X'.sub.p ].sup.+ A.sup.-wherein:Cp is a single .eta..sup.5 -cyclopentadienyl or .eta..sup.5 -substituted cyclopentadienyl group;M is a metal of Group 3, 4, 5, 6, 8, 9, 10 or the Lanthanide Series of the Periodic Table;X each occurrence is an inert anionic ligand, with the proviso that at least one X is R;X' is an inert, neutral, donor ligand;R is hydride hydrocarbyl, silyl, a combination thereof or a substituted derivative thereof having up to 20 carbon, silicon or carbon and silicon atoms;m and p are independently 0 or 1;n is an integer greater than or equal to 1;the sum of m and n is equal to the valence of M; andA.sup.- is a noncoordinating, compatible anion of a Bronsted acid salt.

Abstract: In one embodiment of this invention a surface silicated alumina composition, as opposed to conventional silica alumina, is provided. Such composition may also be fluorided and/or phosphated or phosphited. The resulting compositions are broadly useful but are of particular applicability as supports for chromium olefin polymerization catalysts. In another aspect alumina is fluorided and used with hexavalent chromium catalyst and a co-catalyst or in the alternative with an organochromium catalyst. If desired the support in this embodiment can also be phosphated or phosphited. In another embodiment, aluminum phosphate is formed in the pores of alumina. In contrast with alumina catalyst supports of the prior art, the supports of this invention allow for the production of olefin polymers at high rates of productivity. Also novel high density ultrahigh molecular weight polymers are produced.

Abstract: Fines are reduced in refractory materials by mixing the refractory material with an acid composition in a liquid polar organic compound and thereafter working the mixture until a decrease in volume occurs. The resulting product can be shaped and subjected to conventional finishing treatments. The resulting product exhibits reduced fines and thus is an improved material for use as a catalyst support. The resulting catalyst is of particular utility in the production of film grade ethylene polymer.

Abstract: A process for producing sticky polymers at polymerization reaction temperatures in excess of the softening temperature of the sticky polymers in a fluidized bed reactor catalyzed by a transition metal catalyst, which comprises conducting the polymerization reaction above the softening temperatures of the sticky polymers in the presence of about 0.3 to about 60 weight percent, based on the weight of the final product of an inlet particulate material having a mean particle size of from about 0.01 to about 10 micron meters whereby polymer agglomeration of the sticky polymers is maintained at a size suitable for continuously producing the sticky polymers.

Abstract: A copolymer of ethylene and a higher alpha-olefin, preferably 1-hexene and/or 4-methyl-1-pentene, can be produced using an activated and subsequently carbon monoxide reduced chromium containing catalyst and a trialkyl boran cocatalyst. The polymerization process must be carefully controlled to produce a copolymer resin that can be made into a tough, impact resistant film.

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: A process for polymerizing or copolymerizing a member of the group consisting of an alpha olefin or mixtures thereof, consisting of the steps of:polymerizing an alpha olefin in a polymerization reactor using a polymerization catalyst, a cocatalyst, and an amount of hydrogen adjusted for molecular weight control as measured by melt flow;rapidly changing the melt flow of the polymerized alpha olefin from high to low melt flow by reacting a portion of the unreacted hydrogen in the reactor with a quantity of the alpha olefin present therein by interaction with a hydrogenation catalyst; andremoving the hydrogenation catalyst from the reactor through continuous exchange of the reactor contents.

Abstract: A catalyst system useful for the polymerization of ethylene and other .alpha.-olefins comprising (a) a silica-supported chromium oxide catalyst and (b) a dihydrocarbylboron monohydrocarbyloxide adjuvant. The catalyst system results in .alpha.-olefin polymers having a broadened molecular weight distribution in the high molecular portion.

Abstract: In accordance with one embodiment of this invention, a bis-(cyclopentadienyl)chromium(II) compound is introduced onto an activated phosphate-containing support and utilized in conjunction with an organometal cocatalyst, such as an alkylaluminum. In accordance with another embodiment of this invention, a phosphate-containing zerogel is formed by removing water from an aluminum phosphate-containing hydrogel by means of azeotropic distillation or washing with a volatile, water mis-cible organic compound, activated and thereafter a bis-(cyclopentadienyl)chromium(II) compound is incorporated therewith. In other embodiments of this invention, a phosphate-containing support is formed by forming aluminum phosphate from an aluminum alkoxide or from a melt, or by phosphating silica or alumina, or by forming an aluminum phosphate/silica combination. A support thus formed is activated and a bis-(cyclopentadienyl)chromium(II) compound added.

Abstract: The reaction of the organolanthanide complexes [.eta..sup.5 --(CH.sub.3).sub.5 C.sub.5 ].sub.2 MCl.sub.2.sup.- Li((C.sub.2 H.sub.5).sub.2 O).sub.2.sup.+, M=La, Nd, Sm, Lu, with LiCH[Si(CH.sub.3).sub.3 ].sub.2 provides a straight-forward route to ether-free and halide- free bis(pentamethylcyclopentadienyl) lanthanide alkyls, (.eta..sup.5 (CH.sub.3).sub.5 C.sub.5).sub.2 MCH--[Si(CH.sub.3).sub.3 ].sub.2. The (.eta..sup.5 (CH.sub.3).sub.5 C.sub.5).sub.2 NdCH[Si(CH.sub.3).sub.3 ].sub.2 complexes react with H.sub.2 under mild conditions to yield the corresponding hydrides [(.eta..sup.5 (CH.sub.3).sub.5 C.sub.5).sub.2 MH].sub.2. These complexes have been found to be extremely active homogeneous olefin polymerization catalysts, as well as catalysts for olefin and acetylene hydrogenation.

Abstract: Ethylene is copolymerized or interpolymerized with at least one olefinic comonomer having about 3 to 18 carbon atoms to produce linear low density polyethylene copolymers and terpolymers in a slurry process using liquid propane as the diluent. The copolymer products have desirable physical properties including relatively narrow molecular weight distributions and low elasticities.

Abstract: Polymerization catalyst consisting essentially of treated silica support and zerovalent chromium compound is provided, as well as process for preparation and polymerization process with the invention catalyst. Silica treatment involves contacting a predominantly silica-containing support with at least one compound selected from the group consisting of Group IIA oxide or compounds convertible to the oxide form, a Group VA or VB oxide or compounds convertible to the oxide form or sulfuric acid, and calcining prior to contacting the treated support with a zerovalent chromium compound, thereby producing an active polymerization catalyst.

Abstract: Process for selective production of polyolefin resins of controlled rheology responsive to catalyst morphology in heat activated aluminum treated porous supports e.g., silica gel of regulated moisture content.

Abstract: A method of polymerizing olefins comprising contacting an olefin or mixture of olefins with a catalyst prepared with large pore volume zirconia-silica catalyst supports. The supports are prepared by reacting a zirconium compound of the formula M.sub.4 Zr(C.sub.2 O.sub.4).sub.4.nH.sub.2 O, where M is an alkali metal or ammonium ion and n equals 0 to 10, with a silicon compound of the type A.sub.2 SiO.sub.3, where A is an alkali metal, in an aqueous solution at a pH equal to at least 11, then adding an acidic solution to a pH of about 5-9 to produce a hydrocogel. The hydrocogel is then aged and washed free of soluble by-products with an aqueous washing agent. Water is removed from the washed hydrocogel by azeotropic distillation or by washing with a water miscible solvent and then calcining the resulting xerocogel.

Abstract: A silica-titania cogel is produced in a two-step process wherein in the first step an alkyl polysilicate and/or a tetraalkyl silicate is partially hydrolyzed in an alkaline organic solvent using insufficient water to complete hydrolysis and thereafter a tetraalkyl titanate and an excess of water are added to complete the hydrolysis. The resulting product is as good or better than silica-titania cogels made by expensive prior art techniques and offers the advantage of not requiring washing step to remove alkali metal ions and thus also does not require an azeotrope drying step to remove water.

Abstract: Process for the polymerization of olefins comprising contacting an olefin, admixed with an oxygen-containing gas, with a supported organophosphoryl-chromium oxide catalyst.

Abstract: A process for the polymerization or copolymerization of an olefinically unsaturated monomer which comprises contacting the monomer with a chromium metal catalyst composition which is the product obtained by adsorbing a chromium metal complex which contains allyl hydrocarbon radicals with an inert inorganic oxide support which has --OH groups on its surface and which is free from adsorbed water, said monomer being an olefinically unsaturated monomer other than a polar vinyl monomer.

Abstract: Zeolite supported, organochromium based catalyst compositions are provided which are especially suitable for the polymerization of 1-olefins such as ethylene. Pi-bonded organochromium [II] compounds such as chromocene (dicyclopentadienyl chromium) are reacted with ZSM-5 type zeolites to produce such novel catalysts.

Abstract: A silica composition is calcined at a temperature high enough to remove some but not all of the hydroxyl content. Generally temperatures of at least 400.degree. C. are required and temperatures above 1000.degree. C. are undesirable, the most preferred temperature being about 600.degree.-800.degree. C. The thus calcined silica is then treated with chromyl chloride at an elevated temperature and finally given a treatment in a carbon monoxide ambient. While the final composition contains chlorine which is normally considered a catalyst poison, the material is surprisingly active as an olefin polymerization catalyst.

Abstract: There is provided the polymerization of 1-olefins such as ethylene with zeolite supported, chromium catalyst compositions. Chromium ions are ion exchanged with zeolites to produce such catalysts.

Abstract: Zeolite supported, organometallic derived catalyst compositions are provided which are especially suitable for the polymerization of 1-olefins such as ethylene. Organotitanium and organochromium compounds such as tributylchromium and tetrabutyltitanium are reacted with ZSM-5 type zeolites to produce such novel catalysts.

Abstract: A process is disclosed for polymerizing an olefin to provide a polyolefin of high melt index which comprises contacting the olefin with a catalyst system obtained by heat activating a supported organophosphoryl chromium compound obtained by the reaction of chromium trioxide with an organophosphorous compound having the formula: ##STR1## wherein R is alkyl, aralkyl, aryl cycloalkyl, or hydrogen, but at least one R is other than hydrogen, and combining the heat activated supported material with a melt index increasing amount of at least one organoborane catalyst modifier having the formula: ##STR2## wherein m and n each is zero or 1,R.sub.1 and R.sub.2 are each a hydrocarbyl group of from 1 to 10 carbon atoms, or one of R.sub.1 and R.sub.2 is hydrogen, or together R.sub.1 and R.sub.2 constitute a hydrocarbyl group of from 2 to 10 carbon atoms.

Abstract: Zeolite supported, organochromium based catalyst compositions are provided which are especially suitable for the polymerization of 1-olefins such as ethylene. Pi-bonded organochromium [II] compounds such as chromocene (dicyclopentadienyl chromium) are reacted with ZSM-5 type zeolites to produce such novel catalysts.

Abstract: Zeolite supported, organometallic based catalyst composition are provided which are especially suitable for the polymerization of 1-olefins such as ethylene. Alkyltitanium and alkylchromium compounds such as tributylchromium and tetrabutyltitanium are reacted with ZSM-5 type zeolites to produce such novel catalysts.

Abstract: A fractionable, elastomeric polymer of 1-butene consisting essentially of 30% to 80%, by weight, of an ether-soluble fraction having an intrinsic viscosity exceeding 1.5 and an infrared crystallinity value of about 1% to 15%; and 20% to 70%, by weight, of an ether-insoluble fraction having an infrared crystallinity value of about 20% to 55%; said polymer having an nmr isotacticity of about 20% to 50% and an intrinsic viscosity exceeding 1.5; elastomeric copolymers of 1-butene; polymer blends containing said elastomeric polymers; and a catalytic process for making said elastomeric polymers.

Abstract: Olefin polymerization catalysts are prepared by depositing an organophosphoryl chromium product and a non-volatile aluminum-containing product obtained from the reaction of an aluminum alkoxide and an aluminum salt of a lower aliphatic monocarboxylic acid on an inorganic support material and heating the support material in a non-reducing atmosphere at a temperature above about 300.degree. C. up to the decomposition temperature of the support material.

Abstract: A silica-containing composition suitable for supporting chromium to produce a catalyst capable of giving high melt flow olefin polymers for such applications as injection molding and the like requiring a narrow molecular weight distribution, is produced by treating a silica-containing material at an elevated temperature with either (1), CO, (2) a bromine or iodine component, or (3) an oxygen-containing sulfur component, more specifically a carbon, oxygen and sulfur-containing component. Thereafter, anhydrous chromium can be added, for instance, by means of a hydrocarbon solution of a soluble chromium compound, and the resulting composition activated in air to produce a catalyst. The bromine or iodine treated silica contains bound bromine or iodine if the treating agent is HBr, HI, an organic halide of Br or I or elemental Br or I used in conjunction with a reducing agent.

Abstract: The present invention involves compositions of super absorbent polymers which absorb many times their weight in water and aqueous fluids. Super absorbent polymers in the prior art have effectively absorbed many times their weight of water, however, they become slimy to the touch or become so fluid as to migrate away from their point of application.The absorbent composition of the current invention absorbs substantial amounts of water without becoming slimy and migrating out from its applicator, as in absorbent articles. The absorbent composition of the current invention comprises a copolymer of acrylic acid cross-linked with a first cross-linking component comprising a monomer having at least two vinyl groups and a second cross-linking component comprising an ionic divalent cation. In the current invention, this composition can be mixed with cellulose fibers to enhance wicking.

Abstract: Catalysts, especially for olefin polymerization are prepared by coating an aluminum compound on a selected high pore volume silica gel, and calcining the support at temperatures of from about 200.degree. to 2000.degree. F. The preferred catalyst is prepared with an inorganic support material as aforesaid, thereafter depositing an organophosphoryl chromium compound thereon, and activating the thus-treated support by heating in a non-reducing, preferably oxygen-containing, atmosphere at temperatures of from about 800.degree. to 2000.degree. F. The activated, supported catalyst composition may, but need not necessarily, be combined with a metallic and/or non-metallic reducing agent, to provide a catalyst system useful in the polymerization of 1-olefins.

Abstract: A continuous low pressure gas phase process for the production of solid particulate polymers during an exothermic polymerization reaction in a uniform diameter vertical fluidized bed reactor system which comprises feeding a polymerization catalyst and a gaseous stream containing at least one polymerizable monomer to a fluidized bed of polymer particles and removing the exothermic heat of reaction by indirect cooling means in the reactor and removing dry particulate polymer. Also, apparatus for the polymerization process is described.

Abstract: Olefins are polymerized in the presence of catalysts prepared by combining a heat activated supported organophosphoryl chromium compound with an alkyl borane which has been pretreated with hydrogen.

Abstract: A silica-containing composition suitable for supporting chromium to produce a catalyst capable of giving high melt flow olefin polymers for such applications as injection molding and the like requiring a narrow molecular weight distribution, is produced by treating a silica-containing material at an elevated temperature with either (1) CO, (2) a bromine or iodine component, or (3) an oxygen-containing sulfur component, more specifically a carbon, oxygen and sulfur-containing component. Thereafter, anhydrous chromium can be added, for instance, by means of a hydrocarbon solution of a soluble chromium compound, and the resulting composition activated in air to produce a catalyst. The bromine or iodine treated silica contains bound bromine or iodine if the treating agent is HBr, HI, an organic halide of Br or I or elemental Br or I used in conjunction with a reducing agent.

Abstract: A silica-containing composition suitable for supporting chromium to produce a catalyst capable of giving high melt flow olefin polymers for such applications as injection molding and the like requiring a narrow molecular weight distribution, is produced by treating a silica-containing material at an elevated temperature with either (1), CO, (2) a bromine or iodine component, or (3) an oxygen-containing sulfur component, more specifically a carbon, oxygen and sulfur-containing component. Thereafter, anhydrous chromium can be added, for instance, by means of a hydrocarbon solution of a soluble chromium compound, and the resulting composition activated in air to produce a catalyst. The bromine or iodine treated silica contains bound bromine of iodine if the treating agent is HBr, HI, an organic halide of Br or I or elemental Br or I used in conjunction with a reducing agent.