Abstract: A process for producing a crystalline silicate catalyst having a monoclinic structure, the process comprising providing a crystalline silicate of the MFI-type having a silicon/aluminum atomic ratio lower than 80; treating the crystalline silicate with steam and thereafter leaching aluminum from the crystalline silicate by contact with an aqueous solution of a leachant to provide a silicon/aluminum atomic ratio in the catalyst of at least 80 whereby the catalyst has a monoclinic structure.

Abstract: Process for the production of polypropylene fibers from polypropylene polymers produced by the polymerization of polypropylene in the presence of a metallocene catalyst characterized by a bridged racemic bis(indenyl) ligand substituted at the proximal position. The polypropylene contains 0.5 to 2% 2,1 insertions and has an isotacticity of at least 95% meso diads and is heated to a molten state and extruded to form a fiber preform. The preform is subjected to spinning at a spinning speed of at least 500 meters per minutes and subsequent drawing at a speed of at least 1,500 meters per minute to provide a draw ratio of at least 3 to produce a continuous polypropylene fiber. The draw speed and/or the draw ratio can be varied to produce fibers of different mechanical properties. Different polypropylene polymers produced by different metallocene catalysts can be used. Such fibers can be characterized by having an elongation at break of at least 100% and a specific toughness of at least 0.5 grams per denier.

Abstract: A polyolefin metallocene catalyst which includes two metallocene components, a stereorigid isospecific metallocene catalyst component and a stereorigid syndiospecific metallocene catalyst component, both of which are supported upon the same support. A method of forming a catalyst system includes contacting the above catalyst with a cocatalyst or Lewis acid. A method of polymerization includes contacting an olefin of at least 3 carbon atoms with the catalyst system.

Abstract: A process for polymerization of olefins having increased molecular weight and melting point uses a catalyst formed by combining a chiral, stereorigid metallocene compound with an organoaluminum compound. The metallocene compound has a silicon hydrocarbyl radical as an interannular bridge between two cyclopentadienyl or substituted cyclopentadienyl rings which are coordinated with a metal which is bonded to a hydrocarbon radical or a halogen. The cyclopentadienyl rings are described by the formula (C.sub.5 R'.sub.m) wherein R' is hydrogen or hydrocarbyl radical having from 1-20 carbon atoms, each R' being the same or different. The metal is a group 4b, 5b or 6b metal as designated in the Periodic Table of Elements.

Abstract: Use of a homogeneous blend of a metallocene-catalyzed medium density polyethylene (mMDPE) with low density polyethylene (LDPE) and/or a linear low density polyethylene (LLDPE), to produce blown films, this composition essentially consisting of from 0.5 to 100% by weight of MMDPE and from 0 to 99.5% by weight of LDPE and/or LLDPE.The compositions of this invention have good processability and are used to make blown films which have the good optical properties of LDPE and the good mechanical and processing properties of MDPE.

Abstract: A process for the preparation of a meso/racemic-(bis(indenyl)ethane zirconium dichloride compound comprising (a) reacting zirconium tetrachloride with the solid reaction product of the bis(indenyl)ethane ligand with an alkyllithium in a solvent as reaction medium and (b) recovering a solid mixture of lithium chloride and meso/racemic composition of (bis(indenyl)ethane) zirconium dichloride, characterized in that the solvent used as reaction medium in a reaction (a) is an ether, pentane or a mixture thereof.

Abstract: The present invention discloses a method and apparatus for dehydrogenating ethylbenzene into styrene which method and apparatus eliminate the need for multiple reactors and preheaters by providing a single compact reactor which utilizes the principle of ascending-heat thermal reactor by having an internal heat source such as gas heaters or electric elements.

Abstract: A process for producing a chromium-based catalyst for the production of polyethylene, the process comprising the steps of providing a catalyst support selected from silica, silica-titania and silica-zirconia; reacting the support with one of an aluminium alkyl compound or a chromium salt compound selected from at least one of chromium (III) acetylacetonate, chromium (III) acetate, chromium (III) oxalate and chromium (III) stearate; and thereafter reacting the support with the other of the aluminium alkyl compound or the chromium salt to produce a chromium-impregnated catalyst having a silica-alumina support, the catalyst composition comprising from 0.4 to 1.5 wt % chromium, based on the weight of the chromium-based catalyst and the alumina in the silica-containing support comprising from 0.5 to 4 wt % aluminium in the chromium-based catalyst.

Abstract: An improved zeolite catalyst having enhanced dealkylation activity is provided. The catalyst is prepared by incorporating fluorine into the zeolite structure. In another embodiment, a transition element such as nickel is additionally incorporated into the zeolite structure. The process for producing the catalyst also includes ion-exchange and calcining steps. A mordenite type catalyst has been found to be particularly effective. The catalyst of the present invention demonstrates improved activity for the dealkylation of polyalkylaromatic compounds found in residue from the alkylation process and in heavy reformate streams from refineries. A dealkylation process using the catalyst of the present invention is provided. The dealkylation process shows good selectivity for benzene and monoalkylated aromatic products, and catalyst stability, particularly at high reaction temperatures.

Abstract: Ethylbenzene is produced by alkylation over monoclinic silicalite catalysts having a weak acid site concentration of less than 50 micromoles per gram. A feedstock containing benzene and ethylene is applied to an alkylation reaction zone having at least one catalyst bed containing a monoclinic silicalite catalyst having a weak acid site concentration of less than 50 micromoles per gram. The alkylation reaction zone is operated at temperature and pressure conditions in which the benzene is in a gaseous phase to cause gas-phase alkylation of the aromatic substrate in the presence of the silicalite catalysts to produce an alkylation product. The alkylation product is then withdrawn from the reaction zone for separation and recovery.

Abstract: A process for the production of biaxially-oriented polypropylene film involving the provision of a polypropylene polymer produced by the polymerization of propylene in the presence of a metallocene catalyst characterized by a bridged racemic bis(indenyl) ligand substituted at the proximal position. The polypropylene contains 0.5 to 2% 2,1 insertions and has an isotacticity of at least 96% meso pentads and at least 99% meso diads. The film is formed by stressing the polymer produced from a slot die in the machine direction at a stretch ratio of about 5 or 6 and in the transverse direction at a stretch ratio of about 8 or 9 to produce a biaxially-oriented film having a non-uniform melt temperature of a peak value of less than 160.degree. C. The polypropylene polymer has meltflow index of less than 5 grams per 10 minutes and has an average molecular weight within the range of 100,000-400,000 grams per mole.

Abstract: A process for the production and treatment of a stereoregular polypropylene, such as isotactic polypropylene in which a polymerization reactor is operated under conditions to react propylene supplied to the reactor to produce a stereoregular propylene polymer fluff. A product stream containing the fluff and unreacted propylene is withdrawn from the reactor and at least a portion of the unreacted propylene is separated from the product stream. The propylene polymer fluff is heated to a temperature sufficient to melt the propylene polymer, and a lactone is incorporated into the propylene polymer. The lactone is a 5,7 dialkyl-3-(2,3 dialkyl phenyl)-3H-benzofuran-2-one, in which the 5,7 and 2,3 substituents are of relatively low molecular weights. The phenyl alkyl substituents, each contain 1 or 2 carbon atoms, and the 5,7 alkyl substituents each contain from 2 to 5 carbon atoms.

Abstract: High-solids air-drying or semi-drying alkyd paints essentially comprise, as binder, a conventional air-drying or semi-drying long-oil or medium-oil alkyd resin, and as reactive diluent an oligomer of polyol, polyisocyanate and unsaturated fatty acids. Use of the oligomer as reactive diluent is also claimed.

Abstract: Bicomponent fibers of isotactic polypropylene and syndiotactic polypropylene, methods of making such fibers and products made thereof.

Abstract: 2-trihalogenomethyl-3-halogeno-4-cyano pyrrole derivatives which are substituted in position 5 and optionally in position 1 are used as barnaclecide in antifouling paints, which can therefore be formulated as light- or bright-colored, particularly as bright white. The halogens in positions 2 and 3 are independently selected from the group consisting of florine, chlorine and bromine, preferably florine in position 2 and bromine in position 3. The substituent in position 5 is selected from the group consisting of C1-8 alkyl, C1-8 monohalogenoalkyl, C5-6 cycloalkyl, C5-6 monohalogenocycloalkyl, benzyl, phenyl, mono- and di-halogeno-benzyl or -phenyl, mono- and di-C1-4 alkyl benzyl or phenyl, and monohalogeno mono-C1-4-alkyl benzyl or phenyl, the halogen being selected from the group consisting of chlorine and bromine, prefereably chlorine; the most preferred substituent in position 5 is parachlorophenyl.

Abstract: Bridged metallocenes of Group IVb metals provide improved results when the bridge comprises a neutral electron-donor substituent of general formulaR'"Z R"".sub.jwhereinR'" is a rigid unsaturated hydrocarbon radical between Z and the bridge, such that Z is separated from the bridge by 2 to 5 carbon atomsZ is nitrogen, phosphorus, oxygen or sulphur,R"" is H or an alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl having a maximum of 15 carbon atoms, each R"" being the same or different,j is 1 when Z=O or S and 2 when Z=N or P.

Abstract: Process for the preparation of polyethylene by the homopolymerization of ethylene or by the copolymerization of ethylene and of at least one alpha-olefinic comonomer containing from 3 to 10 carbon atoms, in two reactors for loop polymerization in liquid phase which are connected in series in the presence of a chromium catalyst, in which ethylene and the chromium catalyst are first introduced into the first reactor at a temperature of 95 to 110.degree. C. to produce an ethylene homopolymer of low molecular weight of a melt index MI.sub.2 of at least 1 g/10 minutes and in which the ethylene homopolymer thus obtained is next transferred into the second reactor to which ethylene and optionally the alpha-olefinic comonomer is added, at a temperature of 80 to 90.degree. C. to obtain an ethylene copolymer of high molecular weight.

Abstract: Ethylbenzene is produced by alkylation over a split load of monoclinic silicalite alkylation catalysts having different silica/alumina ratios. A feedstock containing benzene and ethylene is applied to a multi-stage alkylation reaction zone having a plurality of series-connected catalyst beds. At least one catalyst bed contains a first monoclinic silicalite catalyst having a silica/alumina ratio of at least 275. At least one other catalyst bed contains a second monoclinic silicalite catalyst having a silica/alumina ratio of less than about 275. The alkylation reaction zone is operated at temperature and pressure conditions in which the benzene is in a gaseous phase to cause gas-phase alkylation of the aromatic substrate in the presence of the monoclinic silicalite catalysts to produce an alkylation product. The alkylation product is then withdrawn from the reaction zone for separation and recovery.

Abstract: A process for eliminating color from vinyl aromatic/conjugated diene copolymers which process comprises treating the copolymers with a monocarboxylic acid having the general formula R--COOH, where R is a hydrocarbon radical comprising 2 to 4 carbon atoms and R further comprises linear or branched aliphatic radicals, cycloaliphatic radicals, alkenic radicals, aromatic radicals or alkylaromatic radicals.

Abstract: Powder compositions comprising about 5-15 wt % of PVdF-compatible thermoplastic resin, about 50-90 wt % of a thermosetting binder system, about 0-35 wt % of pigments and about 0-3 wt % of leveling agent are disclosed which are particularly suitable for use as primers with a later application of a pigmented PVdF-based top coating. Preferred compositions are based on an epoxy system containing about 8 wt % of PVdF or acrylic thermoplastic resin, 5-25 wt % of pigments and 0.7-1 wt % of leveling agent.