Abstract: A process for producing ultra fine silica particles, the process comprising directing a plasma jet onto a silicon-containing compound thereby to form silica vapor and condensing the silica vapor on a collection surface.

Abstract: The present invention relates to a supported chromium-based catalyst titanated under specific conditions and used for the homopolymerisation or the copolymerisation of ethylene. The polyethylene obtained with this catalyst has high shear resirance and environmental stress crack resistance, and can be used for manufacturing films with improved tear properties.

Abstract: The present invention relates to a chromium/silca-aluminophosphate catalyst, titanated under specific conditions and used for the homopolymerisation or the copolymerisation of ethylene. The polyethylene obtained with this catalyst has a high melt potential and a high shear resistance. The catalyst has a high level of activity.

Abstract: A process for preparing polyethylene, including contacting ethylene monomer and an alpha-olefin comonomer to produce a first polyethylene (HLMI of ≦0.5 g/10 min, density ≦0.925 g/ml). The a catalyst system is a bis tetrahydroindenyl formula (IndH4)2R″MQ2 wherein each Ind is the same or different and is indenyl or substituted indenyl, R″ is a bridge which comprises a C1-C20 alkylene radical, a dialkyl germanium or silicon or siloxane, or an alkyl phosphine or amine radical, which bridge is substituted or unsubstituted, M is a Group IVB transition metal or vanadium and each Q is hydrocarbyl having 1 to 20 carbon atoms or halogen. The polyethylene resin having multimodal molecular weight distribution is formed by mixing the first polyethylene with a second polyethylene (produced with a different catalyst and with a lower molecular weight and higher density than the first polyethylene).

Abstract: The present invention relates to a process for preparing silica-alumina carriers preferably under the form of extrudates. Further, the present invention also provides hydrogenation catalysts prepared thereof. These catalysts are used in an improved process for the reduction of the aromatic hydrocarbons content present in hydrocarbon streams.

Abstract: Metallocene catalysts useful for the preparation of syndiotactic/atactic block polyolefins have the general formula R″(C4R′mC5C4R′n)XMeQ wherein X is an hetero-atom ligand with one or two lone pair electrons selected from the elements of Group VA or VIA which can be substituted or non-substituted; (C4Rm′C5C4Rn′) is a fluorenyl or a symmetrically substituted fluorenyl or cyclopentadienyl ring; R′ is hydrogen or hydrocarbyl radical having from 1-20 carbon atoms, a halogen, an alkoxy, and alkoxy alkyl or an alkylamino or alkylsilylo radical, each R′ may be the same or different and m and n independently are 0, 1, 2, 3 or 4, with the proviso that the bilateraly symmetry is maintained; R″ is a structural bridge between X and the (C4R′mC5C4R′n) ring to impart stereorigidity; Q is a hydrocarbyl radical having 1-20 carbon atoms or is a halogen; Me is a Group IIIB, IVB, VB, or VIB metal as positioned in the Periodic Table of Elements; and Me can be in any o

Abstract: Substituted 1,4,2-oxathiazines and their mono- and di-oxides, disclosed in WO-A-9505739, are used as additive to increase the self-polishing properties of antifouling paints. The additive is used in an amount of 0.5 to 9.9 wt. %, based on the total weight of the dry mass of the composition, preferably 1 to 8 wt. %, most preferably 2 to 4 wt. %. The preferred additive is 3-(3,4-dichlorophenyl)-5,6-dihydro-1,4,2-oxathiazine dioxide.

Abstract: Provided is a high density multimodal polyethylene, having a shear ratio (SR) of 18 or more and a HLMI of 15 g/10 mins or less comprising at least 20% by weight of a high molecular weight fraction, which high molecular weight fraction has: (a) a density (&rgr;) of 0.930 g/cm3 or less; and (b) a high load melt index (HLMI) of 0.30 g/10 mins or less.

Abstract: A process for producing a polyethylene resin having a monomodal molecular weight distribution in a single polymerisation reactor using a chromium-based catalyst system, by copolymerising ethylene and an alpha-olefinic-comonomer having from 3 to 8 carbon atoms, the polyethylene resin comprising a blend of a higher molecular weight fraction polymerised by a first chromium-based catalyst of the system and a lower molecular weight fraction polymerised by a second chromium-based catalyst of the system, wherein the comonomer incorporation in the higher molecular weight fraction is greater than the comonomer incorporation in the lower molecular weight fraction is greater than the comonomer incorporation in the lower molecular weight fraction whereby the higher and lower molecular weight fractions differ in density by from 0.01 to 0.03 g/cc.

Abstract: The present invention relates to a chromium/silica-aluminophosphate catalyst, titanated under specific conditions and used for the homopolymerisation or the copolymerisation of ethylene. The polyethylene obtained with this catalyst has a high melt potential and a high shear resistance. The catalyst has a high level of activity.

Abstract: A process for the production of a magnesium chloride powder for use in a catalyst, the process comprising vaporizing magnesium chloride in a plasma torch and quenching the vapor with a liquid containing an electron donor to form a magnesium chloride-based powder catalyst wherein at least 80% by weight of the magnesium chloride is present as the hexagonal phase thereof. The invention also relates to a precursor for such a catalyst.

Abstract: A process is disclosed for manufacturing coupled radial block copolymers of the S—B—Li type having improved optical properties, which process utilizes coupling agents having from about 3 to about 7 epoxy groups per mole.

Abstract: A process for producing high density polyethylene having a bimodal molecular weight distribution, the process comprising pre-contacting a chromium-based catalyst with an alkyl metal oxane, the chromium-based catalyst comprising chromium oxide on a silica-containing support, to form a catalyst system wherein the atomic ratio of the metal of the oxane to the chromium is less than 1, and polymerising ethylene or copolymerising ethylene and an alpha-olefinic comonomer comprising from 3 to 10 carbon atoms in the presence of the catalyst system. A catalyst system for polymerising ethylene or copolymerising ethylene and an alpha-olefinic comonomer comprising from 3 to 10 carbon atoms to produce high density polyethylene, the catalyst system comprising in combination a chromium-based catalyst comprising chromium oxide on a silica-containing support and an alkyl metal oxane with which the chromium-based catalyst has been precontacted whereby the atomic ratio of the metal of the oxane to the chromium is less than 1.

Abstract: Use of a catalyst system comprising a metallocene catalyst component of general formula R″ (CpRm) (Cp′R′n) MQ2 supported on an inert support in the slurry phase production of linear low density polyolefin, wherein Cp is a cyclopentadienyl moiety, Cp′ is a substituted or unsubstituted fluorenyl ring; R″ is a structural bridge imparting stereorigidity to the component; each R is independently hydrogen or hydrocarbyl having 1 to 20 carbon atoms in which O≦m≦4; each R′ is independently hydrocarbyl having 1 to 20 carbon atoms in which O≦n≦8; M is a Group IVB transition metal or vanadium; and each Q is hydrocarbyl having 1 to 20 carbon atoms or halogen; the metallocene having a centroid-M-centroid angle in the range 105° to 125°.

Abstract: A process for cracking an olefin-containing hydrocarbon feedstock which is selective towards light olefins in the effluent, the process comprising passing a hydrocarbon feedstock containing one or more olefins through a reactor containing a crystalline silicate selected from an MFI-type crystalline silicate having a silicon/aluminium atomic ratio of at least 180 and an MEL-type crystalline silicate having a silicon/aluminium atomic ratio of from 150 to 800 which has been subjected to a steaming step, at an inlet temperature of from 500 to 600° C., at an olefin partial pressure of from 0.1 to 2 bars and the feedstock being passed over the catalyst at an LHSV of from 5 to 30h−1 to produce an effluent with an olefin content of lower molecular weight than that of the feedstock.

Abstract: A metallocene compound having the general formula: CpAXMQ1Q2Cp′A′X′M′Q1′Q2′ wherein Cp and Cp′ are each independently a substituted or unsubstituted cyclopentadienyl moiety; M and M′ are each independently a metal chosen from Group IV B transition metals and vanadium, and coordinate to Cp and Cp′ respectively; X and X′ are each independently a substituted or unsubstituted Group VA or VIA heteroatom and coordinate to M and M′ respectively; A and A′ are bridging groups between Cp and X and between Cp′ and X′ respectively and are independently chosen from —SiR′2—O—SiR′2—, —SinR′m—, —CnR′m— and —CR′2—SiR′2—CR′2—SiR′2—, in which each R′ is independently H or hydrocarbyl having 1 to 20 carbon atoms, n is an integer in the range 1 to 4 and m=2n; each Q1, Q2 and Q1′ and Q2′ is independe

Abstract: A pipe fitting for coupling together opposed ends of two plastics pipes by fusion welding, the pipe fitting comprising an annular body having an inner cylindrical surface of plastics material surrounding a cylindrical cavity for receiving opposed ends of two plastics pipes to be coupled together, an electrically conductive coil provided in said inner cylindrical surface and surrounding the cylindrical cavity, the coil having opposed ends, a pair of terminals each connected to a respective end of the coil and provided on the body for connection to a source of controlled electrical power, and an annular reinforcing member disposed in the body and surrounding the coil, the annular reinforcing member having a grooved surface which interfaces the annular body, the grooved surface defining a plurality of axially facing surfaces.

Abstract: A process for producing high density polyethylene suitable for blow molding and having high environmental stress cracking resistance and rigidity copolymerizing ethylene and an alpha-olefinic comonomer comprising from 3 to 10 carbon atoms, in the presence of a chromium-based catalyst, having an alumina-containing support, and an organoboron compound, wherein the atomic ratio of boron in the organoboron compound to the chromium in the chromium-based catalyst is from around 0.2 to around 0.4.

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

Abstract: A process for cracking an olefin-rich hydrocarbon feedstock which is selective towards propylene in the effluent, the process comprising contacting a hydrocarbon feedstock containing one or more olefinic components of C4 or greater with a crystalline silicate catalyst to produce an effluent having a second composition of one or more olefinic components of C3 or greater, the feedstock and the effluent having substantially the same olefin content by weight therein characterized in that ethylene is added to the feedstock before the feedstock contacts the catalyst.