摘要:
Polymerization processes for ethylene and at least one mono-1-olefin comonomer having from about three to eight carbon atoms per molecule in the presence of a twice-aged catalyst system comprising chromium supported on a silica-titania support and a trialkylboron compound is provided. Novel ethylene copolymers also are produced.
摘要:
A novel magnesium treated silica-containing compound that is useful as a support for chromium based olefin polymerization catalyst systems is provided which produces ethylene polymers having with MWD's that promote good properties particularly in HMW film applications.
摘要:
A copolymer of ethylene and a higher alpha olefin, preferably 1-hexene, can be produced using an activated chromium containing catalyst system and a cocatalyst selected from the group consisting of trialkylboron, trialkylsiloxyaluminum, and a combination of trialkylboron and trialkylaluminum compounds. The polymerization process must be carefully controlled to produce a copolymer resin having an exceptionally broad molecular weight distribution, extremely high PENT ESCR values, and a natural branch profile that impacts branching preferably into the high molecular weight portion of the polymer. The resulting copolymer resin is especially useful in high stiffness pipe applications.
摘要:
An olefin polymerization process is provided comprising contacting an olefin monomer with chromium oxide on a titanium containing silica support having less than about 3 weight percent titanium in combination with an organoboron promoter. Polymers thus produced are useful for blow molding applications.
摘要:
Bridged fluorenyl-containing metallocenes of metals of Groups 4-6 and their use in forming homopolymers of alpha olefins or polymers of ethylene and optionally minor amounts of alpha olefins, wherein in each case at least one of the cyclic groups of the bridged ligand is a fluorenyl and the other is selected from indenyl, tetrahydroindenyl, fluorenyl, and in the case of the polymerization of ethylene optionally cyclopentadienyl.
摘要:
This invention provides catalyst composition for polymerizing at least one monomer to produce a polymer, wherein said catalyst composition comprises as organometal compound, as organoaluminum compound, and a fluorided solid oxide compound.
摘要:
This invention provides catalyst compositions that are useful for polymerizing at least one monomer to produce a polymer. This invention also provides catalyst compositions that are useful for polymerizing at least one monomer to produce a polymer, wherein said catalyst composition comprises a post-contacted organometal compound, a post-contacted organoaluminum compound, and a post-contacted treated solid oxide compound. The post-contacted treated solid oxide compound has been treated with a vanadium compound, calcied, then treated with a halogen-containing compound.
摘要:
This invention provides a chromium catalyst system that comprises[a] a support that comprises silica, wherein said support has a surface area to pore volume relationship as follows0.5.ltoreq.Pore volume.ltoreq.f(SA)wherein said f(SA) is(1.14.times.10.sup.-7)(SA).sup.3 -(1.19.times.10.sup.-4)(SA).sup.2 +(3.19.times.10.sup.-2)(SA)+0.20;and[b] a hexavalent chromium compound;wherein the surface concentration of said hexavalent chromium on said support is from 0.25 to 1 hexavalent chromium atoms per square nanometer.Another embodiment of this invention provides a process to homopolymerize ethylene, or copolymerize ethylene with a comonomer, said process comprises polymerizing ethylene with the above chromium catalyst composition.
摘要:
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.
摘要:
A catalyst system for the polymerization of alpha-olefins comprising a chromium-containing catalyst and an yttrium-containing catalyst wherein the yttrium-containing catalyst is represented by the formula (Cp.sub.2 YX.sub.x).sub.y.M.sub.z L.sub.n, wherein Cp is cyclopentadienyl or cyclopentadienyl substituted with alkyl or alkyl silyl radical or radicals, X is a halogen, M is an alkali metal, L is a suitable electron donor ligand, x is 1 or 2, y is 1 or 2, z is 0 or 1, and n is a number corresponding to the value needed to form a stable complex, with the proviso that when y is 2, z and n are 0 is provided. Also disclosed is a polymerization process employing such a catalyst system, and novel olefin polymers. Polymers thus produced exhibit high bulk density and a broad molecular weight distribution.