摘要:
A method comprising (a) contacting a support and a chromium-containing compound to form chromium-containing support, (b) heat treating the chromium-containing support in an oxidizing atmosphere to form a treated support, (c) contacting the treated support with carbon monoxide to form a CO-contacted support, and (d) contacting the CO-contacted support with hydrogen to form a catalyst. A method comprising oxidizing a chromium-treated support to form a polymerization catalyst, contacting the polymerization catalyst with carbon monoxide to form a reduced polymerization catalyst, contacting the reduced polymerization catalyst with hydrogen to form an activated polymerization catalyst, and contacting the activated polymerization catalyst with ethylene in a reaction zone under suitable reaction conditions to form a random copolymer. A method comprising reducing a polymerization catalyst comprising Cr(VI) to form a polymerization catalyst comprising Cr(II), and treating the polymerization catalyst comprising Cr(II) with hydrogen.
摘要:
Methods and systems for preparing catalyst, such as chromium catalysts, are provided. The valence of at least a portion of the catalyst sent to an activator is changed from Cr(III) to Cr(VI). The catalyst is prepared or activated continuously using a fluidization bed catalyst activator.
摘要:
A system and method for activating chromium catalyst, including: increasing temperature of a chromium catalyst at a first rate for a first period of time to a first temperature; and increasing temperature of the chromium catalyst at a second rate for a second period of time from the first temperature to a second temperature, wherein the first rate is greater than the second rate, and wherein the first period precedes the second period.
摘要:
Silica-coated alumina activator-supports, and catalyst compositions containing these activator-supports, are disclosed. Methods also are provided for preparing silica-coated alumina activator-supports, for preparing catalyst compositions, and for using the catalyst compositions to polymerize olefins.
摘要:
This invention relates to the field of olefin polymerization catalyst compositions, and methods for the polymerization and copolymerization of olefins, including polymerization methods using a supported catalyst composition. In one aspect, the present invention encompasses a catalyst composition comprising the contact product of a first metallocene compound, a second metallocene compound, at least one chemically-treated solid oxide, and at least one organoaluminum compound. The new resins were characterized by useful properties in impact, tear, adhesion, sealing, extruder motor loads and pressures at comparable melt index values, and neck-in and draw-down.
摘要:
This invention relates to the field of olefin polymerization catalyst compositions, and methods for the polymerization and copolymerization of olefins, typically using a supported catalyst composition. In one aspect, this invention encompasses precontacting a metallocene with an olefin or alkyne monomer and an organoaluminum compound, prior to contacting this mixture with the acidic activator-support.
摘要:
New methods for activating chromium catalysts for polymerization processes decrease the amount of time required for activation and increase catalyst activity. Rapid heating to a first temperature is followed by a first hold period before heating to a higher second temperature and maintaining the second temperature for a second hold period. In one aspect, the overall activation process takes less than 10 hours.
摘要:
The present invention provides activator-supports containing alumina-silica compounds with high levels of alumina, and polymerization catalyst compositions employing these activator-supports. Methods for making these activator-supports based on alumina-silica and for using such compounds in catalyst compositions for the polymerization and copolymerization of olefins are also provided.
摘要:
This invention relates to catalyst compositions comprising a first metallocene compound, a second metallocene compound, at least one chemically-treated solid oxide, and at least one organoaluminum compound. This invention also relates to methods to prepare and use the catalyst compositions and new polyolefins. The compositions and methods disclosed herein provide ethylene polymers and copolymers with lower MI, increased melt strength, and good MD tear properties.
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 contacting an organometal compound, an organoaluminum compound, and a treated solid oxide compound.