Abstract:
A process for the gas-phase polymerization of one or more alpha-olefins in the presence of a polymerization catalyst system, the process comprising: a) contacting in a continuous way a gas comprising one or more of said alpha-olefins with said catalyst system in a gas-phase tubular reactor at a temperature from 30°C to 130°C in order to obtain a polymerization degree up to 500 grams per gram of catalyst system; b) feeding in continuous the prepolymer from step a) to a successive gas-phase polymerization reactor; wherein said gas-phase tubular reactor has a length/diameter ratio higher than 100.
Abstract:
The present disclosure provides a catalyst system made from or containing: (A) a solid catalyst component made from or containing (i) a titanium compound supported on a magnesium dichloride; (B) an aluminum alkyl compound; and (C) a halogenated organic ester of formula A-COOR, wherein R is a C1-C10 hydrocarbon group and A is a C1-C15 saturated or unsaturated hydrocarbon group in which at least one of the hydrogen atoms is replaced by a chlorine atom. The present disclosure also provides a process for preparing an olefinic polymer, including a polymerization step of polymerizing an olefin in the presence of the catalyst system. The present disclosure also provides an olefinic polymer made therefrom.
Abstract:
Feeding a supported antistatic compound that does not comprise a transition-metal-based catalyst component to an olefin polymerization reactor allows avoiding the formation of polymer agglomerates in the reactor while at the same time minimizing negative effects on catalyst yield.
Abstract:
The present invention relates to butene-1 copolymers containing up to 40% by mol of ethylene and/or propylene derived characterized by the following properties: d) Product of the reactivity ratios rl·r2≤2; e) Content of butene-1 units in form of isotactic pentads (mmmm)>98%; and f) absence of 4,1 insertions of butene units.
Abstract:
A process for introducing a catalyst powder based on a titanium compound supported on magnesium halide into a gas-phase olefin polymerization reactor, characterized in that it comprises: (a) storing the catalyst powder under an atmosphere of a liquid C 3 -C 12 alkane; (b) withdrawing from step (a) a measured amount of said catalyst powder by means of a rotary valve; (c) transferring said metered amount of catalyst powder to a catalyst activation section by a continuous pick-up flow of a liquid C 3 -C 12 alkane; (d) contacting the catalyst powder with a liquid phase comprising an organo-aluminum compound and optionally an external donor compound, at a temperature ranging from -20 °C to 60 °C; (e) introducing the activated catalyst powder in one or more gas-phase olefin polymerization reactors, where a gaseous mixture comprising at least one alpha-olefin is subjected to polymerization.
Abstract:
The present disclosure provides a gas-phase polymerization process for preparing polyethylene, wherein halogenated alcohols in combination with a Ti based catalyst component and aluminum alkyls as co-catalyst suppress ethane formation or increase polymerization activity.
Abstract:
The present disclosure provides a gas-phase polymerization process for preparing polyethylene, wherein halogenated alcohols in combination with a Ti based catalyst component and aluminum alkyls as co-catalyst suppress ethane formation or increase polymerization activity.
Abstract:
Catalyst component comprising Mg, Ti, and halogen atoms, and is characterized in that (a) the Ti atoms are present in an amount higher than 4% based on the total weight of the said catalyst component, (b) the amount of Mg and Ti atoms is such that the Mg/Ti molar ratio is higher than 2 and (c) by a X-ray diffraction spectrum, in which, in the range of 2θ diffraction angles between 47° and 52°, at least two diffraction lines are present at diffraction angles 2θ of 48.3 ± 0.2°, and 50.0 ± 0.2°, the most intense diffraction lines being the one at 2θ of 50.0 ± 0.2°, the intensity of the other diffraction line being equal to or lower than the intensity of the most intense diffraction line.
Abstract:
A process for the gas-phase polymerization of α-olefÊns CH2=CHR, where R is hydrogen or a hydrocarbon radical having 1-12 carbon atoms, carried out in a first and a second interconnected polymerization zones, wherein the growing polymer particles flow through the first of said polymerization zones (riser) under fast fluidization conditions, leave said riser and enter the second of said polymerization zones (downcomer) through which they flow downward in a densified form, leave said downcomer and are reintroduced into said riser, in which process: (a) the gas mixture present in the riser is totally or partially prevented from entering the downcomer, and (b) the gaseous composition inside a portion of the downcomer is maintained substantially similar to the gaseous composition reacting in the riser.