A gas-phase polymerization reactor for the gas-phase polymerization of olefins including a polymerization zone having a recycle line for (a) withdrawing reaction gas from the reactor, (b) leading the reaction gas through a heat-exchanger for cooling, and (c) feeding the reaction gas back to the reactor, wherein the recycle line has the heat-exchanger, a centrifugal compressor having variable guide vanes, and a butterfly valve, and a related process for preparing an olefin polymer in the gas-phase polymerization reactor.

A system and method for producing 1-butene and ultra-high-molecular-weight polyethylene (UHMWPE), including feeding a catalyst, an antifouling co-catalyst, and ethylene to a reactor, and dimerizing ethylene into 1-butene and polymerizing a relatively small portion of the ethylene into UHMWPE. A product slurry including 1-butene and UHMWPE is discharged from reactor and UHMWPE is removed from the product slurry as a coproduct of the product 1-butene. The coproduct UHMWPE may be a byproduct that is a relatively small amount of the product slurry. The quantity of UHMWPE produced may be small in comparison to the quantity of 1-butene produced.

Polymerization process control methods for making polyethylene are provided. The process control methods include performing a polymerization reaction in a polymerization reactor to produce the polyethylene, where ethylene, and optionally one or more comonomers, in the polymerization reaction is catalyzed by an electron donor-free Ziegler-Natta catalyst and an alkyl aluminum co-catalyst. A melt flow ratio (I.sub.21/I.sub.2) of the polyethylene removed from the polymerization reactor is measured and an amount of long chain branching (LCB) of the polyethylene from the polymerization reactor is controlled by adjusting a weight concentration of the alkyl aluminum co-catalyst present in the polymerization reactor. In addition, an electron donor-free Ziegler-Natta catalyst productivity of the polyethylene being produced in the polymerization reactor is measured from which the amount of LCB of the polyethylene from the polymerization reactor is determined using the measured electron donor-free Ziegler-Natta catalyst productivity and a predetermined relationship between the electron donor-free Ziegler-Natta catalyst productivity and the LCB.

Embodiments of the present disclosure directed towards polymerization catalysts having improved ethylene enchainment. As an example, the present disclosure provides a polymerization catalyst having improved ethylene enchainment, the polymerization catalyst comprising a zirconocene catalyst of Formula (I) where R.sub.1 is a C.sub.1 to C.sub.20 alkyl, aryl or aralkyl group, wherein R.sub.2 is an C.sub.1 to C.sub.20 alkyl, aryl or aralkyl group, and where R.sub.3 is a C.sub.1 to C.sub.20 alkyl or a hydrogen, and where each X is independently a halide, C.sub.1 to C.sub.20 alkyl, aralkyl group or hydrogen. ##STR00001##

A gas-phase polymerization reactor for the gas-phase polymerization of olefins including a polymerization zone having a recycle line for (a) withdrawing reaction gas from the reactor, (b) leading the reaction gas through a heat-exchanger for cooling, and (c) feeding the reaction gas back to the reactor, wherein the recycle line has the heat-exchanger, a centrifugal compressor having variable guide vanes, and a butterfly valve, and a related process for preparing an olefin polymer in the gas-phase polymerization reactor.

A system and method for producing 1-butene and ultra-high-molecular-weight polyethylene (UHMWPE), including feeding a catalyst, an antifouling co-catalyst, and ethylene to a reactor, and dimerizing ethylene into 1-butene and polymerizing a relatively small portion of the ethylene into UHMWPE. A product slurry including 1-butene and UHMWPE is discharged from reactor and UHMWPE is removed from the product slurry as a coproduct of the product 1-butene. The coproduct UHMWPE may be a byproduct that is a relatively small amount of the product slurry. The quantity of UHMWPE produced may be small in comparison to the quantity of 1-butene produced.

Catalytic compositions comprising permethylpentalene based metallocene complexes supported on solid methylaluminoxane are disclosed. The compositions are effective catalysts/initiators in the polymerisation of olefins. Also disclosed are uses of the compositions in olefin polymerisation.

The present invention relates to Ziegler-Natta catalyst components for olefin polymerization employing specific carbonate compounds as an element of solid catalyst composition in conjunction with at least one or more internal donor compounds, for producing polyolefins, particularly polypropylene and ethylene-propylene block co-polymer, which exhibits substantially high rubber content with higher stereo-regularity and hydrogen response.

A process for reducing the loss of catalyst activity of a Ziegler-Natta catalyst is provided. The process includes preparing a Ziegler-Natta (ZN) catalyst by contacting the ZN catalyst with at least one aluminum alkyl compound to produce a reduced ZN catalyst and storing and/or transporting the reduced ZN catalyst for at least 20 days at a temperature of 25 C. or less. The reduced ZN catalyst may be used for polymerizing polyolefin polymers.

Embodiments of the present disclosure directed towards polymerization catalysts having improved ethylene enchainment. As an example, the present disclosure provides a polymerization catalyst having improved ethylene enchainment, the polymerization catalyst comprising a zirconocene catalyst of Formula (I) where R.sub.1 is a C.sub.1 to C.sub.20 alkyl, aryl or aralkyl group, wherein R.sub.2 is an C.sub.1 to C.sub.20 alkyl, aryl or aralkyl group, and where R.sub.3 is a C.sub.1 to C.sub.20 alkyl or a hydrogen, and where each X is independently a halide, C.sub.1 to C.sub.20 alkyl, aralkyl group or hydrogen.

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