A system and method of producing polyethylene, including: polymerizing ethylene in presence of a catalyst system in a reactor to form polyethylene, wherein the catalyst system includes a first catalyst and a second catalyst; and adjusting reactor conditions and an amount of the second catalyst fed to the reactor to control melt index (MI), density, and melt flow ratio (MFR) of the polyethylene.

Activators may comprise compounds represented by the Formula [Ar(EHR.sup.1R.sup.2)(OR.sup.3)]d+[M.sup.k+Q.sub.n].sup.d, wherein: Ar is an aryl group; E is nitrogen or phosphorous; R.sup.1 is a C.sub.1-C.sub.30, optionally substituted, linear alkyl group; R.sup.2 is a C.sub.1-C.sub.30, optionally substituted, linear alkyl group; R.sup.3 is a C.sub.10-C.sub.30, optionally substituted, linear alkyl group; M is an element selected from group 13 of the Periodic Table of the Elements; d is 1, 2 or 3; k is 1, 2, or 3; n is 1, 2, 3, 4, 5, or 6; n−k=d; and each Q is independently hydride, bridged or unbridged dialkylamido, halide, alkoxide, aryloxide, hydrocarbyl, substituted hydrocarbyl, halocarbyl, substituted halocarbyl, or halosubstituted-hydrocarbyl radical. Catalysts systems may comprise these activators and methods of preparing polyolefins may use these catalysts systems.

Activators may comprise compounds represented by the Formula [Ar(EHR.sup.1R.sup.2)(OR.sup.3)]d+[M.sup.k+Q.sub.n].sup.d, wherein: Ar is an aryl group; E is nitrogen or phosphorous; R.sup.1 is a C.sub.1-C.sub.30, optionally substituted, linear alkyl group; R.sup.2 is a C.sub.1-C.sub.30, optionally substituted, linear alkyl group; R.sup.3 is a C.sub.10-C.sub.30, optionally substituted, linear alkyl group; M is an element selected from group 13 of the Periodic Table of the Elements; d is 1, 2 or 3; k is 1, 2, or 3; n is 1, 2, 3, 4, 5, or 6; n−k=d; and each Q is independently hydride, bridged or unbridged dialkylamido, halide, alkoxide, aryloxide, hydrocarbyl, substituted hydrocarbyl, halocarbyl, substituted halocarbyl, or halosubstituted-hydrocarbyl radical. Catalysts systems may comprise these activators and methods of preparing polyolefins may use these catalysts systems.

The present invention relates to substituted 2-iso-propyl-1, 3-dialkoxypropanes, and more particularly to their use as internal donors in Ziegler-Natta catalysts to obtain ethylene (co)polymers with desirable properties. The present disclosure further concerns use of Ziegler-Natta catalyst components comprising said substituted 2-iso-propyl-1, 3-dimethoxypropanes and use of Ziegler-Natta catalysts in ethylene (co)polymerization comprising said Ziegler-Natta catalyst components.

The present invention relates to substituted 2-iso-propyl-1, 3-dialkoxypropanes, and more particularly to their use as internal donors in Ziegler-Natta catalysts to obtain ethylene (co)polymers with desirable properties. The present disclosure further concerns use of Ziegler-Natta catalyst components comprising said substituted 2-iso-propyl-1, 3-dimethoxypropanes and use of Ziegler-Natta catalysts in ethylene (co)polymerization comprising said Ziegler-Natta catalyst components.

The present invention relates to a preparation method of a polypropylene and a polypropylene obtained therefrom. More specifically, it relates to a method of preparing a polypropylene by using a catalyst that includes a novel metallocene compound having an excellent polymerization activity, and a polypropylene obtained by the method. According to the present invention, since the polypropylene is prepared by polymerizing propylene by using a novel metallocene compound having an excellent polymerization activity and hydrogen reactivity, the properties of the polypropylene can be easily controlled and the polypropylene having excellent mechanical properties can be obtained.

The present invention relates to the technical field of catalyst preparation, and discloses a preparation method of a Ziegler-Natta catalyst. The method includes the following steps: subjecting magnesium halide, alcohol and an electron donor to a first contact reaction in the presence of an inert solvent to obtain a magnesium halide alcoholate and performing first cooling; subjecting titanium halide to second cooling; subjecting the cooled titanium halide, the cooled product containing the magnesium halide alcoholate and an electron donor to a second contact reaction; filtering the product of the second contact reaction to obtain the Ziegler-Natta catalyst; and subjecting the Ziegler-Natta catalyst and the heated titanium halide to a third contact reaction. The method has the advantages such as short cycle, high efficiency, etc., being suitable to industrial production.

The present invention relates to the technical field of catalyst preparation, and discloses a preparation method of a Ziegler-Natta catalyst. The method includes the following steps: subjecting magnesium halide, alcohol and an electron donor to a first contact reaction in the presence of an inert solvent to obtain a magnesium halide alcoholate and performing first cooling; subjecting titanium halide to second cooling; subjecting the cooled titanium halide, the cooled product containing the magnesium halide alcoholate and an electron donor to a second contact reaction; filtering the product of the second contact reaction to obtain the Ziegler-Natta catalyst; and subjecting the Ziegler-Natta catalyst and the heated titanium halide to a third contact reaction. The method has the advantages such as short cycle, high efficiency, etc., being suitable to industrial production.

A process for washing a particulate substance comprising: (i) combining a particulate substance and a first washing medium in a first vessel to form a slurry and washing the particulate substance with said washing medium; (ii) transferring the slurry to a hydrocyclone; (iii) removing a first by-product stream depleted in particulate substance and a first product stream enriched in particulate substance from the hydrocyclone; (iv) transferring the first product stream to a second vessel and in the presence of a second washing medium forming a slurry and washing the particulate substance with said second washing medium e.g. by agitation thereof; (v) transferring the slurry to a hydrocyclone; (vi) removing a second by-product stream depleted in particulate substance and a second product stream enriched in particulate substance from the hydrocyclone.

A process for washing a particulate substance comprising: (i) combining a particulate substance and a first washing medium in a first vessel to form a slurry and washing the particulate substance with said washing medium; (ii) transferring the slurry to a hydrocyclone; (iii) removing a first by-product stream depleted in particulate substance and a first product stream enriched in particulate substance from the hydrocyclone; (iv) transferring the first product stream to a second vessel and in the presence of a second washing medium forming a slurry and washing the particulate substance with said second washing medium e.g. by agitation thereof; (v) transferring the slurry to a hydrocyclone; (vi) removing a second by-product stream depleted in particulate substance and a second product stream enriched in particulate substance from the hydrocyclone.