The present invention relates to a supported hybrid vanadium-chromium-based catalyst, characterized in the catalyst is supported on a porous inorganic carrier and a V active site and a inorganic Cr active site are present on the porous inorganic carrier at the same time. The present invention further relates to a process for producing a supported hybrid vanadium-chromium-based catalyst. The invention also provides the preparation method of the catalyst, titanium or fluorine compounds, vanadium salt and chromium salt according to the proportion, different methods of sequence and load on the inorganic carrier, after high temperature roasting, still can further add organic metal catalyst promoter prereduction activation treatment on it. The catalyst of the present invention can be used for producing ethylene homopolymers and ethylene/α-olefin copolymers. The hybrid vanadium-chromium-based catalyst can have high activity and produce polyethylene polymers having the properties of broad molecular weight distribution (Part of the products are bimodal distribution) and excellent α-olefin copolymerization characteristic.

The present invention relates to a supported hybrid vanadium-chromium-based catalyst, characterized in the catalyst is supported on a porous inorganic carrier and a V active site and a inorganic Cr active site are present on the porous inorganic carrier at the same time. The present invention further relates to a process for producing a supported hybrid vanadium-chromium-based catalyst. The invention also provides the preparation method of the catalyst, titanium or fluorine compounds, vanadium salt and chromium salt according to the proportion, different methods of sequence and load on the inorganic carrier, after high temperature roasting, still can further add organic metal catalyst promoter prereduction activation treatment on it. The catalyst of the present invention can be used for producing ethylene homopolymers and ethylene/α-olefin copolymers. The hybrid vanadium-chromium-based catalyst can have high activity and produce polyethylene polymers having the properties of broad molecular weight distribution (Part of the products are bimodal distribution) and excellent α-olefin copolymerization characteristic.

Disclosed herein are a chromium compound represented by Formula 1a or 1b and a catalyst system including the same, exhibiting superior catalytic activity in an olefin trimerization reaction:

[{CH.sub.3(CH.sub.2).sub.3CH(CH.sub.2CH.sub.3)CO.sub.2}.sub.2Cr(OH)]  [Formula 1a]

[{CH.sub.3CH.sub.2CH(CH.sub.2CH.sub.3)CO.sub.2}.sub.2Cr(OH)]  [Formula 1b].

Disclosed herein are a chromium compound represented by Formula 1a or 1b and a catalyst system including the same, exhibiting superior catalytic activity in an olefin trimerization reaction:

[{CH.sub.3(CH.sub.2).sub.3CH(CH.sub.2CH.sub.3)CO.sub.2}.sub.2Cr(OH)]  [Formula 1a]

[{CH.sub.3CH.sub.2CH(CH.sub.2CH.sub.3)CO.sub.2}.sub.2Cr(OH)]  [Formula 1b].

The present invention relates to an oligomerization catalyst including a transition metal or transition metal precursor, a halogen-substituted organic ligand, and a heteroatom ligand, and to a method for selectively preparing 1-hexene or 1-octene from ethylene using the catalyst.

The present invention relates to an oligomerization catalyst including a transition metal or transition metal precursor, a halogen-substituted organic ligand, and a heteroatom ligand, and to a method for selectively preparing 1-hexene or 1-octene from ethylene using the catalyst.

Processes for producing an activated chromium catalyst are disclosed, and these processes comprise contacting a supported chromium catalyst with a gas stream containing from 25-60 vol % oxygen at a peak activation temperature of 550-900° C. to produce the activated chromium catalyst. The linear velocity of the gas stream is 0.18-0.4 ft/sec, and the oxygen linear velocity of the gas stream is 0.05-0.15 ft/sec. The resultant activated chromium catalyst and an optional co-catalyst can be contacted with an olefin monomer and an optional olefin comonomer in a polymerization reactor system under polymerization conditions to produce an olefin polymer.

The present specification relates to an olefin oligomerization method and specifically to an olefin oligomerization method comprising the step of subjecting an olefin to a multimerization reaction by controlling a reaction temperature such that the weight ratio of 1-hexene to 1-octene within a product comprising 1-hexene and 1-octene has a predetermined value, in the presence of an oligomerization catalyst system comprising a ligand compound, a transition metal compound, and a cocatalyst, wherein the predetermined value for the weight ratio of 1-hexene to 1-octene within the product is selected in a range of 1:0.5 to 1:7. By the method, 1-hexene and 1-octene can be produced in a desired ratio.

The present invention relates to a compound represented by the chemical formula 1, a catalyst system for olefin oligomerization comprising the same, and a method for oligomerizign olefins using the same, and the catalyst system for olefin oligomerization according to the present invention has excellent catalytic activity as well as high selectivity for 1-hexene or 1-octene, thereby enabling more efficient preparation of alpha-olefins.

Provided herein are polyethylene compositions with unimodal molecular weight distribution exhibiting an excellent balance of physical properties. The polyethylene compositions may have density of 0.935 to 0.975 g/cm.sup.3 and Melt Index (I.sub.2.16) of 0.1 to 1 g/10 min. Polyethylene compositions of certain embodiments may exhibit environmental stress crack resistance (ESCR, 10% Igepal, ASTM D1693 Cond. B) within the range from 45 to 80 hours, and/or (ESCR, 100% igepal, ASTM D1693 Cond. B) within the range from 70 to 250 hours. Such ESCR outperforms other unimodal resins of similar melt index and density, approaching ESCR performance of more expensive and complex resins with bimodal molecular weight distribution. The polyethylene compositions of certain embodiments may have two distinct crystalline fractions as shown by temperature rising elution fractionation (TREF).