Oligomerization catalyst and method for preparing ethylene oligomer using same

1. A mononuclear or binuclear oligomerization catalyst comprising:

a transition metal or transition metal precursor,

a halogen-substituted organic ligand, and

a heteroatom ligand,

wherein the halogen-substituted organic ligand is a monovalent anionic bidentate organic ligand that coordinates to a transition metal through a non-bonding electron pair of a carbon atom or a heteroatom selected from nitrogen, oxygen and sulfur, and

wherein the heteroatom ligand is a ligand having a P—C—C—P skeleton structure represented by Chemical Formula 2 below, a ligand having a P—N—P skeleton structure represented by Chemical Formula 3 below, or a ligand having a P—C═C—P skeleton structure represented by Chemical Formula 4 below:

in Chemical Formulas 2 to 4,

R 11 to R 14 are each independently hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl, or substituted heterohydrocarbyl;

R 15 to R 16 are each independently hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl, substituted heterohydrocarbyl, or substituted heteroatom; and

R 17 to R 18 are each independently hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl, substituted heterohydrocarbyl, or substituted heteroatom,

wherein the halogen-substituted organic ligand is selected from the following structures:

wherein R 1 and R 2 are each independently halogen, hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl or substituted heterohydrocarbyl, R 3 is hydrogen, halogen, hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl or substituted heterohydrocarbyl, R 1 and R 3 or R 2 and R 3 are optionally linked by hydrocarbylene, substituted hydrocarbylene, heterohydrocarbylene or substituted heterohydrocarbylene to form a ring, provided that at least one of R 1 to R 3 is halogen-substituted hydrocarbyl or halogen-substituted heterohydrocarbyl, wherein R 4 and R 5 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl or substituted heterohydrocarbyl, provided that at least one of R 4 and R 5 is halogen-substituted hydrocarbyl or halogen-substituted heterohydrocarbyl, and wherein the dashed line indicates the non-bonding electron pair and the wave line indicates a bond with the transition metal or transition metal precursor.

2. The mononuclear or binuclear oligomerization catalyst of claim 1 , wherein the halogen-substituted organic ligand is an enolate ligand represented by Chemical Formula 1 below:

in Chemical Formula 1,

R 6 and R 7 are each independently halogen, hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl or substituted heterohydrocarbyl;

R 8 is hydrogen, halogen, hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl, or substituted heterohydrocarbyl;

R 6 and R 8 or R 7 and R 8 are optionally linked by hydrocarbylene, substituted hydrocarbylene, heterohydrocarbylene or substituted heterohydrocarbylene to form a ring; and

at least one of R 6 to R 8 is halogen-substituted hydrocarbyl or halogen-substituted heterohydrocarbyl.

3. The mononuclear or binuclear oligomerization catalyst of claim 2 , wherein at least one of R 6 to R 8 is fluorine-substituted hydrocarbyl or fluorine-substituted heterohydrocarbyl.

4. The mononuclear or binuclear oligomerization catalyst of claim 1 , wherein the transition metal or transition metal precursor is a Group 4, Group 5 or Group 6 transition metal, or a precursor thereof.

5. The mononuclear or binuclear oligomerization catalyst of claim 4 , wherein the transition metal or transition metal precursor is chromium, molybdenum, tungsten, titanium, tantalum, vanadium, zirconium or a precursor thereof.

6. The mononuclear or binuclear oligomerization catalyst of claim 5 , wherein the transition metal or transition metal precursor is a chromium or chromium precursor.

7. The mononuclear or binuclear oligomerization catalyst of claim 6 , wherein the chromium precursor is selected from the group consisting of chromium (III) acetylacetonate, chromium (III) chloride tris-tetrahydrofuran, and chromium (III) 2-ethylhexanoate.

8. The mononuclear or binuclear oligomerization catalyst of claim 1 , wherein the oligomerization catalyst is a complex in which a chromium or chromium precursor coordinates with an enolate ligand represented by Chemical Formula 1 below, and a ligand having a P—C—C—P skeleton structure represented by Chemical Formula 2 below, a ligand having a P—N—P skeleton structure represented by Chemical Formula 3 below, or a ligand having a P—C═C—P skeleton structure represented by Chemical Formula 4 below:

in Chemical Formulas 1 to 4,

R 6 and R 7 are each independently fluorine-substituted (C1-C10)alkyl or fluorine-substituted (C6-C20)aryl, the fluorine-substituted alkyl and the fluorine-substituted aryl of R 6 and R 7 are optionally further substituted with one or more substituents selected from chloro, bromo, (C1-C10)alkyl, (C6-C20)aryl, halo(C1-C10)alkyl, and halo(C6-C20)aryl in addition to fluorine;

R 8 is hydrogen, halogen, (C1-C10)alkyl or (C6-C20)aryl; the alkyl and aryl of R 8 are optionally further substituted with one or more of halogen, (C1-C10)alkyl, (C6-C20)aryl, halo(C1-C10)alkyl, and halo(C6-C20)aryl;

R 6 and R 8 or R 7 and R 8 are optionally linked by (C3-C10)alkylene, (C3-C10)alkenylene, (C6-C20)arylene, (C3-C10)heteroalkylene, (C3-C10)heteroalkenylene or (C6-C20)heteroarylene to form a ring;

R 11 to R 14 are each independently (C6-C20)aryl, (C6-C20)aryl(C1-C10)alkyl, (C1-C10)alkyl, (C2-C10)alkenyl, (C2-C10)alkynyl, (C1-C10)alkoxy, (C6-C20)aryloxy, (C3-C7)cycloalkyl, thio(C1-C10)alkyl, (C1-C10)alkylsilyl, (C6-C20)arylsilyl, (C3-C20)heteroaryl, 5- to 7-membered heterocycloalkyl or —NR 21 R 22 , the R 21 and R 22 are each independently (C1-C10)alkyl, (C6-C20)aryl or di(C1-C10)alkylamino;

R 15 to R 18 are each independently (C6-C20)aryl, (C6-C20)aryl(C1-C10)alkyl, (C1-C10)alkyl, (C2-C10)alkenyl, (C2-C10)alkynyl, (C3-C7)cycloalkyl, (C3-C20)heteroaryl, 5- to 7-membered heterocycloalkyl, (C1-C10)alkoxy, (C6-C20)aryloxy, mono or di(C1-C10)alkylamino, (C1-C10)alkylsilyl or (C6-C20)arylsilyl; and

the aryl, aralkyl, alkyl, alkenyl, alkoxy, aryloxy, cycloalkyl, heteroaryl, heterocycloalkyl of R 11 to R 14 , and the aryl, aralkyl, alkyl, alkenyl, cycloalkyl, heteroaryl, heterocycloalkyl, alkoxy, aryloxy, mono or dialkylamino, alkylsilyl or arylsilyl of R 15 to R 18 are optionally further substituted with one or more selected from the group consisting of (C1-C10)alkyl, (C2-C10)alkenyl, (C2-C10)alkynyl, (C1-C10)alkoxy, (C6-C20)aryloxy, (C1-C10)alkoxysilyl, 5- to 7-membered heterocycloalkyl, di(C1-C10)alkylamino, di(C2-C10)alkenylamino, di(C2-C10)alkynylamino, and halogen.

9. A method for preparing an ethylene oligomer using a catalyst composition including the mononuclear or binuclear oligomerization catalyst of claim 1 and a cocatalyst.

10. The method of claim 9 , wherein the cocatalyst is an organoaluminum compound, an organoboron compound, an organic salt, or a mixture thereof.

11. The method of claim 10 , wherein the cocatalyst is one or a mixture of two or more selected from the group consisting of methyl aluminoxane (MAO), modified methyl aluminoxane (MMAO), ethyl aluminoxane (EAO), tetraisobutyl aluminoxane (TIBAO), isobutyl aluminoxane (IBAO), trimethyl aluminum (TMA), triethyl aluminum (TEA), triisobutyl aluminum (TIBA), tri-n-octylaluminum, methylaluminum dichloride, ethylaluminum dichloride, dimethylaluminum chloride, diethylaluminum chloride, aluminum isopropoxide, ethylaluminum sesquichloride, and methylaluminum sesquichloride.

12. The method of claim 9 , further comprising using an aliphatic hydrocarbon as a reaction solvent.

13. The method of claim 12 , wherein the aliphatic hydrocarbon is at least one selected from hexane, heptane, octane, nonane, decane, undecane, dodecane, tetradecane, 2,2-dimethylpentane, 2,3-dimethylpentane, 2,4-dimethylpentane, 3,3-dimethylpentane, 2,2,4-trimethylpentane, 2,3,4-trimethylpentane, 2-methylhexane, 3-methylhexane, 2,2-dimethylhexane, 2,4-dimethylhexane, 2,5-dimethylhexane, 3,4-dimethylhexane, 2-methylheptane, 4-methylheptane, cyclohexane, methylcyclohexane, ethylcyclohexane, isopropylcyclohexane, 1,4-dimethylcyclohexane, and 1,2,4-trimethylcyclohexane.

14. The method of claim 9 , wherein the ethylene oligomer includes 1-octene in an amount of 30 wt % or more.

15. The method of claim 14 , wherein the ethylene oligomer includes 1-octene in an amount of 50 wt % or more.

16. An oligomerization catalyst comprising:

a transition metal or transition metal precursor,

a halogen-substituted organic ligand, and

a heteroatom ligand,

wherein the transition metal or transition metal precursor is a Group 4, Group 5 or Group 6 transition metal, or a precursor thereof, and

wherein the heteroatom ligand is a ligand having a P—C—C—P skeleton structure represented by Chemical Formula 2 below, a ligand having a P—N—P skeleton structure represented by Chemical Formula 3 below, or a ligand having a P—C═C—P skeleton structure represented by Chemical Formula 4 below:

in Chemical Formulas 2 to 4,

R 11 to R 14 are each independently hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl or substituted heterohydrocarbyl;

R 15 to R 16 are each independently hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl, substituted heterohydrocarbyl, or substituted heteroatom; and

R 17 to R 18 are each independently hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl, substituted heterohydrocarbyl, or substituted heteroatom, wherein the halogen-substituted organic ligand is selected from the following structures:

wherein R 1 and R 2 are each independently halogen, hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl or substituted heterohydrocarbyl, R 3 is hydrogen, halogen, hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl or substituted heterohydrocarbyl, R 1 and R 3 or R 2 and R 3 are optionally linked by hydrocarbylene, substituted hydrocarbylene, heterohydrocarbylene or substituted heterohydrocarbylene to form a ring, provided that at least one of R 1 to R 3 is halogen-substituted hydrocarbyl or halogen-substituted heterohydrocarbyl, wherein R 4 and R 5 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl or substituted heterohydrocarbyl, provided that at least one of R 4 and R 5 is halogen-substituted hydrocarbyl or halogen-substituted heterohydrocarbyl, and wherein the dashed line indicates the non-bonding electron pair and the wave line indicates a bond with the transition metal or transition metal precursor.