Ligand compound, organic chromium compound, catalyst system for ethylene oligomerization, preparation method thereof, and ethylene oligomerization method using the same

An organic chromium compound represented by the following Chemical Formula 2:

• wherein X is phosphorus, arsenic or antimony;
• W is ethylene or propylene;
• R1, R2, R3 and R4 are each independently hydrocarbyl;
• Z is nitrogen;
• R5 is hydrocarbyl;
• Y is each independently halogen, hydrogen, or hydrocarbyl having 1 to 4 carbon atoms;
• and
• n is 2.

A catalyst system for ethylene oligomerization, comprising i) a ligand compound represented by the following Chemical Formula 1 and a chromium source, or ii) an organic chromium compound represented by the following Chemical Formula 2;

• and a cocatalyst:
• wherein X is phosphorus, arsenic or antimony;
• W is ethylene or propylene;
• R1, R2, R3 and R4 are each independently hydrocarbyl;
• Z is nitrogen;
• R5 is hydrocarbyl;
• Y is each independently halogen, hydrogen, or hydrocarbyl having 1 to 4 carbon atoms;
• and
• n is 2.

A preparation method of a catalyst system for ethylene oligomerization, comprising the steps of:

• supporting a cocatalyst on a support;
• and
• supporting an organic chromium compound represented by the following Chemical Formula 2 on the cocatalyst-supported support:
• wherein X is phosphorus, arsenic or antimony;
• W is ethylene or propylene;
• R1, R2, R3 and R4 are each independently hydrocarbyl;
• Z is nitrogen;
• R5 is hydrocarbyl;
• Y is each independently halogen, hydrogen, or hydrocarbyl having 1 to 4 carbon atoms;
• and
• n is 2.

A preparation method of a catalyst system for ethylene oligomerization, comprising the steps of:

• supporting an organic chromium compound represented by the following Chemical Formula 2 on a support;
• and
• supporting a cocatalyst on the organic chromium compound-supported support:
• wherein X is phosphorus, arsenic or antimony;
• W is ethylene or propylene;
• R1, R2, R3 and R4 are each independently hydrocarbyl;
• Z is nitrogen;
• R5 is hydrocarbyl;
• Y is each independently halogen, hydrogen, or hydrocarbyl having 1 to 4 carbon atoms;
• and
• n is 2.