Catalyst composition and process for oligomerization of ethylene

1. A catalyst composition comprising:

(i) a chromium compound;

(ii) a ligand of the general structure R 1 R 2 P—N(R 3 )—P(R 4 )—N(R 5 )—H, wherein R 1 , R 2 , R 3 , R 4 and R 5 are independently selected from halogen, amino, C 1 -C 10 -alkyl, substituted C 1 -C 10 -alkyl, aryl and substituted aryl;

(iii) a modifier containing organic or inorganic halide; and

(iv) an activator or co-catalyst.

2. The catalyst composition according to claim 1 , wherein the chromium compound is selected from organic or inorganic salts, coordination complexes and organometallic complexes of Cr(II) or Cr(III).

3. The catalyst composition according to claim 2 , wherein the modifier is selected from ammonium or phosphonium salts of the type [H 4 E]X, [H 3 ER]X, [H 2 ER 2 ]X, [HER 3 ]X or [ER 4 ]X with E=N or P, X=Cl, Br or I and R=alkyl, cycloalkyl, acyl, aryl, alkenyl, alkynyl or the corresponding bridging di-, tri- or multiunits; HX; or RX.

4. A catalyst composition comprising:

(i) a halide containing chromium compound

(ii) a ligand of the general structure R 1 R 2 P—N(R 3 )—P(R 4 )—N(R 5 )—H, wherein R 1 , R 2 , R 3 , R 4 and R 5 are independently selected from C 1 -C 10 alkyl, aryl and substituted aryl;

(iii) a modifier containing a free amine group; and

(iv) an activator or co-catalyst.

5. The catalyst composition according to claim 4 , wherein the modifier contains a free amine group which is a primary, secondary or tertiary aliphatic amine or an aromatic amine.

6. The catalyst composition according to claim 5 , wherein the activator or co-catalyst comprises trimethyl aluminum, triethyl aluminum, triisopropyl aluminum, triisobutyl aluminum, ethyl aluminum sesquichloride, diethyl aluminum chloride, ethyl aluminum dichloride, methyl aluminoxane (MAO) or mixtures thereof.

7. The catalyst composition according to claim 6 , wherein the molar ligand/Cr ratio is from 0.8:1 to 2.0:1.

8. The catalyst composition according to claim 7 , wherein the molar Al/Cr ratio is from 10:1 to 200:1.

9. The catalyst composition according to claim 8 , wherein the molar modifier/Cr ratio is from 1:1 to 20:1.

10. The catalyst composition according to any of the preceding claims wherein the molar Cr/halide ratio is from 1:1 to 1:10.

11. A process for the oligomerization of ethylene, comprising contacting ethylene with the catalyst composition of claim 3 under ethylene oligomerization conditions.

12. The process according to claim 11 , wherein the chromium compound comprises CrCl 3 (THF) 3 , Cr(III)acetyl acetonate, Cr(III) octanoate, chromium hexacarbonyl, Cr(III)-2-ethylhexanoate, benzene(tricarbonyl)-chromium and Cr(III)chloride.

13. The process according to claim 12 , wherein the modifier comprises tetraphenyl phosphonium chloride, tetraethyl ammoniumchloridemonohydrate, tetraethylammoniumchloride, isopropylamine-hydrochloride, triethylamine-hydrochloride, tetrapropylammonium chloride, tetra-n-butylammonium chloride, tetraethylammonium bromide, p-toluidine-hydrochloride, dimethyldistearylammonium chloride, (tri-n-butyl)-n-tetradecylphosphonium chloride, benzoyl chloride or acetyl chloride; the activator or co-catalyst comprises trimethylaluminum, triethyl aluminum, triisopropyl aluminum, triisobutyl aluminum, ethyl aluminum sesquichloride, diethyl aluminum chloride, ethyl aluminum dichloride, methyl aluminoxane (MAO) or mixtures thereof and the oligomerization is carried out at a pressure of 10 to 50 bar and a temperature of from 20 to 100° C.

14. The process according to claim 13 wherein the molar ligand/Cr ratio is from 0.8:1 to 2.0:1, the molar Al/Cr ratio is from 10:1 to 200:1, the molar modifier/Cr ratio is from 1:1 to 20:1, the molar Cr/halide ratio is from 1:1 to 1:10, the activator or co-catalyst comprises trimethyl aluminum, triethyl aluminum, triisopropyl aluminum, triisobutyl aluminum, ethyl aluminum sesquichloride, diethyl aluminum chloride, ethyl aluminum dichloride, methyl aluminoxane (MAO) or mixtures thereof, and the mean residence time of ethylene in the process is from 1 to 4 hours.

15. The catalyst composition of claim 3 , wherein the chromium compound comprises CrCl 3 (THF) 3 , Cr(III)acetyl acetonate, Cr(III) octanoate, chromium hexacarbonyl, Cr(III)-2-ethylhexanoate, benzene(tricarbonyl)-chromium or Cr(III)chloride.

16. The catalyst composition of claim 15 , wherein the modifier comprises tetraphenyl phosphonium chloride, tetraethyl ammoniumchloride-monohydrate, tetraethylammoniumchloride, isopropylamine-hydrochloride, triethylamine-hydrochloride, tetrapropylammonium chloride, tetra-n-butylammonium chloride, tetraethylammonium bromide, p-toluidine-hydrochloride, dimethyldistearylammonium chloride, (tri-n-butyl)-n-tetradecylphosphonium chloride, benzoyl chloride or acetyl chloride, and the activator or co-catalyst comprises trimethyl aluminum, triethyl aluminum, triisopropyl aluminum, triisobutyl aluminum, ethyl aluminum sesquichloride, diethyl aluminum chloride, ethyl aluminum dichloride, methyl aluminoxane (MAO) or mixtures thereof.

17. The catalyst composition of claim 16 , wherein the molar ligand/Cr ratio is from 0.8:1 to 20:1 and the molar Al/Cr ratio is from 10.1 to 200:1.

18. The catalyst composition of claim 17 , wherein the molar modifier/Cr ratio is from 1:1 to 20:1 and the molar Cr/halide ratio is from 1:1 to 1:10.

19. The catalyst composition of claim 1 , wherein the chromium compound comprises CrCl 3 (THF) 3 or Cr(III)chloride and the modifier comprises a primary, secondary or tertiary aliphatic amine.

20. The catalyst composition of claim 19 , wherein the modifier comprises isopropylamine.