Catalyst composition and process for oligomerization of ethylene

Abstract

A catalyst composition including: (a) a chromium compound; (b) a ligand of the general structure R1R2P—N(R3)—P(XR7)2, wherein X is O or S, R1, R2, and R3 are each independently C1-C10-alkyl, C6-C20-cycloalkyl, arylalkyl, alkylaryl, or trialkylsilyl, or any cyclic derivatives of the ligand, wherein at least one of the P or N atoms of the PNP-unit is a member of the ring system, the ring system being formed from one or more constituent compounds of the ligand by substitution, and R7 is C1-C10-alkyl, C3-C10-cycloalkyl, arylalkyl, or trialkylsilyl; and (c) an activator or co-catalyst.

What is claimed is: 
     
         1 . A catalyst composition comprising:
 (a) a chromium compound;   (b) a ligand of the general structure   R 1 R 2 P—N(R 3 )—P(XR 7 ) 2      
       wherein
 X is O or S, 
 R 1 , R 2 , and R 3  are each independently C 1 -C 10 -alkyl, C 6 -C 20 -aryl, C 3 -C 10 -cycloalkyl, arylalkyl, alkylaryl, or trialkylsilyl, or any cyclic derivatives of the ligand, wherein at least one of the P or N atoms of the PNP-unit is a member of the ring system, the ring system being formed from one or more constituent compounds of the ligand by substitution, and 
 R 7  is C 1 -C 10 -alkyl, C 3 -C 10 -cycloalkyl, arylalkyl, or trialkylsilyl; and 
 (c) an activator or co-catalyst. 
 
     
     
         2 . The catalyst composition according to  claim 1 , wherein the chromium compound is an organic salt, an inorganic salt, a coordination complex, an organometallic complex of Cr(0) or Cr(III), or a combination thereof. 
     
     
         3 . The catalyst composition according to  claim 2 , wherein the chromium compound is CrCl 3 (THF) 3 , Cr(III)acetylacetonate, Cr(III)octanoate, chromium hexacarbonyl, Cr(III)-2-ethylhexanoate, (benzene)tricarbonyl-chromium, or a combination thereof. 
     
     
         4 . The catalyst composition according to  claim 1 , wherein R 1 , R 2 , R 3 , and R 7  are each independently methyl, ethyl, isopropyl, tert-butyl, cyclohexyl, phenyl, benzyl, tolyl, or xylyl. 
     
     
         5 . The catalyst composition according to  claim 1 , wherein the activator or co-catalyst is trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, ethylaluminumsesquichloride, diethylaluminum chloride, ethylaluminumdichloride, methylaluminoxane (MAO), modified methylaluminoxane (MMAO), or a combination thereof. 
     
     
         6 . The catalyst composition according to  claim 1 , wherein the ligand is Ph 2 P-N(i-Pr)-P[S(i-Pr)] 2 , Ph 2 P-N(i-Pr)-P(OC 2 H 5 ) 2 , Ph 2 P-N(i-Pr)P(OCH 3 ) 2 , or a combination thereof. 
     
     
         7 . The catalyst composition according to  claim 1 , additionally comprising a solvent, wherein the solvent is one of aromatic hydrocarbons, straight-chain aliphatic hydrocarbons, cyclic aliphatic hydrocarbons, straight-chain olefins, ethers, or a combination thereof. 
     
     
         8 . The catalyst composition according to  claim 7 , wherein the concentration of the chromium compound is from 0.01 to 100 millimoles per liter. 
     
     
         9 . The catalyst composition according to  claim 1 , wherein the ligand/Cr molar ratio is from 0.5 to 50. 
     
     
         10 . The catalyst composition according to  claim 5 , wherein the Al/Cr molar ratio is from 1:1 to 1000:1. 
     
     
         11 . A catalyst composition, obtainable by combining at least:
 (a) a chromium compound;   (b) a ligand of the general structure   R 1 R 2 P-N(R 3 )-P(XR 7 ) 2      
       wherein
 X is O or S, 
 R 1 , R 2 , and R 3  are each independently C 1 -C 10 -alkyl, C 6 -C 20 -aryl, C 3 -C 10 -cycloalkyl, arylalkyl, alkylaryl, or trialkylsilyl, or any cyclic derivatives of the ligand, wherein at least one of the P or N atoms of the PNP-unit is a member of the ring system, the ring system being formed from one or more constituent compounds of the ligand by substitution, and 
 R 7  is C 1 -C 10 -alkyl, C 3 -C 10 -cycloalkyl, arylalkyl, or trialkylsilyl; and 
 (c) an activator or co-catalyst. 
 
     
     
         12 . A process for tri- and/or tetramerization of ethylene, comprising subjecting the catalyst composition according to  claim 1  to a gas phase of ethylene in a reactor and conducting an oligomerization. 
     
     
         13 . The process according to  claim 12 , wherein the oligomerization is carried out at a pressure of 1 to 200 bar. 
     
     
         14 . The process according to  claim 13 , wherein the oligomerization is carried out at a temperature of from 10 to 200° C. 
     
     
         15 . The process according to  claim 14 , wherein the mean residence time is from 10 minutes to 20 hours. 
     
     
         16 . The process according to  claim 13 , wherein the pressure is 10 to 50 bar. 
     
     
         17 . The process according to  claim 14 , wherein the temperature is from 20 to 100° C. 
     
     
         18 . The process according to  claim 15 , wherein the mean residence time is from 1 to 4 hours. 
     
     
         19 . The catalyst composition according to  claim 1 , wherein the solvent is toluene, benzene, ethylbenzene, cumene, xylenes, mesitylene, hexane, octane, cyclohexane, methylcyclohexane, hexene, heptene, octene, diethylether, tetrahydrofuran, chlorobenzene, or a combination thereof.