Process for preparation of ethylene oligomerization catalyst and oligomerization thereof

Abstract

The present invention describes a catalyst composition for use as a catalyst system for an ethylene oligomerization, providing high activity and produce linear oligomer product having broad weight percent distribution i.e. C.sub.4 to C.sub.16. The catalyst composition comprises a zirconium amide compound, an organoaluminum compound and an additive. The present invention also provides a process for preparation of the zirconium amide compound comprising reacting a zirconium component having formula ZrX.sub.m.nTHF, wherein X is halogen atom; m is an integer having value equal or less than 4 and n is a number equal or less than 2, and a substituted amide of formula RCONR′R″, wherein R, R′ and R″ are saturated or unsaturated aliphatic C.sub.1-C.sub.10 hydrocarbon or aromatic C.sub.6-C.sub.14 hydrocarbon, in the presence of an organic solvent.

Claims

1. A catalyst composition for use as a catalyst system for ethylene oligomerization, said catalyst composition comprising: tetrachlorobis(N,N-diisobutylacetamide)zirconium having the formula of (ZrCl.sub.4.2{CH.sub.3CON[CH.sub.2CH(CH.sub.3).sub.2].sub.2}); an organoaluminum compound; and an additive.

2. The catalyst composition as claimed in claim 1, wherein the organoaluminum compound is selected from an alkylaluminum, a trialkenylaluminum, a dialkylaluminum halide, an alkylaluminum sesquihalide, a dialkylaluminum hydride, a partially hydrogenated alkylaluminum, an aluminoxane, a dialkylaluminum alkoxide and a mixture thereof, wherein: (i) the alkylaluminum is a trialkylaluminum and selected from triethylaluminum, triisopropylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, and tri-n-octylaluminum; (ii) the trialkenylaluminum is triisoprenyl aluminum; (iii) the dialkylaluminum halide is selected from diethylaluminum chloride, dibutylaluminum chloride, diisobutylaluminum chloride and diethyl aluminum bromide; (iv) the alkylaluminum sesquihalide is selected from ethylaluminum sesquichloride, butylaluminum sesquichloride and ethylaluminum sesquibromide; (v) the dialkylaluminum hydride is selected from diethylaluminum hydride and dibutylaluminum hydride; (vi) the partially hydrogenated alkylaluminum is selected from ethylaluminum dihydride and propylaluminum dihydride; (vii) the aluminoxane is selected from methylaluminoxane, isobutylaluminoxane, tetraethylaluminoxane and tetraisobutylaluminoxane; and (viii) the dialkylaluminum alkoxide is diethylaluminum ethoxide.

3. The catalyst composition as claimed in claim 1, wherein a mole ratio of aluminum to zirconium is in a range from 5:1 to 100:1.

4. The catalyst composition as claimed in claim 1, wherein the additive is selected from a group consisting of an ester, an ether, an amine, an anhydride and a sulfur compound.

5. The catalyst composition as claimed in claim 1, wherein the additive is selected from ethyl acetate, ethyl acetoacetate, ethyl benzoate, anisole, tetrahydrofuran, 1,2-dioxane, thiophen and a mixture thereof.

6. The catalyst composition as claimed in claim 1, wherein a mole ratio of the zirconium amide compound and the additive is in a range from 1:0.1 to 1:10.

7. A process for preparation of the catalyst composition for use as a catalyst system for an ethylene oligomerization as claimed in claim 1, the process comprising: adding the tetrachlorobis(N,N-diisobutylacetamide)zirconium having the formula of (ZrCl.sub.4.2{CH.sub.3CON[CH.sub.2CH(CH.sub.3).sub.2].sub.2}) with an organoaluminum compound and an additive, wherein the tetrachlorobis(N,N-diisobutylacetamide)zirconium is prepared by reacting a zirconium component with a substituted amide in the presence of an organic solvent, wherein: the zirconium component is having a formula:
ZrCl.sub.4.nTHF wherein n is a number having a value equal to 2, and the substituted amide is having a formula:
CH.sub.3CON[CH.sub.2CH(CH.sub.3).sub.2].sub.2.

8. A method of preparation of the tetrachlorobis(N,N-diisobutylacetamide)zirconium having the formula of (ZrCl.sub.4.2{CH.sub.3CON[CH.sub.2CH(CH.sub.3).sub.2].sub.2}) of the catalyst composition for use as a catalyst system for ethylene oligomerization as claimed in claim 1, the method comprising: reacting a zirconium component having a formula ZrCl.sub.4.nTHF, wherein n is a number having a value equal to 2, with a substituted amide of formula CH.sub.3CON[CH.sub.2CH(CH.sub.3).sub.2].sub.2, in presence of an organic solvent.

9. The method of preparation of the zirconium amide compound as claimed in claim 8, wherein, the zirconium component is tetrachlorobis(tetrahydrofuran) zirconium, ZrCl.sub.4.2THF.

10. The method of preparation of the zirconium amide compound as claimed in claim 8, wherein a mole ratio of the zirconium component and the substituted amide is in a range from 0.1 to 5.

11. The method of preparation of the zirconium amide compound as claimed in claim 8, wherein the reaction is carried out at a temperature in a range of 20° C. to 170° C.

12. The method of preparation of the zirconium amide compound as claimed in claim 8, wherein the organic solvent is selected from the group consisting of diethyl ether, dichloromethane, tetrahydrofuran, chlorobenzene, toluene, o-chlorotoluene, xylene, chloroform, and cyclohexane.

13. A process for an oligomerization of ethylene without formation of a polymer, the process comprising: contacting ethylene with the catalyst composition as claimed in claim 1 in an inert organic solvent under ethylene oligomerization conditions to obtain linear alpha-olefins with a high degree of linearity having 90 mole percent or greater within a molecular weight range of an oligomer having 4 to 30 carbon atoms.

14. The process as claimed in claim 13, wherein the inert organic solvent is selected from an aromatic hydrocarbon solvent, an unsubstituted or a substituted with halogen; an aliphatic paraffin hydrocarbon; an alicyclic hydrocarbon compound; a halogenated alkane and a mixture thereof, wherein: (i) the aromatic hydrocarbon solvent is selected from toluene, benzene, xylene, chlorobenzene, dichlorobenzene, and chlorotoluene; (ii) the aliphatic paraffin hydrocarbon is selected from pentane, hexane, heptane, octane, nonane, and decane; (iii) the alicyclic hydrocarbon compound is selected from cyclohexane, and decahydronaphthalene; and (iv) the halogenated alkane is selected from dichloroethane, and dichlorobutane.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) The present invention describes a catalyst composition for use as catalyst system for ethylene oligomerization, said catalyst composition comprising of a zirconium amide compound having a general formula ZrX.sub.m.n(RCONR′R″), wherein X is halogen atom; m is an integer having value equal or less than 4; n is a number equal or less than 2; R, R′ and R″ are saturated or unsaturated aliphatic C.sub.1-C.sub.10 hydrocarbon or aromatic C.sub.6-C.sub.14 hydrocarbon, an organoaluminum compound and, an additive.

(2) The zirconium amide compound along with organoaluminum compound and an additive is used as catalyst system for ethylene oligomerization providing high activity and producing linear oligomer product having broad weight percent distribution i.e., C.sub.4 to C.sub.16.

(3) In one feature of the present invention, zirconium amide compound is prepared by reacting zirconium component having formula ZrX.sub.m.nTHF, wherein X is halogen atom; m is an integer having value equal or less than 4 and n is a number equal or less than 2, and substituted amide of formula RCONR′R″, wherein R, R′ and R″ are saturated or unsaturated aliphatic C.sub.1-C.sub.10 hydrocarbon or aromatic C.sub.6-C.sub.14 hydrocarbon, in the presence of organic solvent. In an embodiment, the zirconium component is having formula ZrX.sub.m.nTHF, where X can be chlorine or bromine; m is an integer having value equal or less than 4 and n is a number equal or less than 2. The most preferred zirconium component is tetrachlorobis(tetrahydrofuran) zirconium, ZrCl.sub.4.2THF. In an embodiment, substituted amide is of formula RCONR′R″, wherein R, R′ and R″ are saturated or unsaturated aliphatic C.sub.1-C.sub.10 hydrocarbon or aromatic C.sub.6-C.sub.14 hydrocarbon.

(4) Accordingly, the present invention also provides a process for preparing a substituted amide, said process comprising contacting the acyl halide, represented by RCOX, with the solvating agent and substituted amine to obtain the substituted amide. In an embodiment, the solvating agent can be aromatic or aliphatic and polar or non polar in nature, examples not limiting to diethyl ether benzene, decane, kerosene, ethyl benzene, chlorobenzene, dichlorobenzene, toluene, o-chlorotoluene, xylene, dichloromethane, chloroform, cyclohexane and the like. In an embodiment, acyl halides represented by RCOX where R is H, C.sub.1-C.sub.20 linear or branched alkyl group which can be linked with cyclic rings, C.sub.6-C.sub.14 aryl groups, C.sub.3-C.sub.15, cycloalkyl groups, C.sub.1-C.sub.20 alkoxy group, may or may not contain heteroatom and X is selected from halides. Mixtures of acyl halides can also be used. In another embodiment, substituted amines represented by R′R″NH where R′ & R″ are C.sub.1-C.sub.20 linear or branched alkyl group which can be linked with cyclic rings, C.sub.6-C.sub.14 aryl groups, C.sub.3-C.sub.15 cycloalkyl groups, may or may not contain heteroatom. Mixtures of substituted amines can also be used. R′ & R″ can be same or different. In one feature of the present invention, the acyl halide is added to the solvating agent followed by dropwise addition of the substituted amine. During this addition, the temperature is maintained such that the exothermic is not allowed to increase the temperature by 2° C. This step is important as per safety aspect because addition of acyl halide to amine is displacement reaction which is quite exothermic.

(5) The process of preparation of zirconium amide compound is described. In one feature of the present invention, the mole ratio of zirconium component and substituted amide is from about 0.1 to 5, preferably from 0.5 to 2. In another feature, the temperature of reaction is from about 20° C. to about 170° C., preferably from about 50° C. to about 120° C. In another feature, the zirconium amide compound can be used directly or after purification. In yet another feature, the zirconium amide compound is preferably tetrachlorobis(N,N-diisobutylacetamide)zirconium (ZrCl.sub.4.2{CH.sub.3CON[CH.sub.2CH(CH.sub.3).sub.2].sub.2}.

(6) In one feature of the present invention, the zirconium amide compound along with organoaluminum compound and an additive is used as catalyst system for ethylene oligomerization providing high activity and producing linear oligomer product having broad weight percent distribution i.e., C.sub.4 to C.sub.16. In yet another feature, organoaluminum compound include, not limiting, alkylaluminums such as trialkylaluminum such as triethylaluminum, triisopropylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum; trialkenylaluminums such as triisoprenyl aluminum; dialkylaluminum halides such as diethylaluminum chloride, dibutylaluminum chloride, diisobutylaluminum chloride and diethyl aluminum bromide; alkylaluminum sesquihalides such as ethylaluminum sesquichloride, butylaluminum sesquichloride and ethylaluminum sesquibromide; dialkylaluminum hydrides such as diethyl aluminum hydride and dibutylaluminum hydride; partially hydrogenated alkylaluminum such as ethylaluminum dihydride and propylaluminum dihydride and aluminoxane such as methylaluminoxane, isobutyl aluminoxane, tetraethylaluminoxane and tetraisobutylaluminoxane; diethylaluminum ethoxide, preferably diethylaluminum chloride and ethylaluminum sesquichloride. Mixtures of organoaluminum compound can also be used.

(7) The mole ratio of aluminum to zirconium is from about 5:1 to about 100:1, preferably from about 10:1 to about 70:1.

(8) In one feature, the additive is selected from the group consisting of, esters, ethers, amines, anhydrides and sulfur compounds preferably, ethyl acetate, ethyl acetoacetate, ethyl benzoate, anisole, tetrahydrofuran, 1,2-dioxane, thiophen and mixtures thereof.

(9) The mole ratio of zirconium compound and the additive is from 1:0.1 to 1:10.

(10) In yet another feature, the catalyst for the oligomerization of ethylene produces linear alpha-olefins having a high degree of linearity, such as about 90 mole percent or greater within a desirable molecular weight range, i.e., oligomers of 4 to 30 carbon atoms.

(11) In an embodiment, oligomerization of ethylene is conducted preferably in an inert organic solvent. The inert organic solvents include aromatic hydrocarbon solvents, unsubstituted or substituted with halogens, such as toluene, benzene, xylene, chlorobenzene, dichlorobenzene, chlorotoluene and the like, aliphatic paraffin hydrocarbons, such as pentane, hexane, heptane, octane, nonane, decane and the like, alicyclic hydrocarbon compounds, such as cyclohexane, decahydronaphthalene and the like, halogenated alkanes, such as dichloroethane, dichlorobutane and the like. A mixture of solvents may be used.

(12) The catalyst or catalyst composition utilized in this present invention provides a number of advantages such as: the zirconium amide compound is stable compound and is readily prepared.

(13) The compound is readily soluble when taken along the cocatalyst and additive. The catalyst provides high activity and productivity with linear oligomer product formation having broad weight percent distribution i.e. C.sub.4 to C.sub.16. The process for preparing zirconium amide compound uses ZrCl.sub.4.2THF as a starting compound, which is readily available, very cheap and easy to handle. Excess of amides is not required as 2 moles of amide is sufficient to replace 2 moles of THF in ZrCl.sub.4.2THF and synthesize the required catalyst of formula ZrX.sub.m.2RCONR′R″. Substituted amides were synthesized using acyl chloride and amines in solvating agent & used without further purification or recrystallization.

EXAMPLES

(14) The following examples are included herein for illustrative purposes only. Those skilled in the art will appreciate that many modifications may be made in the invention without changing the essence of invention.

Preparation of N,N-diisobutylacetamide

(15) In 100 ml round bottom flask, added acetyl chloride (1 mole) in diethyl ether followed by dropwise addition of N,N-diisobutylamine (1.5 moles). The temperature is maintained such that the exotherm is not allowed to increase the temperature by 2° C. The addition is continued for one hour followed by stirring for 1.5 h. After the completion of the reaction and removal of ether layer, the unreacted amine is neutralized using acidified water followed brine. The ether is removed from the layer by evaporation under vacuum followed by drying. Yield ˜85%. NMR: 0.92 ppm (12H), 2.20 (4H), 2.38 (2H), 7.23-7.26 (8H)

Preparation of tetrachlorobis(N,N-diisobutylacetamide)zirconium (ZrCl.SUB.4..2{CH.SUB.3.CON[CH.SUB.2.CH(CH.SUB.3.).SUB.2.].SUB.2.}

(16) In 100 ml round bottom flask, added ZrCl.sub.4.2THF (1 mole) and N,N-diisobutylacetamide (2 moles) in toluene and refluxed at 110° C. for 6 h. On cooling, white solid precipitates out and is isolated by removing toluene by evaporation under vacuum. The white solid is further dried in vacuo. Yield ˜90%. Found (%): C, 41.18; H, 7,44; N, 4.86; Cl, 24,6; Zr, 15.91; C20H42O2N2Cl4Zr. Calculated (%): C, 41.61; H, 7.28; N, 4.85; Cl, 24.62; Zr, 15.80.

Oligomerization of Ethylene using tetrachlorobis(N,N-diisobutylacetamide)zirconium

(17) In a charging flask, equipped with nitrogen, 200 ml of dry toluene was added followed by addition of tetrachlorobis(N,N-diisobutylacetamide)zirconium (0.25 mmol). This dark brown mixture was stirred for 15 minutes and dissolution of the catalyst was observed. Then neat EASC (Al/Zr=17.5) was added to the solution followed by addition of ethyl acetate as the additive. At this point complete dissolution of catalyst was observed. This dark brown solution was charged into preconditioned reactor at 30° C. The oligomerization was conducted at 80° C. and 30 bar ethylene pressure for 60 minutes. After the retrieval of clear liquid, it was treated with 10 ml methanol for quenching the catalyst system. There was no wax formation as well as polymer formation and if polymer was detected, it was only in traces.

(18) Ethylene oligomerization using different conditions and details of the conditions is provided in Table 1. The additive used is ethyl acetate (EA). The cocatalyst is ethylene aluminum sesquichloride (EASC).

(19) Abbreviations: 1. EASC=ethylene aluminum sesquichloride 2. DEAC=diethylaluminum chloride 3. EA=ethyl acetate 4. ZrCl.sub.4.2THF=tetrachlorobis(tetrahydrofuran) zirconium 5. ZrCl.sub.4=Zirconium tetrachloride 6. Zr((CH.sub.3).sub.2CHCH.sub.2COO).sub.4=Zirconium tetraisobutyrate 7. TEAL=triethyl aluminum chloride 8. TIPA=triisoprenyl aluminum 9. DBAH=dibutylaluminum hydride 10. DEAE=diethylaluminum ethoxide 11. MAO=methylaluminoxane

(20) TABLE-US-00001 TABLE 1 Distribution of Al/Zr EA Productivity α-olefins (wt %) α-olefins S No. (mol) (mmol) (g LAO/g Zr) C4 C6-C10 C12-C18 C20+ (wt %) OLM#40 17.5 0.125 3300 37.0 55.2 7.6 0.2 >96 OLM#41 0.125 3400 38.7 54.8 6.4 0.1 >96 OLM#43 0.125 3300 39.1 54.6 6.1 0.1 >96 OLM#11 0.0 3100 33.3 60.9 5.7 0.1 >95 ~40 mg polymer OLM#10 0.25 2800 30.0 62.4 7.5 0.1 >97 OLM#13 35   0.125 2900 35.2 59.4 5.3 0.04 >97 OLM#14 25   0.125 3100 40.4 55.7 3.9 0.04 >96 OLM#15 17.5 0.125 2800 38.5 57.1 4.4 0.1 >98 (DEAC) OLM#16 25   0.125 3600 40.2 55.6 4.2 0.03 >98 (DEAC) OLM#50 17.5 0.0 2800 39.9 56.3 3.7 0.1 >98 (EASC/DEAC = 3/1) OLM#53 17.5 0.125 2800 35.5 57.7 6.7 0.2 >98 (DEAC/EASC = 3/1) Comparative Data OLM#56 17.5 0.125 2200 32.3 58.2 9.4 0.03 >90 ZrCl.sub.4•2THF as catalyst OLM# 17.5 0.125 3400 29.9 56.8 12.8 0.5 ≥95 Zr((CH.sub.3).sub.2CHCH.sub.2COO).sub.4 as catalyst OLM#07 17.5 0.125 1000 15.7 70.9 13.0 0.4 ≥90 ZrCl.sub.4 as catalyst OLM#72 ZrCl.sub.4•CH.sub.3 0.125 2700 36.1 57.0 6.1 0.8 ≥94 COOR.sub.1).sub.2.

(21) The above table describes the different attributes of the catalyst system when subjected for oligomerization of ethylene.

(22) As seen from Table 1, the oligomerization experiments according to the examples of the present invention result in comparable activity of the new catalyst with an improved distribution of alpha-olefins (weight percent) with a high amount of C4 to C10. Additionally, the purity of the LAO fractions is significantly improved compared to the results of the comparative examples.

(23) TABLE-US-00002 TABLE 2 Working examples of using different types of alkyl aluminums for oligomerization of ethylene Distribution of Alkyl Al/Zr EA Productivity α-olefins (wt %) α-olefins S No. aluminum (mol) (mmol) (g LAO/g Zr) C4 C6-C10 C12-C18 C20+ (wt %) OLM#41 EASC 17.5 0.125 3400 38.7 54.8 6.4 0.1 >96 OLM#15 DEAC 17.5 0.125 2800 38.5 57.1 4.4 0.1 >98 OLM#80 TEAL 17.5 0.125 2400 87.5 10.2 5.3 >97 OLM#81 TIPA 17.5 0.125 1450 92.3 7.1 0.6 — >92 OLM#82 DBAH 17.5 0.125 1800 68.9 29.6 1.0 0.5 >95 OLM#83 DEAE 17.5 0.125 2100 31.4 38.5 14.9 15.2  >94 OLM#84 MAO 17.5 0.125 1200 61.2 30.2 8.6 — >95

(24) TABLE-US-00003 TABLE 3 Working examples of using different mol ratios of alkyl aluminums for oligomerization of ethylene Distribution of Alkyl Al/Zr EA Productivity α-olefins (wt %) α-olefins S No. aluminum (mol) (mmol) (g LAO/g Zr) C4 C6-C10 C12-C18 C20+ (wt %) OLM#41 EASC 17.5 0.125 3400 38.7 54.8 6.4 0.1 >96 OLM#13 EASC 35 0.125 2900 35.2 59.4 5.3  0.04 >97 OLM#14 EASC 25 0.125 3100 40.4 55.7 3.9  0.04 >96 OLM#101 EASC 5 0.125  180 78.2 18.9 0.6 — >68 OLM#102 EASC 100 0.125  320 35.1 58.9 5.9 0.1 >90 ~100 g polymer OLM#103 EASC 2 0.125 No — — — — — oligomerization OLM#104 EASC 200 0.125 ~120 g polymer — — — — —

(25) TABLE-US-00004 TABLE 4 Working examples of using different additives for oligomerization of ethylene using EASC as cocatalyst and additive as 0.125 mmol Distribution of Al/Zr Productivity α-olefins (wt %) α-olefins S No. (mol) Additive (g LAO/g Zr) C4 C6-C10 C12-C18 C20+ (wt %) OLM#41 17.5 EA 3400 38.7 54.8 6.4 0.1 >96 OLM#111 17.5 THF 3200 34.5 61.4 4.0 0.1 >95 OLM#112 17.5 anisole 3100 26.3 47.2 26.5 0.1 >92 OLM#113 17.5 isobutylamine 2000 38.2 46.3 14.5 1.0 >86 OLM#114 17.5 thiophene 2800 47.8 50.2 2.0 — >92 OLM#115 17.5 Acetic anhydride No — — — — — oligomerization

(26) TABLE-US-00005 TABLE 5 Working examples of using different mol ratio of EA for oligomerization of ethylene using EASC as cocatalyst and Al/Zr mol ratio as 17.5 Distribution of EA Productivity α-olefins (wt %) α-olefins S No. (mol) (g LAO/g Zr) C4 C6-C10 C12-C18 C20+ (wt %) OLM#10 0.0 3100 33.3 60.9 5.7 0.1 >95 ~40 mg polymer OLM#41 0.125 3400 38.7 54.8 6.4 0.1 >96 OLM#11 0.25 2800 30.0 62.4 7.5 0.1 >97 OLM#92 1 3100 35.1 61.8 3.0 0.1 >97 OLM#93 5 3200 33.6 62.4 6.1 0.2 >95 OLM#94 10 3000 37.2 59.2 3.9 0.1 >96 OLM#95 15 No — — — — — oligomerization