Method for oligomerization of olefins

Abstract

The present disclosure relates to a method for oligomerization of olefins. The method for oligomerization of olefins according to the present disclosure not only provides excellent catalytic activity and stable process operation, but also exhibits high selectivity to 1-hexene or 1-octene by using a catalyst system including an activity modifier.

Claims

1. A method for oligomerization of olefins comprising the steps of: preparing a catalyst composition comprising a ligand comprising at least one diphosphino aminyl moiety, a chromium source, and a cocatalyst represented by the following Chemical Formula 1; after preparing the catalyst composition, preparing a catalyst system by mixing the catalyst composition with an activity modifier which is one or more compounds selected from the group consisting of trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, diethylaluminum chloride, and ethylaluminum dichloride; and contacting olefinic monomers with the catalyst system:
R.sup.12[Al(R.sup.11)O].sub.aR.sup.13[Chemical Formula 1] in Chemical Formula 1, R.sup.11, R.sup.12, and R.sup.13 are the same as or different from each other, and are independently hydrogen, a halogen, a C.sub.1-C.sub.20 hydrocarbyl group, or a C.sub.1-C.sub.20 hydrocarbyl group substituted with a halogen, and a is an integer of 2 or more.

2. The method for oligomerization of olefins according to claim 1, wherein the cocatalyst is one or more compounds selected from the group consisting of methyl aluminoxane, ethyl aluminoxane, butyl aluminoxane, and isobutyl aluminoxane.

3. The method for oligomerization of olefins according to claim 1, wherein the chromium source is one or more compounds selected from the group consisting of chromium(III) acetylacetonate, chromium(III) chloride tetrahydrofuran, chromium(III) 2-ethylhexanoate, chromium(III) acetate, chromium(III) butyrate, chromium(III) pentanoate, chromium(III) laurate, and chromium(III) stearate.

4. The method for oligomerization of olefins according to claim 1, wherein the ligand is a compound represented by the following Chemical Formula 3 or Chemical Formula 4: ##STR00004## in Chemical Formula 3, each of R.sup.1 to R.sup.5 is independently a C.sub.1-C.sub.10 alkyl group, a C.sub.1-C.sub.10 alkenyl group, a C.sub.4-C.sub.10 cycloalkyl group, a C.sub.1-C.sub.10 alkoxy group, a C.sub.6-C.sub.15 aryl group, a C.sub.7-C.sub.20 alkylaryl group, or a C.sub.7-C.sub.20 arylalkyl group; ##STR00005## in Chemical Formula 4, L is a linker connecting between the diphosphino aminyl moieties by 2 to 8 carbon atoms, and each of R.sup.6 to R.sup.9 and R.sup.6 to R.sup.9 is independently a C.sub.1-C.sub.10 alkyl group, a C.sub.1-C.sub.10 alkenyl group, a C.sub.4-C.sub.10 cycloalkyl group, a C.sub.1-C.sub.10 alkoxy group, a C.sub.6-C.sub.15 aryl group, a C.sub.7-C.sub.20 alkylaryl group, or a C.sub.7-C.sub.20 arylalkyl group.

5. The method for oligomerization of olefins according to claim 1, wherein in the catalyst composition, a mole ratio of the ligand to the chromium in the chromium source to the aluminum in the cocatalyst is 1:1:1 to 10:1:10,000.

6. The method for oligomerization of olefins according to claim 1, wherein in the catalyst system, a mole ratio of the chromium in the chromium source to the D in the activity modifier is 1:10 to 1:3000.

7. The method for oligomerization of olefins according to claim 1, wherein the olefinic monomers comprise gaseous ethylene.

8. The method for oligomerization of olefins according to claim 1, wherein the step of contacting the olefinic monomers with the catalyst system is carried out at a temperature of 0 to 200 C., and at a pressure of 1 to 300 bar.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a graph showing cumulative flow rates of products over reaction time in the oligomerization reaction of olefins according to an example and a comparative example of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(2) Hereinafter, preferable examples and comparative examples are presented for better understanding of the present invention. However, the following examples are only for illustrating the present invention and the present invention is not limited to or by them.

Synthesis Example

(3) All the reactions were progressed under argon using Schlenk techniques or a glovebox. The synthesized ligands were analyzed by .sup.1H (500 MHz) and .sup.31P (202 MHz) NMR spectra using a Varian 500 MHz spectrometer. Under the argon atmosphere, 10 mmol of 2-ethyl-6-methylaniline and 3 equiv. to amine of triethylamine were dissolved in 80 mL of dichloromethane in a flask. While the flask was immersed in a water bath, 20 mmol of chlorodiphenylphosphine was slowly added thereto, and the mixture was stirred overnight. The solvent was removed under vacuum, and then tetrahydrofuran was added thereto, followed by sufficient stirring, and triethylammonium chloride salt was removed using an air-free glass filter. The solvent was removed from the filtrate to obtain a product (a ligand compound of the following Chemical Formula a).

(4) ##STR00003##

Example 1

(5) Under the argon gas atmosphere, chromium(III) acetylacetonate (17.5 mg, 0.05 mmol) and the ligand compound according to the synthesis example (1.1 eq. to Cr) were added to a flask, 100 mL of methylcyclohexane was added thereto, and the mixture was stirred to prepare a ligand solution of 0.5 mM (based on Cr).

(6) After a Parr reactor with a capacity of 600 ml was placed under vacuum at 180 C. for 2 h, the interior of the reactor was substituted with argon, and the temperature was decreased to 60 C. Thereafter, 140 g of methylcyclohexane and 0.25 ml (Al/Cr=600) of modified methylaluminoxane (MMAO, 8.6 wt % isoheptane solution) were introduced, and 1.5 ml of the above 0.5 mM ligand solution (0.75 mol) was introduced thereto and stirred.

(7) After 1.5 ml of a 0.05 M triethylaluminum solution was introduced thereto and stirred, an ethylene line valve was opened to fill the interior of the reactor with ethylene, and the mixture was stirred at 1000 rpm for 15 min at the temperature of 60 C.

(8) The ethylene line valve was closed, the reactor was cooled down to 0 C. using a dry ice/acetone bath, non-reacted ethylene was slowly vented, and 1 ml of nonane (GC internal standard) was introduced. The liquid part of the reactor was slightly recovered and quenched with water, and the organic layer was filtered with a PTFE syringe filter to perform GC analysis.

(9) 400 mL of an ethanol/HCl solution (10 vol % of an aqueous 12 M HCl solution) was introduced to the remaining reaction solution, and the mixture was stirred and filtered to obtain a polymer. The obtained polymer was dried in a vacuum oven at 60 C. overnight and weighed.

Comparative Example 1

(10) The oligomerization of olefins was conducted according to the same method as in Example 1, except that the triethylaluminum solution was not introduced thereto.

Comparative Example 2

(11) The oligomerization of olefins was conducted according to the same method as in Example 1, except that 4.5 ml of 0.1 M triethylaluminum solution (in methylcyclohexane) (Al/Cr=600) was introduced instead of the modified methylaluminoxane (MMAO), and the 1.5 ml of a 0.05 M triethylaluminum solution was not introduced thereto.

(12) TABLE-US-00001 TABLE 1 Compar- Compar- ative ative Exam- Exam- Exam- ple 1 ple 1 ple 2 Reaction time (min) 15 15 15 Duration of the catalytic activity (min) 7.7 12.3 Catalytic activity total 310 461 (ton/mol Cr/h) conversion value 604 562 Alpha-olefin 1-C.sub.6 26.4 40.5 in liquid 1-C.sub.8 62.3 50.2 (wt %) Sum 88.7 90.7 Solid (wt %) 0.7 0.4

(13) In the above Table 1, the duration of the catalytic activity is defined as the time from an x-intercept where the section in which a flow rate of ethylene is constant after start of the oligomerization reaction of ethylene is extended by a trend line to a point that the oligomerization reaction is completed (that is, 15 min after the start of the reaction).

(14) Further in Table 1, the conversion value of the catalytic activity is a value of which the catalytic activity value shown in the oligomerization reaction of ethylene is weighted based on the duration of the catalytic activity.

(15) A graph showing the cumulative flow rates of the products over reaction time of Example 1 and Comparative Example 1 is shown in FIG. 1.

(16) Referring to Table 1 and FIG. 1, in Example 1, compared to Comparative Example 1, it was possible to operate a stable process, because the increase of the catalytic activity was delayed at the initial stage of the reaction. The activity of Example 1 was also comparable to that of Comparative Example 1 after the lapse of time. Referring to FIG. 1, it was confirmed that the slope (T=0.076x33.25) of the later part of the reaction in the graph of Example 1 closely coincided with the slope (T=0.081x9.67900) in Comparative Example 1.

(17) In Comparative Example 2, triethylaluminum was introduced instead of the modified methylaluminoxane (MMAO), but the oligomerization reaction did not proceed. That is, it was confirmed that triethylaluminum did not function as a cocatalyst. Also, it was confirmed that when triethylaluminum was mixed with a catalyst solution in which no cocatalyst was present, the action of the activity modifier could not be manifested.