CN107282124B - Ethylene tetramerization catalyst composition and tetramerization method - Google Patents

Abstract

The invention provides an ethylene tetramerization catalyst composition, which comprises a ligand compound shown as a formula I, a transition metal compound, a cocatalyst and tert-butyl hydroperoxide; in the formula R¹、R²、R³Identical or different, may be chosen from hydrogen, alkyl, alkoxy, cycloalkyl or halogen; 4R present⁴May be the same or different and are each independently selected from monocyclic or polycyclic aryl groups. The invention also provides a method for ethylene tetramerization, which comprises the step of carrying out ethylene tetramerization reaction in the presence of the catalyst composition for ethylene tetramerization, and the catalyst composition has ultrahigh reaction activity, rapid reaction initiation, stable operation and good repeatability.

Description

Ethylene tetramerization catalyst composition and tetramerization method

Technical Field

The invention relates to the field of ethylene oligomerization, in particular to a catalyst composition for ethylene tetramerization. The invention also relates to a method for tetramerising ethylene.

Background

1-octene is used as an important organic raw material and a chemical intermediate, and is mainly used for producing high-quality Polyethylene (PE). Linear Low Density Polyethylene (LLDPE) produced by copolymerizing 1-octene and ethylene can obviously improve various properties of PE, especially mechanical property, optical property, tear strength and impact strength of polyethylene, and is very suitable for packaging films, agricultural covering films for greenhouses, sheds and the like, and simultaneously 1-octene is also used as an intermediate of plasticizer, fatty acid, detergent alcohol and lubricating oil additive.

Although the value of 1-octene is well known, 1-octene is not currently produced in the art with as high a selectivity as ethylene trimerization produces 1-hexene. The traditional 1-octene production method is an ethylene oligomerization method, the ethylene oligomerization technology is distributed according to Schulz-Flory, not only 1-octene products are obtained, but also other alpha-olefins and a small amount of solid high polymer are obtained, and the selectivity of the target product 1-octene is very low and is not more than 30%. For example, the SHOP process (US3676523) by Shell company gives 11% 1-octene; US patent (US6184428) reports a 1-octene yield of only 19% using a nickel compound as catalyst. The SHOP process, as in US3676523, uses a nickel metal catalyst system for the oligomerization of ethylene, with a 1-octene content of only 11%. Japanese patent JP2002121157 reports the use of zirconium metal catalysts for ethylene oligomerization wherein the 1-octene content is about 15%. Recently reported ethylene tetramerization catalyst systems have been able to synthesize 1-octene with high selectivity, as patent applications CN1741850A (WO2004/056478a1), CN1741849A (WO2004/056479a1), CN101032695A, CN101351424A, CN101415494A, CN1651142A, CN101291734A and patent application US2006/0128910a1 disclose that 1-octene can be produced with high selectivity by catalyzing ethylene tetramerization using P-N-P ligands coordinated with chromium, the content of 1-octene in the product exceeding 60%.

Patent application CN101605605A discloses the use of chromium-based catalysts containing ligands with P-C-P backbone structure for ethylene tetramerization. However, the above-mentioned techniques only disclose limited substituent structures of ligands having P-N-P or P-C-C-P skeleton structures, which are complicated in structure, complicated in preparation steps, and high in cost. The aluminum alkoxide as cocatalyst (including methylaluminoxane, modified methylaluminoxane, etc.) used in the above patent has the problems of high cost and large dosage, and when the aluminum alkoxide is applied to ethylene tetramerization in large scale, the aluminum alkoxide will cause high production cost. Furthermore, in the prior art, water and oxygen are generally considered to be very disadvantageous for ethylene tetramerization processes, and therefore, the reaction needs to be strictly controlled in an anhydrous and oxygen-free environment during the production process. This makes all the ethylene tetramerization or oligomerization reactions known to date very demanding with respect to the process, resulting in very poor reaction initiation and reproducibility of the reaction process.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, the inventors of the present application conducted intensive studies on such phosphorus-containing catalysts, and surprisingly found that ethylene tetramerization reaction under the action of a catalyst composition comprising a ligand compound represented by formula I, a transition metal compound, an aluminum-containing cocatalyst, t-butyl hydroperoxide and an organic solvent has higher reaction activity, reaction initiation is rapid, operation is stable, repeatability is good, and selectivity of 1-octene in the product is greatly improved; thereby overcoming the technical bias of the technicians in the field and achieving unexpected technical effects.

One of the purposes of the invention is to provide a brand-new ethylene tetramerization catalyst composition, which comprises a ligand compound shown as a formula I, a transition metal compound, a cocatalyst and tert-butyl hydroperoxide;

in the formula R¹、R²、R³Identical or different, may be chosen from hydrogen, alkyl, alkoxy, cycloalkyl or halogen; 4R present⁴Which may be the same or different, are each independently monocyclic or polycyclic aryl.

In the prior art, the oxide is generally considered to be detrimental to the ethylene tetramerisation reaction. One skilled in the art will generally require that the tetramerisation reaction be carried out under anhydrous and oxygen-free conditions. According to the research of the invention, the ethylene tetramerization reaction has higher activity and the selectivity of the 1-octene is high under the action of the composition, thereby breaking the thought bias of people and achieving unexpected technical effects.

In a preferred embodiment of the present invention, the composition further comprises an organic solvent. The catalyst composition may contain tert-butyl hydroperoxide in an amount of from 25 to 1500ppm, such as from 25 to 1000ppm, by weight based on the weight of the organic solvent. Within the above range, a better tetramerization activity and a higher selectivity for 1-octene can be obtained. In one embodiment, the preferred weight content of t-butyl hydroperoxide is 150-1000ppm, such as 250-750 ppm. In the above preferable range, more preferable effects can be obtained.

In a preferred embodiment of the present invention, the alkyl group is C₁-C₂₀Straight-chain or branched saturated alkyl, preferably C₁-C₁₀Straight-chain or branched saturated alkyl, more preferably C₁-C₆Straight-chain or branched saturated alkyl groups. Further preferably, the alkyl group is selected from the group consisting of: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, sec-pentyl, isopentyl, n-hexyl, sec-hexyl, isohexyl, n-heptyl and isomers thereof, with methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, sec-pentyl, isopentyl, n-hexyl or isohexyl being even more preferred; most preferred is methyl, ethyl, n-propyl, isopropyl, n-butyl or isobutyl.

In a preferred embodiment of the present invention, the alkoxy group is C₁-C₂₀Straight-chain or branched saturated alkoxy, preferably C₁-C₁₀Straight-chain or branched saturated alkoxy, more preferably C₁-C₆Straight-chain or branched saturated alkoxy groups. Further preferably, the alkoxy group is selected from the group consisting of: methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentoxy, sec-pentoxy, isopentoxy, n-hexoxy, sec-hexoxy, isohexoxy, n-heptoxy and isomers thereof; still more preferably a methoxy group, an ethoxy group, a n-propoxy group, an isopropoxy group, a n-butoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a n-pentyloxy group, a sec-pentyloxy group, an isopentyloxy group, a n-hexyloxy group or an isohexyloxy group; most preferably methoxy group,Ethoxy, n-propoxy, isopropoxy, n-butoxy or isobutoxy.

In a preferred embodiment of the present invention, said cycloalkyl is C₃-C₂₀Saturated cyclic hydrocarbon group, preferably C₃-C₁₀Saturated cyclic hydrocarbon group, more preferably C₃-C₆A saturated cyclic hydrocarbon group; most preferably, the cycloalkyl group is selected from the group consisting of: cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl; most preferably cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl.

In a preferred embodiment of the invention, the halogen is selected from fluorine, chlorine or bromine. The monocyclic or polycyclic aryl groups are selected from phenyl and anthracenyl.

In a preferred embodiment of the invention, R in the ligand is¹-R³Same or different, selected from hydrogen, C₁-C₁₀Alkyl radical, C₁-C₁₀Alkoxy or halogen, preferably selected from hydrogen, C₁-C₆Alkyl radical, C₁-C₆Alkoxy or halogen, more preferably hydrogen, methyl, ethyl, methoxy, chlorine or bromine.

In the present invention, the transition metal compound described in the above-mentioned catalyst composition may be a transition metal compound commonly used in the art. Such as at least one of a chromium compound, a molybdenum compound, an iron compound, a titanium compound, a zirconium compound, and a nickel compound. As the chromium compound, the transition metal compound may be at least one of chromium trichloride, chromium acetylacetonate, chromium isooctanoate, chromium tris (tetrahydrofuran) trichloride, and the like.

In a preferred embodiment of the present invention, the cocatalyst is an organoaluminum compound. The cocatalyst may be, for example, an alkylaluminum compound and/or an aluminoxane compound, which are commonly used in the art. In a specific example, the cocatalyst is preferably at least one of the following compounds: trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, diethylaluminum monochloride, ethylaluminum dichloride, methylaluminoxane, ethylaluminoxane and modified methylaluminoxane.

In the above catalyst composition, the molar ratio of the ligand compound, the transition metal compound and the cocatalyst is 1 (0.1-10) to (1-1000), preferably 1 (0.25-2) to (10-700), such as 1 (0.25-2) to (50-700); more preferably 1 (0.5-2): 100-500) or 1 (0.5-2): 50-500. Within the above range, the composition has higher activity and 1-octene selectivity. In a specific example, the ligand compound, transition metal compound, and cocatalyst are present in a molar ratio of 2: 1:(50-500).

In a preferred embodiment of the present invention, the composition further comprises an organic solvent, that is, the composition comprises the ligand compound represented by formula I, the transition metal compound, the cocatalyst, and tert-butyl hydroperoxide, and an organic solvent. The organic solvent is a solvent commonly used in the art, and may be selected from aromatic hydrocarbons and aliphatic hydrocarbons, for example. The aromatic hydrocarbon compound is preferably at least one selected from the group consisting of benzene, toluene, xylene, monochlorobenzene, dichlorobenzene, trichlorobenzene and monochlorobenzene and derivatives thereof. The aliphatic hydrocarbon compound is selected from at least one of linear alkanes, branched alkanes, and cyclic alkanes, and more preferably at least one of pentane, heptane, cyclohexane, and hexane. The organic solvent is used in such an amount that the other components are (fully) dissolved or dispersed. Wherein the ligand compound, the transition metal compound and the co-catalyst are all in catalytic amounts. In a specific embodiment, the transition metal compound is present in a concentration of 0.05 to 0.3mmol/L, based on the volume of the composition.

It is another object of the present invention to provide a process for the tetramerisation of ethylene comprising carrying out the tetramerisation of ethylene in the presence of the above catalyst composition.

In a particular embodiment of the process according to the invention, the reaction temperature for the ethylene tetramerisation is between 0 and 100 deg.C, such as between 30 and 60 deg.C. Within the temperature range, the method has better comprehensive effect. Wherein, the reaction pressure of the ethylene tetramerization is 0.1-6MPa, such as 2.0-5.0MPa, the pressure range is moderate, and the ethylene tetramerization has better comprehensive effect. In another embodiment of the process of the present invention, the concentration of the transition metal compound is from 0.05 to 0.3mmol/L, calculated on the volume of the composition.

In the ethylene tetramerization method, any two of the ligand compound, the transition metal compound, the cocatalyst and the tert-butyl hydroperoxide in the catalyst composition may be mixed in advance and then added to the reaction system together with the other two, or the three components of the ligand compound, the transition metal compound and the cocatalyst may be directly added to the reaction system for in-situ synthesis, or the ligand compound, the transition metal compound, the cocatalyst and the tert-butyl hydroperoxide may be premixed and then directly added to the reaction system in the form of a mixture. The organic solvent may be added during any of the above mixing modes. In addition, the ligand compound, the transition metal compound and the cocatalyst component of the catalyst may be dissolved in an organic solvent, respectively, and then introduced into a reactor for mixing, or the ligand compound, the transition metal compound and the cocatalyst component of the catalyst may be dissolved in an organic solvent in any order, and then tert-butyl hydroperoxide may be added, and then added to the reaction system. Wherein the amount of the transition metal compound is catalytic.

In the above ethylene tetramerization method, the reaction conditions may be those commonly used in the art. The optimized conditions are as follows: adding ethylene, organic solvent and the catalyst composition into a reactor, and then reacting under the conditions that the ethylene pressure is 0.1-6Mpa and the reaction temperature is 0-100 ℃, wherein the concentration of the transition metal compound is 0.05-0.3 mmol/L. After the reaction is finished, cooling to room temperature, and taking gas and liquid products for chromatographic analysis.

In a preferred example of the above ethylene tetramerization process, the reaction pressure is 0.5 to 5.0 MPa; the reaction temperature is 0-80 ℃. Within the above preferred ranges, the method has a more excellent overall effect.

In the present invention, particularly in the pilot plant and industrial production of ethylene tetramerization, the use of the catalyst composition of the present invention not only eliminates the need to maintain strict oxygen-free operation, but instead, requires the addition of a certain amount of t-butyl hydroperoxide in an organic solvent to complete the present invention. The tert-butyl hydroperoxide as the organic oxide can obviously improve the performance of a catalytic system and the selectivity of a target product.

Ethylene tetramerization was performed using the catalyst composition of the present invention, and after the reaction was completed, gas chromatography and mass spectrometry were performed. The product obtained is mainly C₈Product, next C₆Product, with a small amount of C₄、C₁₀、C₁₂And the like alpha-olefins; the selectivity of 1-octene can exceed 70%. The results show that the catalyst activity is high and the amount of high molecular weight polymer is very small.

According to the catalyst composition provided by the invention, ethylene is subjected to tetramerization reaction under the action of the composition comprising the ligand compound shown in the formula I, the transition metal compound, the aluminum-containing cocatalyst and tert-butyl hydroperoxide, and compared with a reported anhydrous and oxygen-free catalyst composition system, the catalyst composition has ultrahigh reaction activity, and is quick in reaction initiation, stable in operation and good in repeatability.

Detailed Description

The following examples are merely illustrative of the present invention in detail, but it should be understood that the scope of the present invention is not limited to these examples.

In the examples of the present invention, NMR was detected by an AV400MHz NMR spectrometer of Bruker, Switzerland. The gas chromatography was performed using a Hewlett packard 5890 chromatograph. The mass spectrum was detected by a Trace DSQ type gas chromatograph-mass spectrometer (Philippine corporation, USA). 4R in the ligand in each example below⁴The same is true.

Example 1

A stainless steel polymerizer is used. The autoclave was heated to 80 ℃, evacuated, replaced with nitrogen several times, then replaced with ethylene, and cooled to room temperature. Then adding toluene at 30 deg.C while adding 10. mu. mol ligand compound 1 (formula I, wherein R is¹＝R²＝R³＝H，R⁴Phenyl), chromium acetylacetonate and a cocatalyst, triethylaluminium, the total volume of the composition being 100mL, wherein the molar ratio of ligand, chromium salt and cocatalyst is 2: 1: 300, i.e. the molar ratio of Al to Cr is 300; based on the total weight of the organic solvent (toluene), catalyzingThe agent composition contained a t-butyl hydroperoxide in an amount of 750ppm by weight; controlling the reaction pressure to be 2.0MPa, and introducing ethylene to carry out ethylene tetramerization reaction.

After the reaction is finished, cooling the system to room temperature, collecting the gas-phase product in a gas metering tank, collecting the liquid-phase product in a conical flask, and adding 1mL of ethanol as a terminator to terminate the ethylene tetramerization reaction. The gas-liquid product was measured and subjected to gas chromatography (Hewlett packard 5890). The data results are shown in table 1.

Example 2

The same as in example 1 except that the content of t-butyl hydroperoxide was 25 ppm. The data results are shown in table 1.

Example 3

The same as in example 1 except that the content of t-butyl hydroperoxide was 250 ppm. The data results are shown in table 1.

Example 4

The same as in example 1 except that the tert-butyl hydroperoxide content was 1000 ppm. The data results are shown in table 1.

Example 5

The same as example 1 except that triethylaluminum was changed to methylaluminoxane. The data results are shown in table 1.

Example 6

The difference from example 1 is that the molar ratio of Al/Cr was changed to 50. The data results are shown in table 1.

Example 7

The difference from example 1 is that the molar ratio of Al/Cr was changed to 500. The data results are shown in table 1.

Example 8

The same as in example 1, except that a ligand compound 2 is used, wherein R in formula I¹＝R³＝H，R²Methyl, R⁴Is a phenyl group. The data results are shown in table 1.

Example 9

The same as in example 1, except that a ligand compound 3 is used, wherein R in formula I¹＝R³＝H，R²＝Cl，R⁴Is a phenyl group. The data results are shown in table 1.

Example 10

The same as example 1 except that the reaction temperature was changed to 60 ℃. The data results are shown in table 1.

Example 11

The same as example 1 except that the reaction pressure was changed to 5.0 MPa. The data results are shown in table 1.

Comparative example 1

The same as in example 1 except that the content of t-butyl hydroperoxide was 0 ppm. The data results are shown in table 1.

Although the data in Table 1 are only given for some parameters, the skilled person can see from the data in Table 1 that the catalyst activity of the catalyst composition provided by the present invention is improved several times under the same conditions compared to the catalyst activity of the comparative example 1. And the selectivity of 1-octene obtained in the inventive example was higher than that in comparative example 1.

In addition, the ethylene tetramerization reaction of the invention has the advantages of rapid initiation, stable operation and good repeatability. Even when the Al/Cr ratio is as low as 50, the catalyst still has good reaction catalytic activity, so that the ethylene tetramerization reaction cost is greatly reduced, and the catalyst is high in practicability and wide in industrialization prospect.

TABLE 1

It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.

Claims (22)

1. An ethylene tetramerization catalyst composition comprises a ligand compound shown as a formula I, a transition metal compound, a cocatalyst and tert-butyl hydroperoxide;

in the formula, R¹、R²And R³Identical or different, selected from hydrogen, alkyl, alkoxy, cycloalkyl and halogen; 4R present⁴Identical or different, each independently a monocyclic or polycyclic aryl group;

the catalyst composition further comprises an organic solvent, and the weight content of the tert-butyl hydroperoxide contained in the catalyst composition is 25-1500ppm by weight based on the weight of the organic solvent;

the mol ratio of the ligand compound, the transition metal compound and the cocatalyst is 1 (0.1-10) to 1-1000.

2. The composition of claim 1, wherein the catalyst composition further comprises an organic solvent, and the t-butyl hydroperoxide is present in an amount of 25 to 1000ppm by weight, based on the weight of the organic solvent.

3. The composition as claimed in claim 2, wherein the tert-butyl hydroperoxide is contained in an amount of 150-1000ppm by weight, based on the weight of the organic solvent.

4. The composition as claimed in claim 2, wherein the t-butyl hydroperoxide is contained in an amount of 250-750ppm by weight, based on the weight of the organic solvent.

5. Combination according to claim 1Characterized in that the alkyl group is C₁-C₂₀A straight-chain or branched saturated alkyl group; and/or

The alkoxy is C₁-C₂₀A linear or branched saturated alkoxy group; and/or

Said cycloalkyl is C₃-C₂₀A cyclic alkyl group.

6. The composition of claim 5, wherein the alkyl group is C₁-C₁₀A straight-chain or branched saturated alkyl group; and/or

The alkoxy is C₁-C₁₀A linear or branched saturated alkoxy group; and/or

Said cycloalkyl is C₃-C₁₀A cyclic alkyl group.

7. The composition of claim 5, wherein the alkyl group is C₁-C₆A straight-chain or branched saturated alkyl group; and/or

The alkoxy is C₁-C₆A linear or branched saturated alkoxy group; and/or

Said cycloalkyl is C₃-C₆A cyclic alkyl group.

8. The composition according to claim 1, characterized in that the alkyl group is selected from the following groups: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, sec-pentyl, isopentyl, n-hexyl, sec-hexyl, isohexyl, n-heptyl, and isomers thereof; and/or

The alkoxy group is selected from the following groups: methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentoxy, sec-pentoxy, isopentoxy, n-hexoxy, sec-hexoxy, isohexoxy, n-heptoxy and isomers thereof; and/or

The cycloalkyl group is selected from cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl; and/or

The monocyclic or polycyclic aryl groups are selected from phenyl and anthracenyl.

9. The composition of claim 1, wherein the transition metal compound is at least one selected from the group consisting of a chromium compound, a molybdenum compound, an iron compound, a titanium compound, a zirconium compound, and a nickel compound.

10. The composition of claim 9, wherein the transition metal compound is selected from at least one of chromium trichloride, chromium acetylacetonate, chromium isooctanoate, and chromium tris (tetrahydrofuran) trichloride.

11. The composition of claim 1, wherein the co-catalyst is an organoaluminum compound.

12. The composition of claim 11, wherein the cocatalyst is an alkylaluminum compound and/or an aluminoxane compound.

13. The composition of claim 11, wherein the co-catalyst is at least one of the following compounds: trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, diethylaluminum monochloride, ethylaluminum dichloride, methylaluminoxane, ethylaluminoxane and modified methylaluminoxane.

14. The composition of claim 1, wherein the molar ratio of the ligand compound, the transition metal compound and the cocatalyst is 1 (0.25-2) to (10-700).

15. The composition as claimed in claim 14, wherein the molar ratio of the ligand compound, the transition metal compound and the cocatalyst is 1 (0.5-2): 100-.

16. The composition of claim 14, wherein the ligand compound, transition metal compound, and cocatalyst are present in a molar ratio of 2: 1: (50-500).

17. The composition according to any one of claims 1 to 16, further comprising an organic solvent; the organic solvent is selected from aromatic hydrocarbon compounds and aliphatic hydrocarbon compounds.

18. The composition of claim 17, wherein the aromatic hydrocarbon compound is selected from at least one of benzene, toluene, xylene, monochlorobenzene, dichlorobenzene, trichlorobenzene and monochlorobenzene and derivatives thereof; or the aliphatic hydrocarbon compound is selected from at least one of linear alkanes, branched alkanes and cyclic alkanes.

19. The composition of claim 17, wherein the aliphatic hydrocarbon compound is selected from at least one of pentane, heptane, cyclohexane, and hexane.

20. A process for the tetramerisation of ethylene, comprising performing an ethylene tetramerisation reaction in the presence of the catalyst composition for the tetramerisation of ethylene according to any one of claims 1 to 19.

21. The method of claim 20, wherein the reaction temperature of the ethylene tetramerization reaction is 0 to 100 ℃; the reaction pressure is 0.1-6 MPa; and/or the concentration of the transition metal compound is 0.05-0.3mmol/L based on the volume of the composition.

22. The method of claim 21, wherein the reaction temperature of the ethylene tetramerization reaction is 0 to 80 ℃; the reaction pressure is 0.5-5.0 MPa.