RU2570650C1 - Method for obtaining ligomers of alpha-olefin c6, c8 or c10 - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to method of obtaining oligomers of alpha-olefin C₆, C₈ or C₁₀, which includes preparation of olefin raw material, stage of oligomerisation in presence of inert solvent and postmetalocene catalytic system, which contains coordination compound of alcoholate of 5 group of Periodic table metal with organic polydentate ligand and cocatalyst. Method is characterised by the fact that stage of oligomerisation is carried out at temperature from 25 to 80°C, ratio alpha-olefin:solvent equal 1:1-3:1, in presence of reactivator - ethyltrichloroacetate in concentration 10-20 mole/ml³. Catalytic system contains coordination compound of vanadium alcoholate in concentration 0.1-1.0 mole/ml³, and as cocatalyst - diethylaluminium chloride or sesquiethylaluminium chloride in concentration 20-50 mole/ml³.

EFFECT: increase of catalytic activity and selectivity of catalyst with respect to formation of target product with predominant content of trimers.

3 cl, 2 tbl, 9 ex

Description

The invention relates to a method for producing oligomers in the process of oligomerization of alpha-olefins (hexene-1, octene-1 or decene-1), suitable as bases for synthetic base oils and can be used in the petrochemical industry.

Known methods for producing oligomers of alpha-olefins suitable as bases for synthetic base polyalphaolefin oils are distinguished by different types of catalysts used.

The most widely known of these are cationic polymerization catalysts.

The obvious disadvantages of the known methods for oligomerization of alpha-olefins in the presence of complexes of BF ₃ or AlCl ₃ with various compounds include:

- the use of sufficiently toxic and corrosive chemicals from the class of boron and aluminum halides, resulting in increased costs for the disposal of industrial waste, labor protection, equipment wear;

- low productivity of catalytic systems;

- low selectivity of the process, resulting in a reduced yield of the oil fraction, increased specific consumption of raw materials and catalyst.

The use of zeolite catalysts leads to the formation of oligomers, the composition of which is dominated by dimers (from 60 to 90 wt.%).

Meanwhile, it is known that alpha-olefin trimers isolated from the reaction products after hydrogenation are characterized by a unique set of physical properties - high viscosity index, low pour point, high flash point, and low volatility (Table 1). This combination of properties provides the possibility of their use as the basis of synthetic base oils.

Thus, alpha-olefin trimers are the preferred oligomerization product that can be used as high-quality synthetic base oil bases.

High quality requirements for the bases of synthetic polyalphaolefin base oils dictate the need to search for new catalytic systems that are selective with respect to the formation of predominantly trimers of alpha olefins. Postmetallocene catalytic systems based on complex compounds of transition metals and cocatalysts in the form of organoaluminum compounds are one of the actively developing areas for the synthesis of high molecular weight compounds. This is caused, on the one hand, by the need to create a new generation of highly efficient and stereospecific olefin oligomerization catalysts combining the advantages of homogeneous and classical heterogeneous catalysts, and on the other hand, market requirements for new types of oligomeric compounds with a given range of useful properties. Ziegler type postmetallocene catalytic systems include catalytic systems containing at least two components and providing, after the formation of catalytically active centers, the process of oligo- or polymerization of olefinic hydrocarbons.

The basis of the system is a complex compound of a transition metal, the second component is an activator or cocatalyst (in the general case, this role is played by an organometallic compound of a non-transition metal, for example methylaluminoxane, or a weakly coordinated phenylborate base).

In contrast to metallocenes, postmetallocene catalysts can be activated not only by MAO, but also by “standard” in the classical Ziegler-Natta catalysis with organoaluminum activators such as TEA, TIBA, DEAH, etc. Moreover, they are able to work in low concentrations, to form active centers of a monocenter type, to catalyze the oligomerization processes of both lower and higher olefinic hydrocarbons.

This type of catalyst with the greatest efficiency can be used to obtain known and new oligomeric materials with improved properties, for example, the basis of synthetic base oils. The resulting oligomers can have a molecular weight of 200 to 400 g / mol and higher. However, the use of postmetallocene catalyst systems for these purposes has been little studied.

A known method for producing C ₂₀ -C ₆₀ oligomers of α-olefins, which are mainly used octene-1 and decene-1 in the presence of a two-component catalyst system containing aluminum alkyl halide and an organohalogen compound. As the aluminum alkyl halide, ethyl aluminum sesquichloride or diethyl aluminum chloride is used. The organo halide is tert-butyl chloride, alkyl chloride or benzyl chloride. Oligomerization is carried out at a temperature of 100-150 ° C. The yield of oligomeric product is ~ 56%, the average molecular weight is 490-506. US 4952739, 08/28/1990.

The disadvantage of this method is the low (less than 20 wt.%) Yield of target trimers decene-1.

A known method of producing oligomers of alpha-olefins of hexene-1 and decene-1 in the presence of a catalytic system comprising a compound of chromium (3+), 1,3,5-tris (cycloalkyl) -1,3,5-triazocyclohexane and the activator is trialkylaluminum alkylaluminoxane. The oligomerization process is carried out in an inert atmosphere at a temperature of 20-110 ° C. US 2005/0256357 A1, 10.17.2005, WO 0058319 A1, 05/10/2000.

The disadvantage of this method is the poor solubility of the catalyst precursor — a complex of chromium with a 1,3,5-triazocyclohexane ligand, as a result of which long-chain alkyl or cycloalkylalkyl radicals have to be introduced into the ligand structure, which increases the cost of the catalyst precursor.

Another disadvantage is the low stability of the complex, the ease of its dissociation in the presence of polar solvents and some reagents, which generally determines the poor reproducibility of the oligomerization results obtained on such systems.

A known method of producing oligomers of α-olefins C ₈ -C ₁₄ in the presence of a catalytic system comprising BF ₃ , a proton promoter (water, alcohol, or a mixture thereof), and a modifier (1,3-dioxalane or 1,3-dioxane) at a temperature from 20 to 60 ° C, pressure from 0.03 to 0.70 MPa. The ratio of modifier / promoter is 0.5-2 mol / mol. The reaction time is 90-120 minutes. The composition of the obtained product is as follows: C ₂₀ - 62.0%, C ₃₀ - 28.7%, C ₄₀ - 5.6%, C ₅₀ - 0.5%. US 5744676 A, 04/28/1998.

The disadvantage of this method of producing oligomers of alpha-olefins is the low yield of the target product (trimer) and the use of toxic and corrosive catalytic systems based on boron complex.

A known method of oligomerization of α-olefins With ₁₀ -C ₂₄ in the presence of dealuminated zeolite Y with a ratio of SiO ₂ / Al ₂ O ₃ from 6.5 to 60 to obtain oligomers suitable for use as bases for synthetic base oils.

The catalyst is prepared by wet impregnation of a carrier, zeolite Y, with an aqueous solution of metal salts, which use metal cations of groups III B, IV B, VI B, VII V. The amount of metal is 10 wt. % The monomer and catalyst are charged into a three-necked flask equipped with a thermometer, a stirrer, a mantle heater and a water cooler. The mixture is heated with vigorous stirring to a temperature of 160-180 ° C and kept for 4-5 hours. The resulting product is cooled to room temperature, filtered and fractionated in order to distill off unreacted raw materials. The main product of the oligomerization process are dimers (from 55.0 to 69.4 wt.%). The content of the target product (trimers) is negligible and does not exceed 18.5 wt. % US 5120891 A, 06/09/1992.

The disadvantages of this method of producing oligomers of alpha-olefins are the low activity and coking ability of the catalyst during the oligomerization process, as well as the low yield of the target product.

A known method of producing oligomers in the process of oligomerization of hexene-1 and decene-1 using a metallocene catalyst nBuCp ₂ ZrCl ₂ and activator methylaluminoxane (MAO) with a molar ratio Al / Zr 200. The process is carried out at a temperature of 70-90 ° C. The main product of the process are dimers (from 60 to 71%). The dimers are subjected to further polymerization using supported AlCl ₃ catalysts, supported EtAlCl ₂ and supported EtAlCl ₂ supported on a silica gel carrier to obtain a higher molecular weight product. Kissin YV, Schwab F.C. Post-oligomerization of a-olefin oligomer: a route to single-component and multicomponent synthetic lubricating oils. Journal of Applied Polymer Science. 2009, n. 111, p. 273-280.

The disadvantage of this method of producing oligomers of alpha-olefins is the low yield of the target product and a multi-stage process for its preparation, which increases the cost of production.

The closest in technical essence is a method for producing oligomers of C ₃ -C ₁₆ alpha-olefins in the presence of an inert solvent, where the metallocene catalyst bis (cyclopentadienyl) zirconium dichloride in combination with cocatalyst-methylaluminoxane (MAO) is used as a catalyst. The oligomerization process is carried out as follows. Before starting the experiment, the flask with a magnetic stirrer is thoroughly evacuated after purging with argon for 30 minutes. Then a solution of tetradecene-1 (dried with 5A molecular sieves) and 10 ml of dry toluene dried over potassium was fed into the flask, and the mixture was heated to the experimental temperature. At a temperature of 40 ° C, 4 ml of 3.3 M concentrated cocatalyst-methyalumoxane in toluene are added and stirred for 15 minutes. Then add 4 ml of a 6.2 × 10 ^-3 M solution of a catalyst - bis (cyclopentadienyl) zirconium dichloride in toluene. The reaction temperature is maintained with a thermostat in increments of ± 1 ° C. The process is carried out with stirring and at a constant temperature for 1 hour. To terminate the reaction, 50 ml of a 10% aqueous HCl solution are added to the flask and the final mixture is stirred for 2 hours. Then the organic layer is separated from the product and washed twice with 50 ml of distilled water. The toluene solution is subsequently removed from the organic layer using a rotary evaporator. Analysis of the product mixture using high-temperature simulated distillation showed an oligomer yield of 66%. Oligomers consisted of ~ 42% dimers, 26% trimers, 15% tetramers, 8% pentamers, and 9% higher oligomers. US 7129197 B2, 10/31/2006.

The disadvantage of this method of producing oligomers of alpha-olefins is the low content of the target product - tetradecene trimers and the use of metallocene catalysts and alumoxanes, which are expensive chemical compounds, which significantly increases the cost of production.

Another disadvantage is the extremely high sensitivity of the catalysts to oxygen and moisture, which as a result significantly limits their industrial use.

The technical task of this invention is to increase the conversion of C ₆ , C ₈ and C ₁₀ alpha olefins and the yield of the target product (trimer) by implementing the developed method for producing alpha olefin oligomers by oligomerization of C ₆ , C ₈ or C ₁₀ alpha olefins in the presence of postmetallocene catalytic system.

The technical result achieved from the implementation of the invention is to provide high catalytic activity and selectivity of the catalyst in relation to the formation of the target product.

The technical problem is solved in that when oligomers of C ₆ , C ₈ or C ₁₀ alpha-olefins are obtained, the oligomerization stage is carried out at a temperature of from 25 to 80 ° C, an alpha-olefin: solvent ratio of 1: 1-3: 1, in the presence of reactant - ethyl trichloroacetate in a concentration of 10-20 mol / ml, while the catalytic system contains a coordination compound of vanadium alcoholate in a concentration of 0.1-1.0 mol / ml, and as a cocatalyst, ethyl ethyl chloride or sesquietyl aluminum chloride in a concentration of 20-50 mol / ml ³ .

These distinguishing features are significant.

To obtain C ₆ , C ₈ or C ₁₀ alpha-olefin oligomers, the oligomerization step is carried out in a batch reactor. Before the start of the experiment, the reactor is heated to a temperature of 200 ° C and purged with argon for 30 minutes. Then vacuum and cool to room temperature. After cooling the reactor, in a countercurrent of argon, a solution of monomer in a solvent and a calculated amount of cocatalyst - diethylaluminium chloride are fed into it and the mixture is heated to the temperature of the experiment. Next, a solution of the catalyst in toluene and a reactant ethyl trichloroacetate are added. The reactor is sealed and filled with argon to a slight overpressure. The start of the oligomerization process is considered to be the moment of catalyst introduction. The process is carried out with stirring and at a constant temperature for 2-4 hours. Then, isopropyl alcohol and 1M hydrochloric acid are added to the resulting mixture to deactivate unreacted organoaluminum compounds, after which the product is discharged from the reactor and the organic layer is separated on a separatory funnel. The organic layer is washed several times with distilled water until neutral, dried over anhydrous sodium sulfate, filtered and fractionated on a rotary evaporator in order to distill off unreacted feed and toluene. The residue was fractionated in vacuo.

In the process of oligomerization of alpha-olefin C ₆ , C ₈ or C ₁₀ , high process performance was achieved: conversion of alpha olefin ≥78%, yield of the target product (trimer) at least 60 wt. %

The application of the proposed method for producing oligomers of alpha-olefins, provides a high conversion of alpha-olefin, the output of the oligomer and the yield of the target product (table 2).

The method is illustrated by the following examples.

Example 1

The hexene-1 oligomerization process is carried out in a batch reactor. Before the start of the experiment, the reactor is heated to a temperature of 200 ° C and purged with argon for 30 minutes. Then vacuum and cool to room temperature. After cooling the reactor, in a countercurrent of argon, a solution of hexene-1 in toluene with an alpha-olefin: solvent ratio of 1: 1 and 10 ml (0.08 mol) of diethylaluminium chloride is fed into it and the mixture is heated to a temperature of 25 ° C. Next, 2.8 ml (0.2 mol) of a solution of 2,4-di-tert-butyl-6-hydroxymethylphenol vanadyl propylate in 10 ml of toluene and 2.2 ml (0.02 mol) of ethyl trichloroacetate are added. The reactor is sealed and filled with argon to a slight overpressure. The start of the oligomerization process is considered to be the moment of catalyst introduction. The process is carried out with stirring and at a constant temperature of 25 ° C for 2 hours. Then, isopropyl alcohol and 1 M hydrochloric acid are added to the resulting mixture to deactivate unreacted organoaluminum compounds, after which the product is discharged from the reactor and the organic layer is separated on a separatory funnel. The organic layer was washed several times with distilled water until neutral, dried over anhydrous sodium sulfate, filtered and fractionated on a rotary evaporator to distill off the unreacted feed and toluene. The residue was fractionated in vacuo. The result is an oligomer with a yield of 75 wt. %, the yield of the target product (trimer) is 62 wt. %

Example 2

The hexene-1 oligomerization process is carried out in a batch reactor. Before the start of the experiment, the reactor is heated to a temperature of 200 ° C and purged with argon for 30 minutes. Then vacuum and cool to room temperature. After cooling the reactor, in a countercurrent of argon, a solution of hexene-1 in benzene with an alpha-olefin: solvent ratio of 2: 1 and 15 ml (0.12 mol) of diethylaluminium chloride is fed into it, and the mixture is heated to a temperature of 35 ° C. Then, 10 ml (0.7 mol) of a solution of 4-tert-butyl-2- (1,1,1,3,3,3-hexafluoro-2-hydroxypropan-2-yl) phenol of vanadyl propylate in 35 ml of toluene and 2 , 2 (0.02 mol) of ethyl trichloroacetate. The reactor is sealed and filled with argon to a slight overpressure. The start of the oligomerization process is considered to be the moment of catalyst introduction.

The process is carried out with stirring and at a constant temperature of 35 ° C for 3 hours. Then, isopropyl alcohol and 1 M hydrochloric acid are added to the resulting mixture to deactivate unreacted organoaluminum compounds, after which the product is discharged from the reactor and the organic layer is separated on a separatory funnel. The organic layer is washed several times with distilled water until neutral, dried over anhydrous sodium sulfate, filtered and fractionated on a rotary evaporator in order to distill off unreacted feed and toluene. The residue was fractionated in vacuo. The result is an oligomer with a yield of 75 wt. %, the yield of the target product (trimer) is 66 wt. %

Example 3

The hexene-1 oligomerization process is carried out in a batch reactor. Before the start of the experiment, the reactor is heated to a temperature of 200 ° C and purged with argon for 30 minutes. Then vacuum and cool to room temperature. After cooling the reactor in countercurrent with argon, a solution of hexene-1 in xylene with an alpha-olefin: solvent ratio of 3: 1 and 25 ml (0.20 mol) of diethylaluminium chloride is fed into it and the mixture is heated to a temperature of 60 ° C. Then 28 ml (2 mol) of a solution of the catalyst 2,4-di-tert-butyl-6-hydroxymethylphenol vanadyl propylate in 90 ml of toluene and 4.4 ml (0.03 mol) of ethyl trichloroacetate are added. The reactor is sealed and filled with argon to a slight overpressure. The start of the oligomerization process is considered to be the moment of catalyst introduction. The process is carried out with stirring and at a constant temperature of 60 ° C for 4 hours. Then, isopropyl alcohol and 1M hydrochloric acid are added to the resulting mixture to deactivate unreacted organoaluminum compounds, after which the product is discharged from the reactor and the organic layer is separated on a separatory funnel. The organic layer is washed several times with distilled water until neutral, dried over anhydrous sodium sulfate, filtered and fractionated on a rotary evaporator in order to distill off unreacted feed and toluene. The residue was fractionated in vacuo. The result is an oligomer with a yield of 75 wt. %, the yield of the target product (trimer) is 65 wt. %

Example 4

The synthesis is as in Example 1, except that sesquietylaluminium chloride is used as a cocatalyst.

The result is an oligomer with a yield of 78 wt. %, the yield of the target product (trimer) is 66 wt. %

Example 5

The synthesis as in Example 4, except that the oligomerization process is carried out at a temperature of 80 ° C.

The result is an oligomer with a yield of 76 wt. %, the yield of the target product (trimer) is 63 wt. %

Example 6

The synthesis as in Example 1, except that octene-1 is used as the alpha olefin feed.

The result is an oligomer with a yield of 80 wt. %, the yield of the target product (trimer) is 70 wt. %

Example 7

The synthesis as in Example 3, except that decen-1 is used as the alpha olefin feed.

The result is an oligomer with a yield of 83 wt. %, the yield of the target product (trimer) is 72 wt. %

Example 8 (prototype).

Before the experiment, the flask with a magnetic stirrer was thoroughly evacuated after purging with argon for 30 min. Then, a solution of tetradecene-1 (dried with 5A molecular sieves) and 10 ml of dry toluene dried over potassium are fed into the flask and the mixture is heated to the temperature of the experiment. At a temperature of 40 ° C, 4 ml of 3.3 M concentrated methaluminoxane in toluene are added and stirred for 15 minutes. Then add 4 ml of a 6.2 × 10 ^-3 M solution of bis (cyclopentadienyl) zirconium dichloride in toluene. The reaction temperature is maintained with a thermostat in increments of ± 1 ° C. The process is carried out with stirring and at a constant temperature for 1 hour. To terminate the reaction, 50 ml of a 10% aqueous HCl solution are added to the flask and the final mixture is stirred for 2 hours. Then the organic layer is separated from the product and washed twice with 50 ml of distilled water. The toluene solution is subsequently removed from the organic layer using a rotary evaporator. Analysis of the product mixture using high-temperature simulated distillation showed an oligomer yield of 66%. Oligomers consist of ~ 42% dimers, 26% trimers, 15% tetramers, 8% pentamers and 9% higher oligomers.

Example 9 (prototype).

Before the experiment, the flask with a magnetic stirrer was thoroughly evacuated after purging with argon for 30 min. Then, a solution of decene-1 (dried with 5A molecular sieves) and 10 ml of dry toluene dried over potassium was fed into the flask and the mixture was heated to the experimental temperature. At a temperature of 60 ° C, 2 ml of 3.3 M concentrated methaluminoxane in toluene are added and stirred for 15 minutes. Then add 4 ml of a 6.2 × 10 ^-3 M solution of bis (cyclopentadienyl) zirconium dichloride in toluene. The reaction temperature is maintained with a thermostat in increments of ± 1 ° C. The process is carried out with stirring and at a constant temperature at a temperature of 60 ° C for 1 hour. To terminate the reaction, 50 ml of a 10% aqueous HCl solution are added to the flask and the final mixture is stirred for 2 hours. Then the organic layer is separated from the product and washed twice 50 ml of distilled water. The toluene solution is subsequently removed from the organic layer using a rotary evaporator. Analysis of the product mixture using high-temperature simulated distillation showed an oligomer yield of 94%. Oligomers consisted of ~ 60% dimers, 23% trimers, 9% tetramers, 3% pentamers, and 5% higher oligomers.

The main indicators of the process of oligomerization of alpha-olefans C ₆ , C ₈ and C ₁₀ according to examples 1-9 are shown in Table 2.

As can be seen from the table, the use of the claimed method of oligomerization in the presence of a postmetallocene catalyst system of the coordination compound of vanadium alcohol in the presence of a reactant — ethyl trichloroacetate and cocatalyst — diethyl aluminum chloride or sesquietyl aluminum chloride in predetermined molar concentrations, provides the target product with high values of the initial conversion of 78 m %), the yield of the target product (62-72 wt.%) and the ratio of the _trimer / B _oligomer (0.83-9.88) compared with the prototype (0.24-0.39).

Obtained by the claimed method, the products can be used as the basis of synthetic polyolefin base oils for various purposes.

Claims (3)

1. A method for producing alpha-olefin C ₆ , C ₈ or C ₁₀ oligomers, comprising preparing an olefin feed, an oligomerization step in the presence of an inert solvent and a postmetallocene catalyst system containing a coordination compound of a metal alcoholate of group 5 of the Periodic system with an organic polydentate ligand and a cocatalyst different the fact that the oligomerization stage is carried out at a temperature of from 25 to 80 ° C, the ratio of alpha-olefin: solvent equal to 1: 1-3: 1, in the presence of a reactant ethyl trichloroacetate in concentrations of 10-20 mol / ml ³ , while the catalytic system contains a coordination compound of vanadium alcoholate in a concentration of 0.1-1.0 mol / ml ³ , and diethylaluminium chloride or sesquietylaluminium chloride in a concentration of 20-50 mol / ml as a cocatalyst ³ . 2. The method according to p. 1, characterized in that the solvent is selected from a number of aromatic compounds: benzene, toluene or xylene. 3. The method according to p. 1, characterized in that as the alpha-olefin raw materials use hexene-1, octene-1 or decene-1.