RU2221813C1 - Method of preparing catalyst and a method for production of high- molecular poly-alpha-olefins using this catalyst - Google Patents

Abstract

FIELD: polymerization catalysts. SUBSTANCE: invention relates to catalysts for production of higher poly- alpha-olefins used, in particular, as agents lowering hydrodynamic resistance in moving hydrocarbon fluids, for example when pumping crude oil through pipeline. Preparation of catalyst comprises magnesium-containing carrier preparation stage followed by reaction of carrier with titanium tetrachloride and alkyl aromatic ether, magnesium-containing carrier being prepared in two stages, wherein, in the first stage, magnesium metal reacts with aromatic halide in presence of an ether to form suspension containing solution of organomagnesium compound and solid phase and, in the second stage, resulting suspension consecutively interacts with silicon alkoxy- derivative and then with alcohol. Polymerization of alpha-olefins in presence of above-prepared catalyst is carried out at temperature from 0 to 50 C. EFFECT: simplified catalyst preparation procedure, increased catalytic activity, and increased molecular weight of polymer. 7 cl, 2 tbl, 13 ex

Description

 The invention relates to methods for producing high molecular weight higher polyalphaolefins and catalysts for implementing this method. High molecular weight higher polyalphaolefins are used in various fields, in particular, as agents for reducing hydrodynamic resistance during the movement of hydrocarbon liquids, for example, when pumping oil through a pipeline.

A known method of producing higher polyalphaolefins by polymerization of higher alpha-olefins with a number of hydrocarbon atoms from 6 to 10 in a hydrocarbon solvent in the presence of a catalyst obtained by the reduction of titanium tetrachloride with an organoaluminum compound and an organoaluminum cocatalyst (RF Patent 2075485, C 08 F 10/14, 03/20/1997 ) This catalyst allows at a temperature of from -30 to 20 ^o C (mainly at 0 ^o C) within 5 hours to achieve a product conversion of 58-98%. By this method, high molecular weight polymers with a characteristic viscosity [η] = 1.2-1.9 m ³ / kg are obtained. The disadvantages of this method are the low activity of the catalyst used, the need to use low temperatures (0 ^{° C.} ) during polymerization, and the relatively low molecular weight of the obtained polymer.

A known method of producing higher polyalphaolefins using a catalytic system consisting of supported titanium-magnesium catalyst containing titanium tetrachloride on a support — magnesium chloride and a stereo-regulating additive (for example, dibutyl phthalate), and cocatalyst, which is a mixture of trialkylaluminum with an alkoxy silicon compound. Such a catalytic system has a significantly higher activity compared to TiCl ₃ based catalysts and is widely used to produce polypropylene and copolymers of propylene with alpha-olefins. A number of methods for the preparation of supported titanium-magnesium catalysts are described, for example, in the book EP Moore (Jr.), Polypropylene Handbook, Hansen Publishers, 1996.

 The closest in technical essence and the achieved result is a polymerization method using a catalyst obtained in three stages (RF Patent 2152404, C 08 F 4/64, 10.07.2000).

 Stage (a). Contacting metallic magnesium with an aromatic halide RX, in which R is an aromatic group containing from 6 to 20 carbon atoms, X is a halogen atom. The result is a suspension that contains a solution of an organomagnesium compound and a solid by-product, consisting mainly of magnesium chloride. A solution of the organomagnesium compound is separated from the solid by-product and used in the next step (b).

Stage (b). The introduction of a silicon compound containing an alkoxy group or an aryloxy group into a solution of an organomagnesium compound at a temperature of from -20 to 20 ^{° C.} to form a solid product, which in the next step (c) is contacted with titanium tetrachloride to form a catalyst.

This catalyst has a narrow particle size distribution and provides polypropylene powder with a small amount of fine fraction, which is an important advantage in the production of polypropylene in modern industrial processes in a liquid monomer and in the gas phase. The catalyst provides a significantly higher yield during the polymerization of higher olefins in comparison with a catalyst based on TiCl ₃ (RF Patent 2075485, C 08 F 10/14, 03/20/1997).

 The disadvantage of this method of preparation of the catalyst is the presence of a significant amount of solid waste in the first stage of preparation of the catalyst. The need to separate these wastes complicates the preparation of the catalyst.

 The invention solves the problem of simplifying the method of producing a catalyst, further increasing the activity of the catalyst, and also solves the problem of increasing the molecular weight of the obtained polymer and increasing the polymerization temperature.

 The problem is solved by using a catalyst in the polymerization process, which is prepared in three stages as follows.

 Stage (a). When the magnesium metal is reacted with an aromatic halide according to a known method (Patent RF 2152404, C 08 F 4/64, July 10, 2000), a suspension (product I) containing a solution of an organomagnesium compound and a solid phase is obtained, and then this suspension is used without separation of the solution and solid phase for the next stage (b).

 Stage (b). At this stage, the suspension obtained in stage (a) is sequentially reacted with an alkoxy silicon compound and then with an alcohol to form a magnesium-containing carrier (product II).

 The interaction of the magnesium-containing carrier with titanium tetrachloride and alkyl aromatic ether to obtain the final catalyst [stage (c)] is carried out similarly to the known solution.

 In addition to simplifying the catalyst preparation technology and reducing the amount of waste in stage (a), an additional advantage of the catalyst compared to the prototype is a higher activity, which is achieved through the use of alcohol in stage (b) (synthesis of a magnesium-containing carrier).

 Stage (a) in the preparation of the catalyst according to the invention is carried out by contacting the magnesium metal with an aromatic halide, which is preferably used chlorobenzene, bromobenzene and iodobenzene. A combination of two or more organic halides may also be used.

 Preferably, the magnesium and the organic halide are brought into contact with each other in the presence of an inert hydrocarbon solvent and an ether. Examples of solvents are aliphatic, alicyclic or aromatic solvents containing 4-10 carbon atoms. Examples of esters are diethyl ether, diisopropyl ether, dibutyl ether, diisoamyl ether, diallyl ether, tetrahydrofuran (THF) and anisole, preferably dibutyl or diisoamyl ether.

The reaction temperature in stage (a) is from 20 to 150 ^o C, mainly up to 110 ^o C; the interaction time is up to 20 hours, mainly 4-8 hours

After completion of stage (a), a suspension (product I) is obtained consisting of a solution of an organomagnesium compound of the composition Mg ₃ Ph _n Cl _m (n = 3.5-4.5; m = 1.5-2.5) and a precipitate. This product is used for the subsequent step (b).

In step (b), the suspension obtained in step (a) is brought into contact with a silicon alkoxy compound and an alcohol. This is accomplished by first adding a silicon compound containing an alkoxy group at a temperature of from -20 to 20 ^° C and then adding alcohol at a temperature of from 0 to 20 ^° C, holding the reaction medium at a temperature of from 20 to 70 ^° C and purifying the resulting product II by washing with a hydrocarbon solvent.

As the silicon alkoxy compound, a compound of the general formula R ¹ _n Si (OR ² ) _{4-n is used} , where R ¹ and R ² are a hydrocarbon group containing from 1 to 6 hydrocarbon atoms, n = 0 ÷ 2, preferably tetraethoxysilane.

 ROH alcohols are used as the alcohol in step (b), where R is a hydrocarbon group containing from 2 to 8 hydrocarbon atoms, preferably ethanol.

 The molar ratio between silicon and magnesium in step (b) can vary from 0.2 to 20, preferably from 0.2 to 1. The molar ratio between alcohol and magnesium in step (b) can vary from 0.5 to 5, preferably from 1 to 3.

 The product II formed in step (b) is then used to prepare the catalyst in step (c).

 The preparation of the catalyst is carried out by contacting in stage (c) of product II obtained in stage (b) with titanium tetrachloride and alkyl aromatic ether.

The problem is also solved by the method of producing high molecular weight polyalphaolefins, which is carried out by polymerization of the corresponding alpha olefin in the presence of a catalyst prepared according to the method described above, and cocatalyst. Aluminum trialkyls, for example triethyl aluminum, are used as cocatalyst. The polymerization process is carried out at a temperature of from 0 to 50 ^o C.

In the polymerization of olefins, an electron-donating compound is usually added to the reaction medium, which increases the stereo-regulating ability of the catalyst. As such a compound, a silicon alkoxy compound of the composition R ¹ _n Si (OR ² ) _4-n , where R ¹ and R ² is a hydrocarbon group containing from 1 to 6 hydrocarbon atoms, n = 1 ÷ 2, can be used.

Prepared by the proposed method, the catalyst is suitable for the polymerization of olefins containing from 2 to 10 carbon atoms, such as ethylene, propylene, butylene, hexene, octene, decene, dodecene. This catalyst is particularly suitable for the polymerization of hexene and other higher alpha-olefins (C ₆ to C ₁₄ ).

 The polymerization is carried out mainly in the liquid phase in the presence of a hydrocarbon solvent such as hexane, heptane, octane, cyclohexane, benzene, toluene or xylene.

The polymerization temperature is from 0 to 50 ^o C. An important technological advantage of the obtained catalyst is the ability to conduct the polymerization process at an elevated temperature (20-30 ^o C) while maintaining a high molecular weight of the polymer.

 The present invention will be further explained using examples that do not limit the invention.

Example 1
Catalyst Preparation
Stage (a). In a three-necked flask equipped with a reflux condenser and a dropping funnel, 26 g of magnesium powder (1.07 mol) are charged. The flask is purged with nitrogen. The magnesium is heated for 1 hour at 80 ^{° C.} and then a mixture of 173 ml of dibutyl ether and 80 ml of chlorobenzene is added. Then, 0.03 g of iodine and 3 ml of n-butane chloride are successively added to the reaction mixture. After the disappearance of iodine staining, the temperature of the mixture was raised to 97 ^{° C.} and 250 ml of chlorobenzene was slowly added over 2.5 hours. The resulting reaction mixture was stirred vigorously for 8 hours at 97 ^° C. The result was a suspension (product I) containing a solution of an organomagnesium compound of the composition Mg ₃ Ph ₄ Cl ₂ and a solid phase containing MgCl ₂ in the ratio Mg ₃ Ph ₄ Cl ₂ / MgCl ₂ = 2: 1.

Stage (b). The suspension of product I obtained in stage (a) (100 ml, 0.25 mol of Mg) is loaded into the reactor. The reactor is cooled to 0 ^{° C.} and a mixture of 22 ml of tetraethoxysilane (TES) and 38 ml of heptane is added over 2 hours with stirring.

After that, the reaction mixture was kept at 0 ^° C for another 0.5 h and, with vigorous stirring, a mixture of 14.6 ml of ethanol (0.25 mol) and 45.4 ml of heptane was metered in for 1 h. Then, the temperature of the reaction mixture was raised to 70 ^{° C.} and maintained at this temperature for 2 hours. After this, stirring and heating were stopped and the solid product was allowed to precipitate. The liquid above the precipitate is removed by decantation. The solid is washed with heptane (4 times 250 ml). 25.2 g of solid magnesium-containing product II are obtained, suspended in 100 ml of heptane.

Stage (s). The reactor is purged with nitrogen and a mixture of 150 ml of titanium tetrachloride and 150 ml of chlorobenzene and 12 g of product II in 48 ml of heptane is successively loaded into it. The reaction mixture is heated with stirring to 115 ^{° C.} , 7.2 ml of dibutyl phthalate is introduced into it and kept at 115 ^{° C.} for 1 hour. After this, stirring is stopped and the solid product is allowed to settle.

The liquid above the precipitate is removed by decantation, after which the mixture is added. consisting of 150 ml of titanium tetrachloride and 150 ml of chlorobenzene. The reaction mixture is again heated to 115 ^{° C.} and stirred for 30 minutes, after which the solid product is allowed to settle for 30 minutes. This last cycle is repeated again. The resulting solid was washed 5 times using 300 ml of heptane at 60 ^° C. A catalyst suspended in heptane was obtained. The titanium content in the catalyst is 1.9 wt.%.

Polymerization
At a temperature of 20 ^{° C.,} 150 ml of heptane, 5 ml of a solution of triisobutylaluminum (TIBA) in heptane with a concentration of 0.29 mmol / ml (1.45 mmol of TIBA), 1.2 mmol of propyltrimethoxysilane (PTMS) and 62 ml (0.5 mol) of hexene are loaded into a 1 liter reactor -1, which corresponds to the concentration of hexene-1 in the reactor 2.5 mol / l and 0.0144 g of catalyst. The polymerization is carried out at a temperature of 20 ^o C for 1 h. The polymer is discharged, add 20 ml of isopropanol and 20 ml of a solution of ANOX stabilizer in acetone with a concentration of 1 g / l. The polymer is dried to constant weight. The output of polyhexene is 1.0 kg / g cat .; the conversion of hexene-1 is 46%. The intrinsic viscosity of the polymer [η], determined in gasoline at 20 ^{° C.} , is 1.3 m ³ / kg.

Example 2
The catalyst was prepared as described in Example 1, except that in step (b) 21.9 ml of ethanol (0.375 mol, molar ratio of ethanol: Mg = 1.5) and 38.1 ml of heptane were used.

The polymerization of hexene-1 is carried out analogously to example 1, but using 0.0121 g of catalyst. The yield of polyhexene is 1.2 kg / g of catalyst, the conversion of hexene-1 is 46%. Get polyhexene with a characteristic viscosity of 1.6 m ³ / kg

Example 3
The catalyst was prepared as described in Example 1, except that in step (b) 43.8 ml of ethanol (0.75 mol, molar ratio of ethanol: Mg = 3) and 16.2 ml of heptane were used.

The polymerization of hexene-1 is carried out analogously to example 1. The output of polyhexene is 0.8 kg / g cat. Get polyhexene with a characteristic viscosity of 1.3 m ³ / kg

Example A (comparative)
Catalyst Preparation
Stage (a). In a three-necked flask equipped with a reflux condenser and a dropping funnel, 26 g of magnesium powder (1.07 mol) are charged. The flask is purged with nitrogen. The magnesium is heated for 1 hour at 80 ^{° C.} and then a mixture of 173 ml of dibutyl ether and 80 ml of chlorobenzene is added. Then, 0.03 g of iodine and 3 ml of n-butane chloride are successively added to the reaction mixture. After the disappearance of iodine staining, the temperature of the mixture was raised to 97 ^{° C.} and 250 ml of chlorobenzene was slowly added over 2.5 hours. The resulting reaction mixture was stirred vigorously for another 8 hours at 97 ^° C. Then, stirring and heating were stopped and the solid was allowed to settle for 48 h. After that, a solution of an organomagnesium compound with a concentration of 1 mol / L is separated from the precipitate. This solution is used in the future for stage (b).

Stage (b). To a solution of an organomagnesium compound (100 ml, 1 mol / L) was added a mixture of 11.2 ml of tetraethoxysilane (TES) and 38 ml of dibutyl ether with stirring at 0 ^° C for 2 hours. After this, the reaction mixture was kept at 0 ^° C for another 0.5 hour and then the temperature was raised to 60 ^° C. Then the reaction mixture was kept at 60 ^{° C.} for 1 hour. The resulting solid was washed with heptane (4 times, 150 ml each). 13.5 g of a light yellow solid are obtained, suspended in 40 ml of heptane.

 Stage (C) of the preparation of the catalyst is carried out analogously to example 1.

The polymerization of hexene-1 is carried out analogously to example 1, but using 0.015 g of catalyst. The yield of polyhexene is 0.50 kg / g cat., The characteristic viscosity of the polymer is 1.2 m ³ / kg.

Example B (comparative)
Stage (a) is carried out analogously to example 1.

 Stage (b) is carried out as described in example 1, except that in this case, the product obtained after the addition of tetraethoxysilane is not treated with ethanol.

Stage (C) and the polymerization of hexene-1 is carried out analogously to example 1. The yield of polyhexene is 0.55 kg / g cat., The characteristic viscosity of polyhexene is 1.2 m ³ / kg

Example 4
Stage (a) of the preparation of the catalyst is carried out as described in example 1, except that 24.3 g of magnesium (1 mol), 169.5 ml of dibutyl ether (1 mol) and 370 ml of chlorobenzene are used. The result is a suspension of product I.

Stage (b). A suspension of product I (100 ml, 0.2 mol Mg) was charged into the reactor and 40 ml of heptane was added with stirring. The reactor was cooled to -15 ^° C and a mixture of 17.9 ml of tetraethoxysilane (TPP, 0.08 mol) and 42.4 ml of heptane was added with stirring over 1 h. After that, the reaction mixture was kept at -15 ^{° C. for} another 0.5 hours and then the temperature was raised to 60 ^° C. over 1 hour. Then the reaction mixture was kept at 60 ^{° C.} for 1 hour, cooled to a temperature of 20 ^{° C.} and at this temperature at with vigorous stirring, a mixture of 7.8 ml of 2-ethylhexanol (2-EG, 0.05 mol), 8.8 ml of ethanol and 73.4 ml of heptane is metered over 3 hours. Then, the temperature was raised for 1 hour to 70 ^{° C.} and kept at 70 ^{° C.} for 2 hours. After this, stirring and heating were stopped and the solid product was allowed to settle. The liquid above the precipitate is removed by decantation. The solid is washed 4 times using 250 ml of heptane. A magnesium-containing product II is obtained, suspended in 100 ml of heptane.

Stage (C) and the polymerization of hexene-1 is carried out analogously to example 1. The yield of polyhexene is 0.65 kg / g cat., The characteristic viscosity of the polymer is 1.3 kg / m ³ .

Example 5
Steps (a) and (b) of preparing the catalyst are carried out as described in example 4, except that in step (b) a mixture of 15.6 ml of 2-ethylhexanol (0.1 mol), 17.5 ml of ethanol (0.3 mol) and 56.9 ml are used heptane.

Stage (C) and the polymerization of hexene-1 is carried out analogously to example 1. The output of polyhexene is 0.72 kg / g cat., The characteristic viscosity of the polymer is 1.3 kg / m ³ .

Example 6
The preparation of the catalyst is carried out as in example 1, except that the synthesis of the organomagnesium compound in stage (a) is carried out in the presence of diisoamyl ether at a molar ratio of ether / Mg = 1. The polymerization of hexene-1 is carried out under the conditions of example 1. The yield of polyhexene is 1.0 kg / g cat., The characteristic viscosity of the polymer is 1.2 kg / m ³ .

Example 7
The preparation of the catalyst is carried out as in example 1, except that the synthesis of the organomagnesium compound in stage (a) is carried out in the presence of diisoamyl ether at the ratio ether / Mg = 1 and the suspension of the product (I) is treated with C ₆ H ₅ Si (OS ₂ N ₅ ) ₃ with the ratio Si / Mg = 1. The polymerization of hexene-1 is carried out under the conditions of example 1. The yield of polyhexene is 1.1 kg / g cat., The characteristic viscosity of the polymer is 1.3 kg / m ³ .

Example 8
Use the catalyst prepared in example 2. The polymerization of hexene-1 is carried out under the conditions of example 1 except that the polymerization time is 2 hours. The yield of polyhexene under these conditions is 1.5 kg / g cat. ; conversion of hexene-1 - 53%. The intrinsic viscosity of the polymer is 1.4 m ³ / kg.

Example 9
The catalyst prepared in Example 1 was used. The hexene-1 was polymerized under the conditions of Example 8, but triethylaluminum (TEA) was used as a cocatalyst. The yield of polyhexene under these conditions is 1.2 kg / g cat. ; the conversion of hexene-1 reaches 30%. The characteristic viscosity of the polymer is 0.95 m ³ / kg.

Example 10
Use the catalyst prepared in example 1. Carry out the polymerization of octene-1 under the conditions of example 8. The yield of polyoctene is 2.0 kg / g cat. The resulting polymer has an intrinsic viscosity of 0.25 m ³ / kg.

Example 11
The catalyst prepared according to Example 1 was used. The C ₁₂ -C ₁₄ olefin fraction was polymerized under the conditions of Example 8. The polymer yield was 3 kg / g cat. The resulting polymer has an intrinsic viscosity of 0.32 m ³ / kg.

Example 12
Use the catalyst prepared in example 1. The polymerization of hexene-1 is carried out under the conditions of example 8, but at a polymerization temperature of 30 ^{° C.} and a catalyst weight of 0.0086 g. The polymer yield is 3.1 kg / g cat., Conversion - 67%. The obtained polyhexene has an intrinsic viscosity of 0.69 m ³ / kg.

Example 13
The catalyst prepared in Example 2 was used. Hexene-1 was polymerized under the conditions of Example 1, but tetraethoxysilane (TES) was used instead of PTMS. The output of polyhexene is 1.0 kg / g cat .; conversion - 44%. Get polyhexene with a characteristic viscosity of 1.4 m ³ / kg

 As can be seen from the above examples and tables, the present invention allows to simplify the method of preparation of the catalyst, while the resulting catalyst has a higher activity compared to known catalysts. The use of a catalyst according to the proposed method in the polymerization of alpha-olefins leads to an increase in the molecular weight of the resulting polyalphaolefins and an increase in the polymerization temperature.

Claims (7)

1. A method of preparing a catalyst for the production of high molecular weight polyalphaolefins, comprising the step of producing a magnesium-containing support and subsequent reaction of the support with titanium tetrachloride and alkyl aromatic ether, characterized in that the magnesium-containing support is obtained in two stages, where the magnesium metal is reacted with an aromatic halide in the presence of a first step ether to form a suspension containing a solution of an organomagnesium compound and a solid phase, and and the second stage carries out the sequential interaction of the resulting suspension with an alkoxy silicon compound and then with alcohol. 2. The method according to claim 1, characterized in that the ether in the first stage is dibutyl or diisoamyl ether. 3. The method according to any one of claims 1 and 2, characterized in that the silicon alkoxy compound in the second stage is compound R $\genfrac{}{}{0ex}{}{\text{1}}{\text{n}}$ Si (OR ² ) ₄ , where R ¹ and R ² are a hydrocarbon group containing 1-6 hydrocarbon atoms, n = 0-2. 4. The method according to any one of claims 1 to 3, characterized in that in the second stage, ROH alcohol is used, where R is a hydrocarbon group containing 2-8 hydrocarbon atoms. 5. The method according to any one of claims 1 to 4, characterized in that the molar ratio between alcohol and magnesium is 1-3. 6. The method of producing polyalphaolefins by polymerization of alpha olefins With _n H _2n , where n≥6, in the presence of a catalytic system comprising a solid component containing titanium tetrachloride, a magnesium-containing carrier and an electron-donor compound and a cocatalyst consisting of aluminum trialkyl and electron-donor compound, characterized in that use the catalyst obtained according to any one of claims 1 to 5. 7. The method according to claim 6, characterized in that the polymerization process is carried out at a temperature of 0-50 ° C.

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