RU2368624C1 - METHOD OF OBTAINING CATALYST FOR POLYMERISATION OF HIGHER α-OLEFINS AND METHOD OF OBTAINING ULTRA-HIGH MOLECULAR POLY-α-OLEFINS - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: description is given of a method of obtaining a catalyst for polymerisation of α-olefins, involving reacting titanium chloride, diethylaluminium chloride and di-n-butyl ether, distinguished by that, the titanium chloride used is titanium tetrachloride, which is reacted with di-n-butyl ether in an inert hydrocarbon solvent, obtaining product I, and diethylaluminium chloride is reacted with di-n-butyl ether, obtaining product II. Product II is then added to product I and the obtained suspension is held at 90-100°C. Described also is a method of obtaining ultra-high molecular poly-α-olefins through polymerisation of α-olefins CnH_2n, where n=6-10, or their mixture, in the presence of the above described catalyst and dialkylaluminium chloride as a cocatalyst. The process is carried out in a monomer medium in static conditions.

EFFECT: increased catalyst activity, increased monomer conversion, increased average molecular weight of the obtained polymer.

6 cl, 1 tbl, 2 dwg, 14 ex

Description

The invention relates to methods for producing ultra-high molecular weight higher poly-α-olefins and methods for producing catalysts for the polymerization of higher α-olefins. Ultra-high molecular weight polymers of higher α-olefins effectively reduce the hydrodynamic resistance of hydrocarbon fluids. The use of these polymers in the pipeline transportation of oil and oil products can significantly save energy costs for pumping and increase the throughput of pipelines. Such polymers must have a high molecular weight (MM) of ≥8000000, while the higher the MM of the poly-α-olefin used, the less polymer is required to reduce hydrodynamic resistance.

The main link in the production of polyolefins is the catalyst. A huge amount of research and patents has been devoted to the development and improvement of catalysts. Heterogeneous Ziegler-Natta catalysts consisting of transition metal halides (titanium or vanadium) and organoaluminum compounds (Ziegler Catalysts. Ed by: Fink G., Mulhaupt R., Brintzinger HH Berlin: Springer are currently used in industry for the polymerization of α-olefins. , 1995; BAKrentsel, YVKissin, VIKleiner, LL Stotskaya Polymers and Copolymers of Higher α-Olefins. Chemistry, Technology, Applications. Munich Vienna New York: Hanser, Gardner, 1997).

To achieve high MM poly-α-olefins, polymerization must be carried out at a low temperature: -30- + 10 ° C, however, the reaction rate is significantly reduced. In order to provide the necessary balance between the yields of polymers and their MM, Ziegler-Natta catalysts are used in combination with various modifying additives, as a rule, of electron-donating nature. For example, organosilicon compounds are used: polysiloxanes (US 5028574, C08F 4/649, 07/02/1991), trialkoxyalkylsilanes (RU 2171817, C08F 10/14, C08F 4/654, 08/10/2001), organophosphorus compounds (US 4433123, C08F 10 / 00, C08F 4/64, 02.21.1984) and others.

Closest to the proposed method for producing a catalyst for the polymerization of higher α-olefins and a method for producing ultra-high molecular weight poly-α-olefins are a method for preparing a catalyst and a method for producing ultra-high molecular weight polymers of α-olefins (for example, octene-1 polymerization) using this catalyst described in the patent US No. 4415714, C08F 10/00, C08F 4/64, publ. 10/15/1983 - a prototype.

Obtaining a catalyst according to the prototype method is carried out in an inert atmosphere (in dry nitrogen, argon or xenon) as follows. A dry inert gas-free hydrocarbon solvent, a solution of diethylaluminium chloride (AlEt ₂ Cl) in heptane and di-n-butyl ether (n-Bu ₂ O) at a molar ratio of n-Bu ₂ O are successively introduced into the autoclave in an inert gas stream: AlEt ₂ Cl = 0.01-1, after which an industrial catalyst from Stauffer Chemical Co. is added (USA) composition TiCl ₃ · 0,33AlCl ₃ . An autoclave with a mixture of catalyst components is placed in a boiling water bath, the reaction mixture is stirred vigorously for 30 minutes. The resulting suspension is used as a catalyst. The molar ratio of catalyst components: compound Al: n-Bu ₂ O: compound Ti is in the range 1: 0.01: 1-15: 5: 5, preferably 3: 0.5: 5.

The polymerization reaction according to the prototype method is carried out in the temperature range from -10 to 40 ° C, usually at 25 ± 1 ° C. To do this, dry octene-1, free of oxygen, is introduced into the autoclave with a suspension of the catalyst in a hydrocarbon solvent (monomer concentration 15%, molar ratio octene-1: AlEt ₂ Cl: TiCl ₃ = 375: 3: 1) and polymerization is carried out until 5- 20% monomer conversion (usually not more than 10%). Thereafter the reaction was terminated by adding methyl alcohol or isopropyl, as further polymerisation results in a sharp decrease the intrinsic viscosity ([η] _Har), which is an indicator of the average MW of the polymer. The activity of the catalyst in the polymerization reaction ranges from 130 g of polymer / g Ti · h with a molar ratio of n-Bu ₂ O: TiCl ₃ = 0.1 (reaction time 4.6 h, the degree of conversion of the monomer 10.13%) to 375 g of polymer / g Ti · h at a molar ratio of n-Bu ₂ O: TiCl ₃ = 1 (reaction time 1.5 h, monomer conversion 9.48%) - see table 1 in the description of US patent No. 4415714.

The disadvantage of this method of producing a catalyst for the polymerization of higher α-olefins is the low activity of the catalyst (130-375 g of polymer / g Ti · h).

The disadvantages of this known method of producing ultra-high molecular weight poly-α-olefins are the low average molecular weight of the polymer ([η] _har ] = 7.68-8.28 dl / g) and the low degree of conversion of the monomer (~ 10%), which leads to high consumption monomer and catalyst.

The objective of the invention is to develop a method for producing a catalyst for the polymerization of higher α-olefins, which will provide a significant increase in the activity of the catalyst.

The objective of the invention is the development of a method of producing ultra-high molecular weight poly-α-olefins, which will increase the value of the average MM polymer, increase the degree of conversion of the monomer and thereby reduce the consumption of monomer and catalyst.

The solution of this problem is achieved by the proposed method for producing a catalyst for the polymerization of higher α-olefins, including the interaction of titanium chloride, diethylaluminium chloride and di-n-butyl ether, in which titanium tetrachloride is used as titanium chloride, which is reacted with di-n-butyl ether in an inert hydrocarbon solvent to obtain product I, and diethylaluminium chloride is reacted with di-n-butyl ether to obtain product II, then product II is added to product I and the resulting suspension is maintained at 90-100 ° C.

The molar ratio of TiCl ₄ di-n-butyl ether in product I can vary in the range 1: 0.65-1.25.

The molar ratio of diethylaluminium chloride: di-n-butyl ether in product II can vary in the range of 1: 0.83-1.45.

The atomic ratio Ti: A1 in the catalyst may be 1.7-2.2: 1.

The solution of this problem is also achieved by the proposed method for producing ultra-high molecular weight poly-α-olefins, polymerization of α-olefins

C _n H _2n , where n = 6-10, or mixtures thereof in the presence of a titanium-containing catalyst and an organoaluminum co-catalyst, using the catalyst obtained by the above-described inventive method, and dialkyl aluminum chloride as a cocatalyst, and the process is carried out in a monomer medium in static conditions (without stirring).

The polymerization can be carried out with a molar ratio of dialkylaluminum chloride to titanium of 8-12.

The inventive method for producing a catalyst was developed on the basis of detailed studies of the interaction of components of Ziegler-Natta catalysts, including modifying additives of electron-donating nature, in particular, n-Bu ₂ O. It was found that the most active catalyst is obtained by dividing the interaction of the components of the catalyst into separate stages, in this case, TiCl ₄ was chosen as the initial titanium halide: first, at room temperature, TiCl ₄ is reacted with n-Вu ₂ О in an inert carbohydrate a hydrogen solvent, resulting in product I, in which the molar ratio of TiCl ₄ : n-Bu ₂ O can vary from 1: 0.65 to 1: 1.25. Separately is mixed well at room temperature with AlEt ₂ Cl n-Bu ₂ O in a molar ratio of from 1: 0.83 to 1: 1.45, and the resulting product II in the required amount is added to the product I, whereupon the reaction mixture was kept at 90 -100 ° C. The catalyst is a highly dispersed stable suspension of dark cherry color. Product I, product II and the resulting catalyst can be stored for several months without compromising catalytic activity.

The experimentally established molar ratios of the reactants and the temperature regime of the reactions are optimal and can significantly increase the activity of the catalyst. It is important to note that the activity of the catalyst is maintained for a long time polymerization. This allows the reaction to deep conversion of the monomer (conversion reaches 75%) and obtain a large polymer yield (see figure 1). The polymer has a high average MM — the [η] _char value reaches 20.3 dl / g (see FIG. 2).

When developing a method for producing ultra-high molecular weight poly-α-olefins, we took into account the following. There are two types of anti-turbulent additives for pumping hydrocarbon fluids based on polymers of higher α-olefins: solution type additives (e.g. RU 2075485, C08F 10/14, C08F 4/652, F17D 1/17, 03/20/1997) and suspension type additives ( e.g. US 6172151, F17D 1/00, F17D 1/16, C09K 3/00, C08J 5/05, C08J 5/06, 01/09/2001).

Mortar additives (they are also called gel additives, since they have a sufficiently high viscosity) are obtained by polymerization of higher α-olefins in a medium of hydrocarbon solvents. Gel additives have a significant drawback: the content of the useful substance in them cannot exceed 10-12%, otherwise the system loses fluidity and difficulties arise when it is pumped into the pipeline. This leads to a significant increase in transport costs and prevents the use of such additives, especially at large distances from the place of production.

The polymer content in suspension additives is ≥20%, which significantly reduces transport costs. In addition, the procedure for injecting suspension additives having a much lower viscosity is simpler than mortar. The synthesis of suspension additives is usually carried out in bulk liquid monomer (the solvent content in the reaction medium does not exceed several percent). The resulting rubber-like polymer is ground at cryogenic temperatures and a suspension of ground polymer is prepared in an aqueous or non-aqueous medium (RU 2238282, C08F 10/14, C08F 4/642, 10/20/2004).

The method of producing ultra-high molecular weight poly-α-olefins, selected for the prototype (US 4415714), get the solution type additives with all their inherent disadvantages.

The inventive method for producing ultra-high molecular weight poly-α-olefins is intended to produce suspension additives. The polymerization according to the proposed method was carried out in a monomer at a temperature of 3 ± 1 ° C in the presence of the catalyst obtained by the proposed method and dialkylaluminium chloride as a cocatalyst. Due to the high activity of the catalyst, the reaction mass quickly and uniformly thickened, and due to the high dispersion of the catalyst, it did not settle to the bottom of the ampoule even in the absence of mixing. This allowed polymerization under static conditions, which eliminates the possible mechanical degradation of the resulting polymer and simplifies the process technology. The polymer was washed from the catalyst with a 10% solution of HCl in ethyl alcohol and dried in vacuum to constant weight. The resulting solid rubber-like material was used to make suspension additives.

The inventive method of polymerization of higher α-olefins allows to increase the characteristic viscosity ([η] _har ) of the obtained polymer to 20.3 dl / g and the degree of conversion of the monomer to 75% (see table).

We give examples illustrating the invention.

Example 1

1.06 g of TiCl ₄ at room temperature (25 ° C) was mixed with 5 ml (4.35 g) of toluene and 0.7 g of n-Bu ₂ O was added. The molar ratio of TiCl ₄ : n-Bu ₂ 0 = l: l (product I). Separately, 0.37 g of AlEt ₂ Cl was mixed with 0.40 g of n-Bu ₂ O g, and product II was obtained in which the molar ratio of AlEt ₂ Cl: n-Bu ₂ O = l: l. Then, at room temperature, product II was added dropwise to product I to obtain a finely dispersed brown suspension in which the atomic ratio Ti: Al = 1.87: 1. The resulting suspension was heated in a boiling water bath for 2 hours, after which it acquired a dark cherry color and was used as a catalyst.

30.1 g of decene-1, 0.2614 g of diisobutylaluminium chloride (Al-iBu ₂ Cl) and 0.1688 g of the obtained catalyst were successively introduced into a vacuum-filled and argon-filled glass ampoule. The atomic ratio Al: Ti = 10.8. The ampoule was sealed and kept for 4 h at 3 ± 1 ° С without stirring the reaction mixture. The result was a solid rubbery polymer, which was washed from the catalyst with a 10% solution of HCl in ethyl alcohol and dried in vacuum to constant weight. The degree of conversion of decene-1 was 54.3%. The obtained polydecene had [η] _xap = 19.6 dl / g (tetrahydrofuran, 25 ° C).

Examples 2-14

The catalyst was obtained analogously to example 1, only with different ratios of components, the polymerization of decene-1 and other α-olefins under various conditions was carried out analogously to example 1. The results of the experiments are shown in the table.

As can be seen from the examples, the catalyst obtained by the present method has a higher activity. When used in the proposed method for producing ultra-high molecular weight poly-α-olefins, the degree of conversion of the monomer significantly increases and the average MM of the obtained polymer increases, thereby reducing the consumption of monomer and catalyst.

Claims (6)

1. A method of producing a catalyst for the polymerization of higher α-olefins, comprising the interaction of titanium chloride, diethylaluminium chloride and di-n-butyl ether, characterized in that titanium tetrachloride is used as titanium chloride, which is reacted with di-n-butyl ether in inert hydrocarbon solvent to obtain product I, and diethylaluminium chloride is reacted with di-n-butyl ether to obtain product II, then product II is added to product I and the resulting suspension is maintained at 90-100 S. 2. The method of producing the catalyst according to claim 1, characterized in that the molar ratio of TiCl ₄ : di-n-butyl ether in the product I is in the range 1: 0.65-1.25. 3. The method of producing the catalyst according to claim 1 or 2, characterized in that the molar ratio of diethylaluminium chloride: di-n-butyl ether in product II is in the range 1: 0.83-1.45. 4. The method of producing the catalyst according to any one of claims 1 to 3, characterized in that the atomic ratio of Ti: Al in the catalyst is 1.7-2.2: 1. 5. A method of producing ultra-high molecular weight poly-α-olefins by polymerization of α-olefins CnH _2n , where n = 6-10, or mixtures thereof in the presence of a titanium-containing catalyst and organoaluminum cocatalyst, characterized in that they use the catalyst obtained according to any one of claims 1- 4, and dialkylaluminium chloride as a cocatalyst, and the process is carried out in a monomer medium under static conditions. 6. The method according to claim 5, characterized in that the polymerization is carried out at a molar ratio of dialkylaluminum chloride: Ti = 8-12: 1.

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