RU2075485C1 - Process for preparing agent which reduces hydrodynamic resistance of hydrocarbon fluids - Google Patents

Abstract

FIELD: transportation of hydrocarbon liquids. SUBSTANCE: agent which reduces hydrodynamic resistance is prepared by polymerization of alpha-olefins having 6-10 carbon atoms in the presence of catalyst which is essentially product of reducing titanium tetrachloride organoaluminium, and cocatalyst which is organoaluminium compound at minus 30 to minus 20 C. The cocatalyst may be diethylaluminium chloride, triethylaluminium, triisobutylaluminium or mixture thereof. EFFECT: higher efficiency. 2 cl, 1 tbl

Description

 The invention relates to the chemistry of macromolecular compounds, and in particular to methods for producing polymers of higher α-olefins, effectively reducing the hydrodynamic resistance (GDS) of hydrocarbon liquids.

 The use of such polymers in the pipeline transport of oil and oil products can significantly save energy costs for pumping or increase the throughput of pipelines.

 The nature of the GDS effect is such that the polymer additives used for this purpose must have two qualities: first, they must dissolve well in hydrocarbon liquids; secondly, to have a high molecular weight (MM). Moreover, the more MM, the lower the polymer concentration in the oil stream, necessary to achieve this reduction in resistance. For practical use, in addition, the acceptable cost of the product is important. The listed qualities optimally combine the polymers of higher a-olefins obtained by polymerization on Ziegler-Natta catalysts.

The polymerization of higher a-olefins on Ziegler-Natta catalysts is characterized by the fact that the highest molecular weight polymer fraction is formed at equal stages of conversion. Therefore, in US patent N4415714 and N4433123 proposed to terminate the polymerization at the 20% stage of conversion, thereby increasing the average molecular weight of the product. However, the high consumption of monomer and catalyst make this method uneconomical. In addition, the intrinsic viscosity, the molecular weight index of the product here do not exceed 1.15 m ³ / kg.

Another feature of the polymerization of higher a-olefins is that a relatively low temperature, of the order of (-30) (+10) ^o C, is required to achieve a high molecular weight. However, at such temperatures, as a rule, the polymerization rate constant decreases and the process proceeds rather slowly . To accelerate the polymerization at low temperatures, various activating additives are used, as a rule, of an electron-donor nature.

In US Pat. No. 5,028,574, polysiloxanes are used as such an additive. The polymerization is carried out at 0 ^o C and get a poly-a-decene with a characteristic viscosity [η]> 1.20 m ³ / kg .. However, the long process time, 24 hours, is the main disadvantage of this method.

Note that belong to the company "Conoco" nearly all of the patents in this area, which in their studies and, presumably, in the manufacture uses aluminothermic TiCl ₃ catalyst • 1/3 • AlCl ₃ firm "Stauffer Chemical Co", is not very activity in the polymerization of higher α-olefins.

A method of producing drag reducing agents (SGDS) hydrocarbon fluids (US Patent N3692676, kl.C08F 10/00), comprising the polymerization of higher a-mono-olefin in a hydrocarbon solvent at aluminothermic catalyst TiCl ₃ • 1/3 • AlCl ₃ in the presence of organoaluminum cocatalyst diethylaluminium chloride (DEAC) for 31 hours. The yield of the target product 88% reduction in the hydrodynamic resistance of oil 12.0% at an agent concentration of 5 ppm (parts per million).

 The disadvantages of the method are the low value of the reduction of GDS and a long polymerization time.

There is also known a method for producing SGDS agents (US Patent N4647633, class C08F 10/00, 4/64) by polymerization of a-monoolefins also in a hydrocarbon solvent on a TiCl ₃ • 1/3 • AlCl ₃ catalyst, but a mixture acts as an organoaluminum cocatalyst DEAC and triethylaluminium (TEA). The polymerization time of 8 hours, the yield of the target product 64% DR 18.2% at a concentration of agent 2 ppm.

 The disadvantages of the method are the low values of the reduction of HDC and the product yield.

The closest in technical essence and the achieved result is a method for producing SGSD agents by copolymerization of 0.10 moles of a mixture of octene and dodecene in a hydrocarbon solvent medium on 0.0007 moles of a TiCl ₃ • 1/3 • AlCl ₃ catalyst in the presence of 0.0020 moles of a mixture of organoaluminum organic cocatalyst DEAC and accelerator of polymerization of diethylaluminum ethoxide (DEAEO) at 1 ^o C for 7 hours. The yield of the target product 46% DR 28.5% at a concentration of the agent of 2 ppm (US Patent N4845178, CL C08F 4/44).

 The disadvantages of the method are the low value of the decrease in resistance, low yield of the target product, a long polymerization time, high catalyst consumption.

 The task of the invention is to increase the decrease in resistance, yield of the target product, reduce the polymerization time, reduce catalyst consumption.

The problem is solved in that in the claimed method, the (co) polymerization of 0.12 0.80 M of higher a-olefins with the number of hydrocarbon atoms from 6 to 10 is carried out in a hydrocarbon solvent in the presence of 0.002 0.0020 M TiCl ₃ as a catalyst, obtained by reduction of TiCl _{4 with an} organoaluminum compound, and 0.0017 0.0170 M organoaluminum organocatalyst in the temperature range from -30 ^o C to +20 ^o C for 5 hours.

The catalyst obtained by the above method is distinguished by its exceptional activity with respect to higher a-monoolefins with the number of hydrocarbon atoms from 6 to 10. Therefore, it is advisable to use hexene-1, octene-1, decen-1, or a mixture thereof to obtain effective sgds. The use of a-olefins with the number of carbon atoms equal to 12 or more leads to a decrease in molecular weight (and, consequently, the effect of SGDS, probably due to chain transfer to the monomer (examples 13, 14), and (co) polymerization of lower a-monoolefins: ethylene, propylene, butene-1 gives insoluble products in hydrocarbon liquids, also having a lower MM (example 15.) The high activity of the catalyst TiCl ₃ allows to reduce the concentration of the catalyst in 2 to 4 times (examples 1, 2), as well as conduct (co) polymerization of the above a-olefins with ponies ennyh temperatures (-30 ^o C) at a satisfactory rate, which leads to the formation of ultrahigh molecular weight polymers, effectively reducing SDS hydrocarbon liquids, in good yield (Example 6). Increasing the time of polymerization (Example 12) does not lead to an increase in yield or efficiency of the desired product .

As a cocatalyst in the claimed method, an organoaluminum compound of the general formula AlRX _{3-a is used} , where a varies from 1 to 3, R is alkyl or aryl, X is chlorine, preferably DEAC, TEA, triisobutylaluminum (TIBA) or a mixture thereof.

 The established molar ratios of the reactants are selected experimentally and are optimal: the lower limits are determined by the possibility of the reaction of (co) polymerization in order to form an ultrahigh molecular weight polymer, the upper limits by the expediency of the consumption of expensive reagents and the optimal viscosity of the resulting polymer solution.

 Thus, the combination of the above distinguishing features indicates a specific feature of the specified system monomer catalyst socialization catalyst produce polymers of exceptionally high MM, capable of dissolving in any hydrocarbon liquids.

Thanks to the inventive method, it is possible to obtain ultra-high molecular weight polymers within 5 hours in the temperature range from -30 ^o C to +20 ^o C with a yield of 58 98% and a characteristic viscosity of 1.21 1.92 m ³ / kg, which reduce the GDS of heptane by 30.0 58.0% at a polymer concentration of 2 ppm.

 The method was carried out as follows. The calculated amount of monomer and hydrocarbon solvent, for example heptane, was charged into a thermostatically controlled reactor in an inert gas stream. In a separated capsule in an inert atmosphere, a catalyst complex was prepared representing the above catalyst activated by an organoaluminum compound, and the reactor was introduced with stirring. After 5 hours, the polymerization reaction was interrupted by the addition of alcohol, for example methyl. The reaction mass was planted in a 5-7-fold excess of acetone, the resulting polymer was dried to constant weight.

где τ₀ время истечения чистого растворителя, с;
τ время истечения полимерного раствора, с.Hydrodynamic testing of the agents was carried out on a capillary turbo-meter in a solution of n-heptane. The length of the capillary and its inner diameter are 0.878 m and 1.7 • 10 ^-3 m, respectively. The concentration of the CGDS agent in each of the tests was 2 pp. The decrease in GDS was determined by the formula:

where τ _{0 is the} time of expiration of the pure solvent, s;
τ the time of the expiration of the polymer solution, C.

Example 1. 0.409 M n-heptane and 0.120 M octene-decene fraction of a-monoolefins were charged into a reactor at 0 ^° C in an inert gas stream. After preliminary purging, 0.136 M n-heptane, 0.0031 M DEAC and 0.0002 M TiCl ³ were added to the capsule. The prepared catalyst complex in a stream of inert gas and with stirring was introduced into the reactor. After 5 hours, the polymerization reaction was interrupted by the addition of 0.12 M methanol. The reaction mass was planted in a 5-fold excess of acetone, the polymer was dried to constant weight. The yield of the target product 93% [η]> 1.21m ³ / kg, DR 40.4%
Examples 2 15. Obtaining agents SDGS hydrocarbon liquids at different ratios of reagents, the determination of the characteristic viscosity and hydrodynamic testing was carried out analogously to example 1. The results of the experiments are presented in the table.

From the above examples it is seen that increasing the polymerization temperature to +20 ^o C and reducing the ratio of monomer / catalyst to more than 600/1 leads to a decrease in the efficiency of the resulting product to 38.3% and 32.3%, respectively.

 Using the inventive method allows to obtain a highly effective agent sgds hydrocarbon liquids with a good yield and in a shorter period of time. The consumption of the catalyst is reduced by 2 to 4 times.

Claims (2)

1. A method of producing an agent for reducing the hydrodynamic resistance of hydrocarbon liquids by polymerization of higher α-olefins in a hydrocarbon solvent in the presence of a catalyst and an organoaluminum cocatalyst, characterized in that C ₆ C _{1 0} α-olefins are used as higher α-olefins, the product is used as a catalyst reduction of titanium tetrachloride with an organoaluminum compound in the following molar ratio of reactants:
α- monoolefin C ₆ C ₁₀ 0.12 0.80
Catalyst 0.0002 0.0020
Organoaluminum Co-Catalyst 0.0017 0.0170
at (-30) 20 ^o C.  2. The method according to claim 1, characterized in that diethylaluminium chloride, triethylaluminum, triisobutylaluminum or a mixture thereof are used as the organoaluminum cocatalyst.

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