RU2561279C1 - Paraffin dispersant, method for production thereof and fuel composition, content thereof - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: disclosed is a paraffin dispersant, which contains as an active component derivatives of alkyl esters of β-aminopropionic acid of general formula

, where a=0-2, b=0-1, c=0-1, n≥1, x=0-1; y=0-1; z=0-1; x+y+z=a+nb+c≤n+3, R is an alkyl radical with a normal C₁₂-C₂₈ structure. The invention also discloses a method of producing the disclosed paraffin dispersant, a compressing-dispersing additive package containing the disclosed dispersant, and a corresponding fuel composition.

EFFECT: high sedimentation resistance of the fuel composition during cold storage at temperatures lower than the clouding point.

4 cl, 4 tbl, 6 ex, 1 dwg

Description

The invention relates to a new type of paraffin dispersant and fuel compositions containing a depressant additive and a paraffin dispersant, which provide the necessary level of sedimentation stability of the dispersion of paraffins in the fuel composition, mainly diesel fuel in cold storage conditions.

The traditionally used depressants (polymethacrylates, copolymers of vinyl acetate with ethylene, etc.) reduce the pour point and the limiting filterability temperature of diesel fuels. However, they do not prevent their delamination during cold storage. This is due to the fact that finely dispersed systems have a large excess of surface energy and particle enlargement processes occur spontaneously due to internal evaporation or coagulation. As a result of the enlargement of paraffin particles, sedimentation occurs, and the fuel is divided into two layers: the upper one is light and the lower one is cloudy, enriched with paraffins. Both layers are mobile, but when the fuel is taken from the lower layer, the engine works intermittently. The problem of increasing the sedimentation stability of diesel fuel during cold storage is solved with the help of special additives - paraffin dispersants. The effect of their use consists in the formation of very small crystals of paraffins and the prevention of their aggregation for a long time, which leads to greater sedimentation stability of the resulting dispersion of paraffin in diesel fuel.

Currently, there are no sufficiently substantiated descriptions of the mechanism of action of paraffin dispersants in diesel fuel in the literature. Apparently, the stabilization of the dispersion of paraffins in diesel fuel is associated with a decrease in the surface energy of crystals (surface tension at the crystal-liquid interface). Compounds used as dispersants for paraffins exhibit surface activity in the paraffin-diesel system. The adsorption of these surfactants on the surface of the crystals leads to a decrease in interfacial surface tension and, accordingly, the surface energy of the dispersed system. In addition, dispersant molecules contain polar or easily polarizable functional groups. When they are adsorbed on the surface of crystals, due to a certain orientation of the polar regions of the molecules of coexisting phases, a double electric layer forms on the interphase surface, which leads to additional stabilization of the disperse system. Thus, substances capable of stabilizing dispersions of paraffins in diesel should have an affinity for the surface of paraffins, be easily adsorbed on the surface of crystals (or crystallize with paraffins), and contain polar or easily polarizable functional groups capable of forming a double electric layer on the interphase surface.

According to literature data, various oil-soluble nitrogen-containing organic compounds that have surface-active properties in the paraffin crystals - liquid hydrocarbon fuel system are most often used as dispersants for paraffins. Such compounds include full amides of monobasic and polybasic carboxylic acids, ammonium salts of partial amides of polybasic carboxylic acids, amide esters of polybasic carboxylic acids, fat-soluble amines, derivatives of N-succinimide, nitrogen-containing polymers and some other nitrogen-containing compounds.

So, in patent US 4402708, CL. C10L 1/222, publ. 09/06/1983, as dispersants use phthalic acid diamides and ammonium salts of phthalic acid monoamide, obtained on the basis of phthalic anhydride and dialkylamine C ₁₆ -C ₂₄ .

In patent US 2971027, cl. C09B 1/43, publ. 02/07/1961, Ν, Ν′-dialkyl diamides of terephthalic acid are proposed as dispersants for paraffins.

In patent US 3887754, cl. C08J 9/224, published 03.06.1975, as dispersants are C ₈ -C ₁₈ dialkylamides of phthalic, dihydrophthalic and tetrahydrophthalic acids, and in US patents 3444082, cl. C10L 1/143, publ. 05/13/1969 and US 3846093, class C10L 1/143, publ. 11/05/1974, as dispersants, it was proposed to use diamides and ammonium salts of monoamides of alkenyl succinic acids.

Diamides and ammonium salts of mono- and dicarboxylic acids have been described as dispersants (US 4211534, class C10L 1/143, publ. 07/08/1980 and US 3658493 class C10L 1/14, publ. 25.04.1972).

In patent RU 2128210, cl. C10L 1/22, publ. 03/27/1999, an additive composition for improving the cold resistance of middle distillates was proposed, containing imides obtained by the reaction of mono- or dialkylpolyamines with maleic, alkyl maleic, or alkyl succinic anhydrides as an anti-sentimentation additive.

Known dispersing additive is a dispersant of paraffins, which improves the operational properties of medium petroleum distillates (diesel fuels, heating oils, etc.) at low temperatures, and the fuel composition containing it (RU 2330875, class C10L 1/02, publ. 08/10/2008, The paraffin dispersant is the product of the interaction of a C ₁₆ -C ₇₀ alkenyl succinic anhydride and an aliphatic amino alcohol of the general formula: XN [(CH ₂ ) _n OH] ₂ , where X is hydrogen or a C ₁ -C ₅ aliphatic radical, n is an integer of 2 to 5, in the form of a 40-70% solution in a hydrocarbon solvent.

The patent literature describes a large number of other paraffin dispersants based on amides of various mono- or dibasic carboxylic acids, ammonium salts of monoamides of dibasic acids, ammonium salts of monoesters of polybasic acids. Almost all paraffin dispersants that improve the low-temperature properties of fuels are polymer products with a sufficiently high molecular weight, which complicates their introduction into the fuel.

At the same time, the traditionally used depressant additives (polymethacrylates, copolymers of vinyl acetate with ethylene, etc.) reduce the pour point and the limiting filterability temperature of diesel fuels. However, they do not prevent their delamination during cold storage.

The technical result of the proposed paraffin dispersant is to increase the level of sedimentation stability of the dispersion of paraffins in the fuel composition, including diesel fuel, in cold storage conditions below the cloud point and to improve the quality of the fuel composition containing it.

To achieve the technical result, a paraffin dispersant is proposed containing, as an active component, derivatives of alkyl esters-β-aminopropionic acid of the general formula

where a = 0-2, b = 0-1; c = 0-1 ;. n≥1, x = 0-1; y = 0-1; z is 0-1; x + y + z = a + nb + c≤n + 3; R is an alkyl of normal structure C ₁₂ -C ₂₈ .

The structure of the proposed paraffin dispersant is confirmed by IR spectroscopy. Spectra were recorded on an Avatar-360 IR Fourier spectrometer with a spectral resolution of 4 cm ^-1 and averaging over 32 scans. The IR spectrum of a paraffin dispersant with the assignment of absorption bands to functional groups is shown in Fig. one

Since paraffin dispersants mainly belong to the same classes of organic compounds and differ only in the range of raw materials used, acids (mono- and dibasic, aliphatic, cycloaliphatic, aromatic) and amines (monoalkylamines, dialkylamines with hydrocarbon substituents of different lengths and branching) , then they are synthesized by similar methods that share the same disadvantages, namely: high temperatures, deep vacuum, stringent requirements for technological equipment, high I power consumption. In addition, the disadvantages of these products include the low availability and high cost of some items of the raw materials used, namely, substituted aromatic and cycloaliphatic mono- and dibasic acids and mono- and dialkylamines.

A known method of producing dispersants based on phthalic anhydride and dialkylamine C ₁₆ -C ₂₄ (US 4402708, CL C10L 1/222, publ. 09/06/1983). These products and methods for their preparation have several significant disadvantages. Phthalic acid diamide is obtained by amidation of phthalic anhydride with C ₁₆ -C ₂₄ dialkylamines. The synthesis of diamide is carried out at a temperature of 250 ° C for 4 hours with distillation of the water formed during the reaction at a residual pressure of 33 mm RT. Art. The disadvantages of the method include: high energy consumption at the stage of synthesis of diamide, the need to install a heat circuit with an expensive high-temperature coolant, stringent requirements for technological equipment associated with operation at high temperatures in high vacuum. In addition, the high temperature in the synthesis stage leads to a partial resinification of the product. The ammonium salt of phthalic acid monoamide is also obtained by the reaction of phthalic anhydride and C ₁₆ -C ₂₄ dialkylamine in an organic solvent. The synthesis takes place at a low temperature - 30-40 ° C, however, due to the low solubility of the reaction product - ammonium salt - in organic solvents, the reaction is carried out at a concentration of reagents of 10 mass. % Therefore, the entire solvent is distilled off in vacuo at a residual pressure of 40 mm Hg. Art., and the product obtained after distillation is dried for 24 hours. The disadvantages of the method include: high energy intensity of the process, high labor costs when working with solid products and low productivity due to the low concentration of reagents at the synthesis stage.

Closest to the method for producing a dispersant for paraffins is a method for producing dispersants based on imides of alkenyl succinic acid, which is described in patents RU 2296133, cl. C08F 8/32, publ. 03/27/2007 and RU 2296134, cl. C088F 8/32, publ. 03/27/2007 According to these inventions, selected for the prototype of the method for producing the dispersant proposed in the present invention, the paraffin dispersant according to the above patents is obtained in two stages. In the first stage, maleic anhydride is reacted with a polyalphaolefin or polyisobutylene with a molecular weight of 700-1200 in the presence of an initiator at a temperature of 160-180 ° C for 4 hours. In the second stage, the obtained alkenyl succinic anhydride is condensed with polyethylene polyamines or polypropylene polyamines at 160-175 ° C for 4 hours. The disadvantages of these products and methods for their preparation include: high temperatures at both stages of the synthesis, high corrosiveness of the reaction media and, as a result, stringent requirements for the materials of technological equipment, high energy intensity of the process, partial resinification of the product and a significant amount of production waste.

The objective of the present invention is to develop a highly effective paraffin dispersant, the synthesis of which is based on available raw materials, takes place in a mild mode, is easily feasible on an industrial scale and belongs to the class of amines.

To solve this problem, a method for producing a paraffin dispersant of the structural formula is proposed.

where a = 0-2, b = 0-1, c = 0-1, n≥1, x = 0-1; y = 0-1; z is 0-1; x + y + z = a + nb + c≤n + 3, R is an alkyl of normal structure C ₁₂ -C ₂₈ , consisting in the interaction in an organic solution, for example, toluene or xylene, taken in an amount based on the calculation of obtaining the finished product with a concentration 50-70 mass. % active substance, at a temperature of 20-50 ° C for 2-5 hours, double-activated olefins selected from the group consisting of n-alkyl esters of acrylic acid of the general formula CH ₂ = CH-C (O) OR, where R - an alkyl radical of normal structure C ₁₂ -C ₂₈ , mainly acrylates of higher fatty alcohols of various fractional composition C ₁₂ -C ₁₈ , C ₁₆ -C ₁₈ , C ₂₀ -C ₂₂ , C ₂₂ -C ₂₈ with primary and secondary amines, mainly polyethylene polyamines general formula NH ₂ [CH ₂ CH ₂ NH] _n H, where n≥1.

The reaction between the alkyl acrylate and primary or secondary amines proceeds via the double bond mechanism of nucleophilic amine addition. In general terms, the equation of this reaction is as follows:

The presence of an electron-withdrawing ester group near the double bond activates the double bond in the nucleophilic addition reaction. For this reason, this synthesis proceeds at a high speed at a low temperature up to 50 ° C with an almost quantitative yield.

A method of obtaining a dispersant is as follows.

Example 1

A 250 ml three-neck round-bottom flask equipped with a mechanical stirrer and thermometer is placed in a water thermostat heated to 50 ° C. Thereafter, 100 g of C ₁₂ -C ₁₈ alkyl acrylate, 47 g of polyethylene polyamine (PEPA), based on the average molecular weight corresponding to triethylenetetramine, and 63 g of toluene are charged into the reactor. The resulting reaction mixture was stirred at 50 ° C for 3 hours, after which analysis was carried out for the absence of double bonds. Get 210 g of the product with the content of the active component (dispersant) 70 mass. % The resulting product is used as a solution without prior isolation.

Example 2

A 250 ml three-neck round-bottom flask equipped with a mechanical stirrer and thermometer is placed in a water thermostat heated to 20 ° C. Thereafter, 110 g of C ₁₂ -C ₁₈ alkyl acrylate, 31 g of polyethylene polyamine at an average molecular weight corresponding to triethylenetetramine and 60 g of toluene are charged into the reactor. The resulting reaction mixture was stirred at 20 ° C for 5 hours, after which analysis was carried out for the absence of double bonds. Get 201 g of the product with the content of the active component (dispersant) 70 mass. % The resulting product is used as a solution without prior isolation.

Example 3

A 250 ml three-neck round-bottom flask equipped with a mechanical stirrer and thermometer is placed in a water thermostat heated to 40 ° C. Thereafter, 100 g of C ₁₆ -C ₁₈ alkyl acrylate, 39 g of polyethylene polyamine at an average molecular weight corresponding to triethylenetetramine and 59 g of toluene are charged into the reactor. The resulting reaction mixture was stirred at 40 ° C for 2 hours, after which analysis was carried out for the absence of double bonds. Get 198 g of the product with the content of the active component (dispersant) 70 mass. % The resulting product is used as a solution without prior isolation.

Analogously to example 1-3, the dispersant is synthesized (examples 5-6) at various loads of the starting reagents with different product yield and percentage of active substance. The data are given in table. one.

A study of the effectiveness of paraffin dispersants was carried out by sedimentation stability method. A copolymer of ethylene with vinyl acetate, Keroflux 6100, was used as a depressant. It is one of the most efficient, industrial-grade diesel fuel depressors. A paraffin dispersant was considered effective, which, together with the named depressor, ensured the sedimentation stability of diesel fuel at the lowest concentration.

Before testing, for each of the initial samples with an additive, the cloud point (T _pom ) and the limiting filtration temperature (PTF) were determined, the data are given in table. 2.

Sedimentation stability of diesel fuels in the presence and absence of paraffin dispersants was evaluated according to the ARAL method (with additions and amendments of VNIINP), a paraffin deposition test (TestWaxAnti - Settling), which is a 16-hour temperature control of diesel fuel with a depressant additive (and a paraffin dispersant) at a temperature of 6-8 ° C below the cloud point of the base fuel. Glass cylinders at room temperature were filled with 500 ml fuel with or without additives, closed with stoppers, placed in a bath and cooled at a rate of 14 ° C per hour to the test temperature.

After storage at a temperature of 6-8 ° C below the cloud point of the base fuel for 16 hours, the samples were visually evaluated. In the presence of a visible phase boundary, the relative percentage of the upper and lower phases was fixed in percent. The phases were evaluated as clear, cloudy, dispersion or precipitate.

Further, using the equipment for suction at the test temperature, carefully, avoiding mixing, the upper 20% and middle 60% layers were removed, the lower 20% layer was left in the cylinder. In the process of selecting the layers, the suction tube remained immersed in the fuel to a depth of less than 3 mm from the surface.

After heating the upper 20% and lower 20% layers to a temperature of 45 ° C and thermostating the samples for 15 minutes (bringing the samples to a homogeneous state), the cloud point and the limiting filterability temperature were measured. After that, the difference between the cloud point and PTF of the lower phase and the initial fuel and the upper phase and the initial fuel was determined. The fuel was considered to pass the test if these indicators differed from the initial fuel by no more than ± 2 ° C (Tables 2 and 3).

Adding the proposed paraffin dispersant allows you to reduce the concentration of depressant additives by 20% compared with the analogue, the most effective and well-proven Keroflux 3614 dispersant was selected as an analogue, in the case of using the dispersant obtained according to example No. 4 (PTF = -15 ° was used as the limiting dispersant C), and 30% in the case of using the dispersant obtained according to example No. 5 (table. 3).

Paraffin dispersants are usually used not separately, but in combination with depressant additives, i.e. in the form of a depressant-dispersing package containing a depressant based on ethylene vinyl acetate copolymers of the Keroflux brand in an amount of 0.07-0.09 mass. % and a paraffin dispersant according to claim 1 in an amount of 0.005-0.02 mass. % (Tables 2 and 3), which simultaneously reduces the limiting temperature of filterability, the pour point of the fuel and increase its stability in cold storage.

Using the paraffin dispersant proposed in the present invention, a fuel composition based on diesel fuels of various fractional composition is developed, for example, a fraction with T _pom = -5 ° C, PTF = -5 ° C, T _pad = -11 ° C or a fraction with T _pom = -9 ° C, PTF = -11 ° C, T _crest = -16 ° C, which has sedimentation stability in cold storage conditions below the cloud point, containing a depressant-dispersing additive package, including a Keroflux-based ethylene-vinyl acetate copolymer depressant 0.03-0.07 mass. % and a paraffin dispersant according to claim 1 in an amount of 0.01 mass. %

Table 4 shows the physico-chemical parameters of the fuel compositions for compliance with the brand EKO-Z-1 using diesel fuels of various fractional composition, various depressants and the inventive paraffin dispersant, consisting of:

- for fuel composition 1 from diesel fuel of fractional composition with a boiling point, ° C: - 50%, not higher than 270; - 96%, not higher than 358

with T _pom = -5 ° C, PTF = -5 ° C and T _stas = -11 ° C, 0.07% of the mass, a copolymer of ethylene with vinyl acetate Keroflux 6100 and 0.01% of the mass. the claimed dispersant paraffins obtained according to example No. 5;

- for fuel composition 2 from diesel fuel of fractional composition with a boiling point, ° C: - 50%, not higher than 264; - 96%, not higher than 346,

with T _pom = -9 ° C, PTF = -11 ° C and T _stas = -16 ° C, 0.03% of the mass. a copolymer of ethylene with vinyl acetate Keroflux 6180 and 0.01% of the mass. the claimed dispersant paraffins obtained according to example No. 5.

The data given in table. 2-4, show the achievement of the claimed technical result when using and the proposed paraffin dispersant.

Claims (4)

1. Paraffin dispersant containing, as an active component, derivatives of alkyl esters-β-aminopropionic acid of the general formula:

where a = 0-2, b = 0-1, c = 0-1, n≥1, x = 0-1; y = 0-1; z is 0-1; x + y + z = a + nb + c≤n + 3, R is an alkyl of normal structure C ₁₂ -C ₂₈ . 2. A method of obtaining a dispersant of paraffins of the structural formula

where a = 0-2, b = 0-1, c = 0-1, n≥1, x = 0-1; y = 0-1; z is 0-1; x + y + z = a + nb + c≤n + 3, R is an alkyl of normal structure C ₁₂ -C ₂₈ , consisting in the interaction in a solution of an organic solvent, for example, toluene or xylene, taken in an amount based on the preparation of the finished product with a concentration of 50-70 wt. % active substance, at a temperature of 20-50 ° C for 2-5 hours, double-activated olefins selected from the group consisting of n-alkyl esters of acrylic acid of the general formula CH ₂ = CH-C (O) OR, where R - an alkyl radical of normal structure C ₁₂ -C ₂₈ , mainly acrylates of higher fatty alcohols of various fractional composition C ₁₂ -C ₁₈ , C ₁₆ -C ₁₈ , C ₂₀ -C ₂₂ , C ₂₂ -C ₂₈ with primary and secondary amines, mainly polyethylene polyamines general formula NH ₂ [CH ₂ CH ₂ NH] _n H, where n≥1. 3. Depressor-dispersing additive package containing a depressant based on ethylene vinyl acetate copolymers of the Keroflux brand in an amount of 0.07-0.09 wt. % and a paraffin dispersant according to claim 1 in an amount of 0.005-0.02 wt. % 4. A fuel composition based on diesel fuels of various fractional composition, for example, a fraction with T _pom = -5 ° C, PTF = -5 ° C, T _stas = -11 ° C or a fraction with T _pom = -9 ° C, PTF = -11 ° C, T _crest = -16 ° C, possessing sedimentation stability in cold storage conditions below the cloud point, containing a depressant-dispersing additive package including a depressant based on Keroflux ethylene-vinyl acetate copolymers in an amount of 0.03-0.07 wt. % and a paraffin dispersant according to claim 1 in an amount of 0.01 wt. %

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