RU2365618C2 - Water-fuel emulsion - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to novel water-fuel emulsions. Described is water-fuel emulsion, intended for explosion engines, working on liquid hydrocarbon fuel. It includes dispersion medium - hydrocarbon fuel, and dispersion phase - water, different in the following: emulsifying system, intended for obtaining of said water-fuel emulsion, contains: first group of components, represented by low molecular anionic surface-active substance and nonionic surface-active substance in ratio from 3:1 to 6:1 respectively, component or mixture of components from second group, represented by repellent and highly molecular surface-active substance, substance from third group, selected from betaine, propanol-2, sorbitol, oil distillates and substance or substance mixture from fourth group, which are oil-compensating agents.

EFFECT: obtaining of stable water-fuel emulsions.

2 cl, 2 ex

Description

The invention relates to new fuel emulsions, in which the dispersion medium is hydrocarbon fuel, and the dispersed phase is water, the primary field of application of which is the internal combustion engines of vehicles. More specifically, the claimed water-fuel emulsion is motor fuel, and its declared varieties relative to the dispersion medium are represented by diesel fuel and various grades of gasoline.

The relevance of obtaining stable water-fuel emulsions and their use is explained by the need to solve the problems of energy conservation and environmental safety during the operation of energy fuel machines.

Numerous experiments have established that water has the following effects on the working process in internal combustion engines (ICE):

- reduces the combustion temperature and the burning rate of the air-fuel mixture;

- inhibits the development of flame oxidation of hydrocarbons;

- accelerates the conversion of the released carbon monoxide into neutral dioxide;

- reduces the content of nitrogen oxides in the exhaust gases;

- evaporating, increases the pressure in the cylinders;

- interacting with the surface of the working chamber, cleans it of carbon deposits by means of microexplosive action;

- increases the completeness of combustion of the air-fuel mixture;

- equalizes the change in torque in the angle of rotation of the engine and thereby contributes to an increase in engine power.

This is associated with numerous attempts to supply water in various ways to the engine cylinders. As indicated in patents US 1701621 and US 4696638, science recognized the ability to produce an initial concentrated emulsion of water with heavy bicarbonate oil and then dilute motor fuel such as gasoline with this emulsion in order to obtain the final fuel composition.

Nevertheless, the use of the proposed water-fuel emulsions is possible provided that the water-fuel emulsion is stable for 72 hours during operation of the vehicle, for at least a month - with periodic downtime of the vehicle, or at least 3 months - during storage.

In addition, the water-fuel emulsion should have significantly higher environmental performance compared to clean fuel and preferably lower cost than clean fuel.

The prior art.

The use of surface-active substances (surfactants) is a fairly proven approach to obtaining effective emulsifying systems and water-fuel emulsions. Currently, there are many surfactant compositions intended for use in the food and cosmetic industries, as well as in the production of detergents. Some of them are also used to obtain water-fuel emulsions. In addition, there are patents in which emulsions are intended specifically for use as motor fuel. Examples are US patents: 1498340; 1,533,158; 1,701,691; 3,587,581; 3807973; 3,876,391; 4,199,316; 4,244,702; 4696638, in which surfactants include any emulsifier or mixture of emulsifiers used in the art. In more detail, US Pat. No. 3,527,581 describes a water emulsion in gasoline. The surfactant mixture used consists of at least two components, one of which is dissolved mainly in water, the other in the hydrocarbon phase. As a surfactant, a mixture of C ₁₂ -C ₂₀ fatty acids, amines, C ₃ -C ₅ alkylamino alcohols and C ₈ -C ₁₂ alkyl phenols in the alkyl group is used. US patent 3807973 contains a surfactant - diethanolamide fatty acid, mono-ester of triethanolamine and fatty acid triethanolamine and fatty acids triethanolamine.

Other patents include the following. Patent SU 699005 contains a surfactant - a mixture of pentaerythritol diester and oleic acid with polyethylene glycol ether of anhydrosorbate and oleic acid or with tetraethylene glycol ether of isooctyl phenol. Patent SU 810760 contains an additive to the emulsifier SPAN 80 in the form of a carboxylic acid salt, which includes Fe or Cr, which reduces the amount of expensive emulsifier. In SU 816524, it is proposed to use a surfactant composition as an emulsifier, consisting of an oil-soluble mixture of sorbitol and oleic acid esters and a water-soluble Na-salt of diethylhexyl ether sulfosuccinic acid. In the patent SU 1243342, oleic acid diethanolamide and oleic acid diethanolamine soap, which regulates the optimal hydrophilic-lipophilic balance (HLB) of the emulsifier, are used as the main surfactant having emulsifying properties, in addition, it includes diethanolamine, which facilitates the preparation of a microemulsion and monoether acid and diethanolamine, which improves the stability of the emulsion. The patent SU 1246593 contains alkenyl succinimide, which is an effective stabilizer of the water-hydrocarbon emulsion with respect to coalescence and, as a surfactant, ethoxylated alkyl phenol or ethoxylated alcohol to increase sedimentary stability. Patent RU 2213768 provides options for mixing surfactants with aliphatic alcohol. RU 2216573 proposes a method for producing a water-fuel emulsion, which consists in mixing carbon-containing fuel with water and an emulsifier, which is hydrophobic silicic acid. This patent indicates that the homogeneity of the fuel-water mixture is maintained for an arbitrarily long time.

It should be noted that the name “emulsifying system”, adopted in most patents, is sometimes replaced by another: “microemulsion”, “concentrated emulsion”, “emulsion stabilizer”. In an effort to expand the range of emulsions with a large ratio of water and hydrocarbon fuels and to provide high resistance to delamination of water-fuel emulsions, most patents contain multicomponent compositions of emulsifying systems, which complicates the technology for producing water-fuel emulsions, worsens the flammability of fuel and increases the cost of water-fuel emulsions emulsions. This is also due to the fact that there are no sufficiently substantiated data on the choice of surfactants having emulsifying or stabilizing properties for various types of emulsions and various dispersion media and dispersed phases. There are recommendations complemented by intuition and the “trial method”. These recommendations come from various concepts. Usually 3 factors are taken into account: geometric - the minimum segments of the emulsifier molecules and the ratio of the sizes of the polar and nonpolar groups; energy - the minimum retention strength of surfactants in the adsorption layer; concentration - the presence of a saturated adsorption layer. One of the first theories - the theory of oriented wedges - was based on the concept that salts of monovalent acids form direct emulsions and multivalent acids form inverse emulsions. The Bancroft rule is widespread - the higher members of the homologous series of surfactants are poorly soluble in water and poorly stabilize emulsions (for example, sodium stearate). Other criteria are the Donan maximum, the coalescence rate constant, which depends on the volume of the phases, and the system of numbers of hydrophilic-lipophilic balance (HLB) that has recently gained popularity. But this system allows us to predict only the type of emulsion obtained, taking into account the energy factor. It is also believed that surfactant isomers with branched aliphatic chains stabilize inverse emulsions, and with normal ones, direct ones. In addition, cationic emulsifiers should be used in an acidic environment, and anionic emulsifiers in an alkaline environment. If a significant amount of salts is present in the polar phase, it is better to use nonionic emulsifiers.

The technical task of the present invention is to obtain a water-fuel emulsion that meets all the requirements of its use in internal combustion engines as motor fuel and physico-chemical selection of the components that make up the emulsifying system.

The technical result achieved is to increase the resistance of the resulting water-fuel emulsions to sedimentation and coalescence by means of a targeted choice of surfactants and the choice of components that are promoters.

The main idea of the present invention is to use the existing concept of water as a polar phase and of hydrocarbon fuel as a non-polar phase. Water is a covalent compound. It has a significant dipole moment and therefore is a good solvent for substances with ionic and polar nature of the bonds. Dissolution of substances in water is accompanied by hydration, and aqueous solutions of substances are, as a rule, electrolytes. Water itself is a weak electrolyte. Water and hydrocarbon fuel are practically insoluble in each other. The introduction of emulsifying substances transfers these phases into the category of limited solubility. After water is dispersed into hydrocarbon fuel and in the absence of an effective stabilizer, 2 layers (2 phases) are formed: the upper one is hydrocarbon fuel and the lower one is water. The upper layer is a saturated solution of water in hydrocarbon, the lower layer is a saturated solution of hydrocarbon in water. The greater the degree of saturation of the lower layer, the greater its volume. It is important to note that water dissociates into 2 ions: a positively charged hydrogen ion H ⁺ and a negatively charged OH ^- hydroxide ion, forming the equilibrium constant K = [H ⁺ ] [OH ^- ], numerically equal to 1.0 · 10 ^-14 . A hydrogen ion is able to attract negatively charged ions.

With this in mind, it can be stated that for the formation of a high-quality emulsion, surfactants should be chosen that dissociate in water with the release of a surface-active anion. These are anionic surfactants. It is known that at the phase boundary, surfactant diphilic molecules are energetically oriented in the most favorable way to hydrophilic groups in the direction of the polar (water) phase, hydrophobic - in the direction of the non-polar (hydrocarbon) phase. Thus, the surfaces of the emulsion droplets are joined.

In low molecular weight surfactants, the hydrophilic part and the weakly hydrophobic part are highly developed. This is due to their low stabilizing ability. At the same time, equilibrium at the interface is established much faster in the case of low molecular weight surfactants than in the case of high molecular weight surfactants. Therefore, to quickly obtain a stable water-fuel emulsion, it is advisable to use anionic low molecular weight surfactants with promoters that enhance hydrophobic groups. If necessary, they can be supplemented with stabilizing additives, for example, surfactants of this type include:

a) carboxylic acids and their salts of the general formula RCOOMe (where Me is a metal);

b) ROSO OM alkyl sulphates;

c) RA-SO M alkylaryl sulfonates;

d) substances containing other types of anions, for example phosphates, thiosulfates;

d) salts of synthetic fatty acids of fraction C ₁₀ -C ₁₇ , replacing acids of plant and animal origin.

In addition, the non-ionic organic nature of the emulsifying system contributes to its solubility in fuel and water. This solubility is provided by functional groups, for example, such as benzoic or similar aromatic compositions. As a result, unsaturated functional groups must be replaced by non-halogen substituents such as alkyl, carboxyl, amino, nitro, hydroxyl and alkoxyl groups.

As a nonionic emulsifier, individual substances, fractions, or mixtures thereof can be used: esters of polyhydric alcohols and carboxylic acids, polyethylene glycol esters of higher alcohols, acids, alkyl phenols, alkyl polypropylene glycols, block copolymers, as well as alkyl amines, alkyl amines, alkyl ion amides, complexes of anionic and other

It should also be noted that the structure and action of surfactants have not been studied enough to in practice produce emulsions that are long-term resistant to coalescence and sedimentation. This is also evidenced by complex and, as a rule, difficult to explain chemical reactions that transfer the immiscible dispersion medium (fuel) and the dispersed phase (water) into the category of limitedly mixed ones, which, for example, is indirectly indicated by the color change of the water-fuel emulsion during long-term storage. The structural-mechanical factor — the formation of a structured and extremely solvated dispersion medium of an adsorption film — is also of great importance for stabilizing concentrated and highly concentrated emulsions.

This explains the multicomponent nature of emulsifying systems and the empirical approach to their selection. So, for example, US patent 4629472 has 34 components. Against this background, PCT 0475620 looks very brief, in which the emulsifier contains hydrophilic surfactants, such as salts of alkyl carboxyl and alkyl sulfonic acids and ethoxylate alkyl phenols and lipophilic surfactants, such as ethoxylate alkyl phenols and salts of alkyl and alkylaryl sulfonic acids. The emulsifier may contain joint surfactants and polar organic solvents.

Patent SU 1230470 is adopted as a prototype of the present invention, in which the emulsifying system comprises an emulsifier containing a fraction of mono-, di- and triglycerides of C ₁₂ -C ₂₀ fatty acids, an anionic oil-soluble sulfonate surfactant, magnesium naphthenate, ferrocene and, in addition, benzoic acid .

Initially, 3 types of solutions are prepared:

1 - a solution of an emulsifier and benzoic acid;

2 - a solution of magnesium naphthenate and anionic surfactant in paraffin or other oil fraction;

3 - a solution of ferrocene in oil.

As an organic solvent for the emulsifier, benzene, toluene or xylene are recommended. Benzoic acid is dissolved separately in a more polar solvent, for example methanol. Then all three solutions are mixed. High stabilizing properties of the emulsifying system are emphasized.

The disadvantages of obtaining water-fuel emulsions through the specified emulsifying system include the following:

- the complexity of the technology for compiling an emulsifying system on an industrial scale;

- anionic oil-soluble sulfonate surfactant in itself is both an emulsifier and a stabilizer, which, in the presence of an additional effective emulsifier containing a fraction of mono-, di- and triglycerides of fatty acids CC, can lead to the formation of a gel-like solution;

- the statement that “the stabilizer can be stored indefinitely and not undergo chemical decomposition or physical separation” cannot be considered objective, since this statement is true for a normal liquid, that is, a liquid in which internal degrees of freedom are not disturbed by neighboring molecules. In the vast majority of cases, the reversibility or irreversibility of processes is determined by such phenomena as diffusion, momentum transfer, energy transfer, chemical reactions;

- the range of ratios of the components of the emulsifying system and water is not indicated, without which obtaining a stable water-fuel emulsion becomes a long and laborious process.

The aim of the present invention is to obtain an emulsifying system, which includes affordable and inexpensive components and wt.% The ratio of these components and water, providing water-fuel emulsions with improved environmental and commercial indicators.

To achieve this goal, the following approach is proposed.

For given volumes of fuel and water, an anionic low molecular weight surfactant is selected, water and oil soluble, containing unsaturated functional groups that must be replaced by non-halogen substituents, such as alkyl, carboxyl, amino, nitro, hydroxyl and alkoxyl groups. Carboxylic acid salts, alkyl sulfates, alkylaryl sulfonates are common. As non-ionic surfactants, sorbitan oleate and more commercially available, for example sorbitals (TWINs), polyoxyethylene alkyl and polyoxyethylene alkyl phenol ethers (OP-4, OP-7, OP-10) can be used. The ratio of anionic and nonionic surfactants is from 3: 1 to 6: 1. Water repellents are selected, for example poly-d-olefins, polyoxyalkylene glycol, organopolysiloxanes, polyethylene oxide, polypropylene oxide. Of the polar organic solvents, plant-based solvents are preferred, for example betaine, propanol-2, sorbitol, oil discillates.

Oil-compensating agents are selected, the purpose of which is to increase the oiliness of the water-fuel emulsion, for example dimethyl phosphite, nitrated oil, polypropylene glycol.

Since the deposition rate of a particle dispersed in a dispersion medium is proportional to the difference in the densities of the dispersed phase and the dispersion medium, it is possible to further control the deposition rate of the particles using these polar organic solvents and oil-compensating agents and, in addition, they can be promoters.

The best result, as a rule, is the use of compositions of these components.

In the final form, the emulsifying system contains 4 groups of components:

1) emulsifying - anionic / nonionic surfactants;

2) stabilizing - water repellents and high molecular weight surfactants;

3) polar organic solvents;

4) oil-compensating agents.

As options for obtaining water-fuel emulsions using these four groups of components, the following are given.

Option 1.

Diesel fuel (diesel fuel) - 76% by volume.

Technical distilled water - 23% by volume.

Emulsifying system - 1% by volume, including its constituent components in wt.% With respect to water:

component 1 - anionic surfactants (including alkyl sulfates of the general formula), 6.5%; nonionic surfactants (including sorbitan oleate), 2%;

component 2 - polyolefins (including poly-alpha olefins), 8.7%;

component 3 - betaine 3%;

component 4 - nitrated oil 6%.

Option 2

A-92 grade gasoline - 79% by volume.

Technical distilled water - 20% by volume.

Emulsifying system - 1% by volume, including its constituent components in wt.% With respect to water:

component 1 - anionic surfactants (including sulfoethoxylates, salts of carboxylic acids of the general formula), 4.5%; nonionic surfactants (including sorbitan oleate), 1%;

component 2 - siloxane polymers (including polyorganosiloxanes), 10%;

component 3 - propanol-2, 3.5%;

component 4 - sulfonated castor oil, 7.2%.

An oil-compensating agent can be motor oils or their promoters that provide or enhance a lubricating effect, for example tributyl phosphite, tridecanol, tricarbonine, diethylene triamine, poly-4-methylpentene-1, phosphate esters, dialkyl dithiophosphoric thioester.

The above options are applicable in internal combustion engines and allow not to take into account such specific features as the place of oil production, distillation technology, engine wear, etc., and ensure the stability of the resulting water-fuel emulsions for at least 72 hours.

Claims (2)

1. A water-fuel emulsion intended for internal combustion engines operating on liquid hydrocarbon fuel, comprising a dispersion medium — hydrocarbon fuel and a dispersed phase — water, characterized in that the emulsifying system designed to produce said water-fuel emulsion comprises: a first a group of components represented by a low molecular weight anionic surfactant and a nonionic surfactant in a ratio of 3: 1 to 6: 1, respectively, a component or mixture of ponents from the second group represented by a hydrophobizing agent and a high molecular weight surfactant, a substance from the third group selected from betaine, propanol-2, sorbitol, oil distillates, and a substance or mixture of substances from the fourth group, which are oil-compensating agents. 2. The water-fuel emulsion according to claim 1, characterized in that the first group of components includes salts of carboxylic acids, sorbitan oleate, the second group of substances includes polyoxyalkylene glycol, a block polymer, polyorganosiloxanes, the fourth group includes dimethyl phosphite, nitrated oil.