HK1069841A - Fuel comprising an emulsion between water and a liquid hydrocarbon - Google Patents

Description

Fuel comprising water/liquid hydrocarbon emulsion

The present invention relates to a fuel comprising a water/liquid hydrocarbon emulsion, a method of supplying a combustion device with a fuel and a polymeric surfactant for stabilizing said emulsion.

The combustion of liquid hydrocarbons (e.g. for feeding to an internal combustion engine or for generating heat) is known to form a number of pollutants, in particular soot, particulates, carbon monoxide (CO), nitrogen oxides (NOx), sulphur oxides (SOx) and unburnt hydrocarbons, which produce significant atmospheric pollution.

It is also known that the addition of controlled amounts of water to fuel can significantly reduce the production of pollutants. It is believed that this effect is a result of various phenomena arising from the presence of water in the combustion zone. For example, the reduction in peak combustion temperature caused by water reduces the emissions of nitrogen oxides (NOx) whose formation is promoted by high temperatures. In addition, the instantaneous evaporation of the water droplets promotes better dispersion of the fuel within the combustion chamber, thereby significantly reducing the formation of soot, particulates and CO. These phenomena occur without adversely affecting the efficiency of the combustion process.

Several solutions have been proposed to add water to the liquid fuel at the time of use (i.e. at the time of injection of the fuel into the combustion chamber) or to inject the water itself directly into the combustion chamber. However, these solutions require changes to the structure of the combustion device and do not allow an optimal dispersion of water in the fuel, which is an important prerequisite for achieving a significant reduction of pollutants without compromising the heat production rate of the process.

The most promising and the most efforts made to date have therefore been directed towards the formulation of liquid hydrocarbon/water emulsions in the presence of emulsifiers (surfactants) with the aim of dispersing the water homogeneously in the hydrocarbon phase in the form of water droplets of the smallest possible size.

For example, European patent application EP-A-475,620 describes microemulsions of diesel fuel with water containing ｃA cetane booster and an emulsifying system comprising ｃA hydrophilic surfactant and ｃA lipophilic surfactant. These surfactants are selected from C₉-C₂₄Ethoxylation of carboxylic or sulfonic acids C₁₂-C₁₈Alkyl ammonium salts: the hydrophilic surfactant contains at least six ethylene oxide units and the lipophilic surfactant contains less than 6 ethylene oxide units.

European patent application EP- ｃA-630,398 describes ｃA fuel in the form of an emulsion comprising ｃA hydrocarbon fuel, 3 to 35% by weight of water and at least 0.1% by weight of an emulsifying system consisting of sorbitan oleate, polyalkylene glycol and ethoxylated alkylphenol.

International patent application WO 97/34969 describes a water/hydrocarbon emulsion, such as diesel fuel. The emulsion was stabilized by the addition of an emulsifier consisting of sorbitan sesquioleate, polyethylene glycol monooleate and ethoxylated nonyl phenol. The emulsifier has a total HLB (hydrophilic lipophilic balance) value of from 6 to 8.

A process for preparing stable emulsions of liquid fuels and water is described in European patent application EP-A-812,615. The method comprises preparing a first emulsion by mixing fuel, water and surfactant, and subsequently mixing the resulting emulsion with more water to obtain a final emulsion. The emulsion is stabilized with a hydrophilic surfactant or a lipophilic surfactant or a mixture thereof. Lipophilic surfactants which may be used are fatty acid esters of sorbitol, for example sorbitan monooleate, while hydrophilic surfactants suitable for this purpose are fatty acid esters of sorbitol containing polyoxyalkylene chains, for example polyoxyethylene sorbitan trioleate. In addition, the stabilizing effect of the emulsion can also be obtained by adding ethylene glycol or polyethylene glycol.

International patent application WO 92/19701 describes a method for reducing gas turbine NOx emissions, wherein an emulsion of water with diesel fuel is used. The emulsion is stabilized by adding an emulsifier selected from the group consisting of: alkanolamides and ethoxylated alkylphenols obtained by condensing alkylamines or hydroxyalkylamines with fatty acids. The emulsifier preferably has an HLB value of less than or equal to 8. Physical stabilizers such as waxes, cellulose derivatives or resins may be added to improve stability. The above emulsion can be further stabilized by the addition of difunctional block polymers having terminal primary hydroxyl groups, in particular copolymers containing propylene oxide/ethylene oxide blocks, as described in patent application WO 93/07238.

International patent application WO 00/15740 describes an emulsified water-blended fuel composition comprising: (A) hydrocarbons boiling in the gasoline or diesel boiling range; (B) water; (C) a minor emulsifying amount of at least one fuel-soluble salt prepared by reacting (C) (I) at least one acylating agent containing from about 16 to 500 carbon atoms with (C) (II) ammonia and/or at least one amine; and (D) from about 0.001 to about 15%, by weight of the fuel composition mixed with water, of a water-soluble, ash-free, halogen-, bromine-, and phosphorus-free amine salt other than component (C). Acylating agents (C) (I) include carboxylic acids and their reactive equivalents, such as acid halides, anhydrides, and esters (including partial esters and triglycerides).

Based on the applicant's experience, the opportunity to successfully use fuels in the form of water/liquid hydrocarbon emulsions is mainly linked to the possibility of replacing conventional liquid fuels with emulsified fuels without requiring any structural changes to the combustion device and without adversely affecting the proper functioning of the device.

Especially fuels in the form of emulsions need to have a high stability over a long period of time and over a wide temperature range (e.g. storage for at least three months at normal storage conditions, i.e. -20 ℃ to +50 ℃), in order to avoid the formation of a water-rich phase which tends to settle at the bottom of the tank during storage in the tank. The addition of this aqueous phase to the combustion chamber will cause considerable, or even permanent, impairment of the engine performance.

Additionally, applicants have found that the addition of emulsifiers to improve the stability of the emulsion may form carbonaceous deposits that adhere to the internal surfaces of the combustion chamber and injectors during combustion. This phenomenon may adversely affect the operation of the engine, with the result that frequent maintenance is required to remove these deposits.

The applicant has now found that fuels comprising water/liquid hydrocarbon emulsions can be prepared using a polymeric surfactant as defined below as an emulsifier. The resulting fuel has high stability over a long period of time and over a wide temperature range without forming carbonaceous deposits that adhere to metal surfaces.

In a first aspect, the present invention relates to a fuel comprising a water/liquid hydrocarbon emulsion, said emulsion being stabilised by at least one emulsifier, characterised in that said emulsifier comprises a polymeric surfactant obtainable by:

(a) reacting (i) at least one polyolefin oligomer functionalized with at least one group derived from a dicarboxylic acid or derivative thereof with (ii) at least one polyoxyalkylene comprising linear oxyalkylene units, said polyoxyalkylene being linked to a long chain alkyl group optionally containing at least one ethylenic unsaturation; and

(b) (ii) reacting the product of step (a) with (iii) at least one nitrogen compound selected from the group consisting of monoamines, polyamines and quaternary ammonium hydroxides.

In another aspect, the present invention relates to a method of supplying fuel to a combustion apparatus comprising at least one combustion chamber, the method comprising: supplying fuel to said at least one combustion chamber; igniting said fuel in said at least one combustion chamber; wherein the fuel comprises the water/liquid hydrocarbon emulsion described above.

Preferably, the combustion device is an internal combustion engine.

According to another aspect, the present invention relates to a polymeric surfactant obtainable by the reaction of:

(a) reacting (i) at least one polyolefin oligomer functionalized with at least one group derived from a dicarboxylic acid or derivative thereof with (ii) at least one polyoxyalkylene group comprising linear oxyalkylene units, said polyoxyalkylene group being attached to a long chain alkyl group optionally comprising at least one ethylenic unsaturation; and

(b) (ii) reacting the product of step (a) with (iii) at least one nitrogen compound selected from the group consisting of monoamines, polyamines and quaternary ammonium hydroxides.

Preferably, the polyolefin oligomer has an average molecular weight of 300 to 10,000, preferably 500 to 5,000.

The polyolefin oligomers are generally obtained by homopolymerization or copolymerization of at least one olefin containing from 2 to 16 carbon atoms, for example selected from:

α -olefins, i.e. olefins in which the double bond is in the terminal position, such as: ethylene, propylene, 1-butene, isobutylene, 4-methyl-1-pentene, 1-hexene, 1-octene, 2-methyl-1-heptene, etc.;

internal mono-olefins, i.e. olefins in which the double bond is not in the terminal position, such as: 2-butene, 3-pentene, 4-octene, and the like.

The olefin may also be copolymerized with other hydrocarbons containing at least one ethylenic unsaturation, such as monovinyl aromatic hydrocarbons (e.g., styrene, p-methylstyrene, etc.) or conjugated dienes (e.g., 1, 3-butadiene, isoprene, 1, 3-hexadiene, etc.).

Preferably, the polyolefin oligomer is derived from the polymerization of a mixture of olefins having 4 carbon atoms, usually containing from 35 to 75% by weight of 1-butene and from 30 to 60% by weight of isobutene, in the presence of a Lewis acid such as aluminum trichloride or boron trifluoride as catalyst. These polymerization products are commonly referred to as "polyisobutylenes" because they contain predominantly isobutylene repeat units of the formula:

the amount of isobutene units is generally not less than 80 mol%.

The polyoxyalkylenes comprise hydrophilic-imparting linear oxyalkylene units, in particular of the formula-CH₂CH₂O-、-CH₂CH₂CH₂O-or-CH₂CH₂CH₂CH₂Units of O-, or mixtures thereof.

The number of linear oxyalkylene units is determined primarily as a function of the nature and length of the lipophilic moieties present in the polymeric surfactant, particularly the polyolefin oligomers and long chain alkyl groups.

Preferably the polyoxyalkylene is a polyoxyalkylene having from 2 to 40, preferably from 5 to 20, groups of the formula-CH₂CH₂Polyethylene oxide of oxyethylene unit of O-.

Alternatively, the polyoxyalkylene is a polyoxyalkylene having 2 to 30, preferably 5 to 15, groups of the formula-CH₂CH₂Copolymers of oxyethylene units of O "and not more than 12, preferably 1 to 10 branched oxyethylene units of the formula:

wherein R is an alkyl group containing 1 to 3 carbon atoms. Preferably, R is methyl.

In the case of copolymers, the alkylene oxide units are distributed along the chain in random, block or alternating form. The number of oxyalkylene units is expressed as the average number of units per chain.

The polyoxyalkylene is attached to a long chain alkyl group. The alkyl group, optionally containing at least one ethylenic unsaturation, of linear or branched structure, generally contains from 8 to 24 carbon atoms.

The linkage between the polyoxyalkylene and the long-chain alkyl group is preferably carried out via an ester group or an ether group, and can be obtained by the following reaction:

(A) condensing a polyoxyalkylene (polyalkylene glycol) with a fatty acid or derivative thereof, particularly an ester, to form the corresponding polyoxyalkylene monoester;

(B) the fatty alcohols are esterified with alkylene oxides, in particular with ethylene oxide or a mixture of ethylene oxide and propylene oxide.

Examples of fatty acids which can be used in reaction (a) are: myristoleic acid, palmitoleic acid, oleic acid, cis 9-eicosenoic acid, erucic acid, ricinoleic acid, linoleic acid, linolenic acid, arachidonic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, and the like, or mixtures thereof.

Examples of fatty alcohols which can be used in reaction (B) are: octanol, decanol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, oleyl alcohol, linoleyl alcohol, linolenyl alcohol, and the like, or mixtures thereof.

The polyolefin oligomer is functionalized by reaction with a dicarboxylic acid or derivative thereof. In particular, the functionalization can be carried out by the following reaction:

(i) an "ene" -type concerted reaction between a polyolefin oligomer containing at least one ethylenic unsaturation and a dicarboxylic acid derivative containing ethylenic unsaturation;

(ii) anionic condensation reaction between a polyolefin oligomer functionalized with a leaving group (e.g. a halogen atom or a tosyl or mesyl group) and a saturated dicarboxylic acid derivative.

In both cases, the acid halide (preferably acid chloride or acid bromide), C₁-C₄Esters or preferably anhydrides may be used as dicarboxylic acid derivatives.

Dicarboxylic acids containing ethylenic unsaturation may be chosen, for example, from: maleic acid, fumaric acid, citraconic acid, itaconic acid, and the like, or mixtures thereof.

The saturated dicarboxylic acids may be selected, for example: malonic acid, succinic acid, glutaric acid, adipic acid, 2-hexene-1, 6-dioic acid, azelaic acid and the like or mixtures thereof.

Preferably the functionalized polyolefin oligomer is derived from the reaction between maleic anhydride and polyisobutylene containing not less than 65 mole%, preferably not less than 80 mole%, exo double bonds, i.e. vinylidene groups of the formula:

polyisobutenes of this type are commercially available, for example, under the trade names Ultravis  (BP Amoco Chemicals) and Glissopal  (BASF).

More details on the preparation of the functionalized polyolefin oligomers described above are given, for example, in U.S. Pat. Nos. 4,152,499 and 5,567,344.

The condensation reaction of step (a) between the functionalized polyolefin oligomer and the polyoxyalkylene bonded to the long chain alkyl group may be carried out in bulk or in the presence of an organic solvent. To facilitate the removal of the water deriving from the condensation reaction, it is preferred that the organic solvent is chosen from solvents capable of forming an azeotrope with water, such as toluene or xylene or mixtures thereof. The condensation reaction may be carried out at a temperature generally not greater than 200 ℃. When an organic solvent is used, the reaction temperature is generally not greater than the boiling point of the solvent. The reaction time may vary within wide limits and is generally from 3 to 24 hours.

As for step (b), it is carried out by reacting the product of step (a) with (iii) at least one nitrogen compound selected from the group consisting of monoamines, polyamines and quaternary ammonium hydroxides.

The monoamine has only one amine function and may be a primary, secondary or tertiary amine of the formula:

wherein R1, R2 and R2, equal to or different from each other, are selected from: hydrogen; c₁-C₂₄A hydrocarbon group optionally substituted with at least one member selected from the group consisting of hydroxyl and C₁-C₄Alkoxy is substituted by the radical of alkoxy; r1 and R2 may be joined to form a nitrogen-containing aliphatic heterocycle optionally containing at least one additional heteroatom (e.g., nitrogen and/or oxygen); provided that at least one of R1, R2, and R3 is not hydrogen.

The hydrocarbon group may be a linear or branched, saturated or unsaturated aliphatic, alicyclic, aromatic and/or heterocyclic group.

Specific examples of aliphatic monoamines include trimethylamine, ethylamine, diethylamine, triethylamine, tripropylamine, N-butylamine, di-N-butylamine, tributylamine, methyldiethylamine, ethyldimethylamine, dimethylpropylamine, dimethylhexylamine, dimethyloctylamine, allylamine, isobutylamine, dimethylpentylamine, cocoylamine, stearylamine, laurylamine, methyllaurylamine, oleylamine, N-methyloctylamine, dodecylamine, octadecylamine, or mixtures thereof.

Specific examples of the alicyclic monoamine include: cyclohexylamine, cyclopentylamine, cyclohexenylamine, cyclopentylamine, N-ethyl-cyclohexylamine, dicyclohexylamine, or mixtures thereof.

Specific examples of hydroxy-substituted amines (also known as hydroxyamines or alkanolamines) include: ethanolamine, diethanolamine, ethylethanolamine, dimethylethanolamine, diethylethanolamine, bis (3-hydroxypropyl) amine, N- (3-hydroxybutyl) amine, N- (4-hydroxybutyl) amine, N-bis (2-hydroxypropyl) amine, N- (2-hydroxyethyl) morpholine, N- (2-hydroxyethyl) cyclohexylamine, N-3-hydroxycyclopentylamine, N- (hydroxyethyl) piperazine, or mixtures thereof.

Specific examples of the aromatic monoamine include: phenylethylamine, benzyldimethylamine, or mixtures thereof.

The polyamine may be an aliphatic or cycloaliphatic compound. Particularly preferred are alkylene polyamines of the formula:

wherein:

n is 1 to 10, preferably 2 to 7;

r4, R5 and R6, equal to or different from each other, are selected from: hydrogen, alkyl containing 1 to 30 carbon atoms, or hydroxy-substituted alkyl, provided that at least one of R4 and R5 and at least one of R6 is hydrogen;

r7 is an alkylene group containing 1 to 18, preferably 2 to 6, carbon atoms.

Specific examples of the polyamine include: methylene polyamines, ethylene polyamines, butylene polyamines, propylene polyamines, pentylene polyamines, ethylene diamine, triethylene tetramine, propylene diamine, trimethylene tetramine, tetraethylene pentamine, hexaethylene heptamine, pentaethylene hexamine, or mixtures thereof.

The quaternary ammonium hydroxide can be represented by the formula:

wherein:

r8, R9, R10 and R11, equal to or different from each other, are selected from: a C1-C24 hydrocarbyl group optionally substituted with at least one group selected from hydroxyl and C1-C4 alkoxy; r8 and R9 may be joined to form a nitrogen-containing aliphatic heterocycle optionally containing at least one additional heteroatom (e.g., nitrogen and/or oxygen).

The hydrocarbon group may be a linear or branched, saturated or unsaturated aliphatic, alicyclic, aromatic and/or heterocyclic group.

Specific examples of quaternary ammonium hydroxides include: tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, octyltrimethylammonium hydroxide, oleyltrimethylammonium hydroxide, hydroxyethyltributylammonium hydroxide, methoxyethyltributylammonium hydroxide, or mixtures thereof.

The reaction of step (b) may be carried out by mixing the reactants in bulk or in the presence of an inert organic solvent such as xylene or toluene. The reaction temperature may vary within wide limits and is generally from about 20 ℃ to about 180 ℃. The reaction temperature is usually not more than the boiling point of the nitrogen-containing compound (iii), and when an organic solvent is used, the reaction temperature is not more than the boiling point of the solvent. The reaction time may vary within wide limits and is generally from 0.5 to 5 hours.

The product resulting from reaction step (b) comprises an ammonium carboxylate salt or amide or mixture thereof derived from the reaction of the nitrogen compound (iii) with residual carboxyl groups present in the product of step (a). The yield of the salt and/or amide depends mainly on the particular reactants and the reaction conditions, in particular the reaction temperature and time.

The equivalence ratio between the product of step (a) and the nitrogen compound (iii) can vary within wide limits. Generally, the equivalence ratio may be a ratio of 0.5 to 4, preferably about 1. The number of equivalents of product of step (a) corresponds to the number of residual carboxyl groups and can be determined according to known techniques, for example by means of the acid number (generally expressed in mg KOH/g of product). The number of equivalents of nitrogen compound (iii) is the molecular weight of compound (iii) divided by the total number of basic nitrogen atoms present in the molecule.

The amount of polymeric surfactant used in the fuel of the present invention is determined primarily by the amount of water to be emulsified and the type of liquid hydrocarbon used. Preferably the polymeric surfactant as defined above is present in the fuel in an amount of from 0.1 to 5 wt%, preferably from 0.5 to 3 wt%, relative to the total weight of the fuel.

It should be noted that the polymeric surfactants defined above are effective in stabilizing emulsions over a wide temperature range without the addition of other emulsifiers. However, this does not exclude the possibility of adding other products which are capable of altering the stability of the emulsion in some way, in particular other emulsifiers known in the art.

The type of emulsion obtained by using the polymeric surfactants defined above is generally of the water-in-oil type, in which the water droplets are dispersed in a continuous hydrocarbon phase. It is believed that such emulsions ensure the most effective reduction of pollutants due to the presence of water during the combustion stage.

Hair brushThe fuel of the invention comprises liquid hydrocarbons, which are generally derived from petroleum distillation and essentially consist of a mixture of aliphatic, naphthenic, olefinic and/or aromatic hydrocarbons. The viscosity of the liquid hydrocarbon at 40 ℃ is generally from 1 to 53cSt and the density at 15 ℃ is generally from 0.75 to 1.1kg/dm³And may be selected from, for example: gas oil, fuel oil, kerosene, aviation fuel (jet fuel) for use as automotive fuel or for heat generation.

The amount of water emulsified by the liquid hydrocarbon is determined to achieve the desired reduction in pollutants without compromising the heat generation rate of the combustion process. This amount is generally from 3 to 40% by weight, preferably from 7 to 20% by weight, relative to the total weight of the fuel. The water used may be of any type, such as industrial or domestic water. However, it is preferred to use demineralized or deionized water in order to avoid the formation of mineral deposits on the internal surfaces of the combustion chamber and/or on the injectors.

The fuel of the present invention may contain other additives, the nature and amount of which depend on the specific use for which the fuel is intended. These additives may be selected, for example, from: cetane improvers, corrosion inhibitors, lubricants, biocides, defoamers, antifreeze agents, and mixtures thereof.

In particular, cetane improvers are products which improve the knocking properties of the fuel and are generally selected from organic or inorganic nitrates, nitrites and peroxides which are soluble in the aqueous phase or preferably in the hydrocarbonaceous phase, for example organic nitrates (see, for example, patents EP-475,620 and US-5,669,938). Of these, alkyl or cycloalkyl nitrates having up to 10 carbon atoms, such as ethyl nitrate, pentyl nitrate, n-hexyl nitrate, 2-ethylhexyl nitrate, n-decyl nitrate, cyclohexyl nitrate, and the like or mixtures thereof, are preferably used.

The antimicrobial agent may be selected from those known in the art, such as morpholine derivatives, isothiazolin-3-one derivatives, tris (hydroxymethyl) -nitromethane, formaldehyde, oxazolidines or mixtures thereof.

The fuel of the present invention may also include an alcohol that acts primarily as an antifreeze by lowering the freezing point of the aqueous phase. Suitable alcohols for this purpose are, for example: methanol, ethanol, isopropanol, and glycols, or mixtures thereof. The amount of alcohol is generally from 0.5 to 8% by weight, preferably from 1 to 4% by weight, relative to the total weight of the fuel.

The fuel of the present invention is generally prepared by mixing the various components using emulsifying equipment known in the art, wherein the formation of the emulsion may be the result of a mechanical type action exerted by moving parts, or the result of the delivery of the various components to be emulsified to a static type mixing equipment, or the result of a combined mechanical and static action. The emulsion is formed by adding an optionally premixed aqueous phase and a hydrocarbon phase to an emulsification device. The emulsifiers and other additives which may be present may be introduced separately or, preferably, they are premixed into the aqueous or hydrocarbon phase, depending on their solubility properties. The polymeric surfactant is preferably pre-blended into the hydrocarbon phase.

The invention will now be further explained by means of some examples.

Example 1

A. Preparation of polyethylene glycol monoesters (PEG-monoesters)

300g of the oleic acid/linoleic acid mixture (60/40 weight ratio) and 400g of polyethylene glycol (PEG) (molecular weight (MW): 400g/mol) were mixed together in a reactor. 3.5g of methanesulfonic acid as condensation catalyst and 340ml of toluene (with H) as diluent were added with stirring₂O forms an azeotrope). The mixture was gradually heated to 140 ℃ for a total of about 5 hours while distilling and separating H₂The O/toluene azeotrope. After further heating at 160 ℃ for 2 hours and distillation of the residual toluene, the product formed is degassed at 140 ℃ for about 2 hours under vacuum. The residual acidity was 4.5mg KOH/g product.

B. Synthesis of polyisobutene derivatives by reaction with maleic anhydride

95g of Polyisobutene (PIB) (average M) having an exo double bond content of 90%W: 950g/mol of Ultravis  10 from BP Amoco Chemicals), 9.4g of maleic anhydride and 37ml of xylene were placed in a 500ml Teflon  autoclave. After degassing with nitrogen, the autoclave was heated to 190 ℃ and held at this temperature for a total of 22 hours. After the reaction was complete, the autoclave was cooled to 70 ℃ and degassed under vacuum for about 2 hours. The product obtained (101g) was a viscous yellow liquid with a polyisobutene conversion equal to about 43% (determined by chromatography on silica gel using hexane as eluent), a residual content of maleic anhydride lower than 0.2% by weight, and the number of anhydrides (moles of bonding anhydride/100 g of product) (determined by quantitative infrared spectroscopic analysis, based on 1760cm^-1Absorption peak at (b) was 0.052.

C. Synthesis of intermediate ester (step (a))

The maleic anhydride functionalized PIB from reaction B (52.6g) was charged to a reactor and heated to about 50 ℃ before xylene (5g) and the PEG-monoester from reaction a (75g) were added with stirring. The resulting solution was heated at 140 ℃ for 1 hour. The temperature was then maintained at 180 ℃ for 10 hours while distilling and separating H₂An O/xylene azeotrope. The resulting product was a light brown viscous liquid with residual acidity of 5.1mg KOH/g product.

D. Synthesis of Polymer surfactant (step (b))

D1. The product obtained in step C was reacted with 1.45g (═ 1 eq) diethanolamine by stirring at 30 ℃ for 1 hour. The resulting polymeric surfactant was a light brown viscous liquid with a residual acidity of about 0.3mg KOH/g product.

D2. The product from step C was reacted with 1.45g (═ 1 eq) diethanolamine by stirring at 140 ℃ for 4 hours while water was stripped off in vacuo. The resulting polymeric surfactant was a light brown viscous liquid with a residual acidity of about 0.3mg KOH/g product.

D3. The product obtained in step C was reacted with 5.55g (═ 1 eq) of 40 wt% aqueous benzyltrimethylammonium hydroxide solution by stirring at 30 ℃ for 1 hour. The resulting polymeric surfactant was a light brown viscous liquid with residual acidity of less than 0.1mg KOH/g product.

Example 2

1000g of diesel fuel/water emulsion are prepared using the product of reaction D1 as emulsifier.

18.87g of the emulsifier obtained in example 1-D1 were added to 865g of an automobile diesel fuel type EN590 to which 0.565g of 2-ethylhexyl nitrate (cetane booster) had previously been added. The mixture was subjected to the action of a high shear mixer for several minutes, and then 115.00g of water to which 0.565g of a bactericide (isothiazolin-3-one derivative) was previously added was added. The emulsifier was then switched to a maximum stirring speed for about 3 minutes. This gives an emulsion having the following composition:

diesel fuel 86.5% by weight

11.5% by weight of water

1.887% by weight of emulsifier

Cetane number improver 0.0565 wt%

0.0565% by weight of a fungicide

Example 3

1000g of a diesel fuel/water emulsion was prepared in the same manner as in example 2, except that the product of examples 1-D2 was used as an emulsifier.

Example 4

1000g of a diesel fuel/water emulsion was prepared in the same manner as in example 2, except that the product of examples 1-D3 was used as an emulsifier.

Example 5 (comparative example)

1000g of emulsion are prepared in the same manner as described in example 2, the only difference being that 18.87g of a surfactant mixture consisting of 87% by weight of sorbitan monooleate, 3% by weight of sorbitan trioleate and 10% by weight of ethoxylated castor oil (10mol of ethylene oxide) are used instead of the emulsifier of example 1.

Example 6

The emulsions prepared according to examples 2-5 were characterized as follows.

Stability to centrifugation

The stability of the emulsion was evaluated by centrifugation. Two sets of experiments were performed, the first using the freshly prepared emulsion (t ═ 0) and the second using the emulsion stored at room temperature for 24 hours (t ═ 24 hours).

The graduated tube was filled with 15ml of the emulsion. The tubes were placed in a centrifuge rotating at 4000 revolutions per minute (equal to 2525 g; g ═ g acceleration of gravity) for a total time of 30 minutes at room temperature. The amount of water-rich phase separated (creaming) at the bottom of the tube was determined in volume% at regular intervals of 5 minutes of centrifugation.

The results for the emulsions of examples 2-5 are given in table 1.

Static stability under temperature cycling

The storage stability of the emulsion was evaluated by the following method.

A 1000ml glass cylinder filled with the test emulsion was placed in a thermostatically controlled oven whose temperature was controlled according to the following temperature cycle: the temperature was maintained at 40 ℃ for 8 hours, at 20 ℃ for 8 hours and at 5 ℃ for 8 hours. The emulsion was subjected to this temperature cycle for 14 days. Then 15ml samples were taken from the top and bottom of the emulsion and the water content of said samples was determined by Karl-Fisher titration according to ISO standard 3734. The same measurements were performed on samples subjected to a 28 day temperature cycle.

The results for the emulsions of examples 2-5 are given in table 2 (average of three samples).

From the data given in tables 1 and 2, it can be seen that the emulsions of the present invention show high stability against centrifugation and temperature cycling, whereas in the prior art emulsions the aqueous phase tends to settle to a large extent.

Formation of deposits on metal sheets

The stainless steel plate (10 cm. times.5 cm) was placed on a hot plate maintained at a temperature of about 280 ℃ to 300 ℃. Once this temperature was reached, one drop of the emulsion was placed on the steel plate every 30 seconds for a total of 10 drops. After the last drop was placed, the plate was allowed to cool for an additional 30 seconds. Carbonaceous deposits were found to form on the plates. The test is considered positive if the deposit can be wiped off substantially completely and easily by wiping with a dry cloth, whereas the test is negative if a large part of the deposit remains adhering to the plate even after a long wiping time.

Tests carried out with the emulsions according to the invention (examples 2 to 4) gave positive results, with the formation of a thin deposit which is easily removed by wiping. In contrast, the comparative emulsion (example 5) failed the test because it formed a black deposit that could not be removed by wiping.

Lubricity and corrosiveness

The lubricity (measured according to ISO standard 12156/1) of the inventive emulsions (examples 2-4) was about 270 μm compared to the diesel fuel itself, which has a lubricity value of about 385 μm. Thus, the emulsions of the present invention have better anti-stick (anti-grip) properties than the diesel fuel itself.

The evaluation of the corrosivity according to the standard EN590 classifies the emulsion according to the invention as category 1a, equal to the category of diesel fuel itself.

TABLE 1

Emulsion example 2 (inventive)	t＝0
								Centrifuge time (min)	5	10	15	20	25	30
	Emulsion stratification (% by volume)	0.50	1.10	1.75	2.32	2.60	3.02
								t＝24h
	Centrifuge time (min)	5	10	15	20	25	30
								Emulsion stratification (% by volume)	0.50	0.81	151	1.76	2.24	2.70
	Emulsion example 3 (inventive)	t＝0
Centrifuge time (min)									5	10	15	20	25	30
		Emulsion stratification (% by volume)	0.53	1.30	1.87	2.60	2.91	3.54
t＝24h
							Centrifuge time (min)	5	10	15	20	25	30
Emulsion stratification (% by volume)	0.55	0.96	1.71	2.00	2.61	3.29
							Emulsion example 4 (inventive)	t＝0
Centrifuge time (m)in)	5	10	15	20	25	30
								Emulsion stratification (% by volume)	0.40	0.90	1.67	2.12	2.39	2.86
t＝24h
								Centrifuge time (min)	5	10	15	20	25	30
Emulsion stratification (% by volume)	0.42	0.74	1.42	1.67	2.04	2.51
								Emulsion example 5 (comparative example)	t＝0
Centrifuge time (min)	5	10	15	20	25	30
							Emulsion stratification (% by volume)		3.33	6.00	6.67	8.00	9.00	9.67
t＝24h
							Centrifuge time (min)		5	10	15	20	25	30
Emulsion layer amount (% vol)	6.67	9.33	10.00	10.33	10.67	11.00

TABLE 2

Emulsion and method of making	Time (sky)	Top H2O content (% by weight)	H of the bottom2O content (% by weight)
				Example 2 (inventive)	0	11.54
14	11.19	12.22
			28		11.09	12.99
Example 3 (inventive)	0	11.56
				14	11.05	12.26
	28	11.00	13.31
				Example 4 (inventive)	0	11.62
14	11.33	12.24
			28		11.23	12.67
Example 5 (comparative example)	0	10.92
				14	6.06	42.31
	28	1.74	62.46

Claims (39)

1. A fuel comprising a water/liquid hydrocarbon emulsion, said emulsion being stabilized by at least one emulsifier, characterized in that said emulsifier comprises a polymeric surfactant obtained by the reaction of:

(a) reacting (i) at least one polyolefin oligomer functionalized with at least one group derived from a dicarboxylic acid or derivative thereof with (ii) at least one polyoxyalkylene comprising linear oxyalkylene units, said polyoxyalkylene being linked to a long chain alkyl group optionally containing at least one ethylenic unsaturation; and

(b) (ii) reacting the product of step (a) with (iii) at least one nitrogen compound selected from the group consisting of monoamines, polyamines and quaternary ammonium hydroxides.

2. The fuel of claim 1, wherein the polyolefin oligomer has an average molecular weight of 300 to 10,000.

3. The fuel of claim 2, wherein the polyolefin oligomer has an average molecular weight of 500 to 5,000.

4. A fuel as claimed in any one of the preceding claims, wherein the polyolefin oligomer is derived from the polymerisation of a mixture of olefins containing 4 carbon atoms and contains predominantly isobutylene repeat units of the formula:

5. a fuel as claimed in any one of the preceding claims, wherein the polyoxyalkylene comprises linear oxyalkylene units selected from the group consisting of: -CH₂CH₂O-、-CH₂CH₂CH₂O-and-CH₂CH₂CH₂CH₂O-or mixtures thereof.

6. The fuel of claim 5, wherein the polyoxyalkylene comprises 2 to 40 moieties of the formula-CH₂CH₂Ethylene oxide units of O-.

7. The fuel of claim 6, wherein the polyethylene oxide comprises from 5 to 20 ethylene oxide units.

8. A fuel as claimed in any one of claims 1 to 5, wherein the polyoxyalkylene is a polyoxyalkylene containing 2 to 30 members of the formula-CH₂CH₂Ethylene oxide units of O-anda copolymer of no more than 12 branched ethylene oxide units of the formula:

wherein R is an alkyl group containing 1 to 3 carbon atoms.

9. The fuel of claim 8, wherein R is methyl.

10. A fuel as claimed in any one of the preceding claims, wherein the polyoxyalkylene is attached to a long chain alkyl group containing from 8 to 24 carbon atoms of a straight or branched chain structure, optionally containing at least one ethylenic unsaturation.

11. A fuel as claimed in any one of the preceding claims, wherein the polyoxyalkylene is linked to the long chain alkyl group by an ester group.

12. A fuel according to any one of claims 1 to 10, wherein the polyoxyalkylene group is linked to the long chain alkyl group by an ether group.

13. A fuel according to any one of the preceding claims, wherein the fuel is formulated by reaction with a compound selected from the group consisting of acyl halides, C₁-C₄The dicarboxylic acid derivative of the ester and anhydride react to functionalize the polyolefin oligomer.

14. A fuel as claimed in any one of the preceding claims, wherein the functionalised polyolefin oligomer is obtained by reaction between maleic anhydride and a polyisobutene containing not less than 65% exo double bonds.

15. A fuel according to any one of the preceding claims, wherein the nitrogen compound (iii) is a primary, secondary or tertiary amine of the formula:

wherein R1, R2 and R2, equal to or different from each other, are selected from: hydrogen, a C1-C24 hydrocarbyl group optionally substituted with at least one group selected from hydroxyl and C1-C4 alkoxy; r1 and R2 may be joined to form a nitrogen-containing aliphatic heterocycle optionally containing at least one additional heteroatom; provided that at least one of R1, R2, and R3 is not hydrogen.

16. The fuel of any one of claims 1 to 14, wherein the nitrogen compound (iii) is an alkylene polyamine of the formula:

wherein:

n is 1 to 10, preferably 2 to 7;

r4, R5 and R6, equal to or different from each other, are selected from: hydrogen, alkyl containing 1 to 30 carbon atoms, or hydroxy-substituted alkyl, provided that at least one of R4 and R5 and at least one of R6 is hydrogen;

r7 is an alkylene group containing 1 to 18, preferably 2 to 6, carbon atoms.

17. A fuel according to any one of claims 1 to 14, wherein the nitrogen compound (iii) is a quaternary ammonium hydroxide of the formula:

wherein:

r8, R9, R10 and R11, equal to or different from each other, are selected from: a C1-C24 hydrocarbyl group optionally substituted with at least one group selected from hydroxyl and C1-C4 alkoxy; r8 and R9 may be joined to form a nitrogen-containing aliphatic heterocycle optionally containing at least one additional heteroatom.

18. A fuel as claimed in any one of the preceding claims, wherein the polymeric surfactant is present in an amount of from 0.1 to 5% by weight relative to the total weight of the fuel.

19. The fuel of claim 18, wherein the polymeric surfactant is present in an amount of 0.5 to 3 wt.%, relative to the total weight of the fuel.

20. A fuel as claimed in any one of the preceding claims, wherein the liquid hydrocarbon has a viscosity of from 1 to 53cSt at 40 ℃ and a density of from 0.75 to 1.1kg/dm at 15 ℃³。

21. A fuel as claimed in any one of the preceding claims, wherein the water is present in an amount of from 3 to 40% by weight, relative to the total weight of the fuel.

22. The fuel of claim 21, wherein water is present in an amount of 7 to 20 wt.%, relative to the total weight of the fuel.

23. A fuel according to any one of the preceding claims, further comprising at least one cetane booster.

24. The fuel of claim 23, wherein said at least one cetane booster is selected from the group consisting of inorganic nitrates, inorganic nitrites, and inorganic peroxides.

25. The fuel of claim 23, wherein said at least one cetane booster is selected from the group consisting of organic nitrates, organic nitrites, and organic peroxides.

26. A fuel according to any one of the preceding claims, further comprising at least one antimicrobial agent.

27. A fuel according to any one of the preceding claims, further comprising at least one alcohol.

28. The fuel of claim 27, wherein said alcohol is selected from the group consisting of: methanol, ethanol, isopropanol, and glycols, or mixtures thereof.

29. A fuel according to claim 27 or 28, wherein the alcohol is present in an amount of from 0.5 to 8 wt% relative to the total weight of the fuel.

30. The fuel of claim 29, wherein the alcohol is present in an amount of 1 to 4 wt.%, relative to the total weight of the fuel.

31. A method of supplying fuel to a combustion apparatus comprising at least one combustion chamber, the method comprising: supplying fuel to said at least one combustion chamber; igniting said fuel in said at least one combustion chamber; wherein the fuel comprises a water/liquid hydrocarbon emulsion according to any one of claims 1 to 30.

32. The method of claim 31 wherein said combustion device is an internal combustion engine.

33. A polymeric surfactant obtained by the reaction of:

(a) reacting (i) at least one polyolefin oligomer functionalized with at least one group derived from a dicarboxylic acid or derivative thereof with (ii) at least one polyoxyalkylene comprising linear oxyalkylene units, said polyoxyalkylene being linked to a long chain alkyl group optionally containing at least one ethylenic unsaturation; and

(b) (ii) reacting the product of step (a) with (iii) at least one nitrogen compound selected from the group consisting of monoamines, polyamines and quaternary ammonium hydroxides.

34. The polymeric surfactant according to claim 33, wherein the polyolefin oligomer is according to any one of claims 2 to 4.

35. A polymeric surfactant according to claim 33 or 34, wherein polyoxyalkylenes are as defined in any one of claims 5 to 9.

36. A polymeric surfactant according to any one of claims 33 to 35, wherein the long chain alkyl group is as claimed in claim 10.

37. A polymeric surfactant according to any one of claims 33 to 36, wherein a polyoxyalkylene group is attached to the long chain alkyl group of claim 11 or 12.

38. A polymeric surfactant according to any of claims 33 to 37 wherein the polyolefin oligomer is functionalised as described in claim 13 or 14.

39. The polymeric surfactant according to any one of claims 33 to 38, wherein the nitrogen compound (iii) is as defined in any one of claims 15 to 17.