WO2004108864A2

WO2004108864A2 - Water/hydrocarbon emulsified fuel preparation and use thereof

Info

Publication number: WO2004108864A2
Application number: PCT/FR2004/001343
Authority: WO
Inventors: Frederic Tort; Laurent Dalix; Gabrielle Laluet
Original assignee: Total France
Priority date: 2003-06-02
Filing date: 2004-06-01
Publication date: 2004-12-16
Also published as: FR2855525B1; US20060075680A1; CN1798825A; CA2527324A1; EP1636326A2; FR2855525A1; OA13176A; JP2006526680A; WO2004108864A3; BRPI0410865A

Abstract

The invention relates to an emulsified fuel, comprising a major fraction of an emulsion of water and liquid hydrocarbons with a weight ratio of water/hydrocarbons of 5 / 95 to 35 / 65, characterised in containing an emulsifying system with at least 15 % by weight of a fatty acid ester and polyoxyalkylated glycerol with at least one component of the group formed by the esters of fatty acids and sorbitan and the products of condensation of a succinic acid or anhydride with at least one amine, polyamine, fatty acid, polyoxyalkylated fatty acid, alcohol, polyoxyalkylated alcohol and mixtures of the above. The invention further relates to a method for production of such an emulsified fuel, a composition of emulsifying additives for such an emulsified fuel, a method for improvement of the thermal stability of an emulsified fuel by means of use such an additive composition, as well as the use of such an emulsified fuel as engine fuel.

Description

WATER / HYDROCARBON EMULSION FUEL. ITS PREPARATION AND ITS USES

The present invention relates to a fuel comprising an emulsion of water and liquid hydrocarbons, intended for use in engines and thermal machines. More specifically, the present invention relates to a water / hydrocarbon emulsified fuel which exhibits improved stability at high temperature.

For several years, most oil companies have been working on developing fuels (and in particular fuels) including substitutes for petroleum-based hydrocarbons, with a view to both saving hydrocarbons and limiting of pollution. Thus, water quickly appeared as a particularly interesting partial substituent, provided that it was kept in stable emulsion with hydrocarbons. Thus, fuels have appeared on the market consisting of a mixture generally containing at least 5% by weight of water and of hydrocarbons, maintained in emulsion through the use of particular compositions of surfactant additives (or systems emulsifiers). Compared with a traditional fuel consisting exclusively of hydrocarbons, these fuels make it possible, during combustion in a diesel engine, to reduce emissions of polluting compounds such as in particular nitrogen oxides, carbon monoxide, particles solids and unburnt hydrocarbons.

Thus, patent EP 630,398 describes an emulsified fuel based on hydrocarbon fuel and water, the emulsifying system of which consists of a combination of three additives: sorbitan oleate (preferably sorbitan sesquioleate), polyalkylene - glycol (preferably polyethylene glycol) and alkylphenol ethoxylate (preferably nonyl phenol ethoxylate).

Patent EP 888,421 describes a fuel based on an emulsion of water in at least one hydrocarbon, and comprising an emulsifying system comprising at least one sorbitol ester (preferably chosen from sorbitan oleates), at least one ester of fatty acid preferably chosen from oleates and / or stearates and / or ricinoleates of polyethylene glycol, and at least one alkylphenol-polyalkoxylated preferably chosen from nonylphenols and / or polyethoxylated octylphenols.

Application WO 01/48123 proposes to improve the thermal stability of such emulsified fuels, in order to allow the storage and the use of the fuel over a wide temperature range, going from -10 ° C. to 70 ° C. This improvement is obtained by the use of an emulsifying system comprising at least one sorbitol ester (preferably sorbitan sesquioleate), at least one polyalkoxylated fatty acid ester (preferably chosen from oleates, stearates and polyethylene glycol ricinoleates), and at least one compound polyalkoxylated branched hydrocarbon preferably chosen from iso, di and trialkylated alcohols, preferably isotridecyclic alcohols comprising from 3 to 10 ethoxylated groups.

US Patent 6,371,998 describes a liquid hydrocarbon fuel in which lipid vesicles containing water have been incorporated. These lipid vesicles consist for example of 4% by weight of polyoxyethylene-10-alcohol stearate, 7.2% by weight of glycerol distearate, 5% by weight of soy methyl ester, 5% by weight of sesquioleate sorbitan and 78.8% by weight of water.

Finally, patent application WO 01/51593 recommends, to improve the thermal stability over a wide temperature range (-20 to +50 ° C) of a fuel based on an emulsion of water and liquid hydrocarbons, to employ a polymeric emulsifier capable of being obtained by reaction between an oligomer of functionalized polyolefin and a polyoxyalkylene. This application also describes, by way of comparison, emulsifying systems consisting of 87% by weight of sorbitan monooleate, 3% by weight of sorbitan trioleate, and 10% by weight of castor oil ethoxylated with 10 moles of oxide d 'ethylene. However, the emulsified fuels described in the prior art prove to have insufficient stability at high temperature. Indeed, the aqueous and hydrocarbon phases tend to separate quickly when the fuel is kept for several hours at high temperatures, above 60 ° C. This makes in particular the use of these emulsified fuels incompatible with new engine technologies, such as for example diesel engines equipped with direct injection pump systems. In these injection systems, the fuel is subjected to temperatures generally higher than 70 ° C. and, when the engine is stopped, the emulsion which remains stored in the supply system tends to phase out, in particular at level of the injector pump. This phenomenon generates many problems, including significant difficulties in restarting the vehicle. To solve this problem, the present invention aims to provide an emulsified fuel based on hydrocarbons and water, which has improved high temperature stability compared to the emulsified fuels known in the prior art, without degradation of the other properties.

Indeed, the Applicant has discovered that the stability at high temperature of such emulsions could be improved significantly by using a particular emulsifier system, comprising at least two surfactant additives.

To this end, the present invention relates to an emulsified fuel containing a major proportion (typically at least 80%, advantageously at least 90%, more particularly at least 95% by weight) of an emulsion of water and liquid hydrocarbons with a water / hydrocarbon weight ratio ranging from 5/95 to 35 / 65. This fuel is characterized in that it contains an emulsifying system comprising at least 15% by weight of a fatty acid ester of polyol (poly ) oxyalkylated, and at least one constituent from the group formed by fatty acid esters of sorbitan and the condensation products of an acid or of a succinic anhydride with at least one amino, a polyamine, a fatty acid, a (poly) oxyalkylated fatty acid, an alcohol, a (poly) oxyalkylated alcohol and mixtures of these compounds.

Compared with known emulsified fuels, the fuel according to the present invention has excellent thermal stability, allowing its storage and use both at cold or ambient temperature and at high temperatures, of the order of

75 ° C. This notably makes its use perfectly compatible with new engine technologies such as direct injection.

So that the emulsified fuel according to the invention is stable over time, including at high temperature (that is to say so that the water droplets remain thinly and homogeneously dispersed in the hydrocarbon phase, and avoid their coalescence eventually leading to the separation of the aqueous phase and the organic phase), it contains an emulsifying system comprising at least two compounds, either at least the two types of esters, or a fatty acid and polyol ester (poly ) alkoxylated and a condensation product of a succinic acid or anhydride with at least one amine, a polyamine, a fatty acid, a (poly) oxyalkylated fatty acid, an alcohol, a (poly) oxyalkylated alcohol.

The fatty acid ester of sorbitan, hereinafter called the sorbitan ester, consists of a fatty acid ester of sorbitan or a mixture of such esters. The term sorbitan, well known to those skilled in the art, designates a cyclic tetraol which is an anhydride of sorbitol and can be obtained by dehydration of the latter. By tetraol is meant a polyol comprising 4 hydroxyl groups. Sorbitan is generally present in chemical equilibrium with Sorbitol.

Said sorbitan ester may comprise one or more monoesters, one or more polyesters, or a mixture of monoesters and polyesters. It can be obtained for example by esterification of one or more fatty acids and sorbitan. The fatty acids involved in the composition of the sorbitan ester, which can be linear or branched, saturated or unsaturated, advantageously comprise from 6 to 22 carbon atoms, and preferably from 12 to 18 carbon atoms. For example, and without limitation, said fatty acids can be chosen from lauric, palmitic, stearic, oleic, linoleic, linolenic acids, and their mixtures. Preferably, said sorbitan ester comprises at least one sorbitan oleate. Examples of suitable sorbitan oleates are sorbitan monooleate, sorbitan dioleate, sorbitan trioleate, sorbitan tetraoleate, sorbitan sesquioletate. In a particularly preferred manner, said sorbitan ester comprises at least one ester chosen from sorbitan monooleate and sorbitan sesquioletate. The fatty acid ester of (poly) alkoxylated polyol, hereinafter designated polyol ester, can comprise monoesters, polyesters or a mixture of monoesters and polyesters. In the case of polyesters, the fatty acids entering into the composition of each of the ester molecules can be identical or different. Likewise, they can be different from one ester molecule to another so that we are in the case of the mixture of polyesters.

By polyol is meant the alcohols comprising from 2 to 5 hydroxyl groups, preferably the alkylene glycols, glycerol, pentaerythritol, their alkyl derivatives and their mixtures.

The fatty acids involved in the composition of said polyol ester can be linear or branched, saturated or unsaturated, and advantageously comprise from 6 to 22 carbon atoms, and preferably from 12 to 18 carbon atoms. Preferably, they are chosen from the fatty acids naturally present, in free or esterified form, in vegetable and or animal oils, such as, for example, and without limitation, lauric, palmitic, stearic, oleic, linoleic, linolenic acids , and mixtures thereof.

The polyoxyalkylated groups present in the polyol ester are a chain of identical or different oxyalkyl units, each oxyalkyl unit advantageously comprising from 1 to 5 carbon atoms, preferably from 1 to 4 carbon atoms. Preferably, the polyoxyalkylated groups comprise ethoxy units. Preferably, the polyoxyalkylated groups comprise at least one polyethoxy group.

The average number of moles of oxyalkyl units per mole of ester (or number of oxyalkylation) is advantageously between 3 and 50, and preferably between 10 and 35, in particular when the polyol is glycerol. Preferably, the polyol ester consists in whole or in part of a triester of fatty acid (s) and of polyoxylakylated glycerol or of a mixture of such triester. More preferably, it consists in whole or in part of a triester of fatty acid (s) and of polyethoxylated glycerol or of a mixture of such triesters.

Said polyol ester can be obtained for example by polyoxyalkylation of an ester or of a mixture of fatty acid esters and of the polyol or alternatively by esterification of one or more fatty acids and of one or more polyoxyalkylated derivatives of polyol.

Said polyol ester is advantageously obtained by oxyakylation of vegetable and / or animal oil. Thus, according to a preferred embodiment, the polyol ester consists in whole or in part of vegetable oil and / or animal oxyalkylated. Such a product comprises triesters of fatty acids and polyoxyalkylated polyol (preferably glycerol), generally in admixture with monoesters and / or diesters of fatty acids and polyol (preferably glycerol) (poly) oxyalkylated. Said oil may if necessary have undergone a purification treatment, before and / or after its oxyalkylation. Examples of suitable vegetable oils are rapeseed, soybean, castor, sunflower, palm, oils extracted from resinous trees and mixtures of such oils. As suitable animal oil, let us mention purified fats ("yellow grease"), tallow, poultry fats.

According to a particularly preferred embodiment, the polyol ester consists in whole or in part of ethoxylated vegetable oil. According to another preferred embodiment, the polyol ester is a polyalkoxylated alkylene glycol diester and more particularly the polyethoxylated ethylene glycol dioleate, in particular of molecular weight between 200 and 1000.

Said polyol ester is advantageously present in the emulsified fuel according to the invention at a content ranging from 0.5 and 5% by weight, preferably from 0.5 to 2% by weight.

In a first embodiment of the invention, the emulsifying system comprises from 15 to 100% by weight of at least one polyol ester, and at least one constituent of the group formed by the sorbitan ester and the condensation products d 'a succinic acid or anhydride with at least one amino, a polyamine, a fatty acid, a (poly) oxyalkylated fatty acid, an alcohol, a (poly) oxyalkylated alcohol and mixtures of these compounds.

More particularly, the emulsifying system according to the invention contains from 15 to 100% by weight of at least one sorbitan ester in combination with at least one polyol ester. according to a sorbitan ester / polyol ester weight ratio which varies from 20/80 to 80/20 inclusive, preferably from 40/60 to 60/40 inclusive. Even more preferably, the quantities by weight of each of the two types of esters are substantially equal (45/55 to 55/45).

The sorbitan ester is advantageously present in the emulsified fuel according to the invention at a content ranging from 0.5 and 5% by weight, preferably from 0.5 to 2% by weight.

According to a particularly advantageous embodiment, the emulsifying system used in the composition of the emulsified fuel according to the invention also comprises, in addition to the two types of esters, at least one alcohol comprising from 3 to 22 carbon atoms, and preferably from 6 to 12 carbon atoms. This alcohol, which is advantageously a monoalcohol, can be linear or branched, saturated or unsaturated. It preferably comprises at least one branched saturated alcohol. Examples of particularly suitable alcohols include ethyl hexanols (e.g. 2-ethyl hexanol), isopropanol, tert-butanol, isopentanol, isotridecanol, fatty alcohols ( ie comprising from 12 to 22 carbon atoms).

The emulsified fuel according to the invention then advantageously comprises from 0.1 to 5% by weight of said alcohol, preferably from 0.3 to 2%, even more preferably from 0.5 to 1% by weight. The presence of such an alcohol in the emulsifying system of the fuel according to the invention has various advantages. On the one hand, this alcohol plays the role of co-surfactant with respect to said first and second esters, that is to say that it facilitates and reinforces the emulsifying power of these. In addition, it makes it possible to improve the homogeneity in size of the water droplets: the latter are of a more uniform size (more monodisperse distribution) and smaller. This avoids the presence of large droplets, which has the immediate effect of improving the resistance of the fuel to sedimentation (phenomenon of regrouping towards the lower part of the fuel of the water droplets, which is all the faster that the proportion of large droplets is important). According to another embodiment which is also particularly advantageous, the emulsifying system used in the composition of the emulsified fuel according to the invention also comprises from 0 to 85% by weight of at least one compound which is the condensation product of an acid or a succinic anhydride with at least one amino, a polyamine, a fatty acid, a (poly) oxyalkylated fatty acid, an alcohol, a (poly) oxyalkylated alcohol and mixtures of these compounds, hereinafter called condensation product. Preferably, the condensation product of at least one succinic anhydride is used with at least one polyamine.

The succinic acid or anhydride is advantageously substituted by a hydrocarbon radical which is preferably a polymeric radical, for example a polyisobutyl radical.

The presence of such a compound in the emulsifying system of the fuel according to the invention has various advantages. On the one hand, it improves the homogeneity in size of the water droplets. On the other hand, it promotes the compatibility of the emulsified fuel according to the invention with conventional fuels made up entirely of hydrocarbons, so that these two types of fuel are interchangeable. Thus it becomes possible, in a vehicle usually operating with conventional hydrocarbon fuel, to fill the fuel tank with the emulsified fuel according to the invention without having to purge the fuel distribution system, and vice versa. In another preferred form of the invention, the emulsifier system contains from 15 to

85% by weight of at least one polyol ester and 85 to 15% of at least one condensation product. This combination makes it possible to significantly increase the excellent thermal stability of the emulsion containing esters, during its storage and its use both at low temperature and at room temperature and finally at high temperatures, of the order 75 ° C. The preferred emulsifier system in this form of the invention contains 20 to 50% by weight of at least one polyol ester and 50 to 80% of at least one condensation product.

It would not go beyond the scope of the invention, if at least one alcohol of the type described above, that is to say a monoalcohol, to this emulsifying system, could be linear or branched, saturated or unsaturated , comprising from 3 to 22 carbon atoms, and preferably from 6 to 12 carbon atoms.

In addition to the emulsifying agents described above, the emulsified fuel according to the invention can comprise many other emulsifying agents. Those skilled in the art will perfectly know how to perfect the formula of the emulsifier system according to the invention by adding other known emulsifiers, ionic or nonionic, synthetic or of natural origin such as, for example, but not limited to compounds chosen from acids. fatty acids, fatty acid derivatives, fatty alcohols, ethoxylated fatty amines, polyol esters, functionalized polymers and their mixtures. The hydrocarbon phase of the emulsified fuel according to the invention can consist of any mixture of hydrocarbons. It is possible to use for this purpose cuts of hydrocarbons and mixtures of cuts of origin and of very diverse nature. This choice is essentially dictated by the use for which the fuel is intended, by the availability of the various cuts of hydrocarbons, and by economic considerations (cost of fuel).

When the fuel is intended for use as fuel for thermal engines, the hydrocarbon phase advantageously comprises one or more hydrocarbon fractions entering into the composition of traditional fuels, and which can in particular be chosen from petrol fractions (distillation interval generally included in the range 25 to 200 ° C), middle distillates such as for example kerosene cuts (distillation range generally included in the range 160 to 240 ° C) and diesel cuts (distillation range generally included in the range 160 to 400 ° C), biofuels, and mixtures of such cuts. These cuts can come from petroleum refining, agriculture (case of biofuels), or be synthetic hydrocarbons (for example obtained by oligomerization of light olefins, or by Fischer-Tropsch synthesis from light hydrocarbons).

By biofuel is meant light alcohols (such as, for example, ethanol), oils of plant and / or animal origin and esters of such oils. The hydrocarbon phase of the fuel according to the invention can thus advantageously contain from 0.1 to 60% by weight, and preferably from 0.5 to 50% by weight of biofuel. The preferred biofuels are esters of alcohols containing from 1 to 4 carbon atoms and fatty acids or mixtures of fatty acids containing from 16 to 22 carbon atoms. The particularly preferred biofuels are the methyl esters of vegetable oils such as, for example, but not limited to, soybean, rapeseed, sunflower, olive and palm oils.

When the fuel is intended for other uses, the hydrocarbon phase may include one or more of the cuts mentioned above for fuels, and / or possibly other cuts chosen from distillates under intermediate vacuum

(distillation range generally included in the range 350 to 450 ° C), heavy vacuum distillates (distillation range generally included in the range 400 to 550 ° C), or even distillation residues, and generally among all cuts traditionally used in fuels such as for example FOD (Fuel Oil)

Domestic), fuel oils, fuel oils, heating oils and mixtures of such cuts.

In the present description, all the distillation intervals are cited with reference to standard ASTM D 86 (distillation of petroleum products).

The fuel according to the invention is in the form of an emulsion of fine droplets of aqueous phase regularly dispersed in the hydrocarbon phase. Advantageously, the average diameter of the droplets of aqueous phase is less than or equal to 5 μm, preferably 3 μm, even more preferably 1 μm. Preferably, the particle size profile of the drop sizes is of the monodisperse type around a value of approximately 0.5 μm. The above values of average droplet size correspond to measurements carried out by the technique of laser granulometry. The emulsified fuel according to the present invention can advantageously contain one or more biocidal agents, preferably in its aqueous phase. This biocidal agent is preferably a bactericide and / or a fungicide. As nonlimiting examples of biocidal agents, mention may be made of isothiazolones and their chlorinated derivatives, benzalkonium chlorides, organic peroxides, isothiocyanates, thiocyanates, ammonium salts, amine salts, oxazolidines.

The emulsified fuel can also include at least one anti-freeze agent. As anti-freeze agents, it is possible to use, for example, alcohols, glycols, glycol or alcohol derivatives, saline solutions.

It can also contain at least one anti-soot agent. As an example of such agents, let us cite the additives constituted by one or more metallic or alkaline-earth catalysts capable of promoting the post-combustion reactions of the soot. The preferred catalysts are based on magnesium, calcium, barium, cerium, copper, iron or their mixtures. These catalytic soot destruction promoters are all the easier to introduce into the emulsion as they are generally compounds whose salts are soluble in water, therefore in the aqueous phase of the emulsions according to the invention.

When the fuel is intended for use as fuel for heat engines, its sulfur content, determined according to standard NF M 07-100, is preferably less than or equal to 350 ppm, preferably less than or equal to 50 ppm, and again more preferably less than or equal to 10 ppm. When the fuel is intended for use as fuel for thermal machines, its sulfur content, determined according to standard NF M 07-100, is preferably less than or equal to 1% by weight, preferably less than or equal to 0.2 % by weight, and even more preferably less than or equal to 0.1% by weight.

Whatever its use, the content of polycyclic aromatic hydrocarbons in the fuel according to the invention, determined according to standard IP 391, is preferably less than or equal to 11% by weight, more preferably less than or equal to 6% by weight.

Furthermore, for use as a fuel, the emulsified fuel according to the invention preferably contains one or more other additives, which can be any additive usually used in fuels, including for example, but not limited to: - one or more procetane additives , such as for example inorganic or organic nitrates, for example ammonium nitrate, alkyl nitrates in which the alkyl radical, linear or branched, saturated or unsaturated (preferably branched and saturated) contains from 3 to 20 and preferably from 5 to 15 carbon atoms (in particular 2-ethylhexyl nitrate), organic peroxides and in particular aryl peroxides in which the aryl group is a benzyl group or a substituted benzyl group (for example benzoyl peroxide), or the alkyl peroxides in which the alkyl radical, linear or branched, saturated or unsaturated (preferably branched and saturated) contains from 2 to 20 and preferably from 2 to 15 carbon atoms (for example tert-butyl peroxide);

one or more filterability additives such as, for example, ethylene / vinyl acetate (EN A), ethylene / vinyl propionate (ENP), ethylene / vinyl ethanoate (EVE), ethylene / methyl methacrylate (EMMA) copolymers, ethylene / alkyl fumarate;

- one or more anti-foam additives, such as for example polysiloxanes, oxyalkylated polysiloxabes, fatty acid amides;

one or more detergent and / or anti-corrosion additives, such as, for example, amines, succinimides, alkenyl succinimides, polyalkylamines, polyalkyl polyamines and polyetheramines;

- one or more lubricating or anti-wear additives, such as for example fatty acids and their ester or amide derivatives, mono- and polycyclic carboxylic acids and their ester or amide derivatives;

- one or more cloud point additives, such as for example long chain olefin terpolymers / (meth) acrylic ester / maleimide, esters of fumaric or maleic acid esters. one or more anti-sedimentation additives, such as, for example, (meth) acrylic acid / alkyl (meth) acrylate copolymers amidified with a polyamine, polyamine alkenyl succinimides, derivatives of phthalamic acid and fatty amine to double chain;

one or more polyfunctional additives for cold operability, such as for example polymers based on olefin and alkenyl nitrate.

The invention also relates to a process for preparing an emulsified fuel as described above, by emulsifying hydrocarbons and water, in the presence of the emulsifying system and all or part of any other additives. One can use for this purpose all the conventional ways of preparing emulsions. It is advantageous to proceed by mixing all or part of the additives with one and / or the other of the phases, prior to emulsification. For example, it is possible to proceed in the manner described in patent application WO 00/34419, by mixing the emulsifying system with the hydrocarbon phase, then passing the resulting mixture one or more times through an emulsifying system supplied with water. necessary for the formation of the emulsion. It is also advantageous to proceed in the manner described in patent applications WO00 / 034419 and WO 01/36569, by:

(al) premixing of the water and the emulsifying system, followed by dispersion in the hydrocarbon phase, or (a2) simultaneous mixing of the hydrocarbon phase with water and the emulsifying agent, then

(b) emulsification proper by means of an appropriate device, chosen for example from rotor-stators, foam concentrates, static mixers, in-line turbine systems, ultrasonic agitators.

The emulsified fuel according to the present invention can be used in various applications. It can in particular be used as fuel for thermal engines

(notably petrol or diesel), or for fuel cells. Its use as a fuel for diesel engines is particularly advantageous, in particular for new diesel engines fitted with direct injection systems.

The fuel according to the invention can also be used as fuel for thermal machines such as for example industrial or domestic boilers, ovens, turbines, generators. A particularly advantageous use is that as FOD (or Domestic Fuel Oil), that is to say as fuel for domestic boilers.

The invention also relates to an emulsifying additive composition which can be used, for example, in water / hydrocarbon emulsified fuels in order to improve its stability at high temperature. This additive composition comprises 15% by weight of at least one fatty acid ester of (poly) oxyalkylated polyol, and at least one constituent of the group formed by the fatty acid esters of sorbitan and the condensation products a succinic acid or anhydride with at least one amino, a polyamine, a fatty acid, a (poly) oxyalkylated fatty acid, an alcohol, a (poly) oxyalkylated alcohol,

This additive composition preferably contains from 15 to 100% by weight of at least one glycerol ester, and at least one constituent of the group formed by the sorbitan ester and the condensation products of an acid or of a succinic anhydride with at least one amino, a polyamine, a fatty acid, a (poly) oxyalkylated fatty acid, an alcohol, an alcohol

(poly) oxyalkylated and mixtures of these compounds.

Preferably, it contains from 15 to 100% by weight of at least one sorbitan ester in combination with at least the polyol ester as described above, in a weight ratio of sorbitan ester / polyol ester varying from 20/80 to 80/20

Preferably, the weight ratio of sorbitan ester to polyol ester varies from 40/60 to 60/40 inclusive. Even more preferably, the quantities by weight of each of the two types of esters are substantially equal (45/55 to 55/45).

Furthermore, advantageously the composition of emulsifying additives according to the invention also comprises at least one alcohol comprising from 3 to 22 carbon atoms, and preferably from 6 to 12 carbon atoms. This alcohol, which is preferably a monoalcohol, can be linear or branched, saturated or unsaturated. It preferably comprises at least one branched saturated alcohol. The alcohol / polyol ester and alcohol / sorbitan ester weight ratios are identical or different, and advantageously both less than or equal to 1. Preferably, each of these ratios is between 0.2 and 1.

The composition of emulsifying additives according to the invention can moreover comprise from 0 to 85% by weight of at least one compound which is the product of condensation of a succinic acid or anhydride with at least one amine, a polyamine, a fatty acid, a (poly) oxyalkylated fatty acid, an alcohol, a (poly) oxyalkylated alcohol and mixtures of these compounds. Preferably, the condensation product of at least one succinic anhydride is used with at least one polyamine. The succinic acid or anhydride is advantageously substituted by a hydrocarbon radical which is preferably a polymeric radical, for example a polyisobutyl radical.

Preferably, this additive composition will comprise from 15 to 85% by weight of at least one polyol ester and from 85 to 15% of at least one condensation product. More preferably, it will comprise from 20 to 50% by weight of at least one polyol ester and from 50 to 80% of at least one condensation product. This additive composition can also comprise an alcohol as described above.

The composition of additives according to the invention may also comprise one or more of the additives or agents as described above as capable of being incorporated into the emulsified fuel according to the invention, such as for example, but not limited to, one or more several other emulsifying agents, one or more biocidal agents, one or more anti-freeze agents, one or more anti-soot agents, one or more procetane additives, one or more filterability additives, one or more anti-foam additives, one or more several detergent and / or anti-corrosion additives, one or several lubricity or anti-wear additives, one or several cloud point additives, one or several anti-sedimentation additives, one or several polyfunctional cold operability additives . Preferably, the additive composition comprises at least one procetane additive chosen from inorganic or organic nitrates (for example alkyl nitrates), organic peroxides and mixtures of these two types of compounds.

Thus, a particularly preferred additive composition comprises at least four types of additives: at least a first ester, at least a second ester, at least one alcohol and / or a condensation product and at least one procetane additive, each of these additives being as described above.

According to a first embodiment, the additive composition is in the form of a mixture of the additives described above. According to a second embodiment, the composition of additives is in the form of a "mother solution", that is to say a concentrated solution of said additives in a suitable solvent. This solution is prepared by dissolving the emulsifying additives and any other additives and / or agents in the solvent. This solvent can be chosen from aromatic solvents (and in particular solvents based on aromatic or naphtheno-aromatic hydrocarbons, such as for example but not limited to toluene, xylenes, diisopropylbenzene or an oil cut rich in aromatic hydrocarbons), petroleum cuts (in particular naphthas, essences, kerosene, distillates), mineral and / or synthetic oils. The "mother solutions" can contain, for example, from 20 to 80% by weight and preferably from 40 to 70% by weight of additives and agents.

Finally, the invention relates to a method of improving the thermal stability of a water / liquid hydrocarbon emulsified fuel, by using a composition of emulsifying additives as described above. Unless otherwise stated, the ppm are expressed by weight.

The examples below are intended to illustrate the invention, without limiting its scope. Example 1:

In the present example and those which follow, a conventional diesel fuel G is used, conforming to standard EN 590. This diesel fuel has the following characteristics: Distillation interval (ASTM standard D86): initial point: 177.5 ° C point 10% vol: 209.5 ° C point 50% vol: 270.5 ° C point 90% vol: 330.5 ° C end point: 351.7 ° C

Sulfur content (ASTM D5453 standard): 335 ppm Density at 15 ° C (NF EN ISO 12185 standard): 0.8444 kg / m ³ Aniline point (NF M 07-021 standard): 63.4 ° C Cloud point (standard NF EN 23015): -8 ° C Limit filterability (standard NF EN 116): -8 ° C

Pour point (standard NF T 60105): -15 ° C

From the diesel fuel G, the respective emulsified fuels El and E2 are prepared, by emulsifying 87.64% by weight of the said diesel with 10% by weight of water, in the presence of 1.86% by weight of an emulsifying system S and 0.5% by weight of a procetane additive (2, ethylhexyl nitrate).

The emulsified fuel El conforms to the prior art, and its emulsifier system SI consists of:

3 parts by weight of sorbitan monooleate;

2 parts by weight of fatty acid ethoxylated to 6 moles of ethylene oxide per mole of acid; 1 part by weight of isotridecanol ethoxylated at 7.5 moles of ethylene oxide per mole of alcohol.

The fuel E2 is in accordance with the invention, and its emulsifier system S2 consists of: 1 part by weight of a first ester which is sorbitan monooleate; 1 part by weight of a second ester consisting of rapeseed oil ethoxylated with 30 moles of ethylene oxide per mole of triglyceride. Test 1: The stability of the emulsified fuels El and E2 was determined at room temperature, in accordance with the stability test by centrifugation described in standard NF M 07-101. The graph presented in Figure 1 below illustrates the results obtained, in fuel sedimentation rate term (ie phase shift of the emulsion) as a function of the centrifugation time. The higher the sedimentation rate, the more unstable the emulsion. The results presented in FIG. 1 clearly illustrate the beneficial effect, in terms of stability of the emulsion at room temperature, of the emulsifier system S2 according to the invention: the fuel E2 has a stability very clearly superior to that of the fuel El of reference. Test 2: The fuels El and E2 were also subjected to a storage stability test at high temperature (75 ° C). This test was carried out as follows: 450 ml of emulsion are placed in an airtight bottle of 500 ml. This bottle is placed in an oven at 75 ° C. We then study the progressive phase shift by measuring the phase heights per 24 hour time interval. The phase shift time is reached when the phase heights no longer change over time (stationary situation).

Table 1 below indicates the results obtained, in terms of phase shift time (that is to say the time after which the aqueous and organic phases of the emulsified fuel are completely separated).

Table 1

The above results illustrate the significant gain provided by the present invention in terms of high temperature stability of the emulsified fuels: the use of the emulsifier system S2 according to the invention makes it possible to increase the phase shift time to 75 ° by 50%. vs. Thus, the emulsified fuels according to the invention have a very markedly increased storage stability at high temperature, while retaining excellent room temperature stability, superior to that of the emulsified fuels known in the prior art. Example 2:

Test 2 of Example 1 (thermal stability at 75 ° C.) was repeated, using emulsifying systems containing the same two esters as S2 (ester A s sorbitan monooleate; ester B = rapeseed oil ethoxylated at 30 moles ethylene oxide per mole of triglyceride), but by varying the respective proportions of the two esters.

The emulsified fuels were prepared by emulsifying 87.64% by weight of the gas oil G of Example 1 with 10% by weight of water, in the presence of 1.86% by weight of the emulsifying system S and of 0.5% by weight of a procetane additive (2 nitrate, ethylhexyl).

Table 2 below presents the results obtained.

Table 2

The above results illustrate the importance of the respective proportions of the two esters in the emulsified fuels and the emulsifying additive compositions according to the invention. With the emulsifier systems S2 and S3 in accordance with the invention, for which the weight ratios of first ester / second ester are between 20/80 and 80/20, the thermal stability at 75 ° C. is very much greater than that obtained with the S4 system. The best results are obtained with the S2 system, in which the weight contents of the two esters are equal. Example 3:

Test 2 of Example 1 (thermal stability at 75 ° C.) was repeated, using emulsifying systems in accordance with the invention, containing the following two esters: ester A ': sorbitan sesquioleate; ester B ': rapeseed oil ethoxylated with 10 moles of ethylene oxide per mole of triglyceride.

The emulsified fuels were prepared by emulsifying 86% by weight of the gas oil G of Example 1 with 11.70% by weight of osmosis water, in the presence of 2% by weight of the emulsifying system S and 0.3% by weight. weight of a procetane additive (2 nitrate, ethylhexyl).

Table 3 below presents the results obtained.

Table 3

Compared to the preceding examples, this example shows that it is possible, within the framework of the present invention, to vary both the chemical nature and the respective contents of the two esters, according to the results which it is desired to obtain and taking into account the products available, their costs and their compatibility with other additives which may be incorporated into the emulsified fuel. Example 4:

Emulsifier additive compositions in accordance with the invention were prepared, using the emulsifier system S2 of Example 1 (ester A = sorbitan monooleate, ester B = rapeseed oil ethoxylated with 30 moles of ethylene oxide per mole of triglyceride, 50/50), alone or as a mixture with a branched saturated alcohol which is 2, ethyl-hexanol.

Emulsified fuels in accordance with the invention were prepared from these additive compositions by emulsifying 85.4 to 86% by weight (according to the tests) of the gas oil G of Example 1 with 11.7% by weight of water, 2 to 2.6% by weight (according to the tests) of emulsifier system S and 0.3% by weight of a procetane additive (2, ethylhexyl nitrate). The precise diesel content G of the emulsified fuel is adapted, for each test, taking into account the quantity of emulsifying system S.

Three tests were carried out, during which the composition of the emulsifying system S was varied.

The stability of these fuels was determined at room temperature (25 ° C), by means of a test carried out as follows: 100 ml of emulsion are placed in a finely graduated frustoconical flask. After 24 hours of storage of the emulsion at 25 ° C., the volume content of the emulsion in the sedimented phase is determined (by direct reading on the graduated flask) (the sedimented phase consisting of large drops of aqueous phase which are are separated from the emulsion and agglomerated at the bottom of the container).

Table 4 below summarizes the results obtained:

Table 4

The above results illustrate the additional gain in stability provided by the incorporation of a branched saturated alcohol in the emulsifying additive compositions according to the invention.

In this case, the emulsifying additive compositions used in the respective fuels E8 and E9 which comprise, in addition to said first and second esters, 2, ethyl-hexanol, have better resistance to sedimentation: by adding 0.4 % by weight of alcohol, the sedimentation at 25 ° C of the emulsified fuel is reduced by 25%, and by adding 0.6% by weight of alcohol, this phenomenon of sedimentation is completely eliminated. Example 5:

Test 2 of Example 1 (thermal stability at 75 ° C.) was repeated, using emulsifying systems in accordance with the invention, containing the following two surfactants: ester B: rapeseed oil ethoxylated with 30 moles of oxide ethylene per mole of triglyceride.

Surfactant C: condensation product of a polyisobutene succinic anhydride with a tretraethylene pentamine in an amine to anhydride / amine mass ratio of 1.2.

The emulsified fuels were prepared by emulsifying 86.75% by weight of the gas oil G of Example 1 with 11.70% by weight of osmosed water, in the presence of 1.25% by weight of the emulsifying system S and of 0.3 % by weight of a procetane additive (2 nitrate, ethyl-hexyl).

Table 6 below presents the results obtained.

Table 5 Compared to the preceding examples, this example shows that it is possible, within the framework of the present invention, to vary both the chemical nature and the respective contents of the two surfactants, as a function of the results which it is desired to obtain and taking into account the products available, their costs and their compatibility with other additives which may be incorporated into the emulsified fuel. Example 6:

Test 2 of Example 1 (thermal stability at 75 ° C.) was repeated, using emulsifying systems in accordance with the invention, containing the following three tesnsioactive agents: ester A: sorbitan mono oleate; ester B: rapeseed oil ethoxylated with 30 moles of ethylene oxide per mole of triglyceride.

The emulsified fuels were prepared by emulsifying 86.75% by weight of the gas oil G of Example 1 with 11.70% by weight of osmosed water, in the presence of 1.25% by weight of the emulsifying system S and of 0.3 % by weight of a procetane additive (2 nitrate, ethyl-hexyl). Table 6 below presents the results obtained.

Table 6 Compared to the preceding examples, this example shows that it is possible, within the framework of the present invention, to vary both the chemical nature and the respective contents of the two esters, as a function of the desired results. obtain and take into account the products available, their costs and their compatibility with other additives capable of being incorporated into the emulsified fuel. Example 7:

Emulsifier additive compositions in accordance with the invention were prepared, using either the S8 emulsifier system of Example 5 (ester A = sorbitan monooleate, ester B = rapeseed oil ethoxylated with 30 moles of oxide of ethylene per mole of triglyceride,) as a mixture with a branched saturated alcohol which is 2, ethyl-hexanol. ; either the emulsifying system S10 of Example 6 (ester A = sorbitan monooleate, ester B = rapeseed oil ethoxylated with 30 moles of ethylene oxide per mole of triglyceride, surfactant C = condensation product of a polyisobutene succinic anhydride with a tetraethylenepentamine in an amine to anhydride mass ratio of 1.2.) as a mixture with a branched saturated alcohol which is 2, ethyl-hexanol.

Emulsified fuels in accordance with the invention were prepared from these additive compositions by emulsifying 85.4 to 86% by weight (according to the tests) of the gas oil G of Example 1 with 11.7% by weight of water, 2.5% by weight (according to the tests) of emulsifier system S and 0.3% by weight of a procetane additive (2 nitrate, ethyl-hexyl). The precise diesel content G of the emulsified fuel is adapted, for each test, taking into account the quantity of emulsifying system S.

Four tests were carried out, during which the composition of the emulsifying system S was varied.

The stability of these fuels was determined at room temperature (25 ° C), by means of a test carried out as follows: 100 ml of emulsion are placed in a finely graduated frustoconical flask. After 24 hours of storage of the emulsion at 25 ° C., the volume content of the emulsion in the sedimented phase is determined (by direct reading on the graduated flask) (the sedimented phase consisting of large drops of aqueous phase which are are separated from the emulsion and agglomerated at the bottom of the container). Table 7 below summarizes the results obtained:

TABLE 7

In this case, the respective emulsifying systems S 12 and S13 comprise, in addition to said prime; second esters and third surfactant, 2, ethyl-hexanol, have better resistance to sedimentation: by adding 28.5% by weight of alcohol, the phenomenon of sedimentation is completely eliminated. Example 8:

Test 2 of Example 1 (thermal stability at 75 ° C.) was repeated, using emulsifying systems in accordance with the invention, containing the following two surfactants: ester B ": polyethylene glycol 400 dioleate or polyalkoxylated ethylene glycol 400.

Surfactant C condensation product of a succinic acid or anhydride with a polyamine.

Table 8 below presents the results obtained.

TABLE 8

Compared to the preceding examples, this example shows that it is possible, within the framework of the present invention, to vary both the chemical nature and the respective contents of the two surfactants, as a function of the results which it is desired to obtain and taking into account the products available, their costs and their compatibility with other additives which may be incorporated into the emulsified fuel.

Claims

1. Emulsified fuel containing a major proportion of an emulsion of water and liquid hydrocarbons with a water / hydrocarbon weight ratio ranging from 5/95 to 35/65, characterized in that it contains an emulsifying system comprising at least at least 15% by weight of a fatty acid ester of polyoxyalkylated polyol, and of at least one constituent of the group formed by esters of fatty acid and sorbitan and the condensation products of an acid or of a succinic anhydride with at least one amino, a polyamine, a fatty acid, a (poly) oxyalkylated fatty acid, an alcohol, a (poly) oxyalkylated alcohol and mixtures of these compounds.

2. Fuel according to claim 1, characterized in that the fatty acids involved in the composition of sorbitan esters are linear or branched, saturated or unsaturated, and contain from 6 to 22 carbon atoms.

3. Fuel according to claim 2, characterized in that said fatty acids are chosen from lauric, palmitic, stearic, oleic, linoleic, linolenic acids, and their mixtures.

4. Fuel according to any one of the preceding claims, characterized in that the said sorbitan esters comprise at least one sorbitan oleate.

5. Fuel according to claim 4, characterized in that said esters comprise at least one ester chosen from sorbitan monooleate and sorbitan sesquioletate.

6. Fuel according to any one of the preceding claims, characterized in that the polyols of the polyol ester correspond to the alcohols comprising from 2 to 5 hydroxyl groups, preferably to the compounds of the group formed by alkylene glycols, glycerol, pentaerythritol, their alkyl derivatives and their mixtures.

7. Fuel according to any one of the preceding claims, characterized in that the fatty acids involved in the composition of the polyol ester are linear or branched, saturated or unsaturated, and contain from 6 to 22 carbon atoms.

8. Fuel according to any one of the preceding claims, characterized in that the fatty acids involved in the composition of the polyol ester r are chosen from the fatty acids naturally present, in free or esterified form, in vegetable and / or animal oils.

9. Fuel according to any one of the preceding claims, characterized in that the polyoxyalkylated groups present in the polyol ester are a chain of identical or different oxyalkyl units, each oxyalkyl unit comprising from 1 to 5 carbon atoms.

10. Fuel according to any one of the preceding claims, characterized in that the polyoxyalkylated groups present in the polyol ester comprise at least one polyethoxy group.

11. Fuel according to any one of the preceding claims, characterized in that, for the polyol ester, the average number of moles of oxyalkyl units per mole of ester is between 3 and 50.

12. Fuel according to the preceding claim, characterized in that when the fatty acid involved in the composition of the polyol ester is glycerol, the average number of moles of oxyalkyl units per mole of ester is between 10 and 35.

13. Fuel according to any one of the preceding claims, characterized in that the polyol ester consists wholly or partly of a triester of fatty acid (s) and of polyoxylakylated glycerol or of a mixture of such triesters .

14. Fuel according to any one of the preceding claims, characterized in that the polyol ester consists in whole or in part of vegetable oil and / or animal oxyalkylated.

15. Fuel according to the preceding claim, characterized in that the polyol ester consists in whole or in part of ethoxylated vegetable oil.

16. Fuel according to the preceding claim, characterized in that the vegetable oil is chosen from rapeseed, soybean, castor oil, sunflower, palm oil, oils extracted from resinous trees and mixtures of such oils.

17. Fuel according to one of claims 1 to 11 characterized in that the polyol ester is a polyalkoxylated alkylene glycol diester and more particularly the polyethoxylated ethylene glycol dioleate, of molecular weight between 200 and 1000.

18. Fuel according to any one of the preceding claims, characterized in that the polyol ester is present at a content varying from 0.5 and 5% by weight, preferably from 0.5 to 2% by weight.

19. Fuel according to any one of the preceding claims, characterized in that the emulsifying system contains from 15 to 100% by weight of at least one polyol ester, and at least one constituent of the group formed by the ester of sorbitan and the condensation products of a succinic acid or anhydride with at least one amine, a polyamine, a fatty acid, a (poly) oxyalkylated fatty acid, an alcohol, an (ρoly) oxyalkylated alcohol and mixtures of these compounds.

20. Fuel according to any one of the preceding claims, characterized in that the emulsifying system contains from 15 to 100% by weight of at least one sorbitan ester in combination with at least one polyol ester in an ester weight ratio of sorbitan / polyol ester ranging from 20/80 to 80/20.

21. Fuel according to claim 20, characterized in that in the emulsifying system the sorbitan ester / polyrol ester weight ratio varies from 40/60 to 60/40.

22. Fuel according to any one of the preceding claims, characterized in that said at least one constituent of the group formed by fatty acid and sorbitan esters and the condensation products is present at a content varying from 0.5 and 5% by weight, preferably from 0.5 to 2% by weight

23. Fuel according to any one of the preceding claims, characterized in that the emulsifying system comprises from 0 to 85% by weight of at least one condensation product of a succinic acid or anhydride with at least one amine , a polyamine, a fatty acid, a (poly) oxyalkylated fatty acid, an alcohol, a (poly) oxyalkylated alcohol and mixtures of these compounds.

24. Fuel according to any one of the preceding claims, characterized in that the emulsifying system contains from 15 to 85% by weight of at least one polyol ester and from 85 to 15% of at least one condensation product.

25. Fuel according to any one of the preceding claims, characterized in that the succinic acid or anhydride of the condensation product is substituted by a hydrocarbon radical which is preferably a polymeric radical, in particular a polyisobutyl radical.

26. Fuel according to any one of the preceding claims, characterized in that the emulsifying system contains from 20 to 50% by weight of at least one polyol ester and from 50 to 80% of at least one condensation product.

27. Fuel according to any one of the preceding claims, characterized in that the emulsifying system also comprises, at least one alcohol comprising from 3 to 22 carbon atoms.

28. Fuel according to the preceding claim, characterized in that the alcohol comprises at least one branched saturated alcohol.

29. Fuel according to claims 27 or 28, characterized in that the alcohol / polyol ester and alcohol / sorbitan ester weight ratios are identical or different and are both less than or equal to 1.

30. Fuel according to any one of claims 27 to 29, characterized in that it comprises from 0.1 to 5% by weight of said alcohol.

31. Fuel according to any one of the preceding claims, characterized in that the hydrocarbon phase comprises one or more hydrocarbon cuts chosen from petrol cuts, middle distillates such as for example kerosene cuts and diesel cuts, biofuels , and mixtures of such cuts.

32. Fuel according to any one of claims 1 to 30, characterized in that the hydrocarbon phase comprises one or more cuts chosen from intermediate vacuum distillates, heavy vacuum distillates, distillation residues and mixtures of such cuts .

33. Fuel according to any one of the preceding claims, characterized in that its sulfur content, determined according to standard NF M 07-100, is less than or equal to 1% by weight, preferably less than or equal to 0.2 % by weight, and even more preferably less than or equal to 0.1% by weight, very advantageously less than or equal to 10 ppm.

34. Fuel according to any one of the preceding claims, characterized in that it also comprises at least one procetane additive, in particular chosen from organic or inorganic nitrates, organic peroxides and mixtures of these two types of compounds.

35. Process for the preparation of an emulsified fuel according to any one of the preceding claims, by emulsification of hydrocarbons and water, in the presence of the emulsifying system and of all or part of any other additives.

36. The method of claim 35, by mixing the emulsifier system with the hydrocarbon phase, then passing the resulting mixture one or more times through an emulsifier system supplied with water necessary for the formation of the emulsion.

37. The method of claim 35, comprising the following steps: (a1) premixing the water and the emulsifying system, followed by dispersion in the hydrocarbon phase, or

(a2) simultaneous mixing of the hydrocarbon phase with water and the emulsifying agent, then

38. Composition of emulsifying additives comprising 15% by weight of at least one fatty acid ester of (poly) oxyalkylated polyol, and of at least one constituent of the group formed by the fatty acid esters of sorbitan and the condensation products of a succinic acid or anhydride with at least one amino, a polyamine, a fatty acid, a (poly) oxyalkylated fatty acid, an alcohol, a (poly) oxyalkylated alcohol, as defined in l any of claims 1 to 17, 19 to 21 and 23 to 26.

39. Additive composition according to the preceding claim, characterized in that it also comprises at least one alcohol comprising from 3 to 22 carbon atoms.

40. Additive composition according to the preceding claim, characterized in that the alcohol comprises at least one branched saturated alcohol.

41. Composition of additives according to claims 39 or 40, characterized in that the alcohol / polyol ester and alcohol / sorbitan ester weight ratios are identical or different and are both less than or equal to 1.

42. Composition of additives according to any one of claims 38 to 41, comprising at least one procetane additive chosen from organic or inorganic nitrates, organic peroxides and mixtures of these two types of compounds.

43. Additive composition according to any one of claims 38 to 42, which is in the form of a mixture of the additives, or in the form of a concentrated solution of the said additives in a suitable solvent.

44. Method for improving the thermal stability of a water / liquid hydrocarbon emulsified fuel, by using a composition of emulsifying additives according to any one of claims 38 to 43.

45. Use of an emulsified fuel according to any one of claims 1 to 34 as fuel for thermal engines or fuel cells, or as fuel for thermal machines such as for example industrial or domestic boilers, ovens, turbines, generators.

46. Use of an emulsified fuel according to any one of claims 1 to 34 as fuel for diesel engine or as fuel for domestic boilers.