Use of an aqueous composition for lubricating the internal parts of a hydrogen or ammonia engine

Abstract

The present invention relates to the use, for lubricating a drive system comprising an internal combustion engine supplied with a non-hydrocarbon fuel selected from hydrogen and / or ammonia, of a composition comprising water, one or more antifreeze agents selected from glycols, aliphatic monoethers of said glycols and polyhydric aliphatic alcohols, and one or more polyalkylene glycols having a weight-average molar mass of greater than or equal to 200 g.mol-1, this composition not containing any ascorbic acid ester or gallic acid ester or phosphorus compound. The invention also relates to a method for lubricating moving components in a drive system including an internal combustion engine supplied with at least one non-hydrocarbon fuel selected from hydrogen and ammonia, comprising a step of bringing at least said components into contact with such a composition.

Description

[0001] DESCRIPTION

[0002] TITLE: Use of an aqueous composition for lubricating the internal parts of a hydrogen or ammonia engine

[0003] The present invention relates to the use of a particular aqueous lubricating composition for lubricating a powertrain system comprising an internal combustion engine powered by a non-hydrocarbon fuel chosen from hydrogen and / or ammonia.

[0004] The present invention also relates to a method for lubricating an internal combustion engine powered by at least one non-hydrocarbon fuel chosen from hydrogen and ammonia, comprising a step of bringing at least one internal part of the engine into contact with a composition, as described below.

[0005] STATE OF THE PRIOR ART

[0006] In order to reduce greenhouse gas emissions generated by the combustion of hydrocarbon-based fuels, the international community is studying the use of alternative fuels with low carbon dioxide emissions. In this perspective, hydrogen and ammonia are considered promising solutions, particularly for the transport sectors (especially maritime transport) and electricity generation in gas turbines.

[0007] Hydrogen and ammonia have multiple benefits, including but not limited to:

[0008] - These are fully decarbonized fuels that can be produced using different technologies, including from renewable electricity;

[0009] - Their combustion does not generate emissions of carbon dioxide CO2, sulfur gases (SOx), unburned hydrocarbons, or particles;

[0010] - They can be used in existing engines and heating systems with some adaptations. However, internal combustion engines are generally lubricated by lubricating compositions that are essentially formulated from hydrocarbon base oils and additives. Hydrocarbon base oils are derived from refining processes (for Group I to III bases according to the API classification - "American Petroleum Institute") or from synthetic chemistry such as polyalphaolefins (PAO, or Group IV base oils according to the API classification). Group V base oils represent all other sources of unconventional base oils and are generally represented by oxygenated hydrocarbons such as esters and polyglycols.

[0011] During engine operation, a combustion phenomenon occurs of part of the lubricant present on the internal parts of the engine. Even if this combustion is not desired, it is practically impossible to avoid. In the case of engines powered by hydrogen or ammonia, this partial combustion of the engine lubricant leads to emissions of carbon dioxide CO2, unburned hydrocarbons and particulates, which are precisely the emissions that we seek to avoid with the use of these alternative fuels. These unwanted emissions from the lubricant have a negative impact on the environmental balance of engines powered by hydrogen or ammonia.

[0012] It is therefore desirable to further improve the environmental impact of engines powered by hydrogen and / or ammonia, and in particular to reduce undesirable emissions including CO2, unburned hydrocarbons and particles.

[0013] Lubricant compositions formulated with more or less variable quantities of water are also known, including emulsions of water and hydrocarbon oils. These compositions are primarily intended for use in metalworking applications or as transmission fluids.

[0014] However, such compositions have not been used to date to lubricate the internal parts of combustion engines, in particular due to the risks of water evaporation under the thermal flow of combustion, which causes accelerated consumption of the lubricant incompatible with conventional oil change intervals.

[0015] Furthermore, it has generally been considered that the level of lubrication provided by these aqueous compositions could be insufficient in an engine in which the frictional constraints are extremely high, which could lead to an increased risk of breakage of the engine lubricated with such compositions.

[0016] The present invention aims to remedy the problems described above and in particular to reduce the emissions of internal combustion engines powered by hydrogen and / or ammonia.

[0017] The Applicant has now discovered that particular aqueous compositions, as defined below, make it possible to effectively lubricate the internal parts of these specific engines while significantly reducing undesirable emissions compared to the use of conventional lubricants formulated with one or more hydrocarbon bases.

[0018] The present invention thus relates to the use, for lubricating a motorization system comprising an internal combustion engine powered by at least one non-hydrocarbon fuel chosen from hydrogen and / or ammonia, of a composition comprising:

[0019] - water at a content of at least 15% by mass, relative to the total mass of the composition;

[0020] - one or more antifreeze agents chosen from glycols, aliphatic monoethers of said glycols and polyhydric aliphatic alcohols, at a total content of at least 5% by mass, relative to the total mass of the composition; and

[0021] - one or more polyalkylene glycols having a weight-average molar mass greater than or equal to 200 g. mol 1 at a total content of at least 5% by mass, relative to the total mass of the composition, it being understood that said composition does not contain:

[0022] - ascorbic acid ester, nor

[0023] - gallic acid ester, nor

[0024] - of phosphorus compound. In the remainder of the text, the term “aqueous lubricating composition” will refer to a composition used according to the invention as defined above.

[0025] The aqueous lubricating composition according to the invention makes it possible to very effectively lubricate the various moving parts in a mobile or stationary motorization system, including an internal combustion engine powered by hydrogen and / or ammonia, hereinafter referred to as a “hydrogen and / or ammonia engine”.

[0026] For the purposes of the present invention, the term "motorization system" is understood to mean a system comprising all the mechanical parts necessary for the intended mobile or stationary application and including at least one hydrogen and / or ammonia engine. The term "hydrogen and / or ammonia engine" means a combustion engine powered by a hydrogen and / or ammonia-based fuel. In particular, it may be an engine operating solely on hydrogen (hydrogen engine), an engine operating solely on ammonia (ammonia engine), an engine operating with a hydrogen, ammonia mixture or an engine operating on ammonia and diesel (dual fuel ammonia / diesel engine).

[0027] A “stationary” motorization system within the meaning of the invention is a motorization system including a stationary engine, in particular a hydrogen engine. It can find applications, for example, in electrical energy production devices.

[0028] A “mobile” motorization system is more specifically a motorization system implemented in vehicles, including light vehicles, heavy goods vehicles, so-called “off-road” mobile machines, competition vehicles, railway vehicles, or even marine vehicles.

[0029] A mobile motorization system can thus be a vehicle propulsion system.

[0030] For the purposes of the present invention, the term "propulsion system" means a system comprising the mechanical parts necessary for the propulsion of a vehicle. The propulsion system more particularly includes at least one hydrogen and / or ammonia engine.

[0031] The use of the aqueous lubricating compositions according to the invention proves to be particularly advantageous in several respects.

[0032] First of all, hydrogen and / or ammonia engines have the particularity of emitting significant quantities of water vapor during combustion which, when the engine contains a hydrocarbon-based lubricating composition, can lead to problems of emulsification of the lubricating composition, resulting in a degradation of its properties and in particular its lubricating power. The use of a composition as defined above, with an aqueous base, makes it possible to avoid this phenomenon of emulsification of the lubricant.

[0033] Furthermore, in hydrogen and / or ammonia engines lubricated by a traditional hydrocarbon-based lubricating composition, the lubricant droplets in the lubricant chamber can locally create hot spots, which can lead to premature ignition of the air / fuel mixture, and therefore to an abnormal combustion phenomenon known as pre-ignition. However, it is preferable to reduce or even eliminate this abnormal combustion phenomenon, particularly pre-ignition, because this generally results in the presence of a sharp increase in temperatures and pressures in the combustion chamber, and thus have a significant negative impact on the overall efficiency and performance of the engine, or even damage it.

[0034] Advantageously, these abnormal combustion phenomena do not occur with the use of the lubricating composition according to the invention, aqueous-based.

[0035] Furthermore, the composition as defined above has unexpectedly proven to have excellent lubricating power under the operating conditions of combustion engines fueled by hydrogen and / or ammonia, superior to their lubricating power in combustion engines fueled by hydrocarbon fuels.

[0036] Finally, compared to the use of a traditional hydrocarbon-based lubricating composition, the lubrication of hydrogen and / or ammonia engine systems with a composition as defined above makes it possible to further reduce emissions of CO2, unburned hydrocarbons and particles, which further improves the environmental impact of these engine systems.

[0037] The present invention also relates to a process or method for lubricating moving parts in a motorization system including an internal combustion engine powered by at least one non-hydrocarbon fuel chosen from hydrogen and / or ammonia, comprising a step of bringing at least one part of said motorization system into contact with a composition as defined above.

[0038] The invention also relates to a method of operating a motorization system, mobile or stationary, including an internal combustion engine, consisting of supplying said engine with at least one non-hydrocarbon fuel chosen from hydrogen and ammonia and lubricating at least one part of said motorization system with an aqueous lubricating composition as defined above.

[0039] The present invention also relates to a method of operating a motorization system, mobile or stationary, including an internal combustion engine powered by at least one fuel chosen from hydrogen and / or ammonia, consisting of lubricating at least one part of said motorization system with a composition as defined above.

[0040] Other objects, characteristics, aspects and advantages of the invention will appear even more clearly on reading the description which follows.

[0041] In what follows, and unless otherwise indicated, the limits of a domain of values ​​are included in this domain, notably in the expressions "between" and "ranging from ... to ..."

[0042] Furthermore, the expressions "at least one" and "at least" used in this description are respectively equivalent to the expressions "one or more" and "greater than or equal to".

[0043] Finally, in a manner known per se, the term CN compound or group refers to a compound or group containing N carbon atoms in its chemical structure.

[0044] DETAILED DESCRIPTION

[0045] The aqueous lubricating composition

[0046] The lubricating composition used in the present invention comprises at least 15% by mass of water, in particular from 15 to 80% by mass of water, relative to the total mass of the composition.

[0047] Preferably, the water content ranges from 20 to 70% by mass, more preferably from 30 to 65% by mass, and better still from 40 to 60% by mass, relative to the total mass of the composition.

[0048] According to a particular embodiment, the water used in said composition is osmosis or demineralized water, more preferably deionized water.

[0049] The term "osmosed water" means water that has undergone purification, in particular by a reverse osmosis process, which makes it possible to reduce the content of organic and / or mineral compounds, for example to a content of less than 5.0% by weight, preferably less than 1.0% by weight. In the present description, the expressions "demineralized water" or "ultrapure water" are considered equivalent or synonymous with the expression "osmosed water". In particular, the osmosed water may be "deionized water", in other words water that has undergone purification in order to reduce the content of ions, such as Ca ions 2+ and HCO3' generally present in water. Preferably deionized water does not include ions.

[0050] According to a preferred embodiment, the composition used in the invention is single-phase, that is to say it consists of a single aqueous phase. In particular in this embodiment, the composition is not an emulsion such as an oil-in-water emulsion or a water-in-oil emulsion.

[0051] In this embodiment, the composition does not comprise water-insoluble compounds, and in particular no water-insoluble hydrocarbons including water-insoluble base oils. By "water-insoluble oil" is meant in particular an oil which does not dissolve substantially in water at room temperature (25°C). In particular, a water-insoluble oil has a water solubility of less than 0.2 g / L at 25°C.

[0052] Advantageously, in this embodiment the composition does not comprise a lubricating base oil belonging to groups I to IV according to the classes defined in the API classification (or their equivalents according to the ATIEL classification).

[0053] The presence of water-insoluble hydrocarbons, even if it is not desired, is nevertheless tolerated within the framework of the invention because it can come from a migration of residual compounds onto the engine parts coming for example from a previous hydrocarbon lubricant used in the engine.

[0054] Preferably, the composition used in the present invention comprises less than 2% by mass of water-insoluble hydrocarbons, more preferably less than 1% by mass, relative to the total mass of the composition.

[0055] More preferably, the composition comprises less than 2% by mass of water-insoluble lubricating base oil and even better less than 1% by mass, relative to the total mass of the composition.

[0056] Advantageously, said composition is completely free of oil which is not soluble in water.

[0057] The composition used in the present invention does not contain:

[0058] - ascorbic acid ester, nor

[0059] - gallic acid ester, nor

[0060] - of phosphorus compound.

[0061] This means that this composition is a complete example of compounds belonging to each of these three families.

[0062] An ascorbic acid ester means any ester formed between ascorbic acid and one or more carboxylic acid(s). Esters of ascorbic acid include both water-soluble and water-emulsifiable forms, particularly in the form of ionic salts. An ascorbic acid ester comprises one or more ester functions resulting from the reaction of one or more of the hydroxyl functions of ascorbic acid and at least one carboxylic function of one or more carboxylic acid(s).

[0063] An ester of ascorbic acid can thus be a monoester or a polyester, in particular a diester, a triester or a tetraester of ascorbic acid.

[0064] In particular, an ascorbic acid ester may be formed between ascorbic acid and at least one mono- or polycarboxylic acid, for example a monocarboxylic or dicarboxylic acid.

[0065] In particular, an aqueous lubricating composition used according to the invention is free of ascorbyl palmitate.

[0066] Gallic acid ester refers to any ester formed between gallic acid and at least one alcohol. Gallic acid esters include both water-soluble and water-emulsifiable forms, particularly in the form of ionic salts.

[0067] A gallic acid ester may comprise several ester functions resulting from the reaction of the carboxylic acid function of gallic acid and several hydroxyl functions of a polyol.

[0068] A gallic acid ester can thus be a monoester or polyester, notably a diester or a triester of gallic acid.

[0069] In particular, a gallic acid ester may be formed between gallic acid and at least one monoalcohol or polyol, for example a monoalcohol or diol.

[0070] In particular, an aqueous lubricating composition used according to the invention is free of lauryl gallate and octyl gallate.

[0071] A phosphorus compound is any compound containing at least one phosphorus atom. Phosphorus compounds include both water-soluble and water-emulsifiable forms, particularly in the form of ionic salts.

[0072] The compounds excluded from the composition according to the invention include in particular amine phosphates; phosphates such as phosphate esters, in particular alkyl, alkenyl or aryl phosphates; polyphosphates; phosphonates such as phosphonate esters, in particular alkyl, alkenyl or aryl phosphonates; polyphosphonates; carbamylphosphates; and phosphinates.

[0073] In particular, an aqueous lubricating composition used according to the invention does not comprise phosphate ester salts, in particular alkali metal salts of phosphate esters, in particular C 1 -C 8 alkyl or dialkyl phosphate esters, for example of the potassium butylphosphate and potassium dibutylphosphate type.

[0074] The composition used in the present invention advantageously has a kinematic viscosity, measured at 40°C according to standard ASTM D445, of between 20 mm 2 / s and 1000 mm 2 / s, preferably between 25 mm 2 / s and 100 mm 2 / s.

[0075] Advantageously, said composition has a viscosity index in the range from 100 to 350, preferably from 150 to 300.

[0076] Antifreeze agents

[0077] The composition used in the present invention contains one or more antifreeze agents chosen from glycols, aliphatic monoethers of said glycols and polyhydric aliphatic alcohols, these antifreeze agents preferably being water-soluble.

[0078] By "water-soluble" is meant a compound having a water solubility of at least 10 g / L, preferably at least 500 g / L, in water at room temperature (25°C).

[0079] Said antifreeze agents are different from polyalkylene glycols having a weight-average molar mass greater than or equal to 200 g. mol 1 as defined below.

[0080] Glycols are diols in which the two hydroxyl groups are carried by different carbon atoms, preferably by vicinal carbon atoms. Glycol antifreeze agents are more particularly alkylene glycols having from 2 to 6, preferably from 2 to 4, carbon atoms, such as monoethylene glycol, monopropylene glycol and monobutylene glycol, and oxyalkylene glycols, preferably oxyethylene and oxypropylene glycols, having from 4 to 14 carbon atoms, preferably from 4 to 10 carbon atoms, such as diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol and tripropylene glycol.

[0081] Antifreeze agents may also be aliphatic monoethers of glycols as mentioned above, for example monomethyl, monoethyl, monopropyl and monobutyl ethers.

[0082] These may also be polyhydric aliphatic alcohols, in particular glycerol, diglycerol, triglycerol, erythritol and pentaerythritol.

[0083] Preferably, the antifreeze agent(s) are chosen from monoethylene glycol, diethylene glycol, propylene glycol, glycerol and mixtures thereof. Diethylene glycol is particularly preferred.

[0084] According to a particularly advantageous embodiment, the antifreeze agent(s) used according to the invention are biosourced.

[0085] For the purposes of the invention, a “bio-sourced” compound means a compound derived, partially or totally, from biomass, or obtained from renewable raw materials derived from biomass, in particular from plants.

[0086] The composition used in the present invention advantageously contains from 5.0 to 35% by mass of one or more antifreeze agent(s) as defined above, preferably from 10 to 25% by mass and more preferably from 15 to 20% by mass, relative to the total mass of the composition.

[0087] According to a preferred embodiment, the composition contains one or more antifreeze agent(s) chosen from monoethylene glycol, diethylene glycol, propylene glycol, glycerol and mixtures thereof, at a content of 5.0 to 35% by mass, preferably 10 to 25% by mass and more preferably 15 to 20% by mass, relative to the total mass of the composition.

[0088] According to a particularly preferred embodiment, the composition contains diethylene glycol at a content of 5.0 to 35% by mass, preferably 10 to 25% by mass and more preferably 15 to 20% by mass, relative to the total mass of the composition.

[0089] Polyalkylene glycols

[0090] The composition used in the present invention contains one or more polyalkylene glycols having a weight average molar mass greater than or equal to 200 g. mol 1 .

[0091] Polyalkylene glycols (denoted “PAG”) are advantageously chosen from water-soluble or water-soluble polyalkylene glycols.

[0092] By "water soluble" is meant a polyalkylene glycol having a water solubility of at least 10 g / L, preferably at least 500 g / L, in water at room temperature (25°C).

[0093] The polyalkylene glycols may be more particularly formed from C1-C4, preferably C1-C3, more particularly C2-C3, alkylene oxide units.

[0094] Advantageously, the polyalkylene glycol(s) used in the composition according to the invention comprise at least 50% by mass, in particular at least 80% by mass, more preferably at least 90% by mass of propylene oxide and / or ethylene oxide units. In particular, the polyalkylene glycol(s) used in the composition according to the invention consist of propylene oxide and / or ethylene oxide units. It may be a copolymer, optionally random, of ethylene oxide and propylene oxide.

[0095] Preferably, the polyalkylene glycol used in a composition according to the invention may be a copolymer, in particular a random copolymer, of ethylene oxide (EO) and propylene oxide (PO). In particular, the ethylene oxide (EO) and propylene oxide (PO) units are present in the copolymer in an EO / PO mass ratio of between 50 / 50 and 90 / 10, in particular between 60 / 40 and 85 / 15, and more particularly between 70 / 30 and 80 / 20.

[0096] Preferably, the polyalkylene glycol used in a composition according to the invention is obtained by polymerization from one or more alkylene oxide monomers, in particular ethylene oxide and / or propylene oxide, initiated by a compound of alcohol type, in particular of polyol type, preferably by a diol compound.

[0097] In particular, the polyalkylene glycol used according to the invention comprises hydroxyl terminal functions. For the purposes of the invention, the term "terminal functions" means the functions located at the ends of the polymer chains.

[0098] Preferably, said polyalkylene glycol(s) used according to the invention are chosen from polyalkylene glycols having a cloud point (called “Cloud point” in English), in other words having the property of inverse demixing (or “inverse solubility” in English).

[0099] The reverse demixing property characterizes the property of certain polyalkylene glycols to be soluble in water up to a temperature beyond which they become insoluble. This turbidity or "cloudiness" indicates phase separation with water, which results in a deposition of said polyalkylene glycol on the surfaces in contact with the lubricant.

[0100] The temperature at which turbidity and insolubility occur is called the cloud point of the polyalkylene glycol. The cloud point can be determined, for example, according to ASTM D 2024 or DIN EN 1890, typically for a mixture of 1% by mass of polyalkylene glycol in water.

[0101] Preferably, said polyalkylene glycol(s) used according to the invention have a cloud point greater than or equal to 70°C.

[0102] The water solubility and reverse demixing properties of the said polyalkylene glycol(s) used according to the invention advantageously make it possible to increase the lubrication properties.

[0103] Preferably, the polyalkylene glycol(s) have a weight-average molar mass (Mw) of between 250 and 50,000 g. mol 1 , preferably between 1000 and 25,000 g . mol 1 , in particular of at least 1500 g. mol 1and more particularly at least 2000 g . mol 1 .

[0104] As is known per se, the weight-average molar mass can be measured by gel permeation chromatography (GPC).

[0105] Preferably, the polyalkylene glycol(s) have a kinematic viscosity measured at 100°C (KV 100), according to standard ASTM D445, of between 25 and 25,000 mm 2 / s, especially between 50 and 10,000 mm 2 / s.

[0106] Preferably, the polyalkylene glycol(s) have a kinematic viscosity measured at 40°C (KV40), according to standard ASTM D445, of between 250 and 100,000 mm 2 / s, more particularly between 500 and 75,000 mm 2 / s.

[0107] The flash point of the polyalkylene glycol(s) is preferably greater than or equal to 160°C, in particular greater than or equal to 220°C. The flash point can be measured using ISO 2592 or ASTM D92.

[0108] Preferably, the polyalkylene glycol(s) have a viscosity index measured according to standard ASTM D2270, between 100 and 800, preferably between 250 and 550.

[0109] It is understood that the composition used in the present invention may comprise a single polyalkylene glycol or a mixture of several different polyalkylene glycols.

[0110] In particular, said composition may comprise a mixture of at least two distinct polyalkylene glycols, more particularly at least one polyalkylene glycol of low weight-average molar mass, for example between 200 and 2999 g. mol 1 and at least one polyalkylene glycol of high weight-average molar mass, for example between 3000 and 50,000 g . mol - 1 .

[0111] The combination of at least one polyalkylene glycol of low weight-average molar mass and at least one polyalkylene glycol of high weight-average molar mass is particularly advantageous in order to obtain good solubilization of the different compounds introduced into the aqueous lubricating composition.

[0112] According to a particularly advantageous embodiment, said polyalkylene glycol(s) used according to the invention are biosourced.

[0113] The use according to the invention of one or more biosourced PAGs thus makes it possible to further reduce the carbon footprint of the lubricating composition according to the invention. The composition used in the present invention advantageously contains from 5.0 to 50% by mass of one or more polyalkylene glycol(s) as defined above, preferably from 10 to 40% by mass and more preferably from 10 to 20% by mass, relative to the total mass of the composition.

[0114] In a particular embodiment, an aqueous lubricating composition used according to the invention comprises at least:

[0115] - from 15 to 80% by mass, relative to the total mass of the composition, in particular from 30 to 60% by mass of water, preferably deionized water;

[0116] - from 5.0 to 35% by mass, relative to the total mass of the composition, of one or more antifreeze agents chosen from glycols, aliphatic monoethers of said glycols and polyhydric aliphatic alcohols; and

[0117] - from 5.0 to 50% by mass, relative to the total mass of the composition, of one or more polyalkylene glycols having a weight-average molar mass greater than or equal to 200 g. mol 1 , it being understood that said composition does not contain:

[0118] - ascorbic acid ester, nor

[0119] - gallic acid ester, nor

[0120] - of phosphorus compound.

[0121] Additional additives

[0122] The composition used in the present invention may further contain one or more additional additives, different from the antifreeze agents defined above and the polyalkylene glycols as described above. These additives are also different from the ascorbic acid esters, the gallic acid esters and the phosphorus compounds, in particular chosen from those described above.

[0123] It is understood that said additional additive(s) are compatible with their implementation in an aqueous medium. Advantageously, the additives are implemented in a form that is soluble or emulsifiable in water, for example in the form of salts or ionic liquids.

[0124] Such additives may be more particularly chosen from anti-foam agents, biocides, pH regulators, corrosion inhibitors, anti-wear and / or extreme pressure additives, sequestering agents, metal passivating agents, colorants, dispersants, and mixtures thereof.

[0125] Advantageously, the composition used in the invention may comprise one or more additives chosen from antifoam agents, extreme pressure agents, corrosion inhibitors, pH regulators, metal passivating agents, colorants, and mixtures thereof.

[0126] The composition may more particularly comprise from 0.1 to 20% by mass of additives, in particular from 2.0 to 15% by mass of additives, in particular from 5.0 to 13% by mass, relative to the total mass of the composition.

[0127] pH regulators

[0128] The composition used in the present invention may comprise at least one pH regulating additive, in particular an alkaline buffer. The pH regulator advantageously makes it possible to maintain the desired pH of the lubricating composition, in particular in order to preserve an alkaline pH, advantageously between 8 and 15.

[0129] The said pH regulator(s), by ensuring that the pH of the aqueous lubricating composition is maintained between 8 and 15, makes it possible in particular to prevent corrosion of metal surfaces, but also to promote the solubilization of the various compounds in the lubricating composition, in particular the polyalkylene glycol(s).

[0130] The pH regulator can be chosen from the amine family, in particular alkanolamines and amino alcohols.

[0131] This may include a pH regulating additive selected from alkanolamines, such as dimethylethanolamine (DMEA), ethanolamines, such as monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), isopropanolamines, such as monoisopropanolamine (MIPA), diisopropanolamine (DIPA) and triisopropanolamine (TIPA); diglycolamine (DGA); ethylene amines, such as ethylene diamine (EDA), diethylene triamine (DETA), triethylene tetramine (TETA) and tetraethylene pentamine (TEPA); cyclamines, such as cyclohexylamine; 2-amino-2-ethyl-1,3-propanediol; 2-amino-2-methyl-1-propanol; and mixtures thereof.

[0132] The composition may in particular comprise from 0.1% to 10% by mass of pH regulating additive(s), preferably from 0.5% to 5% by mass, relative to the total mass of the composition.

[0133] Advantageously, the composition used in the invention comprises at least one pH regulating additive making it possible to maintain the pH of said lubricating composition between 8 and 15, in particular between 8.5 and 14, more particularly between 9 and 13, said pH regulating additive being chosen in particular from alkanolamines, preferably ethanolamines, and more particularly from dimethylethanolamine (DMEA), triethanolamine (TEA), diglycolamine (DGA) and mixtures thereof.

[0134] Corrosion inhibitors

[0135] The composition used in the present invention may comprise at least one corrosion inhibiting agent. Corrosion inhibitors advantageously make it possible to reduce or even prevent corrosion of metal parts. The nature of the corrosion inhibitor(s) may be chosen with regard to the metal to be protected against corrosion, such as aluminum, steel, galvanized steel, yellow metals, for example copper or brass.

[0136] Inorganic corrosion inhibitors include nitrites, sulfites, silicates, borates, hydroxides, molybdates, zinc, magnesium or nickel sulfates.

[0137] Among the organic corrosion inhibitors that may be mentioned are alkanolamines, such as triethanolamine, aliphatic monocarboxylic acids, in particular having from 4 to 15 carbon atoms, for example octanoic acid, aliphatic dicarboxylic acids having from 4 to 15 carbon atoms, for example decanedioic acid, undecanedioic acid, dodecanedioic acid or mixtures thereof, polycarboxylic acids optionally neutralized by triethanolamine, such as 1,3,5-triazine-2,4,6-tri-(6-aminocaproic acid), alkanoylamidocarboxylic acids, in particular isononanoylamidocaproic acid, and mixtures thereof. Borated amides, products of the reaction of amines or amino alcohols with boric acid, may also be used.

[0138] Preferably, the corrosion inhibitor(s) are distinct from the pH regulating additive(s), in particular making it possible to maintain the pH of the composition between 8 and 15 defined previously.

[0139] The composition may in particular comprise from 0.1% to 5% by mass of corrosion inhibitor(s), in particular as defined above, preferably from 0.5% to 4% by mass, more preferably from 1% to 2.5% by mass, relative to the total mass of the composition.

[0140] Anti-wear / extreme pressure additive

[0141] The composition used in the present invention may comprise at least one anti-wear and / or extreme pressure additive. Their function is to reduce wear and the coefficient of friction, or to prevent metal-metal contact by forming a protective film adsorbed on these surfaces.

[0142] The anti-wear and / or extreme pressure additive(s) may advantageously be chosen from polysulfides, in particular sulfur-containing olefins, sulfur-containing fatty acids and dimercaptothiadiazoles, preferably used in their neutralized form, in particular by inorganic alkalizing agents or alkanolamines, emulsifiable or soluble in water.

[0143] The composition may comprise less than 0.1% by mass of extreme pressure additive of the sulfur-containing fatty acid type, in particular in a neutralized form, preferably less than 0.01% by mass, more particularly less than 0.001% by mass, relative to the total mass of the composition, or even is completely free of extreme pressure additive of the sulfur-containing fatty acid type.

[0144] The sulfur-containing fatty acids may comprise from 8 to 22 carbon atoms, in particular from 12 to 18 carbon atoms. The quantity of sulfur according to standard ASTM D2622 provided by said sulfur-containing fatty acid(s) may be between 5% and 30% by mass, in particular between 10% and 20% by mass, relative to the total mass of the composition.

[0145] Preferably, the quantity of active sulfur at 150°C according to standard ASTM D 1662 provided by said sulfur-containing fatty acid(s) in the aqueous lubricating composition according to the invention is less than or equal to 2% by mass, in particular less than or equal to 1% by mass, more particularly less than 0.1% by mass, relative to the total mass of the lubricating composition.

[0146] For the purposes of the present invention, the term "active sulfur" means the sulfur that a chemical compound is capable of yielding or releasing when this compound is placed under the conditions of the ASTM D 1662 standard. The ASTM D-1662 standard defines an active sulfur level of a compound at a given temperature as a difference expressed as a weight percentage of sulfur content before and after reaction of a sample of this sulfur compound with a given quantity of copper for a fixed time.

[0147] As indicated above, said sulfur-containing fatty acid(s) are generally implemented in an aqueous lubricating composition in their form neutralized by an alkalizing agent, such as sodium hydroxide, potassium hydroxide, or an alkanolamine, such as monoethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine and triisopropanolamine.

[0148] The composition may in particular comprise between 0.01% and 10% by mass of anti-wear and / or extreme pressure additive(s), preferably between 0.2% and 5% by mass, relative to the total mass of the composition.

[0149] Anti-foam

[0150] The composition used in the present invention may comprise at least one anti-foam additive. Anti-foams make it possible to prevent foaming of the lubricating fluid. It may be, for example, an anti-foam agent based on polysiloxanes or acrylate polymers. Preferably, the anti-foam agent is chosen from three-dimensional siloxanes.

[0151] Antifoam agents can also be polar polymers such as polymethylsiloxanes or polyacrylates.

[0152] The composition may comprise from 0.001% to 3.0% by mass of anti-foam additive(s), preferably from 0.005% to 1.5% by mass, more preferably from 0.01% to 1.0% by mass, relative to the total mass of the lubricating composition.

[0153] Metal passivating agents

[0154] The composition used in the present invention may comprise at least one metal passivating agent. Metal passivating agents make it possible to protect metal parts by promoting the formation of metal oxide on their surface.

[0155] The metal passivating agents may be chosen, for example, from triazole derivatives, such as tetrahydrobenzotriazole (THBTZ), tolyltriazole (TTZ), benzotriazole (BTZ), amines substituted with a triazole group, such as N,N-bis(2-ethylhexyl)-

[0156] 1,2,4-triazol-1-yl methanamine, 1'-bis(2-ethylhexyl)-4-methyl-1H-benzotriazol-1-methylamine, N,N-bis(heptyl)-ar-methyl-1H-benzotriazole-1-methanamine, N,N-bis(nonyl)-ar-methyl-1H-benzotriazole-1-methanamine, N,N-bis(decyl)-ar-methyl-1H-benzotriazole-1-methanamine, N,N-bis(undecyl)-ar-methyl-1H-benzotriazole-1-methanamine, N,N-bis(dodecyl)-ar-methyl-1H-benzotriazole-1-methanamine, N,]-bis(2-ethylhexyl)-ar-methyl-1H-benzotriazole-1 -methanamine, 1, ,4-triazoles, benzimidazoles, 2-alkyldithiobenzimidazoles, 2-alkyldithiobenzothiazoles, 2-(N,N-dialkyldithiocarbamoyl)benzothiazoles, 2,5-bis(alkyldithio)-

[0157] 1.3.4-thiadiazoles, such as 2,5-bis(tert-octyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-nonyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-decyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-undecyldithio)-

[0158] 1.3.4-thiadiazole, 2,5-bis(tert-dodecyldithio)-1,3,4-thiadiazole,

[0159] 2,5-bis(tert-tridecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-tetradecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-pentadecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-hexadecyldithio)- 1,3,4-thiadiazole,

[0160] 2.5-bis(tert-heptadecyldithio)-1,3,4-thiadi azole, 2,5-bis (tertoctadecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-nonadecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-eicosyldithio)-1,3,4-thiadiazole,

[0161] 2,5-bis(N,N-dialkyldithiocarbamoyl)- l ,3 ,4-thiadiazoles, 2-alkyldithio-5-mercaptothiadiazoles, and mixtures thereof.

[0162] Preferably, the metal passivating agents are chosen from tetrahydrobenzotriazole (THBTZ), tolyltriazole (TTZ), benzotriazole (BTZ), and their salts, taken alone or in mixtures.

[0163] The composition may in particular comprise from 0.01% to 2.0% by mass of metal passivating agent(s), preferably from 0.1% to 1.0% by mass, more preferably from 0.2% to 0.8% by mass, relative to the total mass of the composition.

[0164] Dyes

[0165] The composition used in the present invention may comprise one or more colorants. The colorants may be natural or synthetic, generally organic.

[0166] The colorants that can be used in an aqueous lubricant composition can be more particularly chosen from natural or synthetic water-soluble colorants, for example the colorants FDC Red 4, DC Red 6, DC Red 22, DC Red 28, DC Red 30, DC Red 33, DC Orange 4, DC Yellow 5, DC Yellow 6, DC Yellow 8, FDC Green 3, DC Green 5, FDC Blue 1, betanin (beetroot), carmine, a chlorophyllin, methylene blue, anthocyanins (enocyanin, black carrot and hibiscus), caramel and riboflavin.

[0167] An aqueous lubricating composition used according to the invention may comprise between 0.01% and 2.0% by mass of colorant(s), preferably between 0.01% and 1.5% by mass, more preferably between 0.02% and 1.0% by mass, relative to the total mass of the composition.

[0168] Sequestering agents

[0169] The composition used in the present invention may comprise at least one sequestering agent. Sequestering agents, also called chelating agents, make it possible to limit the encrustation of metal ions in the composition.

[0170] Examples of sequestering agents include multifunctional organic acids and hydroxy acids, such as ethylenediaminetetraacetic acid (EDTA), pteroyl-L-glutamic acid (PGLU), organic polyacids, such as maleic acid and polyaspartic acid, polysaccharides and carbohydrates, such as inulin, carboxymethylinulin and carboxymethylchitosan.

[0171] The composition may comprise from 0.001% to 2.0% by mass of sequestering agent(s), preferably from 0.01% to 1.0% by mass, relative to the total mass of the composition.

[0172] Biocides and fungicides

[0173] The composition used in the present invention may comprise at least one biocidal and / or fungicidal agent. The biocides and fungicides may be used to improve the biological stability of the composition by limiting the proliferation of bacteria, fungi and yeasts in the lubricating fluid.

[0174] Such biocides may be selected from parabens, aldehydes, reactive acetylacetone compounds, isothiazolinones, phenolic compounds, acid salts, halogenated compounds, quaternary ammoniums, certain alcohols and mixtures thereof.

[0175] Preferably, the biocides may be chosen from optionally substituted benzisothiazolinones (BIT), such as N-butyl-1,2-benzisothiazolin-3-one, methylisothiazolinones (MIT), mixtures of methylisothiazolinone and chloromethylisothiazolinone (MIT / CMIT), orthophenylphenol (OPP) or its sodium salt, 3-iodo-2-propynylbutylcarbamate (IPBC), chlorocresol and N,N-methylenebismorpholine (MBM); sorbic acid; preferably from orthophenylphenol (OPP) or its sodium salt, 3-iodo-2-propynylbutylcarbamate, chlorocresol, benzisothiazolinones and N,N-methyleneisomorpholine.

[0176] The composition may in particular comprise between 0.01% and 10% by mass of biocide(s) and / or fungicide(s), preferably between 0.5% and 5.0% by mass, relative to the total mass of the composition. The use

[0177] According to the present invention, the composition as described above is used to lubricate the various moving parts in a motorization system, mobile or stationary, including an internal combustion engine powered by a fuel based on at least hydrogen and / or ammonia.

[0178] Advantageously, said composition is used to reduce friction between moving parts inside a hydrogen and / or ammonia internal combustion engine. It is also used to reduce wear of said parts. The part(s) of the internal combustion engine lubricated by means of the aqueous lubricating composition are advantageously chosen from: pistons, segments, cylinders, connecting rods, piston pins, bearings, crankshafts, oil pumps, turbochargers, camshafts, distribution systems (including in particular cams, tappets, levers, rocker arms, oil pump).

[0179] The engine can be any internal combustion engine operating by combustion of hydrogen and / or ammonia. It can be a piston engine or a gas turbine.

[0180] As is known per se, a gas turbine, also called a combustion turbine, is a thermodynamic rotating machine from the internal combustion engine family and which can be used for propulsion, electricity production, or as a stationary engine (for example to drive pumps, compressors, etc.).

[0181] Preferably, the internal combustion engine is a piston engine.

[0182] The present invention applies to any known piston engine, including on-board engines and stationary engines. The invention applies in particular to marine engines, heavy goods vehicles, construction machinery or agricultural machinery such as, for example, tractors, public transport vehicles (buses, trains, etc.) as well as to engines of light vehicles such as cars, engines used in air or space propulsion (airplanes, rockets), as well as to engines used in stationary industrial applications.

[0183] The piston engine can be chosen in particular from compression ignition engines or diesel engines, spark ignition engines, mixed fuel engines (in English “dual fuel”).

[0184] According to a first preferred embodiment, the engine is a spark-ignition engine powered by hydrogen, or hydrogen engine.

[0185] According to a second embodiment, the engine is a compression ignition engine or diesel engine fueled by ammonia, or ammonia engine. Use in a marine engine (i.e., a compression ignition engine used for the propulsion of a ship) is particularly preferred.

[0186] According to an advantageous variant of this embodiment, the compression ignition engine is a mixed fuel engine (also commonly called a “dual fuel” engine). In this use, ammonia supplies the engine in combination with a second fuel other than ammonia, such as for example hydrogen and / or a hydrocarbon fuel, preferably a hydrocarbon fuel. The hydrocarbon fuel may be chosen from fuels of petroleum origin and in particular diesel and fuel oils of varying weights, bio-sourced fuels (in particular derived from biomass), and mixtures of these two types of fuels. According to a preferred embodiment, the hydrocarbon fuel is chosen from fuels based on heavy fuel oils (such as marine fuels), bio-sourced fuels and mixtures thereof.

[0187] The ammonia and the second fuel are injected in different proportions depending on the power required from the engine. The second fuel is advantageously injected into the engine to initiate combustion, by self-ignition of a mixture of air and a small quantity of fuel called pilot injection. The ammonia is injected in a mixture with air to fuel the combustion. The pilot injection generally represents less than 10% by mass of the total mass of fuel (ammonia and second fuel) consumed, typically of the order of 5% by mass of the total mass of fuel consumed.

[0188] Particularly preferably, the mixed fuel compression ignition engine is a marine engine, i.e. a mixed fuel diesel engine fitted to a ship.

[0189] The methods

[0190] The present invention also relates to a method for lubricating moving parts in a motorization system including an internal combustion engine powered by at least one non-hydrocarbon fuel chosen from hydrogen and ammonia, comprising a step of bringing at least one of said parts into contact with a composition as defined above.

[0191] The invention also relates to a method of operating a motorization system, mobile or stationary, including an internal combustion engine, consisting of supplying said engine with at least one non-hydrocarbon fuel chosen from hydrogen and ammonia and lubricating at least one part of said motorization system by means of an aqueous lubricating composition as defined above.

[0192] The engine part(s) are advantageously chosen from pistons, rings, cylinders, connecting rods, piston pins, bearings, crankshafts, oil pumps, turbochargers, camshafts, distribution systems (including in particular cams, tappets, levers, rocker arms, oil pump).

[0193] The engine may be any internal combustion engine, including but not limited to those described above.

[0194] Preferably, the internal combustion engine is chosen from piston engines and gas turbines (or combustion turbines).

[0195] According to a first preferred embodiment, the engine is a spark-ignition engine powered by hydrogen.

[0196] According to a second preferred embodiment, the engine is a compression ignition engine fueled by ammonia, preferably a dual fuel compression ignition engine. In this embodiment, the method of operating the engine according to the invention comprises supplying the compression ignition engine with ammonia and another fuel other than ammonia, preferably a hydrocarbon fuel as described above.

Claims

Tl CLAIMS 1. Use for lubricating a motorization system comprising an internal combustion engine powered by at least one non-hydrocarbon fuel chosen from hydrogen and / or ammonia, of a composition comprising: - water at a content of at least 15% by mass, relative to the total mass of the composition; - one or more antifreeze agents chosen from glycols, aliphatic monoethers of said glycols and polyhydric aliphatic alcohols, at a total content of at least 5% by mass, relative to the total mass of the composition; and - one or more polyalkylene glycols having a weight-average molar mass greater than or equal to 200 g. mol 1 at a total content of at least 5% by mass, relative to the total mass of the composition, it being understood that this composition does not contain: - ascorbic acid ester, nor - gallic acid ester, nor - of phosphorus compound.

2. Use according to the preceding claim, characterized in that the water content of the composition ranges from 15 to 80% by mass, preferably from 20 to 70% by mass, more preferably from 30 to 65% by mass, and better still from 40 to 60% by mass, relative to the total mass of the composition.

3. Use according to any one of the preceding claims, characterized in that the antifreeze agent(s) are chosen from monoethylene glycol, diethylene glycol, propylene glycol, glycerol and mixtures thereof, and more preferably diethylene glycol.

4. Use according to any one of the preceding claims, characterized in that the composition contains from 5.0 to 35% by mass of the antifreeze agent(s), preferably from 10 to 25% by mass, and more preferably from 15 to 20% by mass, relative to the total mass of the composition.

5. Use according to any one of the preceding claims, characterized in that the polyalkylene glycol(s) have a weight-average molar mass of between 250 and 50,000 g. mol - 1 , preferably between 1000 and 25,000 g. mol - 1 .

6. Use according to any one of the preceding claims, characterized in that the polyalkylene glycol(s) comprise at least 50% by mass, preferably at least 80% by mass, more preferably at least 90% by mass of propylene oxide and / or ethylene oxide units.

7. Use according to any one of the preceding claims, characterized in that the composition contains from 5.0 to 50% by mass of said polyalkylene glycol(s), preferably from 10 to 40% by mass and more preferably from 10 to 20% by mass, relative to the total mass of the composition.

8. Use according to any one of the preceding claims, characterized in that the composition contains one or more additional additives, chosen from anti-foam agents, biocides, pH regulators, corrosion inhibitors, anti-wear and / or extreme pressure additives, sequestering agents, metal passivating agents, colorants, dispersants, and mixtures thereof.

9. Use according to any one of the preceding claims, for reducing friction between moving parts inside the internal combustion engine and / or for reducing wear of said parts.

10. Use according to any one of the preceding claims, characterized in that the internal combustion engine is a piston engine or a gas turbine, preferably a piston engine.

11. Use according to the preceding claim, characterized in that the engine is a spark-ignition engine powered by hydrogen.

12. Use according to claim 10, characterized in that the engine is a compression ignition engine fueled by ammonia.

13. Use according to the preceding claim, characterized in that the compression ignition engine is a mixed carburetion engine.

14. Method for lubricating moving parts in a powertrain system including an internal combustion engine powered by at least one non-hydrocarbon fuel chosen from hydrogen and ammonia, comprising a step of bringing at least one of said parts into contact with a composition as defined in any one of claims 1 to 8.

15. Method for operating a powertrain system, mobile or stationary, including an internal combustion engine, consisting of powering said engine with at least one non-hydrocarbon fuel chosen from hydrogen and ammonia and lubricating at least one part of said powertrain system using a composition as defined in any one of claims 1 to 8.