Use of an aqueous composition to lubricate the internal parts of a hydrogen or ammonia engine

Abstract

The present invention relates to the use, for lubricating a powertrain system comprising an internal combustion engine powered by a non-hydrogen fuel selected from hydrogen and / or ammonia, of a composition comprising water, at least 10% by mass of one or more polyalkylene glycols with a weight-average molar mass of at least 1500 g / mol; said composition comprising an antifreeze additive content selected from glycols, aliphatic monoethers of said glycols, and polyhydric aliphatic alcohols, strictly less than 1% by mass. The invention also relates to a method for lubricating moving parts in a powertrain system including an internal combustion engine powered by at least one non-hydrogen fuel selected from hydrogen and ammonia, comprising a step of contacting at least some of said parts with such a composition.

Description

Title of the invention: Use of an aqueous composition to lubricate the internal parts of a hydrogen or ammonia engine

[0001] The present invention relates to the use of a particular aqueous lubricating composition to lubricate a drive system comprising an internal combustion engine powered by a non-hydrocarbon fuel selected from hydrogen and / or ammonia.

[0002] The present invention also relates to a method for lubricating an internal combustion engine powered by at least one non-hydrocarbon fuel selected from hydrogen and ammonia, comprising a step of contacting at least one internal part of the engine with a composition, as described below. PRIOR ART

[0003] 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 context, hydrogen and ammonia are considered promising solutions, particularly for the transport sector (especially maritime transport) and electricity generation in gas turbines.

[0004] Hydrogen and ammonia offer multiple advantages, including but not limited to: - These are fully decarbonized fuels that can be produced via different technologies, including from renewable electricity; - Their combustion does not generate emissions of carbon dioxide (CO2), sulfur gases (SOx), unburned hydrocarbons, or particles; - They can be used in existing engines and heating devices, with some adaptations.

[0005] However, internal combustion engines are generally lubricated by lubricating compositions that are essentially formulated from base oils and hydrocarbon 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 polyal-phenolic olefins (PAOs, or Group IV base oils according to the API classification). Group V base oils represent all other unconventional sources of base oils and are generally represented by oxygenated hydrocarbons such as esters and polyglycols.

[0006] During engine operation, some of the lubricant present on the internal engine parts is burned. Although this combustion is undesirable, 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, including carbon dioxide (CO2), unburned hydrocarbons, and particulate matter, which are precisely the emissions that are being avoided with the use of these alternative fuels. These unwanted emissions from the lubricant have a negative impact on the environmental performance of engines running on hydrogen or ammonia.

[0007] 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 particulate matter.

[0008] Lubricant compositions formulated with varying amounts 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.

[0009] However, such compositions have not yet been used to lubricate the internal parts of combustion engines, in particular because of the risks of water evaporation under the thermal flow of combustion, which leads to accelerated consumption of the lubricant incompatible with conventional drain intervals.

[0010] Moreover, it has generally been considered that the level of lubrication provided by these aqueous compositions may be insufficient in an engine in which friction stresses are extremely high, which could lead to an increased risk of engine failure when lubricated with such compositions.

[0011] The present invention aims to remedy the problems described above and in particular to reduce emissions from internal combustion engines powered by hydrogen and / or ammonia.

[0012] The Applicant has now discovered that particular aqueous compositions, as defined below, made 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.

[0013] The present invention thus relates to the use, for lubricating a drive system comprising an internal combustion engine powered by at least one non-hydrocarbon fuel selected from hydrogen and / or ammonia, of a composition comprising: - water; - at least 10% by mass, relative to the total mass of said composition, of one or more polyalkylene glycol(s) with an average molar mass by weight, Mw, of at least 1500 g.mol *; said composition having a content of antifreeze additive(s) selected from glycols, aliphatic monoethers of said glycols and polyhydric aliphatic alcohols, strictly less than 1% by mass, in relation to the total mass of the composition.

[0014] In the following text, "aqueous lubricating composition" will be designated as a composition implemented according to the invention as defined above.

[0015] The aqueous lubricating composition according to the invention makes it possible to lubricate very effectively the various moving parts in a motorization system, mobile or stationary, including an internal combustion engine powered by hydrogen and / or ammonia, hereinafter referred to as "hydrogen and / or ammonia engine".

[0016] For the purposes of this invention, "engine system" means 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. "Hydrogen and / or ammonia engine" means a combustion engine powered by a hydrogen and / or ammonia-based fuel. This may include, in particular, an engine running solely on hydrogen (hydrogen engine), an engine running solely on ammonia (ammonia engine), an engine running on a mixture of hydrogen and ammonia, or an engine running on ammonia and diesel fuel (dual-fuel ammonia / diesel engine).

[0017] A "stationary" drive system within the meaning of the invention is a drive system including a stationary engine, in particular a hydrogen engine. It can, for example, find applications in electrical power generation devices.

[0018] A “mobile” motorization system is more particularly 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.

[0019] A mobile motorization system can thus be a vehicle propulsion system.

[0020] For the purposes of this invention, "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.

[0021] The implementation of aqueous lubricating compositions according to the invention proves particularly advantageous in several respects.

[0022] First, 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 lubricant, can lead to emulsification problems in the lubricant, resulting in a degradation of its properties, particularly its lubricating power. The use of a water-based composition such as the one defined above avoids this lubricant emulsification phenomenon.

[0023] Furthermore, in hydrogen and / or ammonia engines lubricated with a traditional hydrocarbon-based lubricant, lubricant droplets in the lubricant chamber can create localized hot spots, potentially leading to premature ignition of the air / fuel mixture and thus to an abnormal combustion phenomenon known as pre-ignition. It is preferable to reduce or even eliminate this abnormal combustion phenomenon, particularly pre-ignition, as it generally results in a significant increase in temperature and pressure in the combustion chamber, thus having a significant negative impact on the overall efficiency and performance of the engine, and may even damage it.

[0024] Advantageously, these abnormal combustion phenomena do not occur with the use of the aqueous-based lubricating composition according to the invention.

[0025] In addition, the composition as defined above has unexpectedly been found to have excellent lubricating power under the operating conditions of combustion engines powered by hydrogen and / or ammonia, superior to their lubricating power in combustion engines powered by hydrocarbon fuels.

[0026] Finally, compared to the use of a traditional hydrocarbon-based lubricating composition, the lubrication of hydrogen and / or ammonia engine systems with a composition such as defined above makes it possible to further reduce CO2, unburned hydrocarbon and particulate emissions, which further improves the environmental impact of these engine systems.

[0027] The present invention also relates to a process or method for lubricating moving parts in a drive system including an internal combustion engine powered by at least one non-hydrocarbon fuel selected from hydrogen and / or ammonia, comprising a step of bringing at least one part of said drive system into contact with a composition as defined above.

[0028] The invention also relates to a method of operation of 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 engine system with an aqueous lubricating composition as defined above.

[0029] 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.

[0030] Other objects, features, aspects and advantages of the invention will become even clearer upon reading the following description.

[0031] In what follows, and unless otherwise indicated, the bounds of a range of values ​​are included in that range, in particular in the expressions "between" and "ranging from ... to ...". 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". Finally, and quite simply, a compound or group containing N carbon atoms in its chemical structure is designated as a CN compound or group. DETAILED DESCRIPTION

[0032] The aqueous lubricating composition The aqueous lubricating composition according to the present invention comprises water. In particular, water is present as the major solvent, that is to say, in a greater quantity than any other solvent that may be present in the composition.

[0033] The lubricating composition used in the present invention advantageously comprises at least 15% by mass of water, in particular from 15 to 85% by mass of water, relative to the total mass of the composition.

[0034] Preferably, the water content is from 20 to 80% by mass, more preferably from 30 to 70% by mass, and even better from 40 to 60% by mass, relative to the total mass of the composition.

[0035] According to a particular embodiment, the water used in said composition is osmosis or demineralized water, more preferably deionized water.

[0036] “Osmosis water” means water that has undergone purification, particularly by a reverse osmosis process, which reduces the content of organic and / or mineral compounds, for example, to less than 5.0% by weight, preferably less than 1.0% by weight. In this description, the terms “demineralized water” or “ultrapure water” are considered equivalent or synonymous with “osmosis water.” In particular, osmosis water can be "Deionized water" is water that has undergone purification to reduce its ion content, such as the Ca2+ and HCO3 ions commonly found in water. Preferably, deionized water contains no ions.

[0037] According to a preferred embodiment, the composition used in the invention is monophasic, 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.

[0038] In this embodiment, the composition does not include water-insoluble compounds, and in particular no water-insoluble hydrocarbons including water-insoluble base oils.

[0039] The term "water-insoluble oil" includes, in particular, an oil that does not substantially dissolve in water at room temperature (25°C). In particular, a water-insoluble oil has a solubility in water of less than 0.2 g / L at 25°C.

[0040] Advantageously, in this embodiment the composition does not include 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).

[0041] The presence of water-insoluble hydrocarbons, even if not desired, is nevertheless tolerated within the scope of the invention because it may come from a migration of residual compounds on engine parts from, for example, a previous hydrocarbon lubricant used in the engine.

[0042] 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.

[0043] 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.

[0044] Advantageously, said composition is totally free of water-insoluble oil.

[0045] The composition used in the present invention advantageously has a kinematic viscosity, measured at 40°C according to ASTM D445, of between 20 mm2 / s and 1000 mm2 / s, preferably between 25 mm2 / s and 100 mm2 / s.

[0046] Advantageously, said composition has a viscosity index in the range of 100 to 350, preferably from 150 to 300. Polyalkylene glycols

[0047] The composition used in the present invention contains one or more polyalkylene glycols.

[0048] Polyalkylene glycols (denoted "PAG") are more particularly chosen from Water-soluble or hydrosoluble polyalkylene glycols.

[0049] By "water soluble" is meant a polyalkylene glycol having a solubility in water of at least 10 g / L, preferably of at least 500 g / L, in water at room temperature (about 25 °C).

[0050] Preferably, the 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 so-lubility.

[0051] 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 a phase separation with water, resulting in the deposition of said polyalkylene glycol on the surfaces in contact with the lubricant.

[0052] The temperature at which turbidity and insolubility occur is called the cloud point of polyalkylene glycol. The cloud point can be determined, for example, according to ASTM D 2024 or DIN EN 1890 standards, generally for a 1% mass mixture of polyalkylene glycol in water.

[0053] Preferably, the polyalkylene glycol(s) used according to the invention have a cloud point greater than or equal to 70°C.

[0054] The water solubility and reverse demixing properties of said polyalkylene glycol(s) implemented according to the invention advantageously increase the lubrication properties.

[0055] Advantageously, a polyalkylene glycol implemented according to the invention comprises at least 50% by mass, in particular at least 80% by mass, more preferably at least 90% by mass, or even at least 95% by mass of propylene oxide and / or ethylene oxide units. In particular, the polyalkylene glycols implemented according to the invention are composed of propylene oxide and / or ethylene oxide units.

[0056] Preferably, the polyalkylene glycol implemented according to the invention can be a copolymer, in particular a statistical 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.

[0057] Preferably, the polyalkylene glycol implemented 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 an alcohol-type compound, in particular a polyol-type compound, preferably a diol compound.

[0058] In particular, the polyalkylene glycol used according to the invention comprises hydroxyl terminal functions. By "terminal functions", in the sense of the invention, we mean the functions located at the ends of the polymer chains.

[0059] As previously stated, the polyalkylene glycol(s) used according to the invention have an average molar mass by weight (Mw) greater than or equal to 1500 g / mol.

[0060] In particular, a polyalkylene glycol is distinguished from alkylene glycol oligomers having a number of monomeric units less than or equal to ten.

[0061] Preferably, a polyalkylene glycol implemented according to the invention has an average molar mass by weight (Mw) of at least 2000 g.mol ', in particular of at least 2500 g.mol *, in particular of at least 3000 g.mol *, and more particularly between 3000 and 50,000 g.mol *, in particular between 5000 and 25,000 g.mol *, preferably between 5,000 and 15,000 g.mol *.

[0062] The average molar mass by weight can be measured by gel permeation chromatography (GPC).

[0063] Preferably, a polyalkylene glycol implemented according to the invention has a kinematic viscosity measured at 100 °C (KV100), according to ASTM D445, of between 100 and 25,000 mm2 / s, in particular between 150 and 15,000 mm2 / s.

[0064] Preferably, a polyalkylene glycol implemented according to the invention has a kinematic viscosity measured at 40 °C (KV40), according to ASTM D445, of between 500 and 100,000 mm2 / s, more particularly between 1,000 and 70,000 mm2 / s.

[0065] The flash point of a polyalkylene glycol implemented according to the invention is preferably greater than or equal to 160 °C, in particular greater than or equal to 220 °C. The flash point can be measured according to ISO 2592 or ASTM D92.

[0066] Preferably, a polyalkylene glycol implemented according to the invention has a viscosity index measured according to ASTM D2270, between 100 and 800, preferably between 250 and 550.

[0067] It is understood that a single polyalkylene glycol or a mixture of several different polyalkylene glycols, in particular as described above, can be implemented according to the invention.

[0068] In particular, an aqueous lubricating composition according to the invention may comprise a mixture of at least two distinct polyalkylene glycols, more particularly of at least one polyalkylene glycol of low average weight molar mass and at least one polyalkylene glycol of high average weight molar mass.

[0069] It is within the general competence of a person skilled in the art to adjust the nature and content of low and high average molar mass polyalkylene glycols in the polyalkylene glycol mixture, in particular with regard to the viscosity targeted for the final lubricating composition.

[0070] According to a particularly advantageous embodiment, the polyalkylene or polyalkylene glycol(s) implemented according to the invention are bio-based(s).

[0071] For the purposes of the invention, a “bio-based” compound means a compound derived, in whole or in part, from biomass, or obtained from renewable raw materials derived from biomass, in particular from plants.

[0072] Advantageously, the implementation according to the invention of one or more bio-based PAGs thus makes it possible to further reduce the carbon footprint of the lubricating composition according to the invention.

[0073] The aqueous lubricating composition contains at least 10% by mass and preferably at least 15% by mass of said polyalkylene glycol(s). Preferably, it contains from 15 to 50% by mass of said polyalkylene glycol(s), more preferably from 15 to 30% by mass and even more preferably from 16 to 20% by mass, relative to the total mass of the composition

[0074] In a particular embodiment, the polyalkylene glycol(s) are present in an aqueous lubricating composition according to the invention in a mass ratio of the total quantity of polyalkylene glycol(s) to the quantity of water less than or equal to 0.30, in particular between 0.10 and 0.30, more particularly between 0.15 and 0.25, and especially between 0.15 and 0.20.

[0075] According to a particular embodiment, the mixture consisting of water and the polyalkylene glycol(s) represents more than 80% of the total mass of said aqueous lubricating composition.

[0076] Antifreeze additives The aqueous lubricating composition used in the present invention advantageously comprises a reduced content of antifreeze additives, also called antifreeze compounds, selected from glycols, in particular alkylene glycols having 2 to 6 carbon atoms such as monoethylene glycol and / or monopropylene glycol, and oxyalkylene glycols having 4 to 14 carbon atoms such as diethylene glycol; aliphatic monoethers of said glycols; and polyhydric aliphatic alcohols such as glycerol. This content is strictly less than 1% by mass, relative to the total mass of said composition.

[0077] Glycols are diols in which the two hydroxyl groups are attached to different carbon atoms, preferably vicinal carbon atoms. Glycol-type antifreeze additives are more particularly alkylene glycols having 2 to 6, preferably 2 to 4, carbon atoms, such as monoethylene glycol, monopropylene glycol and monobutylene glycol, and oxyalkylene glycols, preferably oxyethylene and oxypropylene glycols, having 4 to 14 carbon atoms, preferably 4 to 10 carbon atoms, such as diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol and tripropylene glycol.

[0078] Preferably, the content of glycol-type antifreeze compound(s), for example monoethylene glycol, diethylene glycol, and / or monopropylene glycol, if present in an aqueous lubricating composition according to the invention, is strictly less than 1.0% by mass, preferably less than or equal to 0.5% by mass, in particular less than or equal to 0.1% by mass, relative to the total mass of the composition.

[0079] Advantageously, an aqueous lubricating composition according to the invention is completely free of glycol-type antifreeze compounds, and thus avoids the toxicity effects associated with these compounds. An aqueous lubricating composition according to the invention therefore advantageously exhibits reduced toxicity.

[0080] Advantageously, by comprising a reduced quantity, or even being devoid of glycol-type antifreeze additives, the aqueous lubricating composition implemented according to the invention exhibits reduced toxicity and environmental footprint.

[0081] The environmental footprint associated with the production of a lubricant can be assessed according to various indicators defined by the European Union, including in particular the "climate change" indicator which is a data point of the global warming potential associated with the emission of greenhouse gases, expressed in equivalent kilograms of carbon dioxide (kg CO2 eq).

[0082] Antifreeze additives known for aqueous lubricants may still be aliphatic monoethers of glycols as previously mentioned, for example monomethyl, monoethyl, monopropyl and monobutyl ethers.

[0083] It may also be polyhydric aliphatic alcohols, in particular glycerol, diglycerol, triglycerol, erythritol and pentaerythritol.

[0084] In particular, the aqueous lubricating composition according to the invention comprises a content of antifreeze additives selected from glycols, aliphatic monoethers of said glycols and polyhydric aliphatic alcohols, strictly less than 1% by mass, in particular less than or equal to 0.5% by mass and more particularly less than or equal to 0.1% by mass, relative to the total mass of the composition.

[0085] According to one embodiment, an aqueous lubricating composition according to the invention is free of such antifreeze additives.

[0086] In a particular embodiment, an aqueous lubricating composition according to the invention comprises:

[0087] - at least 15% by mass, in particular at least 30% by mass and more particularly bound from 30% to 85% by mass, of water, preferably deionized water;

[0088] - at least 15% by mass, in particular from 15% to 50% by mass, more particularly liement of 15% to 30% mass, of one or more polyalkylene glycol(s) (PAG(s)) of average molar mass, Mw, of at least 1500 g.mol1;

[0089] the mass ratio of the total quantity of polyalkylene glycol(s) to the quantity water being less than or equal to 0.30, in particular between 0.10 and 0.30, more particularly between 0.15 and 0.25, and especially between 0.15 and 0.20;

[0090] said aqueous lubricating composition comprising a content of antifreeze additive(s) selected from glycols, aliphatic monoethers of said glycols and polyhydric aliphatic alcohols, strictly less than 1% by mass, preferably less than or equal to 0.5% by mass, or even less than or equal to 0.1% by mass; the contents being indicated in relation to the total mass of said lubricating composition.

[0091] Additional additives The composition used in the present invention may further contain one or more additional additives, other than the polyalkylene glycols as described above and the antifreeze additives defined above.

[0092] It is understood that the said additional additive(s) are compatible with their use in an aqueous medium. Advantageously, the additives are used in a form that is soluble or emulsifiable in water, for example in the form of salts or ionic liquids.

[0093] Such additives may be more particularly chosen from among antifoaming agents, biocides, pH regulators, corrosion inhibitors, anti-wear and / or extreme-pressure additives, sequestering agents, metal passivating agents, colorants, dispersants, and mixtures thereof.

[0094] Advantageously, the composition used in the invention may include one or more additives selected from antifoaming agents, extreme-pressure agents, corrosion inhibitors, pH regulators, metal passivating agents, colorants, and mixtures thereof.

[0095] 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, notably from 5.0 to 13% by mass, relative to the total mass of the composition.

[0096] pH regulators The composition used in the present invention may include at least one pH-regulating additive, in particular an alkaline buffer. The pH regulator advantageously allows the desired pH of the lubricating composition to be maintained, particularly to preserve an alkaline pH, advantageously between 8 and 15.

[0097] 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 the metal surfaces, but also to promote the solubilization of the different compounds in the lubricating composition, in particular of the polyalkylene glycol(s).

[0098] The pH regulator can be chosen from the amine family, in particular al- canolamines and amino alcohols.

[0099] This may include a pH regulating additive selected from among the alkanolamines, such as dimethylethanolamine (DMEA), the ethanolamines, such as monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), the isopropanolamines, such as mono-isopropanolamine (MIPA), diisopropanolamine (DIPA) and triisopropanolamine (TIPA); diglycolamine (DGA); the ethylene amines, such as ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA) and tetraethylenepentamine (TEPA); the cyclamines, such as cyclohexylamine; 2-amino-2-ethyl-1,3-propanediol; 2-amino-2-methyl-1-propanol; and mixtures thereof.

[0100] The composition may include, in particular, 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.

[0101] Advantageously, the composition used in the invention comprises at least one pH regulating additive for maintaining 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 in particular selected from alkanolamines, preferably ethanolamines, and more particularly from dimethylethanolamine (DMEA), triethanolamine (TEA), diglycolamine (DGA) and mixtures thereof.

[0102] Corrosion inhibitors The composition used in the present invention may include at least one corrosion inhibitor. Corrosion inhibitors advantageously reduce or even prevent the corrosion of metal parts. The nature of the corrosion inhibitor(s) can be chosen according to the metal to be protected against corrosion, such as aluminum, steel, galvanized steel, or yellow metals, for example copper or brass.

[0103] Among the inorganic corrosion inhibitors that can be cited are nitrites, sulfites, silicates, borates, sodium, potassium, calcium or magnesium phosphates, alkali metal phosphates, hydroxides, molybdates, zinc, magnesium or nickel sulfates.

[0104] Among the organic corrosion inhibitors that may be cited are alkanolamines, such as triethanolamine, monocarboxylic aliphatic acids, in particular having 4 to 15 carbon atoms, for example octanoic acid, dicarboxylic aliphatic acids having 4 to 15 carbon atoms, for example decanedioic acid, undecanedioic acid, dodecanedioic acid or mixtures thereof, polycarboxylic acids possibly neutralized by triethanolamine, such as 1,3,5-triazine-2,4,6-tri-(6-aminocaproic acid), alcanoyllamidocarboxylic acids, in particular isononanoylamidocaproic acid, and mixtures thereof. Borated amides, products of the reaction of amines or amino alcohols with boric acid, can also be used.

[0105] Preferably, the corrosion inhibitor(s) are separate from the pH regulating additive(s), in particular allowing the pH of the composition to be maintained between 8 and 15 as defined previously.

[0106] The composition may include, in particular, 0.1% to 5% by mass of corrosion inhibitor(s), in particular as defined above, preferably 0.5% to 4% by mass, more preferably 1% to 2.5% by mass, relative to the total mass of the composition.

[0107] Anti-wear / extreme-pressure additive The composition used in the present invention may include 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-to-metal contact by forming a protective film adsorbed onto these surfaces.

[0108] There is a wide variety of anti-wear additives, among which can be cited those chosen from among the phosphosulfur additives such as metallic alkylthiophosphates or their salts.

[0109] Additives that do not provide phosphorus may also be suitable, such as, for example, polysulfides, in particular sulfur olefins.

[0110] According to a particular embodiment, an aqueous lubricating composition according to the invention may comprise at least one extreme-pressure additive selected from sulfur fatty acids and dimercaptothiadiazoles, preferably implemented in their neutralized form, in particular by inorganic alkalizing agents or alkanolamines, emulsifiable or soluble in water.

[0111] The composition may comprise less than 0.1% by mass of an extreme-pressure additive of the sulfur 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 may even be totally free of extreme-pressure additive of the sulfur fatty acid type.

[0112] Sulphur fatty acids may comprise from 8 to 22 carbon atoms, in particular from 12 to 18 carbon atoms.

[0113] The amount of sulfur according to ASTM D2622 provided by the said sulfur 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.

[0114] Preferably, the amount of active sulfur at 150°C according to 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.

[0115] For the purposes of this invention, "active sulfur" means the sulfur that a chemical compound is capable of donating or releasing when that compound is placed under the conditions of ASTM D-1662. ASTM D-1662 defines the active sulfur content of a compound at a given temperature as the difference, expressed as a percentage by weight, in sulfur content before and after reacting a sample of that sulfur compound with a given amount of copper for a fixed time.

[0116] As previously stated, the sulfur-containing fatty acid(s) are generally used 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.

[0117] The composition may include, in particular, 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.

[0118] Anti-foam The composition used in the present invention may include at least one antifoaming additive. Antifoams prevent the foaming of the lubricating fluid.

[0119] This could be, for example, an antifoaming agent based on polysiloxanes or acrylate polymers. Preferably, the antifoaming agent is chosen from among three-dimensional siloxanes.

[0120] Antifoaming agents can also be polar polymers such as polymethylsiloxanes or polyacrylates.

[0121] The composition may comprise from 0.001% to 3.0% by mass of antifoaming 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.

[0122] Metal passivating agents The composition used in the present invention may include at least one metal passivating agent. Metal passivating agents protect metal parts by promoting the formation of metal oxide on their surface.

[0123] Metal passivating agents may, for example, be selected from triazole derivatives, such as tetrahydrobenzotriazole (THBTZ), tolyltryazole (TTZ), benzotriazole (BTZ), amines substituted with a triazole group, such as N,N-bis(2-ethylhexyl)-1,2,4-triazol-1-yl methanamine, N'-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,N-bis(2-ethylhexyl)-ar-methyl-1H-benzotriazole-1-methanamine, 1,2,4-triazoles, benzimidazoles, 2-alkyldithiobenzimidazoles, 2-alkyldithiobenzothiazoles, 2-(N,N-dialkyldithiocarbamoyl)benzothiazoles, 2,5-bis(alkyldithio)-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)-1,3,4-thiadiazole, 2,5-bis(tert-dodecyldithio)-1,3,4-thiadiazole, 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, 2,5-bis(tert-heptadecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-octadecyldithio)-1,3,4-Thiadiazole, 2,5-bis(tert-nonadecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-eicosyldithio)-1,3,4-thiadiazole, 2,5-bis(N,N-dialkyldithiocarbamoyl)-1,3,4-thiadiazoles, 2-alkyldithio-5-mercaptothiadiazoles, and mixtures thereof.

[0124] Preferably the metal passivating agents are chosen from tetrahydrobenzo-triazole (THBTZ), tolyltriazole (TTZ), benzotriazole (BTZ), and their salts, taken alone or in mixtures.

[0125] The composition may include, in particular, 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.

[0126] Dyes The composition used in the present invention may comprise one or more colorants. The colorants may be natural or synthetic, generally organic.

[0127] The colorants that can be used in an aqueous lubricating 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 (enocianin, black carrot and hibiscus), caramel and riboflavin.

[0128] An aqueous lubricating composition implemented 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.

[0129] Seizing agents The composition used in the present invention may include at least one sequestering agent. Sequestering agents, also called chelating agents, limit the encrustation of metal ions in the composition.

[0130] Examples of sequestering agents include those derived from phosphoric acids and phosphonates, such as diethylenetriaminepentamethyl phosphoric acid (DTPMPA), aminotri(methylenephosphonic) acid (ATMP), hydroxyethane diphosphonic acid (HEDP), 1,1-hydroxyethylidene diphosphonate, 2-hydroxyethylamine di(methylenephosphonic) acid (HEAMBP), diethylenetriaminopenta(methylenephosphonic) acid (DTMP), multifunctional organic acids and hydroxylated 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 rinulin, the carboxymethylinulin and carboxymethylchitosan.

[0131] 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.

[0132] Biocides and fungicides The composition used in the present invention may include at least one biocidal and / or fungicidal agent. Biocides and fungicides may be used to improve the biological stability of the composition by limiting the growth of bacteria, fungi, and yeasts in the lubricating fluid.

[0133] Such biocides may be selected from parabens, aldehydes, reactive acetylacetone compounds, isothiazolinones, phenolic compounds, acid salts, halogenated compounds, quaternary ammonium compounds, certain alcohols and mixtures thereof.

[0134] Preferably, the biocides may be selected from among the benzisothiazolinones (BIT), possibly substituted, such as N-butyl-1,2-benzisothiazolin-3-one, the methylisothiazolinones (MIT), mixtures of methylisothiazolinone and chloromethylisothiazolinone (MIT / CMIT), orthophenylphenol (OPP) or its sodium salt, 3-iodo-2-propynylbutylcarbamate (IPBC), chlorocresol, and N,N-methylene-bis-morpholine (MBM); sorbic acid; preferably among orthophenyl-phenol (OPP) or its sodium salt, 3-iodo-2-propynylbutylcarbamate, chloro-cresol, benzisothiazolinones and N,N-methylene-isomorpholine.

[0135] The composition may include, in particular, 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.

[0136] The use 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 at least on hydrogen and / or ammonia.

[0137] Advantageously, said composition is used to reduce friction between moving parts within a hydrogen and / or ammonia internal combustion engine. It is also used to reduce wear on said parts. The internal combustion engine part(s) lubricated by means of the aqueous lubricant composition are advantageously selected from: pistons, piston rings, cylinders, connecting rods, piston pins, bearings, crankshafts, oil pumps, turbochargers, camshafts, and valve train systems (including, in particular, cams, tappets, rocker arms, and oil pump).

[0138] 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.

[0139] In a manner known per se, a gas turbine, also called a combustion turbine, is a rotating thermodynamic machine of the family of internal combustion engines and which can be used for propulsion, electricity production, or as a stationary engine (for example to drive pumps, compressors,...).

[0140] Preferably, the internal combustion engine composition is a piston engine.

[0141] The present invention applies to any known piston engine, including on-board and stationary engines. The invention applies in particular to marine engines, heavy-duty engines, construction equipment engines, and agricultural engines such as tractors, public transport vehicles (buses, trains, etc.), as well as to engines for light vehicles such as cars, engines used in aeronautical or space propulsion (airplanes, rockets), and engines used in stationary industrial applications.

[0142] The piston engine can in particular be chosen from among compression-ignition engines or Diesel engines, spark-ignition engines, dual-fuel engines.

[0143] According to a first preferred embodiment, the engine is an ignition engine controlled by hydrogen, or hydrogen engine.

[0144] According to a second embodiment, the engine is a compression-ignition engine or ammonia-fueled diesel engine, or ammonia engine. Use in a marine engine (i.e., a compression-ignition engine used for ship propulsion) is particularly preferred.

[0145] According to an advantageous embodiment of this design, the compression-ignition engine is a dual-fuel engine. In this application, ammonia powers 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 can be selected from petroleum-based fuels, particularly diesel and fuel oils of varying weights, bio-based fuels (especially those derived from biomass), and mixtures of these two types of fuels. According to a preferred embodiment, the hydrocarbon fuel is selected from heavy fuel oil-based fuels (such as marine fuels), bio-based fuels, and mixtures thereof.

[0146] 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 auto-ignition of a mixture of air and a small quantity of fuel, called pilot injection. Ammonia is injected mixed with air to supply the combustion. The pilot injection generally represents less than 10% by mass of the total mass of fuel (ammonia and second fuel) consumed, typically around 5% by mass of the total mass of fuel consumed.

[0147] In a particularly preferred manner, the mixed-carburetion compression-ignition engine is a marine engine, that is to say, a mixed-carburetion diesel engine equipping a ship.

[0148] The methods The present invention also relates to a method of lubricating moving parts in a motorization system including an internal combustion engine powered by at least one non-hydrocarbon fuel selected from hydrogen and ammonia, comprising a step of bringing at least one of said parts into contact with a composition as defined above.

[0149] The invention also relates to a method of operating a mobile or stationary propulsion system, including an internal combustion engine, consisting of supplying said engine with at least one non-hydrocarbon fuel selected from hydrogen and ammonia and lubricating at least one part of said propulsion system by means of an aqueous lubricating composition as defined below. Before.

[0150] The engine part(s) are advantageously selected from pistons, rings, cylinders, connecting rods, piston pins, bearings, crankshafts, oil pumps, turbochargers, camshafts, distribution systems (including in particular cams, tappets, rocker arms, oil pump).

[0151] The engine can be any internal combustion engine, including but not limited to those described above.

[0152] Preferably, the internal combustion engine is chosen from among compression-ignition engines and gas turbines (or combustion turbines).

[0153] According to a first preferred embodiment, the engine is a hydrogen-powered spark-ignition engine.

[0154] 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 with another fuel other than ammonia, preferably a hydrocarbon fuel as described above.

Claims

Claims

1. Use for lubricating a powertrain 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 least 10% by mass, relative to the total mass of said composition, of one or more polyalkylene glycol(s) with a weight-average molar mass, Mw, of at least 1500 g.mol *; said composition having a content of antifreeze additive(s) chosen from glycols, aliphatic monoethers of said glycols and polyhydric aliphatic alcohols, strictly less than 1% by mass, relative to the total mass of the composition.

2. Use according to the preceding claim, characterized in that the water content of the composition ranges from 15 to 85% by mass, preferably from 20 to 80% by mass, more preferably from 30 to 70% 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 polyalkylene glycol(s) have a weight-average molar mass of at least 2000 g.mol *, in particular at least 2500 g.mol *, in particular at least 3000 g.mol *, and more particularly between 3000 and 50,000 g.mol *, in particular between 5000 and 25,000 g.mol *, preferably between 5,000 and 15,000 g.mol *.

4. 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, and preferably the polyalkylene glycol(s) consist of propylene oxide and / or ethylene oxide units.

5. Use according to any one of the preceding claims, characterized in that the composition contains from 15 to 50% by mass of said polyalkylene glycol(s), preferably from 15 to 30% by mass and more preferably from 16 to 20% by mass, relative to the total mass of the composition.

6. Use according to any one of the preceding claims, characterized in that the assembly consisting of water and said poly- alkylene glycol(s) represents more than 80% of the total mass of the composition.

7. Use according to any one of the preceding claims, characterized in that the content of the composition in antifreeze additives chosen from glycols, aliphatic monoethers of said glycols and polyhydric aliphatic alcohols is less than or equal to 0.5% by mass, preferably less than or equal to 0.1% 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. A method of 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 of operating a mobile or stationary power system, 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 power system by means of a composition such as defined in any one of claims 1 to 8.