Use of a composition of additives for reducing diesel vehicle emissions

Abstract

The present invention relates to the use of a composition of additives for reducing emissions of nitrogen oxides and of at least one type of pollutant selected from carbon monoxide and hydrocarbons which are unburnt during the combustion of a liquid fuel in a compression-ignition internal combustion engine, said composition comprising: (i) one or more additive(s) selected from compounds having at least one alkylphenol group in their structure; and (ii) one or more additives which improve the cetane number, selected from alkyl nitrates, aryl peroxides and alkyl peroxides; wherein the weight ratio of the amount of additive(s) (i) to the amount of additive(s) (ii) is within the range from 1:3 to 3:1. The present invention also relates to a method for reducing emissions of nitrogen oxides and of at least one type of pollutant selected from carbon monoxide and hydrocarbons which are unburnt during the combustion of a liquid fuel in a compression-ignition internal combustion engine which employs this composition of additives.

Description

[0001] The present invention relates to the use of a composition of particular additives for reducing pollutant emissions from vehicles equipped with compression ignition engines or Diesel engines.

[0002] The present invention also relates to a process or method for reducing pollutant emissions from vehicles equipped with compression ignition engines or diesel engines, using this composition of additives in a fuel. STATE OF THE PRIOR ART

[0003] European and global pollution standards applicable to both light and heavy vehicles have imposed increasingly strict constraints on the emission levels of vehicles equipped with compression ignition engines (diesel engines).

[0004] As is well known, because the combustion of fuel in a reciprocating engine is imperfect, these engines emit polluting compounds of various types during the combustion cycles. In particular, there are four regulated pollutants: three gases (carbon monoxide, nitrogen oxides and unburned hydrocarbons) and solid particles. Carbon monoxide (CO) is a toxic gas by inhalation that can be fatal at certain concentrations, nitrogen oxides (NOx) are often associated with local urban pollution problems and unburned hydrocarbons are the result of the incomplete combustion of certain compounds. Solid particles also come from the incomplete combustion of the fuel, starting from carbon-rich compounds (such as aromatics) on which other compounds condense to form solid soot.

[0005] Modern requirements for reducing and controlling these emissions have led engine and vehicle manufacturers to implement exhaust gas aftertreatment systems at the engine outlet. These aftertreatment systems include various technologies, including: selective catalytic reduction devices known as SCR (Selective Catalytic Reduction), which reduce nitrogen oxides NO and NO 2 (commonly called NOx) on a catalytic device in which they are brought into contact with a reducing agent, "NOx trap" (LNT) devices which act by adsorption of NOx then reduction when the conditions are met (operation in a rich mixture); exhaust gas recirculation devices known as EGR (Exhaust Gas Recirculation), and particulate filter type devices commonly called FAP. We can also mention the so-called SCRoF (SCR on Filter) or SCRF or SDPF systems which combine, within a single element, the functions of NOx reduction by SCR and particle filtration.These various exhaust gas post-treatment devices can be installed alone or in combination, as they do not always act on the same pollutants present in the exhaust gases.

[0006] Thus, solutions to the problem of reducing vehicle pollutant emissions have been sought primarily from manufacturers. However, it should be noted that the actual emission levels of even the most recent vehicles, subjected to the strictest new tests following Dieselgate, are not zero. Similarly, it has been shown that this type of vehicle can still emit high levels of pollutants under certain real-world driving conditions (very urban) or depending on the type of pollution control system (IFPEN study for the Ministry of Ecological Transition at the end of 2020 on Euro 6D-Temps vehicles). The studies have also shown that for older vehicles, actual emission levels can be significantly higher than those expected outside the previous European approval cycle (NEDC).It may therefore be particularly interesting to lower actual emission levels beyond the treatments carried out in vehicles.

[0007] We also know of the use of various types of additives in the fuels used in these engines. These additives are chemical compounds that are incorporated in small quantities into fuels in order to improve their intrinsic performance. Examples include cold-holding additives (aimed at improving fuel performance at low temperatures), deposit-reducing additives (aimed at reducing the fouling effect of fuels in engines during combustion), procetane additives (aimed at increasing the cetane number and therefore the energy performance of fuels), etc.

[0008] However, additive manufacturers have done little to address the issue of controlling pollutant emissions. On the contrary, additives are generally considered to have little or no impact on pollutant emissions.

[0009] Thus, the publication entitled "The characteristics of performance and exhaust emissions of a diesel engine using a biodiesel with antioxidants", Bioresource Technology 101 (2010), S78-82, reports the results of a study on the effect on oxidation stability, engine performance and pollutant emissions of known antioxidant additives (in particular compounds with an alkyl-phenol group) in biodiesel-based fuels. The authors conclude that these additives have very little effect on emissions.

[0010] Furthermore, pollutants are often treated individually, meaning that a given technology can only reduce one type of pollutant, for example NOx, and not others (for example carbon monoxide, particles, unburned hydrocarbons, etc.). Different technologies must therefore be juxtaposed to meet regulatory requirements.

[0011] SAE publication 2000-01-1853, for example, provides information on the CO and HC benefit associated with the use of procetane but reveals a slight increase in NOx. SAE publication 2009-01-2697 studies the impact of cetane index on a Cummins 6.7L engine and confirms an increase in NOx associated with high cetane indexes (adjusted by the use of procetane).

[0012] There is therefore still a need to develop comprehensive solutions that address pollutant emissions more comprehensively. These solutions must be compatible with existing solutions. They must be effective, regardless of the engine technology, the actual effectiveness of the aftertreatment system and / or the nature of the fuel, particularly its origin (petroleum and / or bio-sourced). These solutions must also not be provided to the detriment of the other expected properties associated with the use of performance additives in high-quality fuels (engine cleanliness, anti-corrosion, anti-foam, etc.), which must be maintained.

[0013] US 5976201 A describes a diesel fuel composition that produces low levels of emissions, particularly such as CO, NOx, unburned hydrocarbons and particulates. SUBJECT OF THE INVENTION

[0014] The Applicant has now discovered that the use of a particular additive composition, based on the combination of an alkyl-phenol group additive with a procetane additive in well-defined proportions, exhibited significant and unexpected effectiveness in reducing pollutant emissions from fuels used in Diesel engines, and provided a simultaneous reduction effect on at least two types of pollutants including the four main types of pollutants, namely nitrogen oxides (NOx), carbon monoxide (CO), unburned hydrocarbons and solid particles.

[0015] The present invention thus relates to the use, for reducing the emissions of nitrogen oxides and at least one type of polluting agent chosen from carbon monoxide and unburned hydrocarbons during the combustion of a liquid fuel in a compression-ignition internal combustion engine, of an additive composition comprising: (i) one or more additives chosen from compounds having in their structure at least one alkyl-phenol group; (ii) one or more cetane index improving additives chosen from alkyl-nitrates, aryl peroxides and alkyl peroxides; and (iii) one or more deposit reducing additive(s) different from compounds (i) and (ii); wherein the mass ratio of the quantity of additive(s) (i) to the quantity of additive(s) (ii) is in the range from 1:3 to 3:1.

[0016] The incorporation of this additive composition into a diesel engine fuel makes it possible to obtain a significant reduction in the levels of pollutant emissions compared to the same fuel not containing these additives. Particularly unexpectedly, the reduction is obtained simultaneously for several types of pollutant agents including at least nitrogen oxides, carbon monoxide and / or unburned hydrocarbons.

[0017] According to a preferred embodiment, the invention makes it possible to simultaneously reduce emissions of nitrogen oxides, carbon monoxide and unburned hydrocarbons.

[0018] According to a particularly preferred embodiment, the invention makes it possible to further reduce emissions of solid particles.

[0019] The additive composition according to the invention is effective in the different types of fuels intended for diesel engines, also called gas oils, whether of petroleum origin or not, including fuels derived in whole or in part from biomass.

[0020] It also provides the properties required for diesel fuel, and maintains excellent performance levels in terms of engine and injector cleanliness, cetane index, anti-foam and anti-corrosion performance in particular.

[0021] The invention also relates to a process or method for reducing emissions of nitrogen oxides and at least one type of polluting agent chosen from carbon monoxide and unburned hydrocarbons during the combustion of a liquid fuel in a compression-ignition internal combustion engine, comprising the addition to said fuel of an additive composition as defined above.

[0022] Other objects, characteristics, aspects and advantages of the invention will appear even more clearly on reading the description and examples which follow.

[0023] In what follows, and unless otherwise indicated, the limits of a domain of values ​​are included in this domain, in particular in the expressions "between" and "ranging from ... to ...".

[0024] 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”.

[0025] 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. DETAILED DESCRIPTION

[0026] The present invention is described in and by the appended claims. Alkyl phenol compounds:

[0027] The invention uses as additive (i) one or more compound(s) having in their structure at least one alkyl-phenol group.

[0028] This means that this or these compounds have in their formula at least one phenolic nucleus (i.e. a benzene nucleus substituted by one or more hydroxyl -OH groups) substituted by one or more alkyl groups.

[0029] According to a first embodiment, the additive(s) (i) are chosen from compounds (i)a) comprising one or two phenolic nuclei substituted by one or more alkyl groups chosen from methyl and t-butyl (or tert-butyl) groups.

[0030] These compounds (i)a) may more particularly be chosen from methyl-t-butyl phenols, dimethyl-t-butyl phenols, ethyl-t-butyl phenols, t-butyl phenols, di-t-butyl phenols, tri-t-butyl phenols, di-t-butyl-di-methyl phenols, and mixtures thereof.

[0031] Preferred compounds are selected from 2,6-di-t-butyl-4-methylphenol (BHT), 4,6-di-tert-butyl-2-methylphenol, t-butyl hydroquinone (TBHQ), 2,6 and 2,4 di-t-butyl phenol, 2,4-dimethyl-6-t-butyl phenol, 2,4,6-tri-t-butyl phenol, 2,3,6-trimethyl phenol, 2,4,6-trimethyl phenol, 4,4'-methylene bis (2,6-di-t-butyl phenol) (CAS No. 1 18-82-1), alone or in mixture.

[0032] Particularly preferred compounds are chosen from (di)tert-butyl phenols, methyl-tert-butylphenols and di-methyl-tert-butylphenols, their mixtures, and their two-by-two condensation products, such as in particular 2,6-di-t-butyl-4-methyl phenol (BHT), 2,4-dimethyl-6-t-butyl phenol, 2,5-dimethyl-4-t-butyl phenol, 2,6 and 2,4 di-t-butyl phenol, 2,4,6-tri-t-butyl phenol, their mixtures, and their two-by-two condensation products.

[0033] According to a second embodiment, the additive(s) (i) are chosen from modified alkylphenol-aldehyde resins (i)b) capable of being obtained by Mannich reaction of an alkylphenol-aldehyde condensation resin: with at least one aldehyde and / or ketone having from 1 to 8 carbon atoms, preferably from 1 to 4 carbon atoms; and at least one hydrocarbon compound having at least one alkylpolyamine group, having between 1 and 30 carbon atoms, preferably between 4 and 30 carbon atoms, said alkylphenol-aldehyde condensation resin itself being capable of being obtained by condensation: of at least one alkylphenol substituted by at least one alkyl group, linear or branched, having from 1 to 30 carbon atoms, preferably a monoalkylphenol, with at least one aldehyde and / or a ketone having from 1 to 8 carbon atoms, preferably from 1 to 4 carbon atoms.

[0034] The alkylphenol-aldehyde condensation resin can be chosen from any resin of this type already known and in particular those described in documents EP857776, EP1584673.

[0035] The modified alkylphenol-aldehyde resins according to the invention are advantageously obtained from at least one alkylphenol substituted in the para position. Nonylphenol is preferably used.

[0036] The average number of phenolic nuclei per molecule of nonylphenol-aldehyde resin is advantageously in the range from 6 to 25, preferably from 8 to 17, and more preferably from 9 to 16.

[0037] The number of phenolic nuclei can be determined by nuclear magnetic resonance (NMR) or gel permeation chromatography (GPC).

[0038] Advantageously, the modified alkylphenol-aldehyde resins are obtained by using the same aldehyde or the same ketone in both stages of its preparation.

[0039] The modified alkylphenol-aldehyde resins may be obtained from at least one aldehyde and / or ketone selected from formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, 2-ethyl-hexanal, benzaldehyde and / or acetone. Preferably, the modified alkylphenol-aldehyde resin is obtained from at least one aldehyde, preferably at least formaldehyde (or methanal).

[0040] Preferably, the modified alkylphenol-aldehyde resins are capable of being obtained from p-nonylphenol, formaldehyde and at least one hydrocarbon compound comprising at least one alkylpolyamine group.

[0041] Said hydrocarbon compound may be an alkylpolyamine having at least two primary and / or secondary amine groups. In particular, the alkylpolyamine is advantageously chosen from primary or secondary polyamines substituted by, respectively, one or two alkyl groups preferably comprising from 12 to 24 carbon atoms, more preferably from 12 to 22 carbon atoms.

[0042] Preferably, the modified alkylphenol-aldehyde resin is obtained from at least one alkylpolyamine having at least two primary amine groups, preferably three primary amine groups.

[0043] In particular, the modified alkylphenol-aldehyde resin can advantageously be obtained from at least one alkylpolyamine in which all the amine groups are primary amines.

[0044] Preferably, the modified alkylphenol-aldehyde resin is obtained from at least one alkylpolyamine comprising at least one fatty chain having from 12 to 24 carbon atoms, preferably from 12 to 22 carbon atoms.

[0045] A particularly preferred alkylpolyamine is tallow dipropylenetriamine.

[0046] Commercial alkylpolyamines are generally not pure compounds but mixtures. Suitable commercially available alkylpolyamines include fatty chain alkylpolyamines marketed under the names Trinoram ®< , Duomeen ®< , Dinoram ®< , Triameen ®< , Armeen ®< , Polyram ®< , Lilamin ®< and Cemulcat ®< .

[0047] A preferred example is Trinoram ®< S, which is a tallow dipropylenetriamine, also known as N-(Tallowalkyl)dipropylenetriamine (CAS 61791-57-9).

[0048] It is of course possible to combine the two embodiments and to use a combination of compounds (i)a) and (i)b) as described above.

[0049] Thus, according to a preferred embodiment, the additive composition comprises one or more compounds (i)a) comprising one or two phenolic nuclei substituted by one or more alkyl groups chosen from methyl and t-butyl groups, and one or more modified alkylphenol-aldehyde resins (i)b). Cetane index improving additives:

[0050] The invention uses as additives (ii) one or more cetane index improving additives, also known as procetane additives or cetane booster additives.

[0051] The additive(s) (ii) are chosen from alkyl nitrates and aryl or alkyl peroxides.

[0052] Aryl peroxides include benzyl peroxide. Alkyl peroxides include tert-butyl peroxide.

[0053] The additive(s) (ii) are preferably chosen from alkyl nitrates, and more preferably those of formula R-NO 3 with R an alkyl radical comprising from 2 to 12 carbon atoms, preferably from 4 to 8 carbon atoms.

[0054] A particularly preferred additive (ii) is ethyl hexyl nitrate. The composition of additives

[0055] The additive composition used in accordance with the present invention is characterized in that the mass ratio of the quantity of additive(s) (i) to the quantity of additive(s) (ii) is in the range from 1:3 to 3:1.

[0056] Preferably, the mass ratio of the quantity of additive(s) (i) to the quantity of additive(s) (ii) is in the range from 1:2.5 to 2.5:1, preferably from 1:2 to 2:1 and more preferably from 1:1 to 1.5:1. Deposit reducing additives

[0057] The additive composition used in accordance with the present invention comprises one or more detergency additive(s) (iii), also called deposit reducing additive(s), different from the compounds (i) having in their structure at least one alkyl-phenol group and the cetane number improving additives (ii) described above, and which may be chosen from the detergency additives for diesel fuels commonly used. The latter are compounds well known to those skilled in the art.

[0058] The deposit-reducing additives may be chosen in particular (but not limited to) from the group consisting of amines, succinimides, alkenylsuccinimides, polyalkylamines, polyalkyl polyamines, polyetheramines, quaternary ammonium salts, and triazole derivatives, and more preferably from quaternary ammonium salts, and polyisobutylene mono- or polyamines (or PIB-amines), even more preferably from polyisobutylene succinimide (substituted or not by a triazole group), or quaternary ammonium salts and better still from polyisobutylene succinimides functionalized by a quaternary ammonium group, fatty acid amides functionalized by a quaternary ammonium group and their dimers such as di-(alkylamido-propyl-quaternary ammonium) compounds. described for example in European patent application No. 18306589.5, fatty chain alkylamidoalkyl betaines and triazole derivatives. Particularly preferred are polyisobutylene succinimides functionalized with a quaternary ammonium group and polyisobutylene succinimides functionalized with a triazole group.

[0059] Examples of deposit reducing additives are given in the following documents: EP0938535, US2012 / 010112, WO2012 / 004300, US4171959 and WO2006 / 135881.

[0060] Block copolymers formed from at least one polar unit and one apolar unit may also be used, such as, for example, those described in patent application FR 1761700 in the name of the Applicant.

[0061] According to one embodiment, the additive composition comprises at least one deposit-reducing additive consisting of a quaternary ammonium salt, obtained by reaction with a quaternization agent of a nitrogen compound comprising a tertiary amine function, this nitrogen compound being the product of the reaction of an acylating agent substituted by a hydrocarbon group and of a compound comprising at least one tertiary amine group and at least one group chosen from primary amines, secondary amines and alcohols. Preferably, said nitrogen compound is the reaction product of a succinic acid derivative substituted by a hydrocarbon group, preferably a polyisobutenyl succinic anhydride, and of an alcohol or of a primary or secondary amine also comprising a tertiary amine group.Such deposit-reducing additives, as well as preferred combinations of deposit-reducing additives comprising them, are described in particular in patent application WO 2015 / 124584 in the name of the applicant.

[0062] When the additive composition contains one or more deposit-reducing additive(s), preferably the ratio between the total weight content of compounds (i) having in their structure at least one alkyl-phenol group on the one hand and the total weight content of deposit-reducing additive(s) (iii) on the other hand ranges from 1:60 to 1:2, preferably from 1:20 to 1:3.

[0063] Preferably, the total content of deposit reducing additive(s) (iii) in the fuel ranges from 5 to 5,000 ppm by weight, preferably from 10 to 1,000 ppm by weight, and more preferably from 20 to 500 ppm by weight, relative to the total weight of the fuel. Other additives

[0064] The additive composition may also comprise other additives, in addition to the compound(s) (i) having in their structure at least one alkyl-phenol group, the cetane index improving additives (ii) described above, and the deposit reducing additive(s) (iii) described above.

[0065] This or these other additives may be chosen, for example, in a non-limiting manner, from anti-corrosion additives, dispersant additives, demulsifying additives, anti-foaming agents, biocides, reodorants, friction modifiers, lubricity additives or smoothness additives, combustion aid agents (catalytic combustion and soot promoters), cold resistance additives and in particular agents improving the cloud point, the pour point, the TLF (“Filtrability Limit Temperature”), anti-sedimentation agents, anti-wear agents, tracers, solvents / carrier oils and conductivity modifying agents.

[0066] Among these additives, we can cite for example: a) anti-foam additives, in particular (but not limited to) chosen from polysiloxanes, oxyalkylated polysiloxanes, and fatty acid amides derived from vegetable or animal oils. Examples of such additives are given in EP861882, EP663000, EP736590; b) Cold flow improvers (CFIs) selected from ethylene and unsaturated ester copolymers, such as ethylene / vinyl acetate (EVA), ethylene / vinyl propionate (EVP), ethylene / vinyl ethanoate (EVE), ethylene / methyl methacrylate (EMMA), and ethylene / alkyl fumarate copolymers described, for example, in documents US3048479, US3627838, US3790359, US3961961 and EP261957; c) lubrication additives or anti-wear agents, in particular (but not limited to) selected from the group consisting of fatty acids and their ester or amide derivatives, in particular glycerol monooleate, and mono- and polycyclic carboxylic acid derivatives.Examples of such additives are given in the following documents: EP680506, EP860494, WO98 / 04656, EP915944, FR2772783, FR2772784; d) cloud point additives, in particular (but not limited to) selected from the group consisting of long-chain olefin / (meth)acrylic ester / maleimide terpolymers, and fumaric / maleic acid ester polymers. Examples of such additives are given in FR2528051, FR2528051, FR2528423, EP112195, EP172758, EP271385, EP291367; e) polyfunctional cold operability additives selected from the group consisting of olefin and alkenyl nitrate based polymers as described in EP573490; f) anti-corrosion additives such as for example fatty acid ester dimers and aminotriazoles.

[0067] These additional additives may be present in an amount ranging from 5 to 1,000 ppm (each), preferably from 50 to 500 ppm by weight, relative to the total weight of the fuel.

[0068] The additive composition may advantageously comprise an organic solvent, which may for example be chosen from aromatic hydrocarbon solvents such as the solvent sold under the name “SOLVESSO”, alcohols, ethers and other oxygenated compounds, and paraffinic solvents such as hexane, pentane or isoparaffins, including hydrotreated vegetable oils known as HVO, alone or as a mixture.

[0069] According to a preferred embodiment, the additive composition comprises at least one solvent chosen from alcohols. Particularly advantageously, the additive composition contains at least one C1 to C8 monoalcohol, and preferably chosen from ethanol and ethyl-2-hexanol. Liquid fuel

[0070] The use of the additive composition according to the invention applies to a fuel in liquid form at room temperature (20°C) and atmospheric pressure (1,013.10 5< Pa). This fuel is intended to power a Diesel engine.

[0071] Such a fuel typically comprises at least one liquid hydrocarbon cut from one or more sources selected from the group consisting of mineral sources, animal, vegetable and synthetic sources.

[0072] The fuel is advantageously chosen from hydrocarbon fuels and non-essentially hydrocarbon fuels, and mixtures thereof.

[0073] Hydrocarbon fuel means a fuel consisting of one or more compounds consisting solely of carbon and hydrogen.

[0074] A non-essentially hydrocarbon fuel is understood to mean a fuel consisting of one or more compounds consisting not essentially of carbon and hydrogen, i.e. which also contain other atoms, in particular oxygen atoms.

[0075] Hydrocarbon fuels include in particular middle distillates with boiling temperatures ranging from 100 to 500°C. These distillates may, for example, be chosen from distillates obtained by direct distillation of crude hydrocarbons, vacuum distillates, hydrotreated distillates, distillates resulting from catalytic cracking and / or hydrocracking of vacuum distillates, distillates resulting from ARDS (atmospheric residue desulfurization) and / or visbreaking conversion processes, distillates resulting from the recovery of Fischer Tropsch cuts, biodiesels such as distillates resulting from BTL (biomass to liquid) conversion of plant and / or animal biomass and hydrotreated vegetable oils known to those skilled in the art under the name HVO (hydrotreated vegetable oil) or HDRD (hydrogenation-derived renewable diesel).Hydrocarbon fuels are typically gas oils (also called diesel fuels).

[0076] Diesel fuels include, in particular, all commercially available diesel engine fuel compositions. Examples include diesel fuels meeting the NF EN 590 standard.

[0077] Non-essentially hydrocarbon fuels include in particular vegetable and / or animal oils and / or esters of oils.

[0078] Mixtures of hydrocarbon fuel and non-primarily hydrocarbon fuel are typically type B x diesel fuels.

[0079] Diesel type B x is defined as a diesel fuel containing x% (v / v) of vegetable or animal oil esters (including used cooking oils) transformed by a chemical process called transesterification, obtained by reacting this oil with an alcohol to obtain fatty acid esters (FAE). With methanol and ethanol, fatty acid methyl esters (FAME) and fatty acid ethyl esters (FAE) are obtained, respectively. The letter "B" is followed by a number x greater than zero and less than or equal to 100, which indicates the percentage of FAE contained in the diesel. Thus, a B99 contains 99% FAE and 1% middle distillates of fossil origin (mineral source), B20, 20% FAE and 80% middle distillates of fossil origin, etc.We therefore distinguish between type B 0 diesel fuels which do not contain oxygenated compounds, and type Bx diesel fuels which contain x% (v / v) of vegetable oil or fatty acid esters, most often methyl esters (EMHV or EMAG), x designating a number ranging from 0 to 100. When EAG is used alone in engines, the fuel is designated by the term B 100.

[0080] According to a preferred embodiment, the fuel is chosen from diesel fuels, biodiesels, type B diesel fuels x containing x% (v / v) of vegetable or animal oil esters with x a number greater than zero and less than or equal to 100, hydrotreated vegetable oils (HVO), and mixtures thereof.

[0081] According to a particularly preferred embodiment, the fuel is chosen from type B diesels x containing x% (v / v) of vegetable or animal oil esters with x a number greater than zero and less than or equal to 100. The vegetable oil esters are particularly chosen from fatty acid methyl esters (FAME) and fatty acid ethyl esters (FAE).

[0082] The sulfur content of the fuel is preferably less than or equal to 1000 ppm, preferably less than or equal to 500 ppm, and more preferably less than or equal to 50 ppm, or even less than 10 ppm and advantageously sulfur-free. The use

[0083] The additive composition according to the invention is used to reduce the emissions of nitrogen oxides as well as carbon monoxide and / or unburned hydrocarbons during the combustion of a liquid fuel in a compression-ignition internal combustion engine. Preferably, the use is also aimed at reducing particulate emissions.

[0084] This means that the incorporation of the additive composition according to the invention into the liquid fuel produces an effect of reducing the emissions of nitrogen oxides as well as carbon monoxide and / or unburned hydrocarbons at the outlet of compression ignition engines powered by said fuel, compared to the same fuel not comprising the composition according to the invention. Preferably, the reducing effect is produced for the three types of emissions, namely nitrogen oxides, carbon monoxide and unburned hydrocarbons. Preferably, the reducing effect is also produced for particulate emissions.

[0085] According to a first preferred embodiment, the compression ignition engine or Diesel engine is a hybrid Diesel engine or a direct injection Diesel engine, preferably a direct injection Diesel engine and in particular a Diesel engine with a Common-Rail injection system (CRDI in English "Common Rail Direct Injection").

[0086] According to a second preferred embodiment, the compression ignition engine or diesel engine is a marine engine.

[0087] The emission levels of nitrogen oxides, carbon monoxide, unburned hydrocarbons and particles are measured in accordance with the methods defined in European regulation ECE-R83.05.

[0088] This regulation defines a harmonized test procedure for vehicle approval in Europe and the measurement of different types of emissions. This regulation is defined with reference to a standardized test called WLTP (World Harmonized Light Duty Test Procedure), which is a globally harmonized test procedure. This test involves measuring the emissions of a standardized vehicle (Euro 6) during a defined test cycle called WLTC (World Harmonized Light Duty Test Cycle), using high-precision emissions analyzers.

[0089] The additive composition is advantageously used in such a quantity that: the total mass quantity of additives (i) ranges from 10 to 2000 ppm by weight, preferably from 20 to 1000 ppm by weight, more preferably from 50 to 500 ppm by weight and better still from 200 to 400 ppm by weight, relative to the total weight of the fuel; the total mass quantity of additives (ii) ranges from 10 to 1500 ppm by weight, preferably from 20 to 1000 ppm by weight, more preferably from 50 to 500 ppm by weight and better still from 150 to 400 ppm by weight, relative to the total weight of the fuel.

[0090] The use according to the invention is compatible with existing exhaust gas post-treatment devices, and makes it possible to further reduce the levels of pollutants emitted by vehicles equipped with such devices and / or to extend the service life of this equipment and / or to space out maintenance operations on this equipment.

[0091] Thus, according to a particularly advantageous embodiment, the compression ignition engine is equipped with one or more exhaust gas post-treatment devices, preferably chosen from selective catalytic reduction devices known as SCR, exhaust gas recirculation devices known as EGR, particulate filter type devices commonly called FAP, and so-called SCRoF (SCR on Filter) or SCRF or SDPF devices which combine, within the same device, the functions of selective catalytic reduction and particle filtration. The process or method

[0092] The process or method for reducing emissions of nitrogen oxides and at least one type of polluting agent chosen from carbon monoxide and unburned hydrocarbons during the combustion of a liquid fuel in a compression-ignition internal combustion engine, consists of adding to said fuel composition an additive composition as described above.

[0093] Preferably, the method is a method for reducing emissions of nitrogen oxides, carbon monoxide and unburned hydrocarbons. According to a particularly preferred embodiment, it further reduces emissions of solid particles.

[0094] The additives constituting the additive composition may be incorporated into the liquid fuel within a refinery and / or be incorporated downstream of the refinery, either separately or as a mixture, and in this case possibly in dispersion in an organic solvent, in particular in the form of an additive package.

[0095] The combustion of the fuel thus added in the internal combustion engine produces an effect on the reduction of emissions of nitrogen oxides, carbon monoxide and particles measured according to the methods described previously in the context of use. This results in a simultaneous reduction of the different types of pollutants.

[0096] The above description of the additive composition, fuels and its use in fuels powering a compression ignition engine applies entirely to the process or method according to the invention.

[0097] The following examples are given as illustrations of the invention, and should not be interpreted in such a way as to limit its scope. EXAMPLES

[0098] The tests below were carried out using Austrian diesel fuel type B7, meeting the specifications of standard EN590.

[0099] This virgin fuel is called G0.

[0100] A first G1 fuel composition was prepared by adding to G0 fuel an A1 additive package containing the following compounds: Procetane additive: ethyl-hexyl nitrate at a content of 300 ppm by mass in G1 fuel, Polyisobutylene succinimide deposit reducing additive functionalized with a quaternary ammonium group at a content of 42 ppm by mass in G1 fuel, Polyisobutylene succinimide deposit reducing additive functionalized with a triazole group at a content of 30 ppm by mass in G1 fuel.

[0101] A second fuel composition G2 was prepared by adding to fuel composition G1 a mixture of alkyl phenol type compounds (consisting of 15% by mass of 2,6-di-t-butyl-4-methyl phenol, and 85% by mass of the condensation product of 2,4-dimethyl-6-t-butyl phenol and 2,5-dimethyl-4-t-butyl phenol) at a content of 350 ppm by mass in fuel G2.

[0102] Three identical tests were carried out in accordance with the WLTP standardised test protocol, using an Opel Crossland X vehicle equipped with a 1560 cm3, 88 kW diesel engine. This vehicle complies with the Euro 6b standard.

[0103] The WLTP protocol driving cycle consists of driving the vehicle on a rolling test bench over a defined profile of 23 kilometres over a period of 1800 seconds (30 minutes) with an initial cold start. The driving profile alternates between variable driving speeds over four main phases, separated by stops (zero speed).

[0104] The three tests differ only in the nature of the fuel supplying the engine (G0, G1 and G2 respectively).

[0105] For each test, five cycles were carried out (each fuel was thus evaluated 5 times, in order to ensure the robustness and statistical validity of the results).

[0106] The levels of polluting agents emitted during each test were measured in accordance with the methods defined in European regulation ECE-R83.05

[0107] The results obtained (average over the five cycles) are shown in Table I below: [Tableau I] Pollutants G0 G1 G2 NOx (mg / km) 82,1 94,1 68 CO (mg / km) 94,7 58 50 Unburned hydrocarbons + NOx (mg / km) 84,4 97 70,9 Total calculation of gaseous emissions (NOx + CO + unburned hydrocarbons, in mg / km) 179,1 155 120,9 Solid particles (number value, in mg / km) 0,006 0,014 0,0007

[0108] The above results demonstrate that the addition of additive package A1 to virgin diesel G0 leads to a significant increase in nitrogen oxide (NOx) and particulate emissions. Diesel composition G2, further comprising alkylphenol additives in accordance with the invention, makes it possible to significantly reduce NOx emissions by 28% compared to comparative diesel G1 and by 17% compared to virgin reference diesel G0. With regard to particulate matter, composition G2 makes it possible to reduce emissions by 95% compared to comparative diesel G1 and by 88% compared to virgin reference diesel G0.

[0109] Furthermore, the total level of gaseous emissions is very significantly reduced with G2 fuel, compared to comparative fuels G1 and G0.

Claims

1. Use, for reducing emissions of nitrogen oxides and of at least one type of pollutant selected from carbon monoxide and unburnt hydrocarbons during the combustion of a liquid fuel in a compression-ignition internal combustion engine, of a composition of additives comprising: (i) one or more additives selected from compounds having at least one alkylphenol group in their structure; (ii) one or more additives for improving the cetane number, selected from alkyl nitrates, aryl peroxides and alkyl peroxides; and (iii) one or more deposit-reducing additives other than compounds (i) and (ii), wherein the mass ratio of the amount of additive(s) (i) to the amount of additive(s) (ii) is in the range extending from 1:3 to 3:1.

2. Use according to the preceding claim, characterized in that the additive(s) (i) are selected from the compounds (i)a) comprising one or two phenolic rings substituted by one or more alkyl groups selected from methyl and t-butyl groups, and preferably from methyl-t-butylphenols, dimethyl-t-butylphenols, ethyl-t-butylphenols, t-butylphenols, di-t-butylphenols, tri-t-butylphenols, di-t-butyldimethylphenols, and mixtures thereof.

3. Use according to the preceding claim, characterized in that the compound(s) (i)a) are selected from (di)tert-butylphenols, methyl-tert-butylphenols and dimethyl-tert-butylphenols, mixtures thereof, and products of the condensation of pairs thereof, such as in particular 2,6-di-t-butyl-4-methylphenol (BHT), 2,4-dimethyl-6-t-butylphenol, 2,5-dimethyl-4-t-butylphenol, 2,6- and 2,4-di-t-butylphenol, 2,4,6-tri-t-butylphenol, mixtures thereof, and products of the condensation of pairs thereof.

4. Use according to Claim 1, characterized in that the additive(s) (i) are selected from modified alkylphenol-aldehyde resins (i)b) obtainable by Mannich reaction of an alkylphenol-aldehyde condensation resin: • with at least one aldehyde and / or ketone having from 1 to 8 carbon atoms, preferably from 1 to 4 carbon atoms; • and at least one hydrocarbon-based compound having at least one alkylpolyamine group having between 1 and 30 carbon atoms, preferably between 4 and 30 carbon atoms, said alkylphenol-aldehyde condensation resin itself being obtainable by condensation: • of at least one alkylphenol substituted by at least one linear or branched alkyl group having from 1 to 30 carbon atoms, preferably a monoalkylphenol, • with at least one aldehyde and / or ketone having from 1 to 8 carbon atoms, preferably from 1 to 4 carbon atoms.

5. Use according to the preceding claim, characterized in that the modified alkylphenol-aldehyde resins are obtainable from p-nonylphenol, formaldehyde and at least one hydrocarbon-based compound comprising at least one alkylpolyamine group.

6. Use according to either of Claims 4 and 5, characterized in that the modified alkylphenol-aldehyde resins are obtainable from at least one alkylpolyamine having at least two primary amine groups and at least one fatty chain having from 12 to 24 carbon atoms, preferably from 12 to 22 carbon atoms.

7. Use according to any one of the preceding claims, characterized in that the composition of additives comprises one or more compounds (i)a) comprising one or two phenolic rings substituted by one or more alkyl groups selected from methyl and t-butyl groups, and one or more modified alkylphenol-aldehyde resins (i)b).

8. Use according to any one of the preceding claims, characterized in that the additive(s) (ii) are selected from alkyl nitrates of formula R-NO3 with R an alkyl radical comprising from 2 to 12 carbon atoms, more preferentially from 4 to 8 carbon atoms, and better still the additive (ii) is ethylhexyl nitrate.

9. Use according to any one of the preceding claims, characterized in that the mass ratio of the amount of additive(s) (i) to the amount of additive(s) (ii) is in the range extending from 1:2.5 to 2.5:1, preferably from 1:2 to 2:1 and more preferentially from 1:1 to 1.5:1.

10. Use according to any one of the preceding claims, characterized in that the deposit-reducing additive(s) (iii) are selected from the group consisting of amines, succinimides, alkenylsuccinimides, polyalkylamines, polyalkyl polyamines, polyetheramines, quaternary ammonium salts, and triazole derivatives; more preferentially from polyisobutylene succinimides functionalized with a quaternary ammonium group, fatty acid amides functionalized with a quaternary ammonium group and dimers thereof such as di(alkylamidopropyl quaternary ammonium) compounds, fatty-chain alkylamidoalkyl betaines and triazole derivatives; and more preferentially still from polyisobutylene succinimides functionalized with a quaternary ammonium group and polyisobutylene succinimides functionalized with a triazole group.

11. Use according to the preceding claim, characterized in that the ratio between the total weight content of compounds (i) having at least one alkylphenol group in their structure, on the one hand, and the total weight content of deposit-reducing additive(s) (iii), on the other hand, ranges from 1:60 to 1:2, preferably from 1:20 to 1:3.

12. Use according to any one of the preceding claims, characterized in that the fuel is selected from diesels, biodiesels, Bx type diesels containing x% (v / v) of esters of vegetable or animal oils with x a number greater than zero and less than or equal to 100, hydrotreated vegetable oils (HVOs), and mixtures thereof; and preferably from Bx type diesels containing x% (v / v) of esters of vegetable or animal oils with x a number greater than zero and less than or equal to 100, the esters of vegetable oils preferably being selected from fatty acid methyl esters and fatty acid ethyl esters.

13. Use according to any one of the preceding claims for simultaneously reducing emissions of nitrogen oxides, carbon monoxide and unburnt hydrocarbons.

14. Use according to any one of the preceding claims, for additionally reducing emissions of solid particles.

15. Use according to any one of the preceding claims, characterized in that the compression-ignition engine is a hybrid diesel engine or a direct-injection diesel engine, preferably a direct-injection diesel engine and more preferentially a diesel engine with a common rail injection system.

16. Use according to any one of Claims 1 to 14, characterized in that the compression-ignition engine is a marine engine.

17. Method for reducing emissions of nitrogen oxides and of at least one type of pollutant selected from carbon monoxide and unburnt hydrocarbons during the combustion of a liquid fuel in a compression-ignition internal combustion engine, comprising the addition, to said fuel, of a composition of additives as defined in any one of Claims 1 to 11.