USE AND METHOD FOR REDUCING DEPOSITS IN A DIESEL ENGINE

Description

USE AND METHOD

The present invention relates to methods and uses for improving the performance of diesel engines. In particular the invention relates to reducing the impact of deposits in the exhaust gas recirculation system and/or the post combustion system of diesel engines, especially modern diesel engines having a high pressure fuel system.

The addition of detergent additives to combat deposits in the combustion system of diesel engines, for example in the fuel injection system, is well known and a wide variety of detergents have been developed for this purpose.

However less work has been carried out to combat deposits in the exhaust gas recirculation system or the post combustion system. Nevertheless, the presence of deposits in the exhaust gas recirculation system or the post combustion system of a diesel engine can have a significant deleterious effect on the performance of diesel engines, especially modern diesel engines having a high pressure fuel system.

Exhaust gas recirculation (EGR) systems are fitted to diesel vehicles to reduce NO_x emissions. This is achieved by recirculating exhaust gases and thereby increasing the heat capacity of and reducing the oxygen concentration in gases within the combustion chamber. Several types of EGR systems have been developed. High pressure EGR systems are arranged to divert exhaust gases from the combustion chamber, before the exhaust gases reach any turbocharger and/or diesel particulate filter present in the engine, and supply said exhaust gases to the intake manifold downstream of the compressor. The high pressure EGR system therefore operates on the high pressure sides of the intake and exhaust manifolds and supplies the combustion chamber with unfiltered recirculated exhaust gases. Low pressure EGR systems are arranged to divert exhaust gases from the combustion chamber downstream of any turbocharger and/or diesel particulate filter present in the engine, and to supply said exhaust gases to the intake tract upstream of the compressor. The low pressure EGR system therefore operates on the low pressure sides of the intake and exhaust manifolds and supplies the combustion chamber with filtered recirculated exhaust gases. Hybrid (or combined) EGR systems integrate both high pressure EGR and low pressure EGR on the same engine, to combine the benefits of each system. Dedicated EGR (D-EGR) systems are arranged to route the entire exhaust of a sub-group of power cylinders (dedicated cylinders) directly into the intake manifold.

Over time deposits can form within the EGR system. This is a particular issue in diesel engines with high pressure EGR systems, that is, typically, where the recycle stream is taken in advance of any turbocharger, due to the recirculated exhaust gas stream being taken upstream of any turbocharger and diesel particulate filter, meaning that problematic particulate combustion products are re-introduced into the intake manifold and the combustion chamber. One area where deposits cause a particular problem is within the cooler component of the EGR system. If the level of deposits becomes significant then the engine management systems in sophisticated diesel engines may cause the engine to operate with reduced performance and/or enter into a safe running mode. This scenario would have significant impact on the vehicle's operability and would require inspection by a suitably qualified workshop.

A typical EGR system comprises an intake pipe, a valve, a housing, a cooler and an outlet pipe. Deposits build up on the interior surfaces of all portions of the EGR system, but particularly in the cooler.

The post combustion system of a diesel engine typically includes a series of components through which exhaust gases must flow before exiting the vehicle. The post combustion system may include a turbocharger, a diesel oxidation catalyst, a diesel particulate filter, a selective catalytic reduction unit and an ammonia oxidation catalyst. It would be desirable to combat deposits in any or all of these components.

The formation of deposits in the post combustion system may involve the accumulation of soot on components of the post combustion system. In particular, the formation of deposits in the post combustion system may involve an accumulation and/or capture of soot in a diesel particulate filter of the post combustion system.

It would also be beneficial to prevent and/or to remove deposits on sensors within the post combustion system, for example deposits on NO_x sensors, temperature sensors and/or pressure sensors.

It would also be beneficial to prevent and/or to remove the accumulation of soot on components of the post combustion system and/or to prevent and/or to remove soot from a diesel particulate filter of the post combustion system.

The present inventors have surprisingly found that the inclusion of certain compounds as fuel additives is able to combat the effect of deposits in the EGR system and/or the post combustion system.

According to a first aspect of the present invention there is provided the use of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I):

or an anhydride thereof; and/or of a polymer prepared from components (i) and (ii); as an additive in a diesel fuel composition to reduce the impact of deposits in an exhaust gas recirculation (EGR) system and/or the post combustion system of a diesel engine when combusting said diesel fuel composition.

According to a second aspect of the present invention there is provided a method of reducing the impact of deposits in an exhaust gas recirculation (EGR) system and/or the post combustion system of a diesel engine, the method comprising combusting in the engine a diesel fuel composition comprising as an additive a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I):

or an anhydride thereof; and/or a polymer prepared from components (i) and (ii).

Preferred features of the first and second aspects of the invention will now be described.

The present invention involves the use of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) as an additive. For the avoidance of doubt embodiments of the invention may include the use of one or more than one reaction product and/or one or more than one polymer. References herein to “the” or “a” reaction product and/or “the” or “a” polymer include embodiments in which mixtures of two or more reaction products and/or polymers are present.

Each additive used in the present invention may comprise a mixture of compounds and references to an additive or the additive include mixtures, unless otherwise stated. In particular mixtures of isomers and mixtures of homologues are within the scope of the invention. The skilled person will appreciate that commercial sources of some of the additive compounds described herein may comprise mixtures of isomers and/or mixtures of homologues.

The present invention relates to a method and use which reduces the impact of deposits in the EGR system and/or the post combustion system of a diesel engine. The presence of deposits on one or more parts of the post combustion system or on the EGR system of a diesel engine typically has a negative effect on the performance of the engine.

Reducing the impact of deposits may involve reducing or preventing the formation of deposits and/or removing existing deposits and/or changing the nature of the deposits.

In some embodiments reducing the impact of deposits may involve changing the nature of deposits. This means that the structure or composition of deposits which are formed is different in a way that is less detrimental to the performance of the engine, for example by increasing the combustibility and/or thermal conductivity of the deposits.

In some preferred embodiments reducing the impact of deposits involves reducing and/or preventing the formation of deposits and/or the removal of existing deposits.

In some embodiments the first aspect of the present invention provides the use of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) as an additive in a diesel fuel composition to reduce the impact of deposits in the exhaust gas recirculation system of a diesel engine when combusting said diesel fuel composition.

Preferably the use reduces the formation of deposits in the EGR system.

In some embodiments the second aspect of the present invention provides a method of reducing the impact of deposits in the exhaust gas recirculation system of a diesel engine, the method comprising combusting in the engine a diesel fuel composition comprising as an additive a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or a polymer prepared from components (i) and (ii).

Preferably the method reduces the formation of deposits in the EGR system.

In some embodiments the first aspect of the present invention provides the use of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) as an additive in a diesel fuel composition to reduce the impact of deposits in the post combustion system of a diesel engine when combusting said diesel fuel composition.

In some embodiments the second aspect of the present invention provides a method of reducing the formation deposits in the post combustion system of a diesel engine, the method comprising combusting in the engine a diesel fuel composition comprising as an additive a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or a polymer prepared from components (i) and (ii).

In preferred embodiments reducing the impact of deposits involves reducing and/or preventing the impact of deposits in the post combustion system of a diesel engine.

In some embodiments the present invention uses an additive which is the direct reaction product of (i) an alcohol and (ii) a compound of formula (I) or an anhydride thereof. This product is an ester.

In some embodiments the present invention uses a polymeric fuel additive prepared from (i) an alcohol and (ii) a compound of formula (I) or an anhydride thereof.

The polymeric additive may be prepared by polymerising a dicarboxylic acid of formula (I):

or an anhydride thereof and then esterifying the polymerised diacid or polymerised anhydride.

When an anhydride is used the polymer may optionally be hydrolysed to provide acid residues. Suitable hydrolysis conditions will be known to the person skilled in the art.

In preferred embodiments polymeric additive is prepared by polymerising the reaction product of a dicarboxylic acid compound of formula (I) or an anhydride thereof and an alcohol.

Thus the polymeric additive is preferably prepared by forming an ester of a dicarboxylic acid of formula (I) or an anhydride thereof and an alcohol; and then polymerising the ester.

Polymerisation is preferably carried out by a free radical initiated process.

Polymeric additives suitable for use in the present invention preferably have the formula (II):

wherein n is at least 2, x may be 0 or a positive integer, y may be 0 or a positive integer and each R is independently hydrogen or an optionally substituted hydrocarbyl group provided that at least 10% of all R groups are not hydrogen.

The dicarboxylic acid-derived compound used to form the additives of the invention includes free carboxylic acid groups and/or anhydride groups.

When the dicarboxylic acid-derived compound includes anhydride groups these may be an internal cyclic anhydride in which two carboxylic acid groups are reacted together to form an anhydride, for example as shown in formula (III):

Such a cyclic anhydride group may be regarded as equivalent to two free carboxylic acid groups.

In some embodiments the anhydride may be a non-cyclic anhydride.

In the polymer of formula (II) n is at least 2. Preferably n is at least 4, preferably at least 6, more preferably at least 8, for example at least 10. Suitably n is from 10 to 200, preferably from 15 to 80, more preferably from 20 to 60, for example from 25 to 50.

x may be from 0 to 10, for example from 0 to 6, from 0 to 4 or from 0 to 2.

y may be from 0 to 10, for example from 0 to 6, from 0 to 4 or from 0 to 2.

Preferably x+y is at least 1. Preferably x+y is less than 20, preferably less than 15, more preferably less than 10. Preferably x+y is less than 8, preferably less than 6.

Preferably x+y is from 1 to 10, more preferably from 1 to 6, for example from 1 to 4.

Preferably x is 0 and y is at least 1. Preferably y is from 1 to 10, preferably from 1 to 6.

In some preferred embodiments, x is 0 and y is from 1 to 4, preferably from 1 to 3.

Most preferably x+y=1.

For the avoidance of doubt, the definitions of x and y apply to structures shown in formula (I), in formula (II) and in formula (III). These definitions of x and y apply to polymeric additives and to non-polymeric additives suitable for use in the invention.

The following definitions of suitable alcohol and dicarboxylic acid compounds also apply also to both polymeric and non-polymeric additives suitable for use herein.

Some preferred dicarboxylic acid compounds for use in preparing the additives of the present invention are itaconic acid, itaconic anhydride, 2-methylene glutaric acid, 2-methylene glutaric anhydride, 2-methylene adipic acid, 2-methylene adipic anhydride and isomers and/or mixtures thereof.

One especially preferred dicarboxylic acid compound for use herein is itaconic acid, which has the formula (IV):

One preferred anhydride is itaconic anhydride, which has the formula (V):

The additives of the present invention are a reaction product of a dicarboxylic acid or anhydride thereof and an alcohol, preferably an alcohol having at least 4 carbon atoms. In some cases the additives are the polymerised reaction product of the acid/anhydride and alcohol.

In some cases the additives are the reaction product of a polymerised acid/anhydride and an alcohol.

Any suitable alcohol, preferably having at least 4 carbon atoms may be used to prepare the additives of the present invention.

The alcohol may be a monohydric alcohol or a polyhydric alcohol. Monohydric alcohols are preferred.

Suitably the alcohol may be a compound of formula H—(OR²)_m—OR¹, wherein R² is an optionally substituted alkylene or arylene group; R¹ is hydrogen or an optionally substituted hydrocarbyl group; and m is 0 or a positive integer; provided that m is not 0 when R¹ is hydrogen.

In the polymeric additives of the present invention of formula (II), each group R is suitably hydrogen or a group of formula (OR²)_mOR¹.

As used herein, the term “hydrocarbyl substituent” or “hydrocarbyl group” is used in its ordinary sense, which is well-known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character. Examples of hydrocarbyl groups include:

• • (i) hydrocarbon groups, that is, aliphatic (which may be saturated or unsaturated, linear or branched, e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, and aromatic (including aliphatic- and alicyclic-substituted aromatic) substituents, as well as cyclic substituents wherein the ring is completed through another portion of the molecule (e.g., two substituents together form a ring);
  • (ii) substituted hydrocarbon groups, that is, substituents containing non-hydrocarbon groups which, in the context of this invention, do not alter the predominantly hydrocarbon nature of the substituent (e.g., halo (e.g. chloro, fluoro or bromo), hydroxy, alkoxy (e.g. C₁ to C₄ alkoxy), keto, acyl, cyano, mercapto, amino, amido, nitro, nitroso, sulfoxy, nitryl and carboxy);
  • (iii) hetero substituents, that is, substituents which, while having a predominantly hydrocarbon character, in the context of this invention, contain other than carbon in a ring or chain otherwise composed of carbon atoms. Heteroatoms include sulphur, oxygen, nitrogen, and encompass substituents as pyridyl, furyl, thienyl and imidazolyl. In general, no more than two, preferably no more than one, non-hydrocarbon substituent will be present for every ten carbon atoms in the hydrocarbyl group; typically, there will be no non-hydrocarbon substituents in the hydrocarbyl group.

In some embodiments m is 0 and the additive of the present invention may be formed from an alcohol of formula ROH. In such embodiments R¹ is an optionally substituted hydrocarbyl group. Preferably R¹ is an optionally substituted alkyl, alkenyl, aryl, aralkyl or alkaryl group.

R¹ is preferably an optionally substituted hydrocarbyl group having at least 4 carbon atoms. Preferably R¹ is an optionally substituted hydrocarbyl group having 5 to 200 carbon atoms, suitably 6 to 50 carbon atoms, preferably 8 to 30 carbon atoms.

R¹ may be an optionally substituted alkyl, alkenyl or aryl group having at least 5 carbon atoms. In some embodiments R¹ is an optionally substituted C₅ to C₂₀₀ alkyl or alkenyl group, preferably a C₆ to C₅₀ alkyl or alkenyl group, preferably a C₈ to C₃₀ alkyl or alkenyl group.

R¹ may be substituted with one or more groups selected from halo (e.g. chloro, fluoro or bromo), nitro, hydroxy, mercapto, sulfoxy, amino, nitryl, acyl, carboxy, alkyl (e.g. C₁ to C₄ alkyl), alkoxyl (e.g. C₁ to C₄ alkoxy), amido, keto, sulfoxy and cyano.

In some embodiments R¹ has at least 6 carbon atoms. R¹ may have more than 8 carbon atoms. In some embodiments R¹ may have more than 10 carbon atoms, for example more than 12 carbon atoms, more than 14 carbon atoms or more than 16 carbon atoms.

In some embodiments R¹ has less than 30 carbon atoms, preferably less than 28 carbon atoms, suitably less than 26 carbon atoms.

In some preferred embodiments R¹ is an alkyl or alkenyl group having 6 to 50 carbon atoms, preferably 8 to 30 carbon atoms.

Preferably R¹ is an unsubstituted alkyl or alkenyl group. In some preferred embodiments R¹ is an unsubstituted alkenyl group.

R¹ may be straight chained or branched. In some embodiments R¹ is an unsubstituted straight chained or branched alkyl or alkenyl group, having 4 to 50 carbon atoms, preferably 6 to 30 carbon atoms.

In some embodiments R¹ is an optionally substituted alkyl, alkenyl, aryl, alkaryl or aralkyl group having less than 20 carbon atoms, suitably less than 16 carbon atoms.

In some embodiments R¹ is an alkyl, alkenyl, aryl, alkaryl or aralkyl group having 6 to 16 carbon atoms.

In some embodiments R¹ is an unsubstituted alkyl, aryl, alkaryl or aralkyl group having less than 16 carbon atoms.

In some embodiments R¹ is an unsubstituted alkyl, aryl, alkaryl or aralkyl group having less than 12 carbons, suitably less than 10 carbon atoms.

In some embodiments R¹ is an alkaryl group.

In one embodiment R¹ is benzyl.

In some embodiments R¹ is an alkyl group, preferably an unsubstituted alkyl group having 6 to 50, preferably 8 to 30 carbon atoms, for example 12 to 24 carbon atoms.

In some embodiments R¹ is a group CH₃(CH₂)_x wherein x is from 4 to 23, preferably from 9 to 19.

In some preferred embodiments, R¹ is a C₁₂ to C₁₈ alkyl group.

R¹ may be a straight chain, branched or cyclic alkyl group.

Suitable alcohols R′OH for use herein include hexanol, octanol, nonanol, decanol, dodecanol, tetradecanol, cetyl alcohol, stearyl alcohol, 2-ethyl-1-butanol, 2-ethyl-1-hexanol, 2-ethyl-1-heptanol, 2-propylheptanol, 2-ethyl-1-decanol, 2-hexyl-1-decanol, 2-octyl-1-decanol, 2-hexyl-1-dodecanol, 2-octyl-1-dodecanol, 2-decyl-1-tetradecanol, isotridecanol, cyclohexanol, cyclooctanol and benzyl alcohol.

In some embodiments R¹ is an alkenyl group, preferably an unsubstituted alkenyl group having 5 to 36 carbon atoms, more preferably 10 to 30 carbon atoms, suitably 10 to 24 carbon atoms.

R¹ may be a straight chain, branched or cyclic alkenyl group. Suitable alkenyl alcohols include citronellol, oleyl alcohol, 9-decen-1-ol, cis-3-hexen-1-ol, trans-2-hexen-1-ol, 5-hexen-1-ol, 6-methyl-5-hepten-2-ol, 1-octen-3-ol, trans-2-octen-1-ol and 10-undecen-1-ol.

In some embodiments, the alkenyl alcohol is obtainable from a naturally occurring fatty acid, for example by chemical reduction. Such materials may comprise mixtures of alkenyl alcohols. Examples include oleyl alcohol, linoleyl alcohol, and fatty alcohols derived from fatty acids, for example tall oil, coconut oil or palm kernel oil fatty acids.

In some embodiments, the alkenyl alcohol may be derived from terpenes. Examples of such alkenyl alcohols include linalool, fenchyl alcohol, terpineol, borneol, isoborneol, citrol, geraniol, citronellol, phytol and nerol.

In some preferred embodiments, the alcohol is a C₁₈ alcohol, for example stearyl alcohol or oleyl alcohol.

In some embodiments oleyl alcohol is especially preferred.

In some preferred embodiments, R¹ is a branched, saturated alkyl group, such as a branched, saturated C₅ to C₂₄ alkyl group.

Suitable branched alcohols for use herein include 2-ethyl-1-butanol, 2-ethyl-1-hexanol, 2-ethyl-1-heptanol, 2-propylheptanol, 2-ethyl-1-decanol, 2-hexyl-1-decanol, 2-octyl-1-decanol, 2-hexyl-1-dodecanol, 2-octyl-1-dodecanol, 2-decyl-1-tetradecanol and isotridecanol.

In some embodiments 2-ethyl hexanol is especially preferred.

The skilled person will appreciate that commercial sources of alcohols of formula R¹OH will often contain mixtures of compounds, for example mixtures of isomers and/or mixtures of homologues.

Some suitable alcohols for use herein include mixed C₁₆ to C₁₈ monounsaturated alcohols, known as cetostearyl alcohol.

In some embodiments m is not 0 and the additive of the present invention may suitably be formed from an alcohol of formula H—(OR²)_m—OR¹.

In such embodiments R¹ is hydrogen an optionally substituted hydrocarbyl group. R¹ may be as defined above.

R² is an optionally substituted arylene or alkylene group. Preferably R² is an optionally substituted alkylene group.

Preferably R² is an unsubstituted alkylene group.

Preferably R² is an optionally substituted alkylene group having 1 to 50 carbon atoms, preferably 1 to 40 carbon atoms, preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, suitably 1 to 10 carbon atoms, for example 2 to 6 or 2 to 4 carbon atoms.

Preferably R² is an unsubstituted alkylene group having 1 to 50 carbon atoms, preferably 1 to 20, more preferably 1 to 10, suitably 2 to 6, for example 2 to 4 carbon atoms. R may be straight chained or branched.

Suitably R² may be an ethylene, propylene, butylene, pentylene, or hexylene group. When R² has more than 2 carbon atoms any isomer may be present. Preferably R² is an ethylene or a propylene group, most preferably a propylene group.

R² may comprise a mixture of isomers. For example when R² is propylene, the polyhydric alcohol may include moieties —CH₂CH(CH₃)— and —CH(CH₃)CH₂— in any order within the chain.

R² may comprise a mixture of different groups for example ethylene, propylene or butylene units. Block copolymer units are preferred in such embodiments.

R² is preferably an ethylene, propylene or butylene group. R may be an n-propylene or n-butylene group or an isopropylene or isobutylene group. For example R² may be —CH₂CH₂—, —CH₂CH(CH₃)—, —CH₂C(CH₃)₂, —CH(CH₃)CH(CH₃)— or —CH₂CH(CH₂CH₃)—.

Preferably R² is ethylene or propylene. More preferably R² is —CH₂CH₂— or —CH(CH₃)CH₂—. Most preferably R² is —CH(CH₃)CH₂—.

In some embodiments m is at least 1. Preferably n is from 1 to 200, preferably from 1 to 50, more preferably from 1 to 30, more preferably from 1 to 24, preferably from 1 to 20, suitably from 1 to 16.

In some preferred embodiments m is from 8 to 20.

The skilled person will appreciate that commercial sources of alcohols of formula H—(OR²)_m—OR¹ often contain mixtures of compounds, for example in which m may be between 10 and 20.

In preferred embodiments in which m is not 0, R¹ is an optionally substituted alkyl, alkenyl or aryl group, suitably an optionally substituted alkyl or alkenyl group. Preferably R¹ has from 4 to 50 carbon atoms, preferably 4 to 40 carbon atoms, more preferably from 10 to 30 carbon atoms. R¹ may be straight chain or branched. Preferably R¹ is straight chain.

In some embodiments R¹ is a substituted alkyl or alkenyl group, suitably a substituted alkyl group.

Suitable substituents are hydroxy and ester groups. In some embodiments R¹ is a 2-hydroxy alkyl, alkenyl or aryl group.

Suitably R¹ is an unsubstituted alkyl or alkenyl group. Preferably R¹ is an alkyl group, preferably an unsubstituted alkyl group.

Suitably R¹ is selected from an alkyl group having from 1 to 40, preferably 6 to 30, more preferably 10 to 20 carbon atoms.

In some embodiments R¹ is a C4 to C30 alkyl or alkenyl group, m is not 0 and the additive of the present invention is prepared from an alkyl or alkenyl ether of a polyhydric alcohol, for example an ether of a polyethylene glycol, a polypropylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol or tripropylene glycol.

Some especially preferred alcohols for use in preparing the additive of the present invention are of the formula CH₃(CH₂)_aO(CH₂CH(CH₃)O)_bH or an isomer thereof wherein a is from 4 to 30, preferably from 8 to 20, more preferably from 10 to 15, and b is from 1 to 30, preferably from 5 to 25, more preferably from 10 to 20. In one preferred embodiment a is 13 and b is 15.

The alcohol of formula H—(OR²)_m—OR¹ may be selected from:

• • alkanols of formula CH₃(CH₂)_aOH or an isomer thereof wherein a is from 4 to 23;
  • branched or cyclic alkyl alcohols in which m is 0 and R¹ has 6 to 24 carbon atoms;
  • alkenyl alcohols in which n is 0 and R¹ has 6 to 24 carbon atoms;
  • glycol ethers in which m is not 0.

Preferred alkanols of formula CH₃(CH₂)_aOH include stearyl alcohol, tetradecanol, cetyl alcohol, octanol, hexanol, nonanol, decanol and dodecanol.

Preferred branched or cyclic alkyl alcohols in which m is 0 include cyclohexanol, cyclooctanol, 2-propylheptanol, 2-ethyl-1-hexanol, 2-ethyl-1-heptanol, 2-propylheptanol, 2-ethyl-1-decanol, 2-ethyl-1-butanol, 2-hexyl-1-decanol, 2-octyl-1-decanol, 2-hexyl-1-dodecanol, 2-octyl-1-dodecanol, 2-decyl-1-tetradecanol and isotridecanol.

Preferred alkenyl alcohols in which m is 0 include citronellol, oleyl alcohol, 9-decen-1-ol, cis-3-hexen-1-ol, trans-2-hexen-1-ol, 5-hexen-1-ol, 6-methyl-5-hepten-2-ol, 1-octen-3-ol, trans-2-octen-1-ol and 10-undecen-1-ol.

Preferred glycol ethers in which m is not 0 include compounds of formula CH₃(CH₂)_aO(CH₂CH(CH₃)O)_bH or an isomer thereof wherein a is from 10 to 15, and b is from 10 to 20.

Preferably the additive of the present invention is prepared by reacting a dicarboxylic acid compound and an alcohol and then optionally polymerising the resultant ester. The dicarboxylic acid and alcohol are preferably reacted in a molar ratio of from 15:1 to 1:15, suitably from 10:1 to 1:10, preferably from 5:1 to 1:5, more preferably from 2:1 to 1:2, for example from 1.5:1 to 1:1.5 or from 1.2:1 to 1:1.2. For the avoidance of doubt, reference to molar ratios are to the number of moles of each molecule reacted, not the number of functional groups reacted. Thus a 1:1 molar ratio refers to one mole of dicarboxylic acid compound reacting with one mole of alcohol, regardless of the number of acid/hydroxy groups present in each compound.

Most preferably the dicarboxylic acid compound and the alcohol are reacted in an approximately 1:1 molar ratio. By “approximately” unless otherwise stated herein we mean within 10% of the values specified.

The dicarboxylic acid compound and the alcohol react to form an ester. In preferred embodiments the dicarboxylic acid and the alcohol are reacted in an approximately 1:1 molar ratio. The reaction product of the dicarboxylic acid and the alcohol may comprise a mixture of compounds. Preferably the reaction product comprises predominantly monoesters. However some diester may also be present, along with unreacted diacid. When x≠y, two different monoesters can be formed even when a single alcohol is used. Mixtures of alcohols can also be used leading to further mixtures in the product.

In some embodiments in which the alcohol is a diol the reaction product may comprise oligomers. However this is not preferred.

Suitable conditions for carrying out the esterification reaction will be known to those skilled in the art. In some preferred embodiments an acid catalyst is used.

In some embodiments the reaction product obtained following reaction of the dicarboxylic acid and the alcohol is used directly as an additive.

In some embodiments the reaction product obtained following reaction of the dicarboxylic acid and the alcohol is then polymerised.

In some embodiments the additive of the present invention may be prepared by polymerising a dicarboxylic acid and then esterifying some or all of the acid groups on the polymeric acid.

The polymerised additives of the invention are preferably of formula (II):

wherein n is at least 2, x may be 0 or a positive integer, y may be 0 or a positive integer and each R is independently hydrogen or an optionally substituted hydrocarbyl group provided that at least 10% of all R groups are not hydrogen.

In the polymeric additives of the invention as defined in formula (II), at least 10% of all R groups are not hydrogen. Thus at least 10% of all acid residues in the molecule are esterified. For the avoidance of doubt, references to the number of groups which are esterified is a molar ratio rather than a weight ratio.

Preferably least 15% of all R groups in the additive of formula (II) are not hydrogen, more preferably at least 20%, suitably at least 25%, more preferably at least 30%, for example at least 35% or at least 40% of all R groups in the additive of formula (II) are not hydrogen.

Up to 100% of all R groups may not be hydrogen, for example up to 95%, suitably up to 90%, preferably up to 80%, more preferably up to 75%, for example up to 70%, up to 65% or up to 60% of all R groups in the additive of formula (II) are not hydrogen.

R groups that are not hydrogen are an optionally substituted hydrocarbyl group as previously defined herein.

Preferably from 30 to 70% of all R groups in the additive of formula (II) are not hydrogen, preferably from 40 to 60%, more preferably from 45 to 55%.

In preferred embodiments approximately half of all R groups in the additive of formula (II) are not hydrogen. Thus approximately half of the acid groups present in the additive of formula (II) are esterified.

In preferred embodiments in which the polymeric additive of formula (II) is prepared by polymerising the reaction product of a dicarboxylic acid and an alcohol, the additive is prepared by polymerising predominantly monoesters.

In the structure shown in formula (II), in each monomer unit preferably one R group is hydrogen and the other is an optionally substituted hydrocarbyl group.

Polymerisation of the compound of formula (I) or anhydride thereof or of the ester obtained by reaction of this compound with an alcohol is suitably achieved by the addition of a radical initiator. Suitably radical initiators will be known to those skilled in the art and include: azo compounds, for example azobisisobutyronitrile (AIBN); hydroperoxides, for example cumene hydroperoxides, tertiary butyl hydroperoxide, methyl ethyl ketone hydroperoxides; peroxides, for example di-tertiary butyl peroxide, tert-Butyl peroxypivalate, di cumyl peroxide, benzoyl peroxide 1,1′ azobis(cyclohexanecarbonitrile) (ABCN); and persulfates, for example ammonium persulfate, sodium persulfate or potassium persulfate.

Suitable amounts of radical initiator and reaction conditions will be known to the person skilled in the art.

The additives of the invention are preferably the optionally polymerised reaction product of a carboxylic acid and an alcohol.

In some embodiments the additive of the present invention is the reaction product of a dicarboxylic acid compound of formula (I) or an anhydride thereof; and an alcohol of formula R¹OH wherein R¹ is an optionally substituted hydrocarbyl group having 6 to 30, preferably 6 to 24, carbon atoms.

In some embodiments the additive of the present invention is the reaction product of a dicarboxylic acid compound of formula (I) or an anhydride thereof; and an alcohol of formula R¹OH wherein R¹ is a (preferably branched) alkyl group having 6 to 30, preferably 6 to 24, carbon atoms.

In some embodiments the additive of the present invention is the reaction product of a dicarboxylic acid compound of formula (I) or an anhydride thereof; and an alcohol of formula R¹OH wherein R¹ is an optionally substituted alkyl or alkenyl group having 6 to 30, preferably 6 to 24, carbon atoms.

In some embodiments the additive of the present invention is the reaction product of a dicarboxylic acid compound of formula (I) (preferably wherein x+y is less than 6) or an anhydride thereof; and an alcohol of formula R¹OH wherein R¹ is an alkenyl group having 6 to 30, preferably 6 to 24, carbon atoms.

In some embodiments the additive of the present invention is the reaction product of a dicarboxylic acid compound of formula (I) or an anhydride thereof; and an alcohol of formula H—(OR)_n—OR¹ wherein n is from 1 to 24, R is ethylene, propylene or isopropylene, and R¹ is an unsubstituted alkyl group having 6 to 30, preferably 6 to 24, carbon atoms.

In some embodiments the additive of the present invention is the reaction product of itaconic acid or an anhydride thereof; and an alcohol selected from 2-ethyl-1-butanol, 2-ethyl-1-hexanol, 2-ethyl-1-heptanol, 2-propylheptanol, 2-ethyl-1-decanol, 2-hexyl-1-decanol, 2-octyl-1-decanol, 2-hexyl-1-dodecanol, 2-octyl-1-dodecanol, 2-decyl-1-tetradecanol and isotridecanol.

In some embodiments the additive of the present invention is the reaction product of itaconic acid or an anhydride thereof; and an alcohol of formula H—(OR²)_m—OR¹ wherein m is from 1 to 24, R is ethylene, propylene or isopropylene, and R¹ is an unsubstituted alkyl group having 6 to 30, preferably 6 to 24, carbon atoms.

In some embodiments the additive of the present invention is the reaction product of itaconic acid or an anhydride thereof; and an alkenyl alcohol selected from citronellol, oleyl alcohol, 9-decen-1-ol, cis-3-hexen-1-ol, trans-2-hexen-1-ol, 5-hexen-1-ol, 6-methyl-5-hepten-2-ol, 1-octen-3-ol, trans-2-octen-1-ol and 10-undecen-1-ol.

In some embodiments the additive of the present invention is the reaction product of itaconic acid or an anhydride thereof; and citronellol or oleyl alcohol (preferably oleyl alcohol).

In some especially preferred embodiments the additive of the present invention is the reaction product of itaconic acid or an anhydride thereof and 2-ethylhexanol.

In some embodiments the additive of the present invention is the polymerised reaction product of a dicarboxylic acid compound of formula (I) or an anhydride thereof; and an alcohol of formula R¹OH wherein R¹ is an optionally substituted hydrocarbyl group having 6 to 30, preferably 6 to 24, carbon atoms.

In some embodiments the additive of the present invention is the polymerised reaction product of a dicarboxylic acid compound of formula (I) or an anhydride thereof; and an alcohol of formula R¹OH wherein R¹ is a (preferably branched) alkyl group having 6 to 30, preferably 6 to 24, carbon atoms.

In some embodiments the additive of the present invention is the polymerised reaction product of a dicarboxylic acid compound of formula (I) or an anhydride thereof; and an alcohol of formula R¹OH wherein R¹ is an optionally substituted alkyl or alkenyl group having 6 to 30, preferably 6 to 24, carbon atoms.

In some embodiments the additive of the present invention is the polymerised reaction product of a dicarboxylic acid compound of formula (I) (preferably wherein x+y is less than 6) or an anhydride thereof; and an alcohol of formula R¹OH wherein R¹ is an alkenyl group having 6 to 30, preferably 6 to 24, carbon atoms.

In some embodiments the additive of the present invention is the polymerised reaction product of a dicarboxylic acid compound of formula (I) or an anhydride thereof; and an alcohol of formula H—(OR)_n—OR¹ wherein n is from 1 to 24, R is ethylene, propylene or isopropylene, and R¹ is an unsubstituted alkyl group having 6 to 30, preferably 6 to 24, carbon atoms.

In some embodiments the additive of the present invention is the polymerised reaction product of itaconic acid or an anhydride thereof; and an alcohol selected from 2-ethyl-1-butanol, 2-ethyl-1-hexanol, 2-ethyl-1-heptanol, 2-propylheptanol, 2-ethyl-1-decanol, 2-hexyl-1-decanol, 2-octyl-1-decanol, 2-hexyl-1-dodecanol, 2-octyl-1-dodecanol, 2-decyl-1-tetradecanol and isotridecanol.

In some embodiments the additive of the present invention is the polymerised reaction product of itaconic acid or an anhydride thereof; and an alcohol of formula H—(OR²)_m—OR¹ wherein m is from 1 to 24, R is ethylene, propylene or isopropylene, and R¹ is an unsubstituted alkyl group having 6 to 30, preferably 6 to 24, carbon atoms.

In some embodiments the additive of the present invention is the polymerised reaction product of itaconic acid or an anhydride thereof; and an alkenyl alcohol selected from citronellol, oleyl alcohol, 9-decen-1-ol, cis-3-hexen-1-ol, trans-2-hexen-1-ol, 5-hexen-1-ol, 6-methyl-5-hepten-2-ol, 1-octen-3-ol, trans-2-octen-1-ol and 10-undecen-1-ol.

In some embodiments the additive of the present invention is the polymerised reaction product of itaconic acid or an anhydride thereof; and citronellol or oleyl alcohol (preferably oleyl alcohol).

In some especially preferred embodiments the additive of the present invention is the polymerised reaction product of itaconic acid or an anhydride thereof and 2-ethylhexanol.

In some preferred embodiments the additive of the present invention is the polymerised reaction product of itaconic acid or an anhydride thereof and 2-ethylhexanol wherein the polymer has a weight average molecular weight of from 2000 to 50000, preferably from 4000 to 30000, more preferably from 5000 to 20000, for example from 6000 to 15000, suitably from 8000 to 12000.

Weight average molecular weight may be measured by gel permeation chromatography.

In some embodiments the diesel fuel composition comprises from 0.1 to 10000 ppm, preferably from 1 to 1000 ppm, preferably from 5 to 250 ppm, for example 5 to 100 ppm of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii).

The reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or a polymer prepared from components (i) and (ii) may be added to diesel fuel at any convenient place in the supply chain. For example, the additive may be added to fuel at the refinery, at a distribution terminal or after the fuel has left the distribution terminal. If the additive is added to the fuel after it has left the distribution terminal, this is termed an aftermarket application. Aftermarket applications include such circumstances as adding the additive to the fuel in the delivery tanker, directly to a customer's bulk storage tank, or directly to the end user's vehicle tank. Aftermarket applications may include supplying the fuel additive in small bottles suitable for direct addition to fuel storage tanks or vehicle tanks.

By diesel fuel we include any fuel suitable for use in a diesel engine either for road use or non-road use. This includes but is not limited to fuels described as diesel, marine diesel, heavy fuel oil, industrial fuel oil, etc.

The diesel fuel composition used in the present invention may comprise a petroleum-based fuel oil, especially a middle distillate fuel oil. Such distillate fuel oils generally boil within the range of from 110° C. to 500° C., e.g. 150° C. to 400° C. The diesel fuel may comprise atmospheric distillate or vacuum distillate, cracked gas oil, or a blend in any proportion of straight run and refinery streams such as thermally and/or catalytically cracked and hydro-cracked distillates.

The diesel fuel composition may comprise non-renewable Fischer-Tropsch fuels such as those described as GTL (gas-to-liquid) fuels, CTL (coal-to-liquid) fuels and OTL (oil sands-to-liquid).

The diesel fuel composition may comprise a renewable fuel such as a biofuel composition or biodiesel composition.

The diesel fuel composition may comprise 1st generation biodiesel. First generation biodiesel contains esters of, for example, vegetable oils, animal fats and used cooking fats or oils. This form of biodiesel may be obtained by transesterification of oils, for example rapeseed oil, soybean oil, canola oil, safflower oil, palm oil, corn oil, peanut oil, cotton seed oil, tallow, coconut oil, physic nut oil (Jatropha), sunflower seed oil, used cooking oils, hydrogenated vegetable oils or any mixture thereof, with an alcohol, usually a monoalcohol, usually in the presence of a catalyst.

The diesel fuel composition may comprise second generation biodiesel. Second generation biodiesel is derived from renewable resources such as vegetable oils and animal fats and processed, often in the refinery, using, for example, hydroprocessing such as the H-Bio process developed by Petrobras. Second generation biodiesel may be similar in properties and quality to petroleum based fuel oil streams, for example renewable diesel produced from vegetable oils, animal fats etc. and marketed by ConocoPhillips as Renewable Diesel and by Neste as NExBTL.

The diesel fuel composition may comprise third generation biodiesel. Third generation biodiesel utilises gasification and Fischer-Tropsch technology including those described as BTL (biomass-to-liquid) fuels. Third generation biodiesel does not differ widely from some second generation biodiesel, but aims to exploit the whole plant (biomass) and thereby widens the feedstock base.

In some embodiments the diesel fuel composition may comprise a pyrolysis oil, for example a plastic pyrolysis oil or a biomass (wood, vegetable oil, algae) pyrolysis oil.

The diesel fuel composition may contain blends of any or all of the above diesel fuel compositions.

In some embodiments the diesel fuel composition may be a blended diesel fuel comprising bio-diesel. In such blends the bio-diesel may be present in an amount of, for example up to 0.5%, up to 1%, up to 2%, up to 3%, up to 4%, up to 5%, up to 10%, up to 20%, up to 30%, up to 40%, up to 50%, up to 60%, up to 70%, up to 80%, up to 90%, up to 95% or up to 99%.

In some embodiments the fuel composition may comprise neat biodiesel.

In some preferred embodiments the fuel composition comprises at least 5 wt % biodiesel. In some embodiments the fuel composition may comprise GTL fuel or be a neat GTL fuel. In some embodiments the fuel composition may comprise a blend of a first generation biodiesel and a second generation biodiesel (or renewable diesel), for example a blend comprising 80 vol % of a first generation biodiesel and 20 vol % of a second generation biodiesel.

In some embodiments the diesel fuel composition may comprise a secondary fuel, for example ethanol. Preferably however the diesel fuel composition does not contain ethanol.

The diesel fuel composition used in the present invention may contain a relatively high sulphur content, for example greater than 0.05% by weight, such as 0.1% or 0.2%.

However, in preferred embodiments the diesel fuel composition has a sulphur content of at most 0.05% by weight, more preferably of at most 0.035% by weight, especially of at most 0.015%. Fuels with even lower levels of sulphur are also suitable such as, fuels with less than 50 ppm sulphur by weight, preferably less than 20 ppm, for example 10 ppm or less.

The diesel fuel composition used in the present invention preferably comprises at least 5 wt % biodiesel and less than 50 ppm sulphur.

Various metal species may be present in the diesel fuel composition. This may be due to contamination of the fuel during manufacture, storage, transport or use or due to contamination of fuel additives. Metal species may also be added to fuels deliberately. For example, transition metals are sometimes added as fuel borne catalysts, for example to improve the performance of diesel particulate filters.

Other metal-containing species may also be present as a contaminant, for example through the corrosion of metal and metal oxide surfaces by acidic species present in the fuel or from lubricating oil. In use, fuels such as diesel fuels routinely come into contact with metal surfaces for example, in vehicle fueling systems, fuel tanks, fuel transportation means etc. Typically, metal-containing contamination may comprise transition metals such as zinc, iron and copper; Group I or Group II metals and other metals such as lead.

In addition to metal-containing contamination which may be present in diesel fuels there are circumstances where metal-containing species may deliberately be added to the fuel. For example, as is known in the art, metal-containing fuel-borne catalyst species may be added to aid with the regeneration of particulate traps. The presence of such catalysts may also give rise to injector deposits when the fuels are used in diesel engines having high pressure fuel systems.

Metal-containing contamination, depending on its source, may be in the form of insoluble particulates or soluble compounds or complexes. Metal-containing fuel-borne catalysts are often soluble compounds or complexes or colloidal species.

In some embodiments, the diesel fuel may comprise metal-containing species comprising a fuel-borne catalyst. Preferably, the fuel borne catalyst comprises one or more metals selected from iron, cerium, platinum, manganese, Group I and Group II metals e.g., calcium and strontium. Most preferably the fuel borne catalyst comprises a metal selected from iron and cerium.

Typically, the total amount of all metal-containing species in the diesel fuel, expressed in terms of the total weight of metal in the species, is between 0.1 and 50 ppm by weight, for example between 0.1 and 20 ppm, preferably between 0.1 and 10 ppm by weight, based on the weight of the diesel fuel.

The diesel fuel compositions used in the present invention may include one or more further additives such as those which are commonly found in diesel fuels. These include, for example, antioxidants, dispersants, detergents, metal deactivating compounds, wax anti-settling agents, cold flow improvers, cetane improvers, dehazers, stabilisers, demulsifiers, antifoams, corrosion inhibitors, lubricity improvers, dyes, markers, combustion improvers, metal deactivators, odour masks, drag reducers and conductivity improvers. Examples of suitable amounts of each of these types of additives will be known to the person skilled in the art.

The present invention reduces the impact of deposits in the EGR system and/or the post combustion system of a diesel engine.

The diesel engine may be a direct injection diesel engine or an indirect injection diesel engine.

In some embodiments the engine may be an off road engine, for example a marine, rail or stationary engine. Stationary engines include engines for power generation and pumping.

Most preferably the engine is a direct injection diesel engine.

The post combustion deposit control additives used in the present invention have been found to be particularly effective in modern diesel engines having a high pressure fuel system.

Suitably the present invention may be used to reduce the formation or deposits in the post combustion system of a diesel engine having a high pressure fuel system. Suitably the diesel engine has a fuel pressure in excess of 1350 bar (1.35×10⁸ Pa). It may have a pressure of up to 2000 bar (2×10⁸ Pa) or more.

Such diesel engines may be characterised in a number of ways.

Such engines are typically equipped with fuel injection equipment meeting or exceeding “Euro 5” emissions legislation or equivalent legislation in the US or other countries.

Such engines are typically equipped with fuel injectors having a plurality of apertures, each aperture having an inlet and an outlet.

Such engines may be characterised by apertures which are tapered such that the inlet diameter of the spray-holes is greater than the outlet diameter.

Such modern engines may be characterised by apertures having an outlet diameter of less than 500 μm, preferably less than 200 μm, more preferably less than 150 μm, preferably less than 100 μm, most preferably less than 80 μm or less.

Such modern diesel engines may be characterised by apertures where an inner edge of the inlet is rounded.

Such modern diesel engines may be characterised by the injector having more than one aperture, suitably more than 2 apertures, preferably more than 4 apertures, for example 6 or more apertures.

Such modern diesel engines may be characterised by an operating tip temperature in excess of 250° C.

Such modern diesel engines may be characterised by a fuel injection system which provides a fuel pressure of more than 1350 bar, preferably more than 1500 bar, more preferably more than 2000 bar.

Two non-limiting examples of such high pressure fuel systems are: the common rail injection system, in which the fuel is compressed utilizing a high-pressure pump that supplies it to the fuel injection valves through a common rail; and the unit injection system which integrates the high-pressure pump and fuel injection valve in one assembly, achieving the highest possible injection pressures exceeding 2000 bar (2×10⁸ Pa). In both systems, in pressurising the fuel, the fuel gets hot, often to temperatures around 100° C., or above.

Preferably, the diesel engine has fuel injection system which comprises a common rail injection system.

In common rail systems, the fuel is stored at high pressure in the central accumulator rail or separate accumulators prior to being delivered to the injectors. Often, some of the heated fuel is returned to the low pressure side of the fuel system or returned to the fuel tank. In unit injection systems the fuel is compressed within the injector in order to generate the high injection pressures. This in turn increases the temperature of the fuel.

In both systems, fuel is present in the injector body prior to injection where it is heated further due to heat from the combustion chamber. The temperature of the fuel at the tip of the injector can be as high as 250-350° C.

Thus the fuel is stressed at pressures from 1350 bar (1.35×10⁸ Pa) to over 2000 bar (2×10⁸ Pa) and temperatures from around 100° C. to 350° C. prior to injection, sometimes being recirculated back within the fuel system thus increasing the time for which the fuel experiences these conditions.

The EGR system recirculates the exhaust gases to lower the oxygen concentration in the combustion chamber. This reduces the generation of NO_x gases.

The EGR system includes a cooler. This component lowers the temperature of the recirculated exhaust gases.

Exhaust gases enter the EGR system after they pass through or are generated within the combustion chamber. The exhaust gases may contain materials resulting from incomplete combustion. These materials may deposit within the EGR system. One component where deposit build up frequently occurs is in the cooler of the EGR system.

Previously these deposits have not been studied in the same level of detail as other fuel system or combustion deposits. Indeed the finding of such deposits appears to be a relatively recent phenomenon. Particularly strong reviews of the work done to elucidate how they may form and why they are a problem can be found in Lance et al International Journal of Heat and Mass Transfer 126, (2018), 509-520 and SAE 2014-01-0629.

The present inventors have studied the nature of the deposits found in the EGR system and in particular within the cooler. It has been surprisingly found that the formation of these deposits in particular can be reduced by the addition a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) into the diesel fuel combusted in the engine.

In some embodiments the formation of deposits within the cooler of the EGR system are reduced by in particular can be reduced by the addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) into the diesel fuel combusted in the engine.

In some embodiments the formation of deposits within the cooler of the EGR system are reduced by the addition of: a polymer prepared from (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof; into the diesel fuel combusted in

The use of the first aspect and/or the method of the second aspect may involve reducing the impact of deposits in the exhaust gas recirculation system of a diesel engine which is a high pressure, low pressure, hybrid or dedicated EGR system. Suitably the exhaust gas recirculation system is a high pressure, hybrid or dedicated EGR system. Preferably the exhaust gas recirculation system is a high pressure system. The high pressure EGR may be either a stand-alone high pressure EGR system or part of a hybrid or a dedicated EGR system.

Preferably the use or method of the present invention reduces the formation of deposits in a high pressure EGR system of a diesel engine.

By reducing the formation of deposits in an EGR system we mean that when a fuel comprising the EGR deposit reducing additive is combusted in an engine, a reduced level of deposits is obtained compared to when an otherwise identical fuel is combusted under identical conditions except for the inclusion of the EGR deposit reducing additive.

Suitably addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) into the diesel fuel combusted in an engine reduces the formation of deposits in an EGR system by at least 5%, preferably by at least 10%, for example at least 15% or at least 20%. Suitably said reductions are provided by using 5 to 100 ppm of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii), in said diesel fuel.

In some embodiments the addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) into the diesel fuel combusted in an engine may reduce the formation deposits in an EGR system by at least 30%, for example at least 40% or at least 50%.

Suitably addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride and/or of a polymer prepared from components (i) and (ii) into the diesel fuel combusted in an engine reduces the formation of deposits in the cooler an EGR system by at least 5%, preferably by at least 10%, for example at least 15% or at least 20%.

In some embodiments the addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) into the diesel fuel combusted in an engine may reduce the formation deposits in the cooler of an EGR system by at least 30%, for example at least 40% or at least 50%.

Suitably addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof into the diesel fuel combusted in an engine reduces the formation of deposits in an EGR system by at least 5%, preferably by at least 10%, for example at least 15% or at least 20%.

In some embodiments the addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof into the diesel fuel combusted in an engine may reduce the formation deposits in an EGR system by at least 30%, for example at least 40% or at least 50%.

Suitably addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride into the diesel fuel combusted in an engine reduces the formation of deposits in the cooler an EGR system by at least 5%, preferably by at least 10%, for example at least 15% or at least 20%.

In some embodiments the addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof into the diesel fuel combusted in an engine may reduce the formation deposits in the cooler of an EGR system by at least 30%, for example at least 40% or at least 50%.

Suitably addition of a polymer prepared (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof into the diesel fuel combusted in an engine reduces the formation of deposits in an EGR system by at least 5%, preferably by at least 10%, for example at least 15% or at least 20%.

In some embodiments the addition of a polymer prepared (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof into the diesel fuel combusted in an engine may reduce the formation deposits in an EGR system by at least 30%, for example at least 40% or at least 50%.

Suitably addition of a polymer prepared (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof into the diesel fuel combusted in an engine reduces the formation of deposits in the cooler an EGR system by at least 5%, preferably by at least 10%, for example at least 15% or at least 20%.

In some embodiments the addition of a polymer prepared (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof into the diesel fuel combusted in an engine may reduce the formation deposits in the cooler of an EGR system by at least 30%, for example at least 40% or at least 50%.

The reduction in deposits in an EGR system may be measured by any suitable means.

One simple means by which the level of deposits in an EGR system may be determined is by weighing the system before and after use. One or more parts of the system may be weighed.

Preferably the present invention reduces the total amount of deposits formed in an EGR system by at least 5%, preferably at least 10%, more preferably at least 15%, for example at least 20% or at least 30%.

Suitably the present invention reduces the total amount of deposits formed within the cooler of an EGR system.

Preferably the present invention reduces the total amount of deposits formed within the cooler of an EGR system by at least 5%, preferably at least 10%, more preferably at least 15%, for example at least 20% or at least 30%.

Suitably said reductions are provided by using 5 to 100 ppm of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii), in said diesel fuel.

The deposits that form in the EGR system may be analysed. This may be achieved, for example by extracting the deposits or a portion thereof into a solvent. The sample may be separated into soluble and non soluble fractions; these may then be separately analysed by methods known to those skilled in the art, for example elemental analysis, thermogravimetric analysis and/or gas chromatography mass spectrometry.

The deposits that form in the EGR system may be analysed for example by thermogravimetric analysis (TGA). A significant proportion of the deposits that occur on the cooler of an EGR system were found to be carbonaceous deposits that degrade at temperatures of between 400 to 540° C. when subjected to thermogravimetric analysis (TGA).

Thermogravimetric analysis (or TGA) involves measuring the mass of a sample over time as it is heated. This technique is well know to the person skilled in the art and the selection of an appropriate method and suitable equipment will be within the competence of one skilled in the art.

The post combustion system of diesel engines is provided to reduce the emission of pollutants such as particulates and harmful gases into the environment. The formation of deposits on parts of the post combustion system can reduce the efficiency of the system and lead to an increase in the emission of particulate deposits and/or harmful gases.

In some embodiments the impact of the deposits may be reduced by a change in the nature of deposits.

Preferably the present invention reduces the formation of deposits in the post combustion system.

By reducing the formation of deposits in a post combustion system we mean that the when a fuel comprising a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) is combusted in an engine, a reduced level of deposits is obtained compared to when an otherwise identical fuel is combusted under identical conditions except for the inclusion of the post combustion deposit reducing additive.

Suitably the addition of the reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) into the diesel fuel combusted in an engine reduces the formation of deposits in one or more components of the post combustion system by at least 0.01%, preferably by at least 0.1%, for example at least 1% or at least 2%.

In some embodiments the addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) into the diesel fuel combusted in an engine may reduce the formation deposits in one or more components of the post combustion system by at least 3%, for example at least 4% or at least 5%, or at least 9 wt %.

Suitably the addition of the reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof into the diesel fuel combusted in an engine reduces the formation of deposits in one or more components of the post combustion system by at least 0.01%, preferably by at least 0.1%, for example at least 1% or at least 2%.

In some embodiments the addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof into the diesel fuel combusted in an engine may reduce the formation deposits in one or more components of the post combustion system by at least 3%, for example at least 4% or at least 5%, or at least 9 wt %.

Suitably the addition of a polymer prepared from (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof into the diesel fuel combusted in an engine reduces the formation of deposits in one or more components of the post combustion system by at least 0.01%, preferably by at least 0.1%, for example at least 1% or at least 2%, or at least 9 wt %.

In some embodiments the addition of a polymer prepared from (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof into the diesel fuel combusted in an engine may reduce the formation deposits in one or more components of the post combustion system by at least 3%, for example at least 4% or at least 5%, or at least 9 wt %.

By the post combustion system of a diesel engine we mean to refer to any part of the engine through which exhaust gases pass after finally leaving the combustion system.

The post combustion system may comprise one or more components selected from a turbocharger, a diesel oxidation catalyst, a diesel particulate filter, a selective catalytic reduction unit and an ammonia oxidation unit. The post combustion system may include these components in any order and this may order vary from vehicle to vehicle. The present invention may reduce the impact of deposits in or on one or more of these components.

In some embodiments addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) into the diesel fuel combusted in an engine reduces the formation of deposits in the turbocharger, suitably by at least 0.01%, preferably by at least 0.1%, for example at least 1% or at least 2%.

The present invention may reduce deposits on a fixed geometry turbocharger or on a variable geometry turbocharger. Variable geometry turbochargers having moving parts which are controlled by the engine management system. This allows the aspect ratio of the turbocharger to be changed to optimise performance at different speeds. The formation of deposits can lead to parts sticking. As a result the turbocharger will not provide the correct level of boost and may ultimately fail. The reduction of deposits on the turbocharger is therefore highly beneficial.

Preferably the present invention reduces deposits on the turbine wheel of the turbocharger.

In some embodiments the addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) into the diesel fuel combusted in an engine may reduce the formation deposits in the turbocharger by at least 3%, for example at least 4% or at least 5%, or at least 9 wt %.

In some embodiments addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) into the diesel fuel combusted in an engine reduces the formation of deposits in the diesel oxidation catalyst, suitably by at least 0.01%, preferably by at least 0.1%, for example at least 1% or at least 2%.

The diesel oxidation catalyst typically comprises a ceramic support structure coated with metals such as palladium, platinum and/or rhodium. The formation of deposits in the diesel oxidation catalyst can lead to a reduction in flow rate through the catalyst and/or poisoning of the catalyst.

In some embodiments the addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) into the diesel fuel combusted in an engine may reduce the formation deposits in the diesel oxidation catalyst by at least 3%, for example at least 4% or at least 5%, or at least 9 wt %.

Suitably addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) into the diesel fuel combusted in an engine reduces the formation of deposits in the diesel particulate filter, suitably by at least 0.01%, preferably by at least 0.1%, for example at least 1% or at least 2%.

Suitably addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof into the diesel fuel combusted in an engine reduces the formation of deposits in the diesel particulate filter, suitably by at least 0.01%, preferably by at least 0.1%, for example at least 1% or at least 2%.

Suitably addition of a polymer prepared from (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof into the diesel fuel combusted in an engine reduces the formation of deposits in the diesel particulate filter, suitably by at least 0.01%, preferably by at least 0.1%, for example at least 1% or at least 2%.

The diesel particulate filter is designed to capture from the exhaust gases particulates such as soot which are formed in the combustion chamber. These particulates collect on the filter and are burnt off at intervals by the increasing temperature of the exhaust gases and the injection of additional fuel. This process is known as filter regeneration.

The present invention may increase the interval between regenerations. This can improve the fuel economy of the engine and reduce emissions. By a reduction in regenerations we mean to include a reduction in active, passive or parked regenerations of the diesel particulate filter. For example there may be a reduction in the number of regeneration events per 1000 km.

In some embodiments the addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) into the diesel fuel combusted in an engine may reduce the formation deposits in the diesel particulate filter by at least 3%, for example at least 4% or at least 5%, or at least 9 wt %.

In some embodiments the addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and the diesel fuel combusted in an engine may reduce the formation deposits in the diesel particulate filter by at least 3%, for example at least 4% or at least 5%, or at least 9 wt %.

In some embodiments the addition of a polymer prepared from (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof into the diesel fuel combusted in an engine may reduce the formation deposits in the diesel particulate filter by at least 3%, for example at least 4% or at least 5%, or at least 9 wt %.

In some embodiments addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) into the diesel fuel combusted in an engine reduces the formation of deposits in the selective catalytic reduction unit, suitably by at least 0.01%, preferably by at least 0.1%, for example at least 1% or at least 2%.

Selective catalytic reduction is used to remove NOx and other harmful gases from the exhaust stream and involves the use of ammonia as a reductant in the presence of a catalyst. The selective catalytic reduction unit comprises a porous ceramic support and a catalyst, typically comprising a metal or a zeolite.

The formation of deposits on the selective catalytic reduction unit can lead to a reduction in flow rate through the unit and/or poisoning of the catalyst.

In some embodiments the addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) into the diesel fuel combusted in an engine may reduce the formation deposits in the selective catalytic reduction unit by at least 3%, for example at least 4% or at least 5%.

In some embodiments addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) into the diesel fuel combusted in an engine reduces the formation of deposits in the ammonia oxidation catalyst, suitably by at least 0.01%, preferably by at least 0.1%, for example at least 1% or at least 2%.

The ammonia oxidation catalyst is used to oxidise any ammonia present in the exhaust gases after passing through the selective catalytic reduction unit.

The formation of deposits on the ammonia oxidation catalyst can lead to a reduction in flow rate through the catalyst and/or poisoning of the catalyst.

In some embodiments the addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) into the diesel fuel combusted in an engine may reduce the formation deposits in the ammonia oxidation catalyst by at least 3%, for example at least 4% or at least 5%.

In some embodiments addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) into the diesel fuel combusted in an engine reduces the formation of deposits on sensors within the post combustion system, suitably by at least 0.01%, preferably by at least 0.1%, for example at least 1% or at least 2%.

Suitably said reductions are provided by using 5 to 100 ppm of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii), in said diesel fuel.

In some embodiments, addition of from 5 to 100 ppm of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) into the diesel fuel combusted in an engine reduces the formation of deposits in the cooler an EGR system by at least 5%, preferably by at least 10%, for example at least 15% or at least 20%; and reduces the formation deposits in the diesel particulate filter by at least 3%, for example at least 4% or at least 5%, or at least 9 wt %.

In some embodiments, addition of from 5 to 100 ppm of a polymer prepared from components (i) and (ii) into the diesel fuel combusted in an engine reduces the formation of deposits in the cooler an EGR system by at least 5%, preferably by at least 10%, for example at least 15% or at least 20%; and reduces the formation deposits in the diesel particulate filter by at least 3%, for example at least 4% or at least 5%, or at least 9 wt %.

Sensors may be present in the post combustion to measure temperature, pressure and/or concentrations of gases such as NO_x in the exhaust gases. If deposits are present on or around the sensors they may be unable to function correctly or inaccurate measurements may be taken leading to incorrect information being provided to the engine management system. This can lead to poor performance of the engine.

In some embodiments the addition of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) into the diesel fuel combusted in an engine may reduce the formation deposits on sensors within the post combustion system by at least 3%, for example at least 4% or at least 5%.

The reduction in deposits in post combustion system may be measured by any suitable means.

One simple means by which the level of deposits in a part of a post combustion system may be determined is by weighing the part of the system before and after use. One or more parts of the system may be weighed.

Other less direct methods may also be used. For example an improvement in fuel economy may indicate longer regeneration intervals on a diesel particulate filter.

Preferably the present invention provides an improvement in fuel economy of at least 0.1%, preferably at least 0.5%, suitably at least 1%, for example at least 2%.

The engine management system of a vehicle may be interrogated to assess the performance of components such as the turbocharger, the diesel particulate filter, the diesel oxidation catalyst and the selective catalytic reduction unit.

The invention may result in fewer error messages being provided by the engine management system to a driver.

An increase in the necessary maintenance intervals for a catalytic components may also indicate improved performance due to deposit reduction.

The deposits that form in the post combustion system may be analysed. This may be achieved, for example by extracting the deposits or a portion thereof into a solvent. The sample may be separated into soluble and non soluble fractions; these may then be separately analysed by methods known to those skilled in the art, for example elemental analysis, thermogravimetric analysis and/or gas chromatography mass spectrometry.

Thermogravimetric analysis (or TGA) involves measuring the mass of a sample over time as it is heated. This technique is well know to the person skilled in the art and the selection of an appropriate method and suitable equipment will be within the competence of one skilled in the art.

When post composition deposits contain soot, the soot density can be measured, for example using an AVL483 microsoot sensor.

Particle size of the soot can be measured by techniques known to these skilled in the art.

The reduction of deposits in the post combustion system of a diesel engine according to the present invention offers significant benefits.

These include, but are not limited to: an increase in power generation; an increase in torque; an increase in fuel economy; a reduction in emissions; a reduction in combustion chamber deposits; an acceleration improvement; driveability improvements; a reduction in cold start issues; lower soot formation; mitigation of lubricant degradation and/or performance loss; a reduction in diesel exhaust fluid and consumption e.g. urea consumption; reduction in wear on all post combustion components (including but not limited to the turbo charger, oxidation catalyst, DPF, SCR CAT, sensors, and injectors within the post combustion system); increased longevity of exhaust components; and the protection of intake components downstream of the EGR, for example swirl flaps, throttles and the intake manifold (due to a reduction in the likelihood of blocking etc.). In some embodiments of the present invention of a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) reduces the formation of deposits in an EGR system, preferably by at least 5%, for example by at least 20% or at least 50%.

In some embodiments of the present invention a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) or an anhydride thereof and/or of a polymer prepared from components (i) and (ii) reduces the impact of deposits on one or more of a turbocharger, a diesel oxidation catalyst, a diesel particulate filter, a selective catalytic reduction unit and an ammonia oxidation catalyst.

In some embodiments of the present invention a reaction product of (i) an alcohol and (ii) a dicarboxylic acid compound of formula (I) and/or of a polymer prepared from components (i) and (ii) removes deposits on sensors within the post combustion system, for example deposits on NO_x sensors, temperature sensors and/or pressure sensors.

Any feature of the invention may be combined with any other feature as appropriate.

The invention will now be further described with reference to the following non-limiting examples. In the examples which follow the values given in parts per million (ppm) are by weight.

EXAMPLE 1

Additive A1, an additive of the present invention was prepared as follows:

A 500 mL, 3-neck round bottom flask was fitted with a magnetic stirrer, condenser, Dean-Stark apparatus, gas inlet/outlet, stirrer hotplate and oil bath. Oleyl alcohol (206.19 g, 0.768 mol), itaconic acid (100 g, 0.768 mol) and p-toluenesulfonic acid (0.439 g, 2.30 mmol) were combined and heated to 165° C. (internal temperature). The reaction mass was held at 165° C. for 6 hours and water was removed. The reaction mass became homogenous and a colour change to orange was observed. After cooling to room temperature, the reaction mass was transferred to a 2 L separating funnel and toluene (270 mL) was added. The toluene-diluted reaction mass was washed with 1:1 water-methanol (1×540 mL), the organic phase separated and volatiles removed on the rotary evaporator, providing a viscous orange liquid (257.6 g).

The acid value of Additive A1 was 2.0 mmolH⁺/g.

EXAMPLE 2

Additive A2, an additive of the present invention was prepared as follows:

A 100 mL, 3-neck round bottom flask was fitted with a magnetic stirrer, condenser and stirrer hotplate. Citronellol (20 g, 0.128 mol), itaconic acid (16.52 g, 0.127 mol) and p-toluenesulfonic acid (0.073 g, 0.38 mmol) were combined and heated to 160° C. (internal temperature) for 6 hours. After cooling to room temperature, a sample (15 g) of the total reaction mass was taken and dissolved in toluene (15 mL). The toluene solution was washed with 1:1 water-methanol (1×30 mL), the organic phase separated and volatiles removed on the rotary evaporator, providing a viscous orange liquid (13.6 g).

The acid value of Additive A2 was 2.7 mmolH⁺/g.

EXAMPLE 3

Additive A3, an additive of the present invention was prepared using a method analogous to the methods described in examples 1 and 2.

The acid value of Additive A3 was 2.4 mmolH⁺/g.

EXAMPLE 4

Additive A4, a polymeric additive of the invention was prepared as follows:

To a 1 L reactor charged with 2-ethylhexanol (250 g, 1.918 moles) was added toluene (215.7 g) and heated to 90° C. To the stirred liquid was added itaconic acid (250 g, 1.921 moles) and p-toluenesulfonic acid (3.31 g). The reaction was heated towards 120° C., whilst removing water by distillation over 7 hours. The products where cooled to room temperature and unreacted itaconic and p-toluenesulfonic acid removed by filtration and washing with water. The toluene was removed on a rotary evaporator to leave a yellow/orange liquid (2-ethylhexyl itaconate, 412.9 g)

To a 250 ml reactor was charged 2-ethylhexyl itaconate (120 g) was added cyclohexane (51.43 g) and the reactor contents sparged with Nitrogen for 1 hour whilst heating to 80° C. Trigonox 25-C75 (0.685 g, 0.5 wt, %, tert-Butyl peroxypivalate) was added and the reaction was mixed at 80° C. for 1 hour before adding further Trigonox 25-C75 (0.685 g) and heating for a further 3 hours at 80° C. The cyclohexane was removed on a rotary evaporator and Aromatic 150 (69.7 g) added to leave a clear amber viscous liquid (184.4 g, Mw 10932, acid value of 2.4 mmolH⁺/g).

EXAMPLE 5

Additive A5, a polymeric additive of the invention was prepared as follows:

Step 1—Esterification to 2-Ethylhexyl Itaconate

A clean 1 L oil jacketed reactor with overhead stirrer, was purged with nitrogen and charged with 2-ethylhexanol (300.91 g, 2.31 moles), aromatic 150 (236.32 g) and stirred. Itaconic acid (250.51 g, 1.925 moles) and para-toluene sulphonic acid (1.54 g, 0.2 wt. %) were added and the reaction heated to 120° C. Water was distilled from the reaction as an azeotrope with A150 for 4 hours. The reaction mixture was heated to 80° C. and washed with water (2×150 ml) by stirring for 10 minutes and allowing to separate for 1 hour and draining the lower aqueous. The residual water was removed under vacuum at 80° C. for 1 hour.

Step 2—Polymerisation to Poly 2-Ethylhexyl Itaconate

The reaction mixture from step 1 was heated to 72° C. and purged with nitrogen.

Trigonox 25-C75 (6×2 g) was added over 5 hours, with an addition each hour. The reaction was heated for a further 6 hours before diluting with further aromatic A150 (207.42 g) to leave a pale amber, viscous clear liquid (836.29 g)—additive A5—comprising 55 wt % of active agent content.

EXAMPLE 6—ENGINE TESTING

Engine testing was carried out as described below to assess the performance of the additives of the present invention in the reduction of deposits in the post combustion system of diesel engines and in the reduction of deposits in the exhaust gas recirculation system of a diesel engine.

Engine Details

A Euro 6 compliant 2.0 litre, HSDI engine was connected to a test automation system and test bed fitted with an engine dynamometer. The engine was controlled by an ECU supplied by the engine manufacturer. The engine had had over 1100 h of use prior to the first test. The engine oil was changed prior to performing the first test.

Modifications/Test Setup

• • 1. No SCR Catalyst or associated components were present in the exhaust system.
  • 2. High pressure EGR cooler is artificially controlled to 40° C. for the duration of the test.

The base fuel was an RF-06-03 diesel fuel (Haltermann Carless, UK) having the following specification:

Feature	Units	Results	Minimum	Maximum	Method

Density 15° C.	kg/m3	836.0	833.0	837.0	ASTM D4052
Marker (Red)	—	Pass	—	—	VISUAL
Cetane Number		53.9	52.0	54.0	ASTM D613
I.B.PI.	° C.	214.3			ASTM D86
10% v/v Recovered at	° C.	232.0			ASTM D86
50% v/v Recovered at	° C.	275.5	245.0	—	ASTM D86
90% v/v Recovered at	° C.	330.2			ASTM D86
95% v/v Recovered at	° C.	348.0	345.0	350.0	ASTM D86
F.B.PI.	° C.	356.2	—	370.0	ASTM D86
Aromatics by FIA	% (V/V)	19.8	Corrected for		ASTM D1319
Olefins by FIA	% (V/V)	5.5
Flash Point, Pensky Closed	° C.	92.0	55.0	—	ASTM D93
Sulphur Content	mg/kg	<3.0	—	10.0	ASTM D5453
Viscosity at 40° C.	mm2/s	3.062	2.300	3.300	ASTM D445
Cloud Point	° C.	−18			ASTM D2500
CFPP	° C.	−20	—	−15	EN 116
Lubricity (WSD 1.4) at 60° C.	μm	180	—	400	ISO 12156-1
Carbon Residue (on 10% Dist. Res)	% (m/m)	<0.10	—	0.20	ASTM D4530
Ash	% (m/m)	<0.001	—	0.010	ASTM D482
FAME Content: None Detected	—	Pass	—	—	EN 14078
Polycyclic Aromatic Hydrocarbons	% (m/m)	5.8	3.0	6.0	EN 12916
Total Aromatic Hydrocarbons	% (m/m)	22.2			EN 12916
Water Content	mg/kg	50	—	200	IP 438
Water & Sediment	% (V/V)	<0.010			ASTM D2709
Strong Acid Number	mg	0 KOH/g	—	0.02	ASTM D974
Oxidation Stability	mg	<0.1 per	—	2.5	ASTM D2274
		100 ml
Copper Corrosion, 3 hrs at 100° C.	—	1B	—	—	ASTM D130
Oxygen Content	% (m/m)	<0.04	ELEMENTAL		Elemental Analysis
Carbon Content	% (m/m)	86.89	ASTM D5291		ASTM D5291
Hydrogen Content	% (m/m)	13.11	ASTM D5291		ASTM D5291
Carbon Weight Fraction		0.8889	CALCULATION		Calculation
C/H Mass Ratio		6.63	CALCULATION		Calculation
Atomic H/C Ratio		1.7979	CALCULATION		Calculation
Atomic O/C Ratio		<0.0003	CALCULATION		Calculation
Gross Heat of Combustion	MJ/kg	45.72	IP 12		IP 12
Net Heat of Combustion	MJ/kg	42.94	IP 12		IP 12
Net Heat of Combustion	btu/lb	18460	CALCULATION		Calculation

Test Additives, Treat Rate:

The example additive A5 was dosed at 100 ppm into the base diesel fuel described above to provide test fuel 1. Therefore test fuel 1 contained 55 ppm of the active agent (poly 2-ethylhexyl itaconate).

Method of Soot Deposition Measurement (DPF & EGR Soot Weight)

The quantity of soot deposited in the EGR cooler was established by weighing the component before and after each test.

The quantity of soot deposited in the DPF was established by weighing both components before and after each test.

The EGR cooler is thoroughly cleaned using tap water sprayed at high pressure through the cooler matrix. This cleaning process is performed until no more deposit can be seen in the cooler matrix with the naked eye.

The EGR cooler was then placed into an oven, pre-heated to 185° C., affixed to a set of scales. The weight measurement was taken as an average is taken over 15 minutes, once the scales had stabilised. This weighing process is repeated at the end of the test. The variance between the weight measured before and after the test represents the change in mass due to soot deposition.

Prior to the initial weighing, the DPF is passively regenerated on the test bed to remove any residual soot. Once the regeneration is complete, the DPF is placed into an oven, pre-heated to 185° C., affixed to a set of scales. The weight measurement was taken as an average over 15 minutes, once the scales had stabilised. This weighing process is repeated at the end of the test. The variance between the weight measured before and after the test represents the change in mass due to soot deposition.

Test Procedure

• • [D] EGR Cleaned and weighed
  • [D] DPF+Slave EGR Installation
  • Engine Start+Warm-Up
  • Passive DPF Regeneration by varying the engine speed and load until the regeneration is complete. The differential pressure across the is used to monitor the regeneration progress.
  • Engine Stop
  • Change to test fuel
  • [C] DPF+Slave EGR Removal
  • [C] DPF Start-of-Test (SOT) Weighing
  • [C] DPF+[C] EGR Installation
  • Engine Start+Warm-Up
  • 8-Hour Steady-State Test Cycle
    • 1200 RPM
    • 60 Nm
  • Engine Stop
  • [D] DPF Removal and End-of-Test (EOT) Weighing
  • [D] EGR Removal and EGR End of Test Weighing

[C] indicates a clean component

[D] indicates a fouled component

RESULTS

		Treat	EGR cooler	DPF Soot
		rate	Soot Weight	Weight
Test fuel	Additive	(ppm)	[g]	[g]

Base fuel	—	—	1.59	36.35
1	A5	100	1.24	33.00

These results demonstrate that the use of the additives described herein in a diesel fuel composition may provide a significant reduction in deposits in an exhaust gas recirculation system of a diesel engine combusting said fuel.

These results also demonstrate that the use of the additives described herein in a diesel fuel composition may provide a significant reduction in deposits in the post combustion system of a diesel engine combusting said fuel, specifically a reduction in the soot deposited on the diesel particulate filter of the post combustion system.