Fuel lubricity improvers and their applications

Abstract

A fuel lubricity improver and its application, the fuel lubricity improver comprising a dicarboxylic acid monoester compound represented by structural formula (I): [Formula 1] JPEG2023521642000053.jpg25169 R1 is a single bond, a substituted or unsubstituted C 2-6 or a group having the structure -R3-R4-R5-, wherein R2 is a substituted or unsubstituted C 1-40 R3 and R5 each independently represent a single bond or a substituted or unsubstituted C 1-3 R4 represents a substituted or unsubstituted C 3-12 The fuel lubricity improver can significantly improve the lubricity of the fuel, can be used at low dosages, and can significantly reduce the cost of using the lubricity improver.

Description

Detailed Description of the Invention

[0001] (Cross-Incorporation of Related Applications) This application claims priority to the Chinese patent application No. 202010237464.X, filed on March 30, 2019, entitled "Lubricant Additive Composition for Diesel Fuel, Preparation Method Thereof, and Diesel Fuel Composition," and to the Chinese patent application No. 202010240138.4, filed on March 30, 2019, entitled "Lubricant Additive Composition for Diesel Fuel, Preparation Method Thereof, and Diesel Fuel Composition," the entire contents of which are incorporated herein by reference. [Technical Field] This application relates to the field of fuel additives, and more particularly to ester-based fuel lubricity improvers, their preparation methods and applications. [Background technology] Due to the poor lubricity of low-sulfur diesel, low-sulfur and ultra-low-sulfur diesel fuels are often modified with lubricity improvers (also known as lubricity additives or antiwear agents) to improve their lubricity. This method has advantages such as low cost, flexible production, and low pollution, and has attracted widespread attention in the industry. The lubricity additives for low-sulfur diesel fuel currently used in the industry are mainly classified as acid-based lubricity additives and ester-based lubricity additives. Acid-based lubricity additives mainly contain long-chain unsaturated fatty acids such as oleic acid, linoleic acid, and linolenic acid, and a typical product is refined tall oil fatty acid. Ester-based lubricity additives are produced by the esterification reaction of the above fatty acids with polyols. While the use of fatty acid-based lubricity additives to solve diesel fuel lubricity issues is relatively low cost, increasing usage due to upgraded diesel fuel emission standards and the deterioration of diesel fuel lubricity can lead to problems such as excessive acidity in diesel fuel and increased corrosion risk. Although used in small amounts, fatty acid ester-based lubricity additives can suffer from high cost and problems of emulsification and cloudiness when the formulated diesel fuel comes into contact with water.

[0002] In aircraft turbine engine fuel injection systems, all components are lubricated by fuel. However, deterioration of fuel lubricity can lead to severe wear on the fuel plunger pump ball, a drop in fuel injection pressure, a reduction in engine speed, and even a grounding accident. Therefore, lubricity additives are needed to improve lubricity. Dimer acid, obtained by polymerization of conjugated or non-conjugated unsaturated fatty acids, primarily oleic, linoleic, and linolenic acids, via the Diels-Alder addition reaction, is the primary component of aviation fuel lubricity improvers currently used in most countries. However, the high synthesis cost of dimer acid lubricity additives makes the use of dimer acid itself as an aviation fuel lubricity improver expensive.

[0003] Compared to other fuels, gasoline is the lightest and least lubricious liquid fuel. Gasoline has an extremely low content of natural anti-wear impurities, making the lubrication effect of its main components extremely important. Furthermore, improved gasoline also contains significant amounts of oxygen-containing compounds (e.g., lower alcohols) that readily absorb water and olefins that are easily oxidized, which can adversely affect gasoline's lubricity. Improving gasoline lubricity not only reduces fuel injection pump wear and extends engine life, but also improves energy utilization efficiency and reduces specific fuel consumption. Similar to solving the lubricity issues of aviation and diesel fuels, an effective way to improve gasoline lubricity is to add lubricity additives to gasoline. Current gasoline lubricity additives are often derived from fatty amines or ether amines, which are expensive to prepare. Furthermore, prepared lubricity additives are nitrogen-containing compounds that generate nitrogen oxides during gasoline combustion and use, causing exhaust pollution and violating the principle of clean fuel use.

[0004] Therefore, there is a compelling need in the art for fuel lubricity improvers that significantly improve the lubricity of fuels and that are low cost to use. Summary of the Invention One object of the present application is to provide new fuel lubricity improvers that can significantly improve the lubricity of fuels and can be used in relatively low dosages, thereby significantly reducing the cost of using the lubricity improver.

[0005] In order to achieve the above object, in one aspect, the present application provides: A fuel lubricity improver containing a dicarboxylic acid monoester compound represented by structural formula (I):

[0006] [ka]

[0007] R1 is a single bond, a substituted or unsubstituted C 2-6 or a group having the structure -R3-R4-R5-, R2 is a substituted or unsubstituted C 1-40 represents a hydrocarbyl group, R3 and R5 each independently represent a single bond or a substituted or unsubstituted C 1-3 represents a divalent alkyl group of the formula: R4 is a substituted or unsubstituted C 3-12 represents a divalent alicyclic group represented by the formula: The "substitution" means at least one C 1-4 A fuel lubricity improver is provided, which means that it is substituted with linear or branched chain hydrocarbyl groups.

[0008] In another aspect, the present application provides a fuel composition comprising a fuel component and a lubricity improver according to the present application, wherein the content of the dicarboxylic acid monoester compound is 5-400 ppm, based on 100% by mass of the fuel.

[0009] In another aspect, the present application provides a method for improving the lubricity of a fuel, comprising the step of adding a lubricity improver according to the present application to the fuel, wherein the amount of the dicarboxylic acid monoester compound used is 5-400 ppm, based on the mass of the fuel taken as 100%.

[0010] In a further aspect, the present application provides a method for producing a method of treating a cancer cell comprising: The dicarboxylic acid monoester compound has the following structural formula (I):

[0011] [ka]

[0012] R1 and R2 are defined as above, and provide for the use of dicarboxylic acid monoester compounds as fuel lubricity improvers.

[0013] In another aspect, the present application provides a method for producing a method of manufacturing a pharmaceutical composition comprising:

[0014] [ka]

[0015] R1 is a single bond, a substituted or unsubstituted C 2-6 or a group having the structure -R3-R4-R5-, R2 is a substituted or unsubstituted C 5-14 represents a linear or branched alkyl group, R3 and R5 each independently represent a single bond or a substituted or unsubstituted C 1-3 represents a divalent alkyl group of the formula: R4 is a substituted or unsubstituted C 3-6 represents a divalent alicyclic group represented by the formula: The "substitution" means at least one C 1-4 Dicarboxylic acid monoester compounds of structural formula (I), meaning substituted with linear or branched hydrocarbyl groups, suitable for use as fuel lubricity improvers, are provided.

[0016] The fuel lubricity improver of the present invention has the advantages of being easy to obtain from raw materials, being simple and easy to produce, being able to significantly improve the lubricity of fuel, requiring only a small amount to be added, and being able to significantly reduce the cost of using the lubricity improver.

[0017] Furthermore, when the fuel lubricity improver according to the present application contains the unsaturated dicarboxylic acid monoester compound of structural formula (I), it is not likely to cause emulsification or cloudiness in diesel fuel, and its anti-emulsification effect is equivalent to that of fatty acid-based lubricity improvers and superior to that of fatty acid glyceride-based lubricity improvers. BRIEF DESCRIPTION OF THE DRAWINGS The drawings constitute a part of the specification and are intended to provide a further understanding of the present application and are not to be considered as limiting the present application, which can be read with reference to the drawings in combination with the following detailed disclosure.

[0018] [Figure 1] This shows a photograph of the wear scar of diesel fuel b measured using a diesel lubricity tester manufactured by PCS in the UK. The corrected wear scar diameter (WS1.4) is 651 μm.

[0019] [Figure 2] This shows a photograph of the wear scar measured after adding 200 mg / kg of monoisooctyl maleate obtained in Example II-1 to diesel fuel b, and the corrected wear scar diameter (WS1.4) is 208 μm.

[0020] Detailed Disclosure of the Invention The present application will now be described in more detail with reference to specific embodiments thereof and the accompanying drawings. It should be noted that the specific embodiments of the present application are provided for illustrative purposes only and are not intended to be limiting in any way.

[0021] Any specific numerical value (including the endpoints of a numerical range) disclosed in the context of this application should not be construed as being limited to the exact value of that numerical value, but should also be construed as encompassing all values ​​close to that exact value, such as all values ​​within a range of ±5% of that exact value. Furthermore, for any numerical range disclosed herein, any combination can be made between the endpoints of the range, between an endpoint value and any specific value within the range, or between two specific values ​​within the range, to obtain one or more new numerical ranges. Such new numerical ranges should also be considered to be specifically disclosed in this application.

[0022] Unless otherwise stated, terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Where terms are defined herein and their definitions differ from the common understanding in the art, the definitions herein shall prevail.

[0023] As used herein, the term "divalent" group refers to a group obtained by removing two hydrogen atoms from the corresponding compound. For example, the term "C 2-6 The term "divalent alkenyl group" refers to a group obtained by removing two hydrogen atoms from a straight or branched chain olefin having 2 to 6 carbon atoms, such as ethylene, propylene, 1-butene, 2-butene, isobutylene, pentene, hexene, etc., and the carbon-carbon double bond can be in the main chain or in a side chain of the group. 1-3 A divalent alkyl group of "C" is a group obtained by removing two hydrogen atoms from an alkane of 1 to 3 carbon atoms, such as methylene, ethylene, propylene, etc. 3-12 A "divalent alicyclic group" is a group obtained by removing two hydrogen atoms from a saturated or unsaturated alicyclic hydrocarbon having 3 to 12 carbon atoms, such as cyclopropane, cyclobutane, cyclopentane, cyclopentene, cyclohexane, or cyclohexene.

[0024] As used herein, the term "hydrocarbyl group" refers to a group obtained by removing one hydrogen atom from an aliphatic, alicyclic, or aromatic hydrocarbon. The term "aliphatic hydrocarbon" refers to a straight-chain or branched-chain, saturated or unsaturated hydrocarbon. For example, C 1-40Examples of hydrocarbyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, isooctyl, n-nonyl, isononyl, n-decyl, isodecyl, n-undecyl, isoundecyl, n-dodecyl, n-tridecyl, isotridecyl, 3-hexen-1-yl, octadecenyl, cyclohexyl, p-nonylphenyl, benzyl, and the like.

[0025] In the context of this application, any undescribed matter or content other than that explicitly described shall be considered to be the same as that known in the art without any change. Furthermore, any embodiment described in this specification can be freely combined with one or more other embodiments described in this specification. Any technical solution or technical idea obtained thereby shall be considered to be part of the original disclosure or original description of this specification, and shall not be considered as new matter not disclosed or anticipated in this specification, unless it is obvious to a person skilled in the art that such combination is obviously irrational.

[0026] All patent and non-patent literature cited herein is incorporated in its entirety and is hereby incorporated by reference, including, but not limited to, textbooks and periodicals.

[0027] As described above, in a first aspect, the present application provides a fuel lubricity improver comprising a dicarboxylic acid monoester compound represented by structural formula (I):

[0028] [ka]

[0029] R1 is a single bond, a substituted or unsubstituted C 2-6 or a group having the structure -R3-R4-R5-, R2 is a substituted or unsubstituted C 1-40 represents a hydrocarbyl group, R3 and R5 each independently represent a single bond or a substituted or unsubstituted C 1-3 represents a divalent alkyl group of the formula: R4 is a substituted or unsubstituted C 3-12 represents a divalent alicyclic group represented by the formula: The "substitution" means at least one C 1-4 Fuel lubricity improvers are provided, meaning they are substituted with linear or branched chain hydrocarbyl groups.

[0030] In a preferred embodiment, R is a single bond, substituted or unsubstituted C 2-4 or a group having the structure -R3-R4-R5-, wherein R2 is a substituted or unsubstituted C 1-18 R3 and R5 each independently represent a single bond or a methylene group; R4 is a substituted or unsubstituted C 3-10 represents a divalent alicyclic group of the formula:

[0031] In a preferred embodiment, R2 is C 1-18 a linear or branched hydrocarbyl group of C 4-18 alicyclic hydrocarbyl groups of the formula C 7-18 The aryl-substituted hydrocarbyl or hydrocarbyl-substituted aryl groups are selected from the group consisting of:

[0032] In some particularly preferred embodiments, the dicarboxylic acid monoester compound is selected from the group consisting of maleic acid monoester, fumaric acid monoester, itaconic acid monoester, citraconic acid monoester, methyl fumaric acid monoester, 2,3-dimethylmaleic acid monoester, glutaconic acid monoester, or any combination thereof. More preferably, the dicarboxylic acid monoester compound is monomethyl maleate, monoethyl maleate, mono-n-propyl maleate, mono-n-butyl maleate, mono-n-octyl maleate, mono-n-nonyl maleate, mono-n-decyl maleate, mono-n-dodecyl maleate, monomethyl itaconate, monoethyl itaconate, mono-n-propyl itaconate, mono-n-butyl itaconate, mono-n-octyl itaconate, mono-n-decyl itaconate, mono-n-dodecyl itaconate, monoisopropyl maleate, monoisobutyl maleate, mono-sec-butyl maleate, mono-tert-butyl maleate, monoisooctyl maleate (mono-2-ethylhexyl maleate), The carboxylic acid is selected from the group consisting of monoisononyl leate, monoisodecyl maleate, isoundecyl maleate, isotridecyl maleate, monoisopropyl itaconate, monoisobutyl itaconate, monoisooctyl itaconate, monoisononyl itaconate, monoisodecyl itaconate, monoisoundecyl itaconate, monoisotridecyl itaconate, mono-3-hexen-1-yl maleate, monooleyl maleate, mono-3-hexen-1-yl itaconate, monooleyl itaconate, monocyclohexyl maleate, monocyclohexyl itaconate, mono-p-nonylphenyl maleate, mono-p-nonylphenyl itaconate, monobenzyl maleate, monobenzyl itaconate, or any combination thereof.

[0033] In another particularly preferred embodiment, the dicarboxylic acid monoester compound is selected from the group consisting of 1,2-cyclopentanedicarboxylic acid monoester, 1,2-cyclohexanedicarboxylic acid monoester, tetrahydrophthalic acid monoester, methylhexahydrophthalic acid monoester, methyltetrahydrophthalic acid monoester, 1-methyl-1,2-cyclohexanedicarboxylic acid monoester, 4-methyl-1,2-cyclohexanedicarboxylic acid monoester, 3-methyl-1,2-cyclohexanedicarboxylic acid monoester, 4-methyl-4-cyclohexene-1,2-dicarboxylic acid monoester, 3-methyl-4-cyclohexene-1,2-dicarboxylic acid monoester, or any combination thereof. More preferably, the dicarboxylic acid monoester compound is selected from the group consisting of 1,2-cyclohexanedicarboxylic acid monoester, tetrahydrophthalic acid monoester, methylhexahydrophthalic acid monoester, methyltetrahydrophthalic acid monoester, or any combination thereof.

[0034] The fuel lubricity improver of the present application may further contain appropriate amounts of fuel and / or organic solvent, minor amounts of unreacted raw materials, and inevitable reaction by-products such as dicarboxylic acid diester compounds.

[0035] In a second aspect, the present application provides a method for preparing a compound comprising reacting a dicarboxylic acid or anhydride thereof having structural formula (II) with an alcohol or phenol having structural formula (III):

[0036] [ka]

[0037] [ka]

[0038] R1 and R2 are defined as above, providing a method for preparing a fuel lubricity improver.

[0039] In a preferred embodiment, the reaction conditions include: a molar ratio of the dicarboxylic acid or anhydride to the alcohol or phenol of 1:0.5-1:1.5; a reaction temperature of 50-250°C; a reaction time of 0.1-10 hours; a reaction pressure of normal pressure or high pressure; a catalyst may or may not be used; and a solvent may or may not be used.

[0040] In a more preferred embodiment, the reaction conditions include a molar ratio of the dicarboxylic acid or anhydride to the alcohol or phenol of 1:0.8-1:1.3, a reaction temperature of 50-200°C, a reaction time of 1-6 hours, a reaction pressure of atmospheric pressure, and no catalyst or solvent is used.

[0041] In a preferred embodiment, the dicarboxylic acid or anhydride having structural formula (II) includes, but is not limited to, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, 2,3-dimethylmaleic acid, 2,3-dimethylmaleic anhydride, and the like.

[0042] In a preferred embodiment, the alcohol or phenol having the structural formula (III) can be an aliphatic alcohol, alicyclic alcohol, or aromatic alcohol or phenol, having a carbon number of C1-C30, preferably C1-C18. When an aliphatic alcohol is used, the carbon number is C1-C24, preferably C1-C18. When an alicyclic alcohol is used, the carbon number is C3-C20, preferably C4-C10, including, but not limited to, cyclobutanol. When an aromatic alcohol or phenol is used, the carbon number is C6-C30, preferably C7-C18.

[0043] In the method of the present application, the reaction may be carried out in the presence or absence of a catalyst. The catalyst may be one or more acid catalysts selected from the group consisting of sulfuric acid, hydrochloric acid, p-toluenesulfonic acid, phosphoric acid, boric acid, acidic ion exchange resins, etc.; ionic liquid catalysts such as 1-butylpyridine / AlCl4 ionic liquid; one or more inorganic salt solid phase catalysts such as FeCl3 and AlCl3; one or more zeolite catalysts such as ZSM-5, HZSM-5, and Al-MCM-41; one or more heteropolyacid catalysts such as PW12 / MCM-41 and SiW12 / MCM-41; 2- / ZrO2-TiO2, SO4 2- / TiO2-Al2O3, etc., solid superacid catalysts; alkaline catalysts such as NaOH, KOH, sodium methoxide, solid superbases, NaH, etc. The reaction may be performed with or without a solvent, but the solvent may be hydrocarbons such as alkanes and aromatic hydrocarbons, for example, petroleum ether, gasoline, toluene, xylene, etc.

[0044] According to the present application, after the reaction is complete, the catalyst (if used) is removed by filtration and the resulting product may be used directly as the fuel lubricity improver of the present application, or alternatively, the product may be separated and purified, such as by removing the solvent and unreacted raw materials, in accordance with the specifications for the lubricity additive product. Solvents and unreacted raw materials that meet the specifications do not affect the performance of the lubricity additive of the present application, and these components do not adversely affect the performance of the fuel when added to the fuel.

[0045] According to the present invention, a fuel lubricity additive concentrate can be obtained by adding an appropriate amount of fuel to the reaction product.

[0046] In a third aspect, the present application provides a fuel composition comprising a fuel component and the fuel lubricity improver according to the present application, wherein the content of the dicarboxylic acid monoester compound is 5 to 400 ppm, preferably 10 to 300 ppm, based on 100% by mass of the fuel component.

[0047] In a preferred embodiment, the fuel component may be selected from diesel fuel, gasoline and aviation fuel.

[0048] In some preferred embodiments, the fuel composition comprises a diesel fuel component and a fuel lubricity improver according to the present application, and the content of the dicarboxylic acid monoester compound is 10 to 400 ppm, preferably 50 to 300 ppm, when the mass of the diesel fuel component is taken as 100%.

[0049] According to the present invention, the diesel fuel may include various low-sulfur diesel engine fuels, for example, the fuel may be a fuel for compression-ignition internal combustion engines conforming to the Chinese national standard GB / T19147 for automotive diesel fuel, obtained by blending fractions having a distillation range of 160-380°C, which are prepared by processing crude oil (petroleum) through various refining processes in a refinery, such as atmospheric and vacuum distillation, catalytic cracking, catalytic reforming, coking, hydrotreating, hydrocracking, etc.

[0050] The diesel fuel may be second-generation biodiesel, which is derived from renewable resources such as vegetable oils and animal fats and contains long-chain branched or unbranched hydrocarbons, typically prepared by hydrogenating vegetable oils through hydroprocessing in a refinery. Second-generation biodiesel may have properties and qualities similar to petroleum-based fuels.

[0051] The diesel fuel may be third-generation biodiesel, which is prepared from high-cellulose, non-petroleum biomass, such as wood waste, crop straw, or solid waste, and microbial oils by gasification and Fischer-Tropsch techniques.

[0052] The diesel fuel may be a coal-to-liquid (CTL) diesel fuel, i.e., a diesel fuel obtained by Fischer-Tropsch synthesis using coal as a raw material, or a diesel fuel obtained by direct liquefaction of coal. The diesel fuel may also be a blended diesel fuel obtained by adding an oxygen-containing diesel fuel blending component to a petroleum-based diesel fuel. Here, the oxygen-containing diesel fuel blending component refers to an oxygen-containing compound or a mixture of oxygen-containing compounds that can be blended with various diesel fuels to meet specific specifications. The oxygen-containing diesel fuel blending component is typically an alcohol or ether, or a mixture thereof, such as ethanol or polyoxymethylene dimethyl ether (PODEn, DMMn, or OME).

[0053] Depending on the needs of the application, the diesel fuel composition of the present application may further contain one or more additives, for example, phenolic antioxidants, polymeric amine ashless dispersants, flow improvers, cetane improvers, metal deactivators, antistatic agents, preservatives, rust inhibitors, and demulsifiers.

[0054] The polymeric amine ashless dispersant may include one or more of alkenyl succinimides and / or alkenyl succinamides, Mannich base ashless dispersants, polyether amine ashless dispersants, and polyolefin amine ashless dispersants. The flow improver is preferably a (meth)acrylate homopolymer and / or a polymer of ethylene and vinyl acetate. The cetane number improver may be a nitrate ester or a peroxide, such as isooctyl nitrate or di-tert-butyl peroxide. The metal deactivator may be one or more of an ammonium salt formed from benzotriazole and a fatty amine, a product obtained by the Mannich reaction of benzotriazole, formaldehyde, and a fatty amine, a Schiff base, and an organic polycarboxylic acid.

[0055] In some preferred embodiments, the fuel composition comprises an aviation fuel component and a fuel lubricity improver according to the present application, and the content of the dicarboxylic acid monoester compound is 5 to 200 ppm, preferably 5 to 50 ppm, when the mass of the aviation fuel component is taken as 100%.

[0056] According to the present application, the aviation fuel may be a fuel for aviation turbine engines, and may be aviation fuel formed from a first atmospheric side stream fraction obtained by atmospheric distillation of a petroleum refinery; a hydrotreated and hydrocracked component produced by a hydrotreating process, for example, No. 3 aviation fuel produced in accordance with GB 6537; or an aviation fuel component produced by coal liquefaction, including direct coal liquefaction and indirect coal liquefaction (Fischer-Tropsch synthesis); or an aviation fuel component produced by Fischer-Tropsch synthesis from synthesis gas; or an aviation fuel produced from renewable biomass feedstocks, for example, a hydrocarbon aviation fuel produced by hydrodeoxygenation of animal fats and vegetable oils, or an aviation fuel component produced by various catalytic reactions using waste oil, or cellulose or hemicellulose as raw materials.

[0057] Depending on the needs of the application, the aviation fuel composition of the present application may also contain other additives, such as one or more of naphthenic acid or dimer acid based lubricity additives, metal deactivators, antistatic agents, rust inhibitors, and anti-icing agents.

[0058] In some preferred embodiments, the fuel composition comprises a gasoline component and a fuel lubricity improver according to the present application, and the content of the dicarboxylic acid monoester compound is 5 to 400 ppm, preferably 10 to 300 ppm, when the mass of the gasoline component is taken as 100%.

[0059] According to the present application, the gasoline is a refined petroleum fraction having a distillation range of 30-220°C, which may contain appropriate additives and is suitable for use as a fuel for ignition engines, including automotive gasoline and aviation piston engine fuel (also known as aviation gasoline). Automotive gasoline mainly includes catalytically cracked gasoline, reformed gasoline, aromatic hydrocarbons, alkylated gasoline, isomerized gasoline, etc., and is divided into four grades, No. 89, No. 92, No. 95, and No. 98, based on research octane number. The gasoline described herein may contain various oxygen-containing compounds, such as methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME), diisopropyl ether (DIPE), methanol, ethanol, butanol, etc. The gasoline may be automotive gasoline, automotive ethanol gasoline, or aviation gasoline that meets the specifications of GB17930, GB18351, and GB1787.

[0060] Depending on the needs of the use, the gasoline compositions of the present application may further contain additives such as one or more of antioxidants, rust inhibitors, detergents, dispersants, and anti-knock agents.

[0061] In a fourth aspect, the present application provides a method for improving the lubricity of a fuel, comprising adding a lubricity improver according to the present application to the fuel, wherein the amount of the dicarboxylic acid monoester compound used is 5-400 ppm, preferably 10-300 ppm, based on the mass of the fuel taken as 100%.

[0062] In some preferred embodiments, the method comprises adding the lubricity improver of the present application to a low sulfur diesel fuel, wherein the dicarboxylic acid monoester compound is used in an amount of 10-400 ppm, preferably 50-300 ppm, based on 100% by mass of the diesel.

[0063] In some preferred embodiments, the method comprises adding the lubricity improver according to the present application to aviation fuel, wherein the dicarboxylic acid monoester compound is used in an amount of 5-200 ppm, preferably 5-50 ppm, based on 100% by mass of the aviation fuel.

[0064] In some preferred embodiments, the method comprises adding the lubricity improver of the present application to gasoline, wherein the dicarboxylic acid monoester compound is used in an amount of 5-400 ppm, preferably 10-300 ppm, based on 100% mass of the gasoline.

[0065] In a fifth aspect, the present application provides the use of a dicarboxylic acid monoester compound as a fuel lubricity improver, the dicarboxylic acid monoester compound having the following structural formula (I):

[0066] [ka]

[0067] R1 and R2 are defined as above.

[0068] In a sixth aspect, the present application provides dicarboxylic acid monoester compounds of structural formula (I) suitable as fuel lubricity improvers.

[0069] [ka]

[0070] where R1 is a single bond, a substituted or unsubstituted C 2-6 or a group having the structure -R3-R4-R5-, R2 is a substituted or unsubstituted C 5-14 represents a linear or branched alkyl group of the formula: R3 and R5 each independently represent a single bond or a substituted or unsubstituted C 1-3 represents a divalent alkyl group of the formula: R4 is a substituted or unsubstituted C 3-6 represents a divalent alicyclic group represented by the formula: The "substitution" means at least one C 1-4 This means that the alkyl group is substituted with a straight or branched chain hydrocarbyl group.

[0071] In a preferred embodiment, the dicarboxylic acid monoester compound is selected from compounds having the following structural formula:

[0072] [Table 1] JPEG0007803873000010.jpg63169

[0073] Two specific embodiments of the fuel lubricity improver of the present application will be described in detail below.

[0074] First Class of Embodiments In a first class of embodiments, the fuel lubricity improver of the present application comprises at least a cyclic dicarboxylic acid monoester compound selected from the group consisting of compounds of structural formula (I-1):

[0075] [ka]

[0076] where n is an integer between 1 and 8, m is an integer between 0 and 3, x is an integer between 0 and 8, y1 and y2 are integers between 0 and 2, and R is C 1-30 represents a hydrocarbyl group of the formula:

[0077] In a preferred embodiment, n is an integer from 1 to 6, m is an integer from 0 to 1, x is an integer from 0 to 6, y1 and y2 are integers from 0 to 2, and R is C 1-18 represents a hydrocarbyl group of the formula:

[0078] In a more preferred embodiment, n is 4 or 5, m is 0, x is an integer of 0-6, y1 and y2 are integers of 0-1, and R is C 4-12 represents a hydrocarbyl group of the formula:

[0079] In a particularly preferred embodiment, When n is 1, x is 0, y1 and y2 are 1, and m is 0, the monoester compound of structural formula (I-1) is a 1,2-cyclopropanedicarboxylic acid monoester, When n is 1, x is 0, y1 and y2 are 1, and m is 1, the monoester compound of structural formula (I-1) is 1,2-cyclopropanediacetic acid monoester; When n is 1, x is 2, y1 and y2 are 2, and m is 0, the monoester compound of structural formula (I-1) is a 1,1-cyclopropanedicarboxylic acid monoester; When n is 2, x is 0, y1 and y2 are 1, and m is 0, the monoester compound of structural formula (I-1) is a 1,2-cyclobutanedicarboxylic acid monoester; When n is 2, x is 0, y1 and y2 are 1, and m is 1, the monoester compound of structural formula (I-1) is 1,2-cyclobutanediacetic acid monoester; When n is 3, x is 0, y1 and y2 are 1, and m is 0, the monoester compound of structural formula (I-1) is a 1,2-cyclopentanedicarboxylic acid monoester, When n is 3, x is 0, y1 and y2 are 1, and m is 1, the monoester compound of structural formula (I-1) is 1,2-cyclopentanediacetic acid monoester; When n is 3, x is 1, one of y1 and y2 is 1 and the other is 2, and m is 0, the monoester compound of structural formula (I-1) is a 1,3-cyclopentanedicarboxylic acid monoester; When n is 4, x is 0, y1 and y2 are 1, and m is 0, the monoester compound of structural formula (I-1) is a 1,2-cyclohexanedicarboxylic acid monoester, When n is 4, x is 0, y1 and y2 are 1, and m is 1, the monoester compound of structural formula (I-1) is 1,2-cyclohexanediacetic acid monoester; When n is 4, x is 1, one of y1 and y2 is 1 and the other is 2, and m is 0, the monoester compound of structural formula (I-1) is a 1,3-cyclohexanedicarboxylic acid monoester; When n is 4, x is 2, y1 and y2 are 2, and m is 0, the monoester compound of structural formula (I-1) is a 1,4-cyclohexanedicarboxylic acid monoester; When n is 4, x is 2, y1 and y2 are 1, and m is 0, the monoester compound of structural formula (I-1) is 4-cyclohexene-1,2-dicarboxylic acid monoester (also called tetrahydrophthalic acid monoester), When n is 4, x is 2, y1 and y2 are 1, and m is 1, the monoester compound of structural formula (I-1) is 4-cyclohexene-1,2-diacetic acid monoester; When n is 5, x is 0, y1 and y2 are 1, and m is 0, the monoester compound of structural formula (I-1) is 3-methyl-1,2-cyclohexanedicarboxylic acid monoester (also called 3-methylhexahydrophthalic acid monoester), 4-methyl-1,2-cyclohexanedicarboxylic acid monoester (also called 4-methylhexahydrophthalic acid monoester), etc. When n is 5, x is 2, y1 and y2 are 1, and m is 0, the monoester compounds of structural formula (I-1) include methyltetrahydrophthalic acid monoester, 4-methyl-4-cyclohexene-1,2-dicarboxylic acid monoester, and 3-methyl-4-cyclohexene-1,2-dicarboxylic acid monoester.

[0080] According to the present application, the cyclic dicarboxylic acid monoester compound is preferably selected from the group consisting of 1,2-cyclopentanedicarboxylic acid monoester, 1,2-cyclohexanedicarboxylic acid monoester, tetrahydrophthalic acid monoester, methylhexahydrophthalic acid monoester, methyltetrahydrophthalic acid monoester, 1-methyl-1,2-cyclohexanedicarboxylic acid monoester, 4-methyl-1,2-cyclohexanedicarboxylic acid monoester, 3-methyl-1,2-cyclohexanedicarboxylic acid monoester, 4-methyl-4-cyclohexene-1,2-dicarboxylic acid monoester, and 3-methyl-4-cyclohexene-1,2-dicarboxylic acid monoester. Further, the cyclic dicarboxylic acid monoester compound is preferably selected from the group consisting of 1,2-cyclohexanedicarboxylic acid monoester, tetrahydrophthalic acid monoester, methylhexahydrophthalic acid monoester, and methyltetrahydrophthalic acid monoester.

[0081] According to the present application, the R group in structural formula (I-1) may be an aliphatic hydrocarbyl group, an alicyclic hydrocarbyl group, or an aromatic hydrocarbyl group. The aliphatic hydrocarbon may be linear or branched, and may be saturated or unsaturated. The unsaturated aliphatic hydrocarbon may be an aliphatic hydrocarbon containing at least one carbon-carbon double bond (ethylene bond) or at least one carbon-carbon triple bond (acetylene bond). The alicyclic hydrocarbon may be a saturated alicyclic hydrocarbon (cycloalkane) or an unsaturated alicyclic hydrocarbon. The aromatic hydrocarbon may be a monocyclic aromatic hydrocarbon or a bicyclic or polycyclic aromatic hydrocarbon. The alicyclic hydrocarbon and aromatic hydrocarbon may have various substituents on their rings.

[0082] In a preferred embodiment, R is C 1-18 Aliphatic hydrocarbyl group, C 4-18 alicyclic hydrocarbyl groups, and C 7-18 It is selected from the group consisting of aryl-substituted hydrocarbyl groups or hydrocarbyl-substituted aryl groups.

[0083] According to the present application, when R is a saturated aliphatic hydrocarbyl group, R may be a linear or branched alkyl group. When R is a linear alkyl group, preferred are methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, mono-n-dodecyl (lauryl ester), n-tetradecyl, n-hexadecyl, n-octadecyl, etc. When R is a branched alkyl group, preferred are isopropyl, isobutyl, sec-butyl, isopentyl, isohexyl, isoheptyl, isooctyl (particularly 2-ethylhexyl), isononyl, isodecyl, isoundecyl, isotridecyl, isopentadecyl, isoheptadecyl, etc.

[0084] According to the present application, when R is an unsaturated aliphatic hydrocarbyl group, it is preferably allyl, 2-butenyl, 3-butenyl, isopentenyl, 3-hexenyl, 2-octenyl, 3-nonenyl, 2-decenyl, 7-dodecenyl, 1,5-hexadienyl, 2,4-nonadienyl, 2,4-decadienyl, 9,11-dodecadienyl, 9-octadecenyl, and the like.

[0085] According to the present application, when R is an alicyclic hydrocarbyl group, it is preferably a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a 3-cyclohexenyl group, a 2-cyclohexenyl group, or the like.

[0086] R may also be a substituted aryl group, such as phenyl, methylphenyl, p-nonylphenyl, p-dodecylphenyl, etc. R may also be an aliphatic hydrocarbyl group having an aromatic ring, such as benzyl (phenylmethyl), phenylethyl, etc.

[0087] In a particularly preferred embodiment, the cyclic dicarboxylic acid monoester compound is selected from the group consisting of monobutyl 1,2-cyclohexanedicarboxylate, monooctyl 1,2-cyclohexanedicarboxylate, monoisooctyl 1,2-cyclohexanedicarboxylate, monoisononyl 1,2-cyclohexanedicarboxylate, monobutyl tetrahydrophthalate, monooctyl tetrahydrophthalate, monoisooctyl tetrahydrophthalate, monoisononyl tetrahydrophthalate, monobutyl phthalate, monooctyl phthalate, monoisooctyl phthalate, and mono-sec-octyl phthalate. monoisooctyl methylhexahydrophthalate, monoisononyl methylhexahydrophthalate, monobutyl methylhexahydrophthalate, monobutyl methylhexahydrophthalate, monooctyl methylhexahydrophthalate, monoisooctyl methylhexahydrophthalate, monoisononyl methylhexahydrophthalate, monolauryl methylhexahydrophthalate, monobutyl methyltetrahydrophthalate, monooctyl methyltetrahydrophthalate, monoisooctyl methyltetrahydrophthalate, monoisononyl methyltetrahydrophthalate, monolauryl methyltetrahydrophthalate, and the like.

[0088] In a first class of embodiments, the fuel lubricity improver of the present application is a compound represented by structural formula (II): 5-18 A cyclic dicarboxylic acid or anhydride thereof and C of structural formula (III) 1-30 It is prepared by reacting with an alcohol or phenol to produce a cyclic dicarboxylic acid monoester compound of structural formula (I-1).

[0089] In a preferred embodiment, the reaction conditions are 5-18 Cyclic dicarboxylic acid or its anhydride and C 1-30 The molar ratio of alcohol or phenol is 1:0.5-1:1.5, the reaction temperature is 50-250°C, and the reaction time is 0.1-10 hours.

[0090] Second Class of Embodiments In a second class of embodiments, the fuel lubricity improver of the present application comprises at least an unsaturated dicarboxylic acid monoester compound represented by structural formula (I-2):

[0091] [ka]

[0092] where n is an integer between 2 and 6, and R is C 1-40 is a hydrocarbyl group of the formula:

[0093] In a preferred embodiment, n is an integer from 2 to 4, R is C 1-18 is a hydrocarbyl group of the formula:

[0094] According to the present application, the unsaturated dicarboxylic acid monoester compound is a C 4-8 It refers to a monoester obtained by esterifying one of the carboxyl groups of a dicarboxylic acid compound.

[0095] In a preferred embodiment, when n is 2, the compound represented by structural formula (I-2) is a maleic acid monoester or a fumaric acid monoester; when n is 3, the compound represented by structural formula (I-2) is an itaconic acid monoester, a citraconic acid monoester (methyl maleic acid monoester), a mesaconic acid monoester (methyl fumaric acid monoester), a glutaconic acid monoester, or the like; and when n is 4, the compound represented by structural formula (I-2) is preferably a 2,3-dimethyl maleic acid monoester, an ethyl maleic acid monoester, a hexenedioic acid monoester, or the like.

[0096] In a preferred embodiment, the unsaturated dicarboxylic acid monoester compound is selected from the group consisting of maleic acid monoester, fumaric acid monoester, itaconic acid monoester, citraconic acid monoester (methyl maleic acid monoester), mesaconic acid monoester (methyl fumaric acid monoester), 2,3-dimethylmaleic acid monoester, glutaconic acid monoester, and the like.

[0097] In a particularly preferred embodiment, the unsaturated dicarboxylic acid monoester compound is selected from maleic acid monoesters represented by structural formula (I-2-1) and itaconic acid monoesters represented by structural formula (I-2-2) or structural formula (I-2-3).

[0098] [ka]

[0099] [ka]

[0100] [ka]

[0101] where R is C 1-30 is a hydrocarbyl group of the formula C 1-18 is a hydrocarbyl group of the formula:

[0102] According to the present application, the R group in structural formulas (I-2), (I-2-1), (I-2-2), and (I-2-3) may be an aliphatic hydrocarbyl group, an alicyclic hydrocarbyl group, or an aromatic hydrocarbyl group. The aliphatic hydrocarbon may be linear or branched, and may be saturated or unsaturated. The unsaturated aliphatic hydrocarbon may be an aliphatic hydrocarbon having at least one carbon-carbon double bond (ethylene bond) or at least one carbon-carbon triple bond (acetylene bond). The alicyclic hydrocarbon may be a saturated alicyclic hydrocarbon (cycloalkane) or an unsaturated alicyclic hydrocarbon. The aromatic hydrocarbon may be a monocyclic aromatic hydrocarbon or a bicyclic or polycyclic aromatic hydrocarbon. The alicyclic hydrocarbon and aromatic hydrocarbon may have various substituted hydrocarbyl groups on their rings. Furthermore, preferably, R is C 1-18 Aliphatic hydrocarbyl group, C 4-18 Alicyclic hydrocarbyl groups, and C7-18 It is an aryl-substituted hydrocarbyl group or an alkyl-substituted hydrocarbyl group.

[0103] According to the present application, when R is a saturated aliphatic hydrocarbyl group, it may be a straight-chain alkyl group or a branched alkyl group. When R is a straight-chain alkyl group, the compound of structural formula (I-2-1) may be monomethyl maleate, monoethyl maleate, mono-n-propyl maleate, mono-n-butyl maleate, mono-n-pentyl maleate, mono-n-hexyl maleate, mono-n-heptyl maleate, mono-n-octyl maleate, mono-n-nonyl maleate, mono-n-decyl maleate, mono-n-undecyl maleate, mono-n-dodecyl maleate (lauric acid), or the like. maleate), mono-n-tetradecyl maleate, mono-n-hexadecyl maleate, mono-n-octadecyl maleate, etc., and is preferably selected from the group consisting of monomethyl maleate, monoethyl maleate, mono-n-propyl maleate, mono-n-butyl maleate, mono-n-octyl maleate, mono-n-nonyl maleate, mono-n-decyl maleate, mono-n-dodecyl maleate, etc. The compounds of structural formulas (I-2-2) and (I-2-3) are monomethyl itaconate, monoethyl itaconate, mono-n-propyl itaconate, mono-n-butyl itaconate, mono-n-pentyl itaconate, mono-n-hexyl itaconate, mono-n-heptyl itaconate, mono-n-octyl itaconate, mono-n-nonyl itaconate, mono-n-decyl itaconate, mono-n-undecyl itaconate, and mono-n-dodecyl itaconate (itaconate). It may be selected from the group consisting of mono-n-tetradecyl itaconate, mono-n-hexadecyl itaconate, mono-n-octadecyl itaconate, and the like, and is preferably selected from the group consisting of monomethyl itaconate, monoethyl itaconate, mono-n-propyl itaconate, mono-n-butyl itaconate, mono-n-octyl itaconate, mono-n-decyl itaconate, mono-n-dodecyl itaconate (lauryl itaconate), and the like.

[0104] According to the present application, when R is a branched alkyl group, the compound of structural formula (I-2-1) may be selected from the group consisting of monoisopropyl maleate, monoisobutyl maleate, mono-sec-butyl maleate, mono-tert-butyl maleate, monoisoamyl maleate, monoisohexyl maleate, monoisooctyl maleate (mono-2-ethylhexyl maleate), monoisononyl maleate, monoisodecyl maleate, monoisoundecyl maleate, monoisododecyl maleate, monoisotridecyl maleate, monoisotetradecyl maleate, monoisopentadecyl maleate, and monoisoheptadecyl maleate, and is preferably selected from the group consisting of monoisopropyl maleate, monoisobutyl maleate, mono-sec-butyl maleate, monoisooctyl maleate, monoisononyl maleate, monoisodecyl maleate, monoisoundecyl maleate, and monoisotridecyl maleate. The compounds of structural formulas (I-2-2) and (I-2-3) may be selected from the group consisting of monoisopropyl itaconate, monoisobutyl itaconate, mono-sec-butyl itaconate, mono-tert-butyl itaconate, isoamyl itaconate, monoisohexyl itaconate, monoisooctyl itaconate (mono-2-ethylhexyl itaconate), monoisononyl itaconate, monoisodecyl itaconate, monoisoundecyl itaconate, monoisotridecyl itaconate, and the like, and are preferably selected from the group consisting of monoisopropyl itaconate, monoisobutyl itaconate, monoisooctyl itaconate (mono-2-ethylhexyl itaconate), monoisononyl itaconate, monoisodecyl itaconate, monoisoundecyl itaconate, and the like.

[0105] According to the present application, when R is an unsaturated aliphatic hydrocarbyl group, the compound of structural formula (I-2-1) is selected from the group consisting of monoallyl maleate, mono-3-butylen-1-yl maleate, monoisopentenyl maleate, mono-3-hexyn-1-yl maleate, mono-1-hepten-3-yl maleate, monomethylheptenyl maleate, mono-2-octen-1-yl maleate, mono-3-nonen-1-yl maleate, mono-2-decen-1-yl maleate, mono-7-dodecen-1-yl maleate, mono-1,5-hexadienyl maleate, and mono-1,5-hexadienyl maleate. It may be selected from the group consisting of mono-2,4-decadien-1-yl maleate, mono-9,11-dodecadienyl maleate, monooleyl maleate, etc., and is preferably selected from the group consisting of monoallyl maleate, mono-3-buten-1-yl maleate, monoisopentenyl maleate, mono-3-hexen-1-yl maleate, mono-1-hepten-3-yl maleate, monomethylheptenyl maleate, mono-3-nonen-1-yl maleate, mono-2,4-decadien-1-yl maleate, monooleyl maleate, etc. The compounds of structural formulas (I-2-2) and (I-2-3) include monoallyl itaconate, mono-2-buten-1-yl itaconate, mono-3-buten-1-yl itaconate, monoisopentenyl itaconate, mono-3-hexen-1-yl itaconate, mono-1-hepten-3-yl itaconate, monomethylheptenyl itaconate, mono-2-octen-1-yl itaconate, mono-3-nonen-1-yl itaconate, mono-2-decen-1-yl itaconate, mono-7-dodecen-1-yl itaconate, and monoisopropyl itaconate. It may be selected from the group consisting of mono-1,5-hexadiene itaconate, mono-2,4-nonadiene-1-yl itaconate, mono-2,4-decadien-1-yl itaconate, mono-9,11-dodecadienyl itaconate, monooleyl itaconate, and the like, and is preferably selected from the group consisting of monoallyl itaconate, mono-3-buten-1-yl itaconate, monoisopentenyl itaconate, mono-3-hexen-1-yl itaconate, mono-3-nonen-1-yl itaconate, monooleyl itaconate, and the like.

[0106] According to the present application, when R is an alicyclic hydrocarbyl group, the compound of structural formula (I-2) is preferably selected from the group consisting of monobutyl maleate, monocyclopentyl maleate, monocyclohexyl maleate, mono-3-cyclohexen-1-yl maleate, mono-2-cyclohexenyl maleate, monocyclohexyl itaconate, mono-2-cyclohexenyl itaconate, etc.

[0107] According to the present application, when R is a substituted aryl group, the compound of structural formula (I-2) is preferably selected from the group consisting of mono-p-nonylphenyl maleate, mono-p-dodecylphenyl maleate, mono-p-nonylphenyl itaconate, and mono-p-dodecylphenyl itaconate.

[0108] According to the present application, when R is an aliphatic hydrocarbyl group having an aromatic ring, the compound of structural formula (I-2) is preferably selected from the group consisting of monobenzyl maleate, monophenylethyl maleate, monobenzyl itaconate, monophenylethyl itaconate, monophenylpropyl itaconate, etc.

[0109] In a second class of embodiments, the fuel lubricity improver of the present application is a compound represented by structural formula (II): 4-8 An unsaturated dicarboxylic acid or anhydride thereof and C of structural formula (III) 1-30 It is prepared by reacting with an alcohol or phenol to obtain an unsaturated dicarboxylic acid monoester compound of structural formula (I-2).

[0110] In a preferred embodiment, the reaction conditions are 4-8 Unsaturated dicarboxylic acid or its anhydride and C 1-30 The reaction temperature is 50-250°C, the reaction time is 0.1-10 hours, and the reaction pressure is normal or high.

[0111] In preferred embodiments, the present application provides the following technical solutions:

[0112] A diesel lubricity additive composition containing at least a cyclic dicarboxylic acid monoester compound selected from the group consisting of compounds of structural formula 1,

[0113] [ka]

[0114] 1. A diesel lubricity additive composition, wherein n is an integer of 1 to 8, m is an integer of 0 to 3, x is an integer of 0 to 8, y1 and y2 are integers of 0 to 2, and R represents a C1 to C30 hydrocarbyl group.

[0115] A2. The lubricant additive composition of item A1, wherein n is an integer of 1-6, m is an integer of 0-1, x is an integer of 0-6, y1 and y2 are integers of 0-2, and R is a C1-C18 hydrocarbyl group.

[0116] A3. The lubricant additive composition according to item A1 or A2, wherein R is selected from the group consisting of C1-C18 straight or branched chain aliphatic hydrocarbyl groups, C4-C18 cycloaliphatic hydrocarbyl groups, and C7-C18 aryl-substituted hydrocarbyl groups or hydrocarbyl-substituted aryl groups.

[0117] A4. The lubricity additive composition according to item A1, wherein the cyclic dicarboxylic acid monoester compound is selected from the group consisting of 1,2-cyclopentanedicarboxylic acid monoester, 1,2-cyclohexanedicarboxylic acid monoester, tetrahydrophthalic acid monoester, phthalic acid monoester, methylhexahydrophthalic acid monoester, methyltetrahydrophthalic acid monoester, 1-methyl-1,2-cyclohexanedicarboxylic acid monoester, 4-methyl-1,2-cyclohexanedicarboxylic acid monoester, 3-methyl-1,2-cyclohexanedicarboxylic acid monoester, 4-methyl-4-cyclohexene-1,2-dicarboxylic acid monoester, and 3-methyl-4-cyclohexene-1,2-dicarboxylic acid monoester.

[0118] A5. The lubricity additive composition according to item A1, wherein the cyclic dicarboxylic acid monoester compound is 1,2-cyclohexanedicarboxylic acid monoester, tetrahydrophthalic acid monoester, phthalic acid monoester, methylhexahydrophthalic acid monoester, or methyltetrahydrophthalic acid monoester.

[0119] A6. A method for preparing a diesel fuel lubricity additive, wherein the lubricity additive is prepared by reacting a C5-C18 cyclic dicarboxylic acid or anhydride with a C1-C30 alcohol or phenol.

[0120] A7, the preparation method according to item A6, comprising reacting a C5-C18 cyclic dicarboxylic acid or its anhydride with a C1-C30 alcohol or phenol in a molar ratio of 1:0.5-1.5 at a reaction temperature of 50°C-250°C.

[0121] A8. The preparation method according to item A6 or A7, wherein the cyclic dicarboxylic acid or anhydride thereof is selected from the group consisting of 1,2-cyclohexanedicarboxylic acid, phthalic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, methylhexahydrophthalic acid, 1,2-cyclohexanedicarboxylic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, phthalic anhydride, methyltetrahydrophthalic anhydride, and methylhexahydrophthalic anhydride.

[0122] A9. The preparation method according to item A6 or A7, wherein the alcohol or phenol is selected from the group consisting of C1-C18 aliphatic alcohols, C4-C18 alicyclic alcohols, and C7-C18 aromatic alcohols or phenols.

[0123] A10. The preparation method according to item A6 or A7, wherein the alcohol or phenol is selected from the group consisting of methanol, ethanol, propanol, n-butanol, sec-butanol, cyclohexanol, 3-cyclohexene-1-methanol, benzyl alcohol, isooctanol, isononanol, decanol, isodecanol, lauryl alcohol, oleyl alcohol, nonylphenol; and isononanol, isoundecanol, isotridecanol obtained by polymerization of ethylene, propylene, or butylene.

[0124] A11. The preparation method according to item A6 or A7, wherein a C5-C12 cyclic anhydride is reacted with a C1-C18 alcohol or phenol in a molar ratio of 1:0.8-1.3 at a reaction temperature of 60°C-180°C for a reaction time of 0.5-10 hours without using a catalyst or solvent.

[0125] A12. The preparation method according to item A6 or A7, wherein a C5-C12 cyclic dicarboxylic acid is reacted with a C1-C18 alcohol or phenol in a molar ratio of 1:0.8-1.3 at a reaction temperature of 70°C-250°C for a reaction time of 3-15 hours with or without a catalyst and a solvent.

[0126] A13: A method for improving the lubricity of diesel fuel, comprising adding to low-sulfur diesel fuel a cyclic dicarboxylic acid monoester compound according to any one of items A1 to A5 in an amount of 10 to 400 ppm, when the mass of the low-sulfur diesel fuel is taken as 100%.

[0127] A14. A diesel fuel composition comprising a low-sulfur diesel fuel and a cyclic dicarboxylic acid monoester compound according to any one of items A1 to A5, wherein the amount of the cyclic dicarboxylic acid monoester compound is 10-400 ppm when the mass of the diesel fuel is taken as 100%.

[0128] B1, containing at least an unsaturated dicarboxylic acid monoester compound of structural formula 2,

[0129] [ka]

[0130] 1. A diesel fuel lubricity additive composition, wherein n is an integer from 2 to 6, and R is a C1-C40 hydrocarbyl group.

[0131] B2. The lubricant additive composition according to item B1, wherein n is an integer from 2 to 4, and R represents a C1-C18 hydrocarbyl group.

[0132] B3. The lubricant additive composition according to item B1 or B2, wherein R is selected from C1-C18 linear or branched aliphatic hydrocarbyl groups, C4-C18 cycloaliphatic hydrocarbyl groups, and C7-C18 aryl-substituted hydrocarbyl groups or hydrocarbyl-substituted aryl groups.

[0133] B4. The antiwear composition according to Item B1, wherein the unsaturated dicarboxylic acid monoester compound is one or more selected from the group consisting of maleic acid monoester, fumaric acid monoester, itaconic acid monoester, citraconic acid monoester, methyl fumaric acid monoester, 2,3-dimethylmaleic acid monoester, and glutaconic acid monoester.

[0134] B5, the unsaturated dicarboxylic acid monoester compound is selected from the group consisting of monomethyl maleate, monoethyl maleate, mono-n-propyl maleate, mono-n-butyl maleate, mono-n-octyl maleate, mono-n-nonyl maleate, mono-n-decyl maleate, mono-n-dodecyl maleate, monomethyl itaconate, monoethyl itaconate, mono-n-propyl itaconate, mono-n-butyl itaconate, mono-n-octyl itaconate, mono-n-decyl itaconate, mono-n-dodecyl itaconate, monoisopropyl maleate, monoisobutyl maleate, mono-sec-butyl maleate, monoisopropyl ...isopropyl maleate, mono-sec-butyl maleate, monoisopropyl maleate, monoisopropyl maleate, mono-sec-butyl maleate, monoisopropyl maleate, monoisopropyl maleate, monoisopropyl maleate, monoisopropyl maleate, monoisopropyl maleate, mono The lubricating additive composition according to Item B1, wherein the carboxylic acid is selected from monoisooctyl maleate, monoisononyl maleate, monoisodecyl maleate, monoisopropyl itaconate, monoisobutyl itaconate, monoisooctyl itaconate, monoisononyl itaconate, monoisodecyl itaconate, mono-3-hexyn-1-yl maleate, monooleyl maleate, mono-3-hexyn-1-yl itaconate, monooleyl itaconate, monocyclohexyl maleate, monocyclohexyl itaconate, mono-p-nonylphenyl maleate, mono-p-nonylphenyl itaconate, monobenzyl maleate, and monobenzyl itaconate.

[0135] B6, a method for preparing a diesel fuel lubricity additive, wherein said lubricity additive is obtained by reacting a C4-C8 unsaturated dicarboxylic acid or anhydride with a C1-C30 alcohol or phenol.

[0136] B7. The method according to item B6, comprising reacting a C4-C8 unsaturated dicarboxylic acid or anhydride with a C1-C30 alcohol or phenol in a molar ratio of 1:0.5-1.5 at a reaction temperature of 50°C-250°C.

[0137] B8. The preparation method according to item B6 or B7, wherein the unsaturated dicarboxylic acid or anhydride thereof is selected from the group consisting of maleic acid, maleic anhydride, fumaric acid, itaconic anhydride, citraconic acid, citraconic anhydride, methyl fumaric acid, 2,3-dimethylmaleic acid, and 2,3-dimethylmaleic anhydride.

[0138] B9. The method according to item B6 or B7, wherein the alcohol or phenol is selected from the group consisting of C1-C18 aliphatic alcohols, C4-C18 cycloaliphatic alcohols, and C7-C18 aromatic alcohols or phenols.

[0139] B10. The method according to item B6 or B7, wherein the alcohol or phenol is selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, cyclohexanol, 3-cyclohexene-1-methanol, benzyl alcohol, n-octanol, isooctanol, isononanol, n-decanol, isodecanol, lauryl alcohol, oleyl alcohol, nonylphenol, and isononanol, isoundecanol, isotridecanol obtained by polymerization of ethylene, propylene, or butene.

[0140] B11. The method according to item B6 or B7, comprising reacting maleic anhydride or itaconic anhydride with a C1-C18 alcohol or phenol in a molar ratio of 1:0.8-1.3 at a reaction temperature of 50°C-120°C for a reaction time of 0.5-8 hours without using a catalyst or solvent.

[0141] B12. The method according to item B6 or B7, comprising reacting maleic acid or itaconic acid with a C1-C18 alcohol or phenol in a molar ratio of 1:0.8-1.3 using a catalyst with or without a solvent at a reaction temperature of 70°C-250°C for a reaction time of 3-15 hours.

[0142] B13: A method for improving the lubricity of diesel fuel, comprising the step of adding to low-sulfur diesel fuel an unsaturated dicarboxylic acid monoester compound according to any one of items B1 to B5 in an amount of 10 to 400 ppm, when the mass of the diesel is taken as 100%.

[0143] B14. A diesel fuel composition comprising a low-sulfur diesel fuel and an unsaturated dicarboxylic acid monoester compound according to any one of items B1 to B5, wherein the content of the unsaturated dicarboxylic acid monoester compound is 10-400 ppm when the mass of the diesel fuel is taken as 100%.

[0144] (Example) The present application will be further described below with reference to examples, but the present application is not limited thereto.

[0145] In the following examples, the lubricity of diesel fuels was evaluated by measuring the wear scar diameter (WSD) at 60°C using a High-Frequency Reciprocating Rig (HFRR, PCS Instruments, UK) according to method SH / T0765, with a reported result of WS1.4 corrected for the effects of temperature and humidity.

[0146] The dicarboxylic acid monoester compounds used in each of the examples and comparative examples of the present application can be synthesized by the methods described herein or can be purchased as existing industrial products. Unless otherwise specified, they are commercially available industrial products.

[0147] The following Examples I-1 and I-2 compare the effectiveness of lubricity improvers according to the present application (Examples I-1 to I-6) and lubricity improvers other than the present application (Comparative Examples I-1 to I-4) when used in diesel fuel. The types and sources of the lubricity improvers used are listed in Table I-1 below.

[0148] [Table 2]

[0149] The preparation process for the homemade lubricity improvers listed in Table I-1 is detailed below.

[0150] Example I-5 A 1000 mL reactor equipped with an electric stirrer, thermometer, and reflux condenser was charged with 336 g of 1,2-cyclohexanedicarboxylic anhydride (hexahydrophthalic anhydride, manufactured by Taiwan Nanya Plastics (Taiwan Plastics Group) Co., Ltd.) and 345.6 g of isononanol (3,5,5-trimethyl-1-hexanol, manufactured by Tokyo Chemical Industry Co., Ltd.) so that the molar ratio of hexahydrophthalic anhydride to isononanol was approximately 1:1.2. The mixture was heated to 115 °C with stirring and reacted for 3 hours. After that, the unreacted isononanol was removed by distillation under reduced pressure at an elevated temperature, yielding 6202 g of a product mainly containing monoisononyl 1,2-cyclohexanedicarboxylate.

[0151] Example I-6 A 1000 mL reactor equipped with an electric stirrer, thermometer, and reflux condenser was charged with 336 g of methyl-1,2-cyclohexanedicarboxylic anhydride (methylhexahydrophthalic anhydride, mass fraction 99%, manufactured by Guangzhou Kwaibang Chemical Co., Ltd.) and 316.8 g of isononanol (3,5,5-trimethyl-1-hexanol, manufactured by Tokyo Chemical Industry Co., Ltd.) so that the molar ratio of methyl-1,2-cyclohexanedicarboxylic anhydride to isononanol was approximately 1:1.1. The mixture was heated to 100°C with stirring and reacted for 4.5 hours, yielding approximately 770 g of a product containing mainly monoisononyl methyl-1,2-cyclohexanedicarboxylate.

[0152] Example I-1 This example compares the effects of the lubricity improvers of the examples and comparative examples when used in diesel fuel. The lubricity improvers were blended with petroleum-based diesel fuel a and diesel fuel b, respectively. Diesel fuel a was obtained from Sinopec Yanshan Branch, and diesel fuel b was obtained from Sinopec Gaoqiao Branch. The physicochemical properties of diesel fuel a and diesel fuel b are shown in Table I-2. The wear scar diameters (WS1.4) of the diesel fuels before and after the addition of the lubricity improvers, measured according to the HFRR method (ISO 12156-1), are shown in Tables I-3 and I-4. The smaller the wear scar diameter, the better the diesel lubricity. Currently, most global diesel standards, such as European Standard EN 590, Chinese Automotive Diesel Standard GB 19147, and Beijing Municipal Automotive Diesel Standard DB 11 / 239, require a wear scar diameter of less than 460 μm (60°C) as the pass criterion for diesel lubricity.

[0153] [Table 3] JPEG0007803873000020.jpg25169

[0154] [Table 4] JPEG0007803873000022.jpg56169

[0155] [Table 5] JPEG0007803873000024.jpg119169

[0156] As can be seen from Tables I-3 and I-4, alcohol compounds and phenol compounds have almost no anti-wear effect and are unable to improve the lubricity of diesel fuel, whereas the addition of the monoester compounds of the present invention surprisingly improves the lubricity of diesel fuel.

[0157] For the low-sulfur diesel fuels shown in Table I-3, the monoester compounds of the present invention can significantly improve the lubricity of diesel fuels at very low amounts. For example, the monoester compounds of Examples I-1 and I-2 can reduce the wear scar diameter of diesel fuel a from 564 μm to 266 μm and 257 μm at a dosage of 150 mg / kg, respectively. On the other hand, the diisooctyl hexahydrophthalate compound of Comparative Example I-1 does not improve the lubricity of diesel fuels. The di(2-ethylhexyl) phthalate compound of Comparative Example I-2 also does not improve diesel lubricity. Even the fatty acid-based (Comparative Example I-3) and fatty acid ester-based (Comparative Example I-4) diesel fuel lubricity improvers commonly used in the industry today can only reduce the wear scar diameter of diesel fuel a to 427 μm and 394 μm at a dosage of 150 mg / kg. When the amount used is further reduced to 80 mg / kg, the monoester compound of the present invention still allows the lubricity of diesel fuel a to meet the requirements of the diesel fuel specification. However, at this amount used, the compounds of Comparative Examples I-3 and I-4 have poor anti-wear effect and are insufficient to make the diesel fuel meet the requirements of the diesel fuel specification, i.e., a wear scar diameter of 460 μm or less.

[0158] For the ultra-low sulfur diesel fuels shown in Table I-4, the monoester compounds of the present application surprisingly improved the lubricity of the diesel fuel at very low dosages. For example, it was surprising that the monoesters of Examples I-1 and I-2, when used at a dosage of 200 mg / kg, reduced the wear scar diameter of diesel fuel b from 651 μm to 296 μm and 281 μm, respectively.

[0159] When added at a dosage of 200 mg / kg, diisooctyl hexahydrophthalate (Comparative Example I-1) reduced the wear scar diameter of diesel fuel B from 651 μm to 638 μm, with little antiwear effect, demonstrating that diester compounds are not good lubricity improvers. The fatty acid-based (Comparative Example I-3) and fatty acid ester-based (Comparative Example I-4) diesel fuel lubricity improvers, at 200 mg / kg, only reduced the wear scar diameter of diesel fuel B to 432 μm and 387 μm, respectively.

[0160] Even when the amount is further reduced to 120 mg / kg or 100 mg / kg, the monoester compound of the present invention can still improve the lubricity of diesel fuel b to meet the requirements of diesel fuel specifications.On the other hand, when the products of Comparative Examples I-1, I-2, I-3, and I-4 are added at an amount of 120 mg / kg, the wear scar diameter of diesel fuel b is reduced to 651 μm, 652 μm, 519 μm, and 482 μm, respectively, which indicates a low anti-wear effect and cannot meet the standard of 460 μm or less required by the diesel fuel specifications.

[0161] Example I-2 The examples compare the effects of the lubricity improvers of the examples and comparative examples when used in coal-based diesel fuel. Each lubricity improver is mixed with coal-based diesel fuel c, which is a direct coal liquefaction diesel fuel obtained from China Shenhua Coal Liquefaction Chemical Co., Ltd. Its physicochemical properties are shown in I-5. The wear scar diameter WS1.4 of the diesel fuel after adding the lubricity improver, measured according to the HFRR method (ISO 12156-1), is shown in Table I-6.

[0162] [Table 6]

[0163] [Table 7]

[0164] As can be seen from the results of the above examples, the lubricity improver of the present invention is surprisingly more effective than fatty acid-based or fatty acid ester-based lubricity improvers, and by using it as a diesel lubricity improver, the lubricity of low-sulfur diesel fuel can be significantly improved while the amount added can be significantly reduced.

[0165] The following Example II-1 compares the effects of the lubricity improvers of the present application (Examples II-1 to II-20) and lubricity improvers other than the present application (Comparative Examples II-1 to II-6) when used in diesel fuel. The types and sources of the lubricity improvers used are listed in Table II-1 below.

[0166] [Table 8] JPEG0007803873000028.jpg72169

[0167] The methods for preparing the homemade lubricity improvers listed in Table II-1 are detailed below.

[0168] Example II-2 A 1000 mL reactor equipped with an electric stirrer, thermometer, and reflux condenser was charged with 215.6 g of maleic anhydride (mass fraction 99.5%, purchased from Shanxi Qiaoyou Chemical Co., Ltd.) and 372 g of lauryl alcohol (mass fraction 99.9%, PALMAC, Malaysia) so that the molar ratio of maleic anhydride to lauryl alcohol was approximately 1.1:1. The mixture was heated to 95°C with stirring and reacted for 3 hours. After that, the mixture was heated and distilled under reduced pressure to remove unreacted maleic anhydride, yielding 581 g of monolauryl maleate. The reaction scheme is as follows:

[0169] [ka]

[0170] Example II-3 A 2000 mL reactor equipped with an electric stirrer and a thermometer was charged with 490 g of maleic anhydride (mass fraction 99.5%, purchased from Zibo Tengda Chemical Co., Ltd.) and 720 g of isononanol (Exxal™ 9s, 2,6-dimethyl-4-heptanol, mass fraction 99.5%, purchased from Exxon-Mobil) so that the molar ratio of maleic anhydride to isononanol was approximately 1:1. The mixture was heated to 85°C with stirring and reacted for 5 hours. After that, the mixture was heated and distilled under reduced pressure to remove unreacted isononanol and maleic anhydride, yielding 1006 g of monoisononyl maleate (mono-2,6-dimethyl-4-heptyl maleate).

[0171] Example II-4 A 2000 mL reactor equipped with an electric stirrer and thermometer was charged with 450 g of maleic anhydride (mass fraction 99.5%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) and 910 g of p-nonylphenol (mass fraction 98%, purchased from Huainan Science and Technology Co., Ltd.) so that the molar ratio of maleic anhydride to p-nonylphenol was approximately 1:0.9. The mixture was heated to 110°C with stirring and reacted for 12 hours. The mixture was then heated and distilled under reduced pressure to remove unreacted p-nonylphenol and maleic anhydride, yielding 1296 g of mono-p-nonylphenyl maleate. The reaction scheme is as follows:

[0172] [ka]

[0173] Example II-5 A 2000 mL reactor equipped with an electric stirrer and thermometer was charged with 475 g of maleic anhydride (mass fraction 99.5%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) and 796 g of benzyl alcohol (benzyl alcohol, mass fraction 99%, purchased from Shanghai Meryer Chemical Technology Co., Ltd.) so that the molar ratio of maleic anhydride to benzyl alcohol was approximately 1:1. The mixture was heated to 90°C with stirring and reacted for 8 hours. After that, the mixture was heated and distilled under reduced pressure to remove unreacted benzyl alcohol and maleic anhydride, yielding 1196 g of monobenzyl maleate. The reaction scheme is as follows:

[0174] [ka]

[0175] Example II-6 A 2000 mL reactor equipped with an electric stirrer and thermometer was charged with 500 g of maleic anhydride (mass fraction 99.5%, purchased from Beijing Innochem Technology Co., Ltd.) and 665 g of cyclohexanol (mass fraction 98%, purchased from Beijing Innochem Technology Co., Ltd.) so that the molar ratio of maleic anhydride to cyclohexanol was approximately 1:1.3. The mixture was heated to 85°C with stirring and reacted for 4 hours. After this, the mixture was heated and distilled under reduced pressure to remove unreacted cyclohexanol and maleic anhydride, yielding 1096 g of monocyclohexyl maleate. The reaction scheme is as follows:

[0176] [ka]

[0177] Example II-7 A 2000 mL reactor equipped with an electric stirrer and a thermometer was charged with 550 g of maleic anhydride (mass fraction 99.5%, purchased from Beijing Innochem Technology Co., Ltd.) and 504 g of 3-cyclohexene-1-methanol (mass fraction 98%, purchased from Shanghai BiDe Pharmaceutical Technology Co., Ltd.) so that the molar ratio of maleic anhydride to 3-cyclohexene-1-methanol was approximately 1:0.8. The mixture was heated to 75°C with stirring and reacted for 6 hours. After that, the mixture was heated and distilled under reduced pressure to remove unreacted 3-cyclohexene-1-methanol and maleic anhydride, yielding 997 g of mono-3-cyclohexene-1-methyl maleate. The reaction scheme is as follows:

[0178] [ka]

[0179] Example II-12 A 2000 mL reactor equipped with an electric stirrer, thermometer, and reflux condenser was charged with 560 g of itaconic anhydride (mass fraction 98%, purchased from Zhejiang Guoguang Biochemical Co., Ltd.) and 650 g of isooctanol (2-ethylhexanol, mass fraction 99.9%, purchased from Sinopec Qilu Chemical Co., Ltd.) so that the molar ratio of itaconic anhydride to isooctanol was approximately 1:1. The mixture was heated to 95°C with stirring and reacted for 4 hours. After that, the temperature was increased and the mixture was distilled under reduced pressure to remove unreacted isooctanol and itaconic anhydride, yielding 1193 g of monoisooctyl itaconate.

[0180] Example II-13 A 1000 mL reactor equipped with an electric stirrer, thermometer, and reflux condenser was charged with 260 g of itaconic acid (mass fraction 99.6%, purchased from Zhejiang Guang Biochemical Co., Ltd.), 446 g of lauryl alcohol (mass fraction 99.9%, PALMAC, Malaysia), and 7 g of p-toluenesulfonic acid so that the molar ratio of itaconic acid to lauryl alcohol was approximately 1.1:2. The mixture was heated to 165°C with stirring and reacted for 6 hours. After that, the temperature was raised and the mixture was distilled under reduced pressure to remove unreacted raw materials, yielding 611 g of monolauryl itaconate.

[0181] Example II-14 A 2000 mL reactor equipped with an electric stirrer and a thermometer was charged with 571 g of itaconic anhydride (mass fraction 98%, purchased from Zhejiang Guoguang Biochemical Co., Ltd.) and 792 g of isononanol (Exxal (trademark) 9s, mass fraction 99.5%, purchased from Exxon-Mobil) such that the molar ratio of itaconic anhydride to isononanol was approximately 1:1.1. The mixture was heated to 90°C with stirring and reacted for 5 hours. After that, the mixture was heated and distilled under reduced pressure to remove unreacted isononanol and itaconic anhydride, yielding 1286 g of monoisononyl itaconate.

[0182] Example II-15 A 500 mL reactor equipped with an electric stirrer, thermometer, and reflux condenser was charged with 56 g of itaconic anhydride (mass fraction 97%, purchased from Aladdin Reagents Co., Ltd.) and 121 g of nonylphenol (mass fraction 99.5%, purchased from Chung Shan, Taiwan) so that the molar ratio of itaconic anhydride to nonylphenol was approximately 1.1:1. The mixture was heated to 100°C with stirring and reacted for 5.5 hours, yielding 171 g of a mixture primarily containing mono-p-nonylphenyl itaconate.

[0183] Example II-16 A 2000 mL reactor equipped with an electric stirrer and a thermometer was charged with 490 g of itaconic anhydride (mass fraction 95%, purchased from Tokyo Chemical Industry Co., Ltd.) and 540 g of benzyl alcohol (benzyl alcohol, mass fraction 99.5%, purchased from Shandong Luxi Group Co., Ltd.) so that the molar ratio of itaconic anhydride to benzyl alcohol was approximately 1:1. The mixture was heated to 100°C with stirring and reacted for 4.5 hours. After that, the mixture was heated and distilled under reduced pressure to remove unreacted benzyl alcohol and itaconic anhydride, yielding 996 g of monobenzyl itaconate.

[0184] Example II-17 A 500 mL reactor equipped with an electric stirrer, a thermometer, and a reflux condenser was charged with 147 g of itaconic anhydride (mass fraction 97%, purchased from Aladdin Reagents) and 180 g of cyclohexanol (mass fraction 98%, purchased from Aladdin Reagents) so that the molar ratio of itaconic anhydride to cyclohexanol was approximately 1.1:1. The mixture was heated to 80°C with stirring and reacted for 6 hours, after which the unreacted cyclohexanol was removed by distillation under reduced pressure to obtain 296 g of monocyclohexyl itaconate.

[0185] Example II-19 A 500 mL reactor equipped with an electric stirrer, thermometer, and reflux condenser was charged with 150 g of citraconic anhydride (mass fraction 98%, purchased from TCI Shanghai Co., Ltd.) and 192 g of isooctanol (2-ethylhexanol, mass fraction 99.9%, manufactured by Sinopec Qilu Chemical Co., Ltd.) so that the molar ratio of citraconic anhydride to isooctanol was approximately 1.1:1. The mixture was heated to 75°C with stirring and reacted for 8 hours. After that, the unreacted isooctanol was removed by distillation under reduced pressure, yielding 329 g of monoisooctyl citraconic acid. The reaction scheme is as follows:

[0186] [ka]

[0187] Example II-20 A 1000 mL reactor equipped with an electric stirrer and a thermometer was charged with 196 g of maleic anhydride (mass fraction 99.5%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) and 316.8 g of 7-methyl-1-octanol (mass fraction 99%, purchased from Hubei Wanye Pharmaceutical Co., Ltd.) so that the molar ratio of maleic anhydride to 7-methyl-1-octanol was approximately 1:1.1. The mixture was heated to 90°C with stirring and reacted for 4 hours, yielding 498 g of a product mainly containing mono-7-methyl-1-octyl maleate.

[0188] Example II-1 This example compares the effects of the lubricity improvers of the examples and comparative examples when used in diesel fuel. The lubricity improvers were mixed with diesel fuel a and diesel fuel b, respectively, as shown in Table I-2. The wear scar diameters WS1.4 of the diesel fuels before and after the addition of the lubricity improvers are shown in Tables II-2 and II-3. The smaller the wear scar diameter, the better the lubricity of the diesel fuel.

[0189] [Table 9] JPEG0007803873000036.jpg228169JPEG0007803873000037.jpg21169

[0190] [Table 10] JPEG0007803873000039.jpg227169JPEG0007803873000040.jpg111169

[0191] As can be seen from Tables II-2 and II-3, the addition of alcohol compounds such as lauryl alcohol does not substantially improve the lubricity of diesel fuel, whereas the addition of the unsaturated dicarboxylic acid monoester compound of the present invention surprisingly improves the lubricity of diesel fuel.

[0192] For the low-sulfur diesel fuel shown in Table II-2, the unsaturated dicarboxylic acid monoester compounds of the present invention significantly improve the lubricity of the diesel fuel even at very low dosages. For example, Examples II-1 and II-2 can reduce the wear scar diameter of diesel fuel A from 564 μm to 211 μm and 205 μm at a dosage of 150 mg / kg. In contrast, monomethyl dodecenyl succinate of Comparative Example II-1 can only reduce the wear scar diameter to 398 μm. Furthermore, the diisooctyl maleate compound of Comparative Example II-2 has no effect on improving the lubricity of diesel fuel. Even the fatty acid-based (Comparative Example II-3) and fatty acid ester-based (Comparative Example II-4) diesel fuel lubricity improvers currently commonly used in the industry can only reduce the wear scar diameter of diesel fuel A to 427 μm and 394 μm at a dosage of 150 mg / kg. This shows that the unsaturated dicarboxylic acid monoester compounds of the present invention exhibit excellent antiwear effects. When the amount used is further reduced to 80 mg / kg, the unsaturated dicarboxylic acid monoester compound of the present invention can still make the lubricity of diesel fuel a meet the requirements of the diesel fuel specification, but the anti-wear effect of the comparative product at this amount is so poor that it cannot meet the requirement of the diesel fuel specification of 460 μm or less.

[0193] For the ultra-low sulfur diesel fuels shown in Table II-3, the unsaturated dicarboxylic acid monoester compounds of the present invention surprisingly improve the lubricity of the diesel fuel at very low dosages. For example, it is surprising that when the monoesters of Examples II-1 and II-2 are used at dosages of 200 mg / kg, the wear scar diameter of diesel fuel b is reduced from 651 μm to 208 μm and 206 μm, respectively.

[0194] At a dosage of 200 mg / kg, the monomethyl dodecenylsuccinate of Comparative Example II-1 only reduces the wear scar diameter of diesel fuel b from 651 μm to 389 μm. At a dosage of 200 mg / kg, the fatty acid-based (Comparative Example II-3) and fatty acid ester-based (Comparative Example II-4) diesel fuel lubricity improvers only reduce the wear scar diameter of diesel fuel b to 432 μm and 387 μm, respectively. When the dosage is further reduced to 120 mg / kg, the unsaturated dicarboxylic acid monoester compound of the present invention still enables diesel fuel b to meet the lubricity requirements of diesel fuel specifications. On the other hand, at a dosage of 120 mg / kg, the products of Comparative Examples II-1, II-3, and II-4 only reduce the wear scar diameter of diesel fuel b to 471 μm, 519 μm, and 482 μm, respectively. This indicates a low antiwear effect, insufficient to allow the diesel fuel to meet the lubricity requirement of 460 μm or less in the diesel fuel specification. Comparing the effects of Comparative Examples II-5 and II-6 with those of Examples II-8 and II-1, respectively, further reveals that the antiwear effect of the dicarboxylic acid monoesters having long chain substituents is significantly worse.

[0195] As can be seen from Example II-1, the preferred maleic acid monoester and itaconic acid monoester are more effective in improving the lubricity of diesel fuel, while the trans-configured fumaric acid monoester and the branched methyl maleic acid monoester are slightly less effective.

[0196] The following Example III-1 compares the effects of the lubricity improvers according to the present application (Examples III-1 to III-3) and lubricity improvers other than the lubricity improver according to the present application (Comparative Examples III-1 to III-3) when used in aviation fuel. The types and sources of the lubricity improvers used are shown in Table III-1 below.

[0197] [Table 11]

[0198] The methods for preparing the homemade lubricity improvers listed in Table III-1 are detailed below.

[0199] Example III-3 50 g of maleic anhydride (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) and 104.9 g of isodecanol (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) were weighed and charged into a three-neck flask reactor equipped with a stirrer, a thermometer, and a reflux condenser. The mixture was reacted at 90 °C for 3 hours and then cooled to room temperature to obtain a product mainly containing monoisodecyl maleate product.

[0200] Comparative example III-3 100 g of dodecenylsuccinic anhydride (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) and 70.4 g of isononanol (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) were weighed and placed in a three-neck flask reactor equipped with a stirrer, thermometer, and reflux condenser. The mixture was reacted at 140°C for 3 hours and then cooled to room temperature to obtain a product mainly containing monoisononyl dodecenylsuccinate.

[0201] Example III-1 This example compares the effects of the lubricity improvers of the examples and comparative examples when used in aviation fuel. The physicochemical properties of the aviation fuels used are shown in Table III-2. Each lubricity improver was added to aviation fuel, and the wear scar diameter of the aviation fuel after adding the lubricity improver was measured according to SH / T 0687 (ASTM D5001). The water reactivity and water separation index of the aviation fuel after adding the lubricity improver were measured according to the methods of GB / T 1793 and SH / T 0616, and the results are shown in Table III-3.

[0202] [Table 12] JPEG0007803873000043.jpg27169

[0203] [Table 13]

[0204] As can be seen from Table III-3, the dicarboxylic acid monoester lubricity improver of the present invention is more effective in improving the lubricity of aviation fuel than the comparative examples, and the results of the water reactivity and water separation index tests are comparable to those of the comparative examples of aviation fuel lubricity improver.

[0205] The following Example IV-1 compares the effects of lubricity improvers according to the present application (Examples IV-1 to IV-4) and lubricity improvers other than the present application (Comparative Examples IV-1 to IV-4) when used in gasoline. The types and sources of the lubricity improvers used are listed in Table IV-1 below.

[0206] [Table 14]

[0207] Example IV-1 Example IV-1 compares the effectiveness of the lubricity improvers of the Examples and Comparative Examples when used in gasoline. Each lubricity improver was blended with gasoline. The physicochemical properties of the automotive ethanol gasoline (E10) and automotive gasoline used are shown in Table IV-2. The wear scar diameter (WSD) of the gasoline at 25°C was measured using a high-frequency lubrication rig (HFRR, PCS Instruments, UK). The smaller the wear scar diameter, the better the lubricity of the gasoline or the better the effectiveness of the lubricity improver. The results are shown in Table IV-3.

[0208] [Table 15] JPEG0007803873000047.jpg116169

[0209] [Table 16]

[0210] As can be seen from Table IV-3, the wear scar diameters of blank No. 92 automotive ethanol gasoline (E10) and No. 95 automotive gasoline measured using an HFRR tester at 25°C were high, at 848 μm and 843 μm, respectively. However, the addition of the dicarboxylic acid monoester lubricity improver of the present invention significantly improved the lubricity of the gasoline. When added at a dosage of 150 mg / kg, the monoester of Example IV-1 reduced the wear scar diameter of No. 92 automotive ethanol gasoline (E10) to 378 μm, and when added at a dosage of 200 mg / kg, reduced the wear scar diameter of No. 92 automotive ethanol gasoline (E10) to 296 μm, a much better effect than the fatty acid-based and fatty acid glyceride-based lubricity improvers currently commonly used in the industry. For example, the lubricity improvers of Comparative Examples IV-1 and IV-2, when used at a dosage of 200 mg / kg, can only reduce the wear scar diameter to 533 μm and 498 μm, respectively. Dicarboxylic acid diester compounds, such as the plasticizer diisooctyl maleate (Comparative Example IV-4), have little effect on improving gasoline lubricity; when added at a dosage of 200 mg / kg, they can reduce the wear scar diameter of No. 92 motor ethanol gasoline (E10) to 822 μm. Gasoline detergents also have an insignificant effect on improving gasoline lubricity. For example, the product of Comparative Example IV-3, when added at a dosage of 180 mg / kg, can only reduce the wear scar diameter of No. 95 motor gasoline to 786 μm.

[0211] The present application has been described in detail with reference to preferred embodiments, but is not intended to be limited to the above embodiments. Various simple modifications can be made to the technical solution of the present invention within the scope of the technical idea of ​​the present application, and all such modifications are included in the scope of the present application.

[0212] Furthermore, it should be noted that the various technical features described in the above embodiments can be combined in any suitable manner unless they are contradictory, and although the present application does not describe various possible combinations in order to avoid unnecessary repetition, such combinations also fall within the scope of the present application.

[0213] Furthermore, any combination of different embodiments of the present invention should also be considered as being disclosed in the present invention, unless it is contrary to the spirit of the present invention. [Brief explanation of the drawings]

[0214] [Figure 1] This shows a photograph of the wear scar of diesel fuel b measured using a diesel lubricity tester manufactured by PCS in the UK, with the corrected wear scar diameter (WS1.4) being 651 μm. [Figure 2] 1 shows a photograph of the wear scar measured after adding 200 mg / kg of monoisooctyl maleate obtained in Example II-1 to diesel fuel b, and the corrected wear scar diameter (WS1.4) is 208 μm.

Claims

1. A fuel lubricity improver containing a dicarboxylic acid monoester compound represented by structural formula (I): 【Chemistry 1】 R １ is -R ３ -R ４ -R ５ represents a group having the structure R ２ is a substituted or unsubstituted C １－４０ represents a hydrocarbyl group, R ３ and R ５ are each independently a single bond or a substituted or unsubstituted C １－３ represents a divalent alkyl group of the formula: R ４ is a substituted or unsubstituted C ３－１２ represents a divalent alicyclic group represented by the formula: The "substitution" means at least one C １－４ A fuel lubricity improver, which means substituted with straight or branched chain hydrocarbyl groups.

2. R ２ is a substituted or unsubstituted C １－１８ represents a hydrocarbyl group, R ３ and R ５ each independently represents a single bond or a methylene group, R ４ is a substituted or unsubstituted C ３－１０ 2. The lubricity improver of claim 1, wherein the divalent alicyclic group represents

3. R ２ is C １－１８ a linear or branched hydrocarbyl group of C ４－１８ and an alicyclic hydrocarbyl group of the formula C ７－１８ 2. The lubricity improver of claim 1, wherein the aryl-substituted hydrocarbyl or hydrocarbyl-substituted aryl group is selected from the group consisting of:

4. 2. The lubricity improver of claim 1, wherein the dicarboxylic acid monoester compound is selected from the group consisting of 1,2-cyclopentanedicarboxylic acid monoester, 1,2-cyclohexanedicarboxylic acid monoester, tetrahydrophthalic acid monoester, methylhexahydrophthalic acid monoester, methyltetrahydrophthalic acid monoester, 1-methyl-1,2-cyclohexanedicarboxylic acid monoester, 4-methyl-1,2-cyclohexanedicarboxylic acid monoester, 3-methyl-1,2-cyclohexanedicarboxylic acid monoester, 4-methyl-4-cyclohexene-1,2-dicarboxylic acid monoester, 3-methyl-4-cyclohexene-1,2-dicarboxylic acid monoester, or any combination thereof.

5. 5. The lubricity improver of claim 4, wherein the dicarboxylic acid monoester compound is selected from the group consisting of 1,2-cyclohexanedicarboxylic acid monoester, tetrahydrophthalic acid monoester, methylhexahydrophthalic acid monoester, methyltetrahydrophthalic acid monoester, or any combination thereof.

6. 2. The lubricity improver of claim 1, wherein the dicarboxylic acid monoester compound is selected from the group consisting of monobutyl 1,2-cyclohexanedicarboxylate, monooctyl 1,2-cyclohexanedicarboxylate, monoisooctyl 1,2-cyclohexanedicarboxylate, monoisononyl 1,2-cyclohexanedicarboxylate, monobutyl tetrahydrophthalate, monooctyl tetrahydrophthalate, monoisooctyl tetrahydrophthalate, monoisononyl tetrahydrophthalate, monobutyl methylhexahydrophthalate, monooctyl methylhexahydrophthalate, monoisooctyl methylhexahydrophthalate, monoisononyl methylhexahydrophthalate, monolauryl methylhexahydrophthalate, monobutyl methyltetrahydrophthalate, monooctyl methyltetrahydrophthalate, monoisooctyl methyltetrahydrophthalate, monoisononyl methyltetrahydrophthalate, monolauryl methylhexahydrophthalate, monobutyl methyltetrahydrophthalate, monooctyl methyltetrahydrophthalate, monoisooctyl methyltetrahydrophthalate, monoisononyl methyltetrahydrophthalate, monolauryl methyltetrahydrophthalate, or any combination thereof.

7. A fuel composition comprising a fuel component and the lubricity improver according to any one of claims 1 to 6, wherein the content of the dicarboxylic acid monoester compound is 5 to 400 ppm when the mass of the fuel component is taken as 100%.

8. A method for improving the lubricity of fuel, comprising the step of adding the lubricity improver according to any one of claims 1 to 6 to fuel, wherein the amount of the dicarboxylic acid monoester compound used is 5 to 400 ppm when the mass of the fuel is taken as 100%.

9. The dicarboxylic acid monoester compound has the following structural formula (I): 【Chemistry 2】 R １ is -R ３ -R ４ -R ５ represents a group having the structure R ２ is a substituted or unsubstituted C １－４０ represents a hydrocarbyl group, R ３ and R ５ are each independently a single bond or a substituted or unsubstituted C １－３ represents a divalent alkyl group of the formula: R ４ is a substituted or unsubstituted C ３－１２ represents a divalent alicyclic group represented by the formula: The "substitution" means at least one C １－４ Use of dicarboxylic acid monoester compounds, meaning substituted with straight or branched chain hydrocarbyl groups, as fuel lubricity improvers.

10. The use according to claim 9, wherein the dicarboxylic acid monoester compound is as defined in any one of claims 2 to 6. 【Request Item 11】 【Chemistry 3】 R １ is a substituted or unsubstituted C ２－６ or a divalent alkenyl group of the formula -R ３ -R ４ -R ５ represents a group having the structure R ２ is a substituted or unsubstituted C ５－１４ represents a linear or branched alkyl group of the formula: R ３ and R ５ are each independently a single bond or a substituted or unsubstituted C １－３ represents a divalent alkyl group of the formula: R ４ is a substituted or unsubstituted C ３－６ represents a divalent alicyclic group represented by the formula: The "substitution" means at least one C １－４ means that the alkyl group is substituted with a linear or branched hydrocarbyl group of the formula A dicarboxylic acid monoester compound of structural formula (I) suitable for use as a fuel lubricity improver, selected from the group consisting of monoisononyl maleate (mono-7-methyl-1-octyl maleate), monoisoundecyl maleate, monoisotridecyl maleate, monoisoamyl itaconate, monoisononyl itaconate (mono-3,5,5-trimethylhexyl itaconate), mono-7-methyloctyl itaconate, monoisodecyl itaconate, monoisoundecyl itaconate, monoisotridecyl itaconate, monoisononyl cyclohexanedicarboxylate, monoisononyl hexahydrophthalate, and monoisononyl methylhexahydrophthalate.

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