Unsaturated fatty acid glyceride type diesel oil antiwear agent and method for preparing the same

Abstract

The application discloses a preparation method of unsaturated fatty acid glyceride type diesel oil anti-wear agent, which comprises the following steps: carrying out esterification reaction of unsaturated fatty acid and glycerol under the catalysis of alkali at 120-180 DEG C; adding solid polybasic acid into the esterification product to remove the catalyst; and carrying out molecular distillation on the product to obtain the product. The unsaturated fatty acid glyceride type diesel oil anti-wear agent obtained by the method has an acid value of less than or equal to 1 mg KOH / g, free glycerol of less than or equal to 0.5%, and metal ion content of less than or equal to 50 mg / kg, which meets the requirements of ester type anti-wear agent of Sinopec purchasing standard, has low production cost, and can significantly improve the lubricity of low-sulfur diesel oil when used as diesel oil anti-wear agent.

Description

Technical Field

[0001] This invention relates to the field of fuels, and more specifically, to a method for preparing an unsaturated fatty acid glyceride type diesel anti-wear agent. Background Technology

[0002] With increasing global attention to environmental issues, the production of high-quality clean energy has become the development direction of the modern oil refining industry, leading to progressively higher standards for diesel production. This clean diesel is characterized by low aromatic content, high cetane number, light distillate, low sulfur, and low nitrogen. Sulfur is the most harmful element increasing atmospheric pollutant levels, thus requiring strict control of sulfur compound content in diesel fuel. Currently, clean diesel is mainly produced using a hydrogenation process, which removes sulfur compounds while also reducing nitrogen and oxygen compounds. It is known that the lubricity of diesel fuel depends primarily on the content of anti-wear impurities; polycyclic aromatic hydrocarbons, oxygen-containing impurities, and nitrogen-containing impurities are very effective anti-wear agents. Lower nitrogen and oxygen compound content reduces the lubricity of diesel fuel itself, leading to fuel pump wear and failure.

[0003] Because low-sulfur diesel fuel has poor lubricity, it is typically treated with lubricating additives to improve its lubrication performance, especially ultra-low-sulfur diesel fuel. This method offers advantages such as low cost, flexible production, and minimal pollution, and has gained widespread attention in industry.

[0004] Existing low-sulfur diesel anti-wear agents mainly include two types: acid-type and ester-type. Acid-type anti-wear agents primarily consist of long-chain fatty acids such as oleic acid, linoleic acid, linolenic acid, and ricinoleic acid. Ester-type anti-wear agents are products of the esterification reaction of these fatty acids with polyols. With the upgrading of diesel standards and the increasing quality requirements, the restrictions on the content of impurities and harmful substances in both acid-type and ester-type anti-wear agents are becoming increasingly stringent. Since 2007, China Petroleum & Chemical Corporation (Sinopec) has implemented procurement, access, and inspection standards for diesel anti-wear agents, currently adhering to Q / SHCG 57-2017, which imposes strict requirements on the saturated fatty acid content, metal content (such as sodium), acid value, and pour point of ester-type anti-wear agents. This procurement standard has been recognized by other domestic diesel producers and is being used as a reference in the use of anti-wear agents.

[0005] Ester-type anti-wear agents are esterification reaction products mainly composed of unsaturated fatty acid monoglycerides, obtained by the esterification reaction of unsaturated fatty acids such as oleic acid and linoleic acid with polyols such as glycerol. Currently, the difficulty in preparing ester-type anti-wear agents lies in how to separate the metals introduced by the catalyst. Because fatty acids and glycerol have low reactivity, without a catalyst, the reaction must be carried out at high temperature (220℃) for a long time (more than 18 hours), which leads to the oxidation of unsaturated fatty acids and the polymerization of glycerol, generating byproducts such as high molecular weight compounds, triglycerides, and polyglycerol fatty acid esters. Adding a catalyst can accelerate the reaction process at low temperatures. Alkaline catalysts such as NaOH, KOH, and sodium methoxide are inexpensive and have good catalytic effects, but separation remains a challenge.

[0006] CN105154148 discloses a method for preparing an unsaturated fatty acid glyceride diesel anti-wear agent, which is prepared by unsaturated fatty acids and glycerol through a reduced pressure reaction catalyzed by a glycerol manganese chloride complex. However, this method has problems such as the difficulty in preparing the glycerol manganese chloride complex catalyst, its high price, large dosage, and low product yield. In addition, the product has an excessively high content of free glycerol, which affects the product quality.

[0007] CN102965201 discloses a method for preparing a glycerol ester diesel anti-wear agent, which is prepared by reacting oleic acid and linoleic acid with glycerol at a high temperature of 180-260°C for a long time without a catalyst under an inert gas protection. Although this method avoids the contamination of the product by various metal ions brought by the catalyst, the long-term high-temperature reaction will cause the product to generate oxidative polymerization byproducts and polyglycerol esters, which will affect the product performance. At the same time, the product contains too much unreacted glycerol, which can easily cause diesel filter clogging during use.

[0008] CN108018092A discloses compositions with anti-wear properties for diesel fuel, diesel fuel compositions, and their preparation methods. This includes the reaction of unsaturated fatty acids with glycerol under the catalysis of industrially common alkaline compounds such as NaOH to obtain unsaturated fatty acid glycerides, followed by two-stage molecular distillation to obtain a product meeting Sinopec standard Q / SHCG 57. While this method uses a low-cost alkaline catalyst to carry out the esterification reaction at temperatures not exceeding 180°C, thus mitigating the oxidative polymerization of polyunsaturated fatty acids and the occurrence of polyglycerol ester side reactions, it requires two-stage molecular distillation under high temperature (200-350°C) and ultravacuum (absolute pressure 0.01-30 Pa). The first-stage molecular distillation removes unreacted substrates and impurities, and the remaining portion undergoes second-stage molecular distillation. The light fraction from the second-stage molecular distillation is the final product, while the heavier fraction consists of residual catalyst and triglycerides. This method requires high equipment investment and high operating energy consumption, while also resulting in low product yield and increased preparation costs. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing ester-type anti-wear agents with mild process conditions and low cost.

[0010] The present invention also provides an unsaturated fatty acid glyceride diesel anti-wear agent prepared by the above method.

[0011] The present invention also provides a diesel composition containing the above-mentioned unsaturated fatty acid glyceride diesel anti-wear agent.

[0012] In a first aspect, the present invention provides a method for preparing an unsaturated fatty acid glyceride diesel anti-wear agent, the method comprising: esterifying unsaturated fatty acids and glycerol under alkaline catalysis at 120-180°C; adding a solid polyacid to the esterification product to remove the catalyst; and performing primary molecular distillation on the treated product to obtain the product.

[0013] Secondly, the present invention provides an unsaturated fatty acid glyceride diesel anti-wear agent prepared by the above method.

[0014] Thirdly, the present invention provides a diesel composition comprising an unsaturated fatty acid glyceride diesel anti-wear agent prepared by the above method.

[0015] This invention fully utilizes the catalytic activity of alkaline catalysts to reduce reaction temperature and reaction time. At the same time, by adding solid polybasic acid, the catalyst can be efficiently removed without introducing other contaminants. Since the metal elements in the residual catalyst in the product have been removed by the solid polybasic acid, only one-stage molecular distillation is needed to obtain an anti-wear agent with low acid value, free glycerol and metal ion content.

[0016] Through the above technical solution, this invention yields an ester-type anti-wear agent that meets the procurement standards of Sinopec Group, with an acid value ≤1mg KOH / g, free glycerol ≤0.5%, and metal ion content ≤50mg / kg. Furthermore, the method of this invention uses readily available raw materials, is low in cost, and is simple to produce. When the prepared anti-wear agent is added to diesel fuel, it is less likely to cause turbidity, has a small wear track diameter, a high average oil film formation rate, and a low average coefficient of friction. Moreover, it has a low pour point, reducing the risk of filter clogging. Therefore, the diesel anti-wear agent prepared by this invention can significantly improve the lubricity of low-sulfur diesel fuel at low temperatures.

[0017] Other features and advantages of the present invention will be described in detail in the following detailed description section. Detailed Implementation

[0018] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0019] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0020] The preparation method of the unsaturated fatty acid glyceride diesel anti-wear agent provided by the present invention includes:

[0021] (1) The raw material containing unsaturated fatty acids with 12-24 carbon atoms is subjected to esterification reaction with glycerol in the presence of an alkaline catalyst at 120-180℃;

[0022] (2) Add a solid polybasic acid to the esterification product to remove the catalyst;

[0023] (3) The product after step (2) is subjected to molecular distillation to obtain a fatty acid glyceride type anti-wear agent product.

[0024] In step (1), the raw material containing unsaturated fatty acids with 12-24 carbon atoms has 12-24 carbon atoms, preferably 18-22. The content of unsaturated fatty acids in the reaction raw material is preferably 90% by weight or more, and the content of saturated fatty acids is less than 2.5% by weight. The unsaturated fatty acids are preferably oleic acid, linoleic acid, linolenic acid, or ricinoleic acid. According to a preferred embodiment of the present invention, the content of linoleic acid in the raw material containing unsaturated fatty acids is ≥40% by weight, more preferably ≥45% by weight, such as 45-75% by weight.

[0025] The glycerol content is preferably industrial glycerol with a content of 95% or more, and more preferably industrial glycerol with a content of 98% or more or medical grade glycerol with a content of 99% or more.

[0026] The alkaline catalyst can be one or more inorganic alkaline substances, such as sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, sodium methoxide, potassium methoxide, etc., preferably sodium hydroxide, potassium hydroxide, or sodium methoxide. The amount of catalyst used is 0.1% to 2% of the total amount of reactants, preferably 0.5% to 1.2% of the total amount of reactants.

[0027] The reaction temperature is 120–180°C, preferably 140–160°C. The esterification reaction can be carried out by blowing water with an inert gas such as nitrogen or argon, or by adding a solvent such as xylene and refluxing to separate the water. It is preferred to use nitrogen as the inert gas to blow water. The reaction is stopped when the acid value of the reactants is less than 10 mg KOH / g, preferably less than 5 mg KOH / g. The reaction time is generally 1–10 h, preferably 3–8 h.

[0028] The solid polyacid in step (2) is selected from C2 to C8 polyacids with a melting point higher than 80°C. It can be a dicarboxylic acid or a tricarboxylic acid. The carbon chain can be straight, or it can contain a benzene ring or an unsaturated bond, or it can have a hydroxyl group. For example, it can be oxalic acid, malonic acid, succinic acid, adipic acid, maleic acid, fumaric acid, citric acid, malic acid, tartaric acid, phthalic acid, etc. More preferably, it can be one or more of oxalic acid, malonic acid, succinic acid, and citric acid.

[0029] The solid polyacid can also be selected from the anhydride of the corresponding polyacid, because the anhydride of the polyacid readily reacts with the residual water in the reaction system to generate a polyacid. Therefore, adding the anhydride of the polyacid, such as maleic anhydride, succinic anhydride, phthalic anhydride, etc., can also achieve a similar effect.

[0030] The amount of solid polybasic acid added can be 0.5 to 4 times the molar amount of the base catalyst, preferably 1 to 2 times. After adding the solid polybasic acid, the reaction is carried out at 30 to 80°C, preferably 40 to 60°C, for 0.5 to 1 hour. Then, the generated solid polybasic acid salt and excess solid polybasic acid are separated by filtration or sedimentation and centrifugation.

[0031] In step (3), the product of the esterification reaction is purified by molecular distillation, preferably single-stage molecular distillation (short-path distillation). The temperature of molecular distillation can be 120-200℃, preferably 140-180℃. The absolute pressure of molecular distillation can be 0.05-50Pa, preferably 0.1-20Pa. The heavy component separated by molecular distillation is the unsaturated glycerol ester anti-wear agent product, and the light component is unreacted glycerol and fatty acids, which can be reused.

[0032] Those skilled in the art generally believe that in the esterification reaction of step (1), the amount of NaOH added is small and will not have an adverse effect on the reaction product. However, the inventors of this application have discovered that NaOH actually eventually produces sodium oleate, which can dissolve in the reaction system, making separation difficult. This application adds a polybasic acid or anhydride to the reaction system, which can react with sodium oleate. The resulting solid polybasic acid sodium is insoluble in the reaction system and can be separated from the system. At the same time, excess solid polybasic acid can also be separated from the system due to its high melting point.

[0033] Secondly, the present invention provides an unsaturated fatty acid glyceride diesel anti-wear agent prepared by the above method.

[0034] Thirdly, the present invention provides a diesel composition comprising an unsaturated fatty acid glyceride diesel anti-wear agent prepared by the above method.

[0035] The anti-wear agent content is 10-1000g per ton of base diesel oil, preferably 50-500g.

[0036] The diesel composition of the present invention may also contain one or more of the following additives: phenolic antioxidants, high molecular weight amine ashless dispersants, flow improvers, cetane number improvers, metal passivators, antistatic agents, corrosion inhibitors, rust inhibitors, and demulsifiers.

[0037] The present invention will be described in detail below through examples. In the following examples, the chemical composition of the raw materials and the products obtained in each step was analyzed by an Agilent gas chromatograph according to the methods of EN 14103 and SH / T 0796; the lubricity of diesel fuel was determined by measuring the wear scar diameter (WSD) at 60°C on a high-frequency reciprocating tester (HFRR, PCS Instruments, UK) according to the method of SH / T 0765, and the results were reported as WS1.4 after correcting for the effects of temperature and humidity.

[0038] All data in the examples were obtained according to the corresponding standard analytical methods. Due to the presence of unsaponifiable matter in the raw materials, the total fatty acid content was less than 100%. The product was a fatty acid glyceride. The content of the glyceride was characterized by acid value and free glycerol content, and the fatty acid composition was analyzed after methyl esterification of the glyceride.

[0039] The composition of the fatty acid raw materials used in the following examples or comparative examples is shown in Table 1 below. The refined tall oil fatty acid was purchased from the unsaturated fatty acid with the brand name 2LT produced by Arizonal Company, USA, and the refined cottonseed oil fatty acid was purchased from the unsaturated fatty acid with the code KMJ-031 produced by Xinjiang Dasen Chemical Company.

[0040] In addition, the glycerin is a pharmaceutical-grade product from Coconut Palm Brand in Malaysia (content 99.5%), and the NaOH is an analytical grade reagent from Sinopharm Group.

[0041] Table 1

[0042] Lauric acid 0.005 0.017 Myristic acid 0.006 0.011 Palmitic acid 0.262 1.831 Palmitoleic acid 0.301 0.089 stearic acid 1.409 0.4313 Oleic acid 34.320 28.990 Linoleic acid 55.120 62.351 Alpha-linolenic acid 2.366 1.960 Arachidonic acid 0.211 0.034 Arachidonic acid 2.990 1.380 Rosin acid 1.530 0 succinic acid 0.041 0.081 Erucic acid 0.0875 0.3765 Saturated fatty acids 1.934 2.4053 Unsaturated fatty acids 95.1845 95.1465

[0043] Example 1

[0044] (1) Esterification reaction

[0045] 1000g tall oil fatty acid (Arizonal brand 2LT product, cloud point -10℃), 359.6g glycerol, and 13.5g NaOH (NaOH accounts for 1% of the reactants) were placed in a reactor equipped with an electric stirrer, thermometer, reflux condenser, and reflux water separator. The mixture was heated and stirred to 160℃. Nitrogen gas was used to purge the water generated in the reaction and condense it into the water separator. After 6 hours of reaction, 56.6g of water was separated, and 1293.5g of reaction product was collected. The analytical results are shown in Table 2.

[0046] (2) Neutralization catalyst

[0047] Take 500g of the reaction product from the previous step, add 12.4g of oxalic acid (analytical grade reagent from Aladdin Reagent Company, with a molar ratio of oxalic acid to NaOH of approximately 1.1:1), and place it in a reactor equipped with an electric stirrer and a thermometer. Stir at 50℃ for 0.5h, let stand for 2h, and then take out the supernatant. Separate the turbid lower layer using a German Eppendorf high-speed centrifuge to obtain the supernatant and combine them. The sampling and analysis results are shown in Table 2.

[0048] (3) Molecular distillation

[0049] 400g of the reaction product from the previous step was subjected to first-stage molecular distillation using a VKL70-5FDRR fully heated gear pump molecular distillation apparatus from VTA GmbH (Germany), with the temperature controlled at 160℃ and the absolute pressure at 1.0 Pa. 369.5g of the heavy fraction from the first-stage molecular distillation was collected as the final product, and the analytical results are shown in Table 2.

[0050] Table 2

[0051]

[0052] Example 2

[0053] (1) Esterification reaction

[0054] 1000g of refined cottonseed oil fatty acids (cloud point -13℃), 334g of glycerol, and 10.6g of NaOH (NaOH accounts for 0.8% of the reactants) were placed in a reactor equipped with an electric stirrer, thermometer, reflux condenser, and reflux water separator. The mixture was heated and stirred to 160℃. Nitrogen gas was used to purge the water generated in the reaction and condense it into the water separator. After 8 hours of reaction, 51.8g of water was separated, and 1253.2g of reaction product was collected. The analytical results are shown in Table 3.

[0055] (2) Neutralization catalyst

[0056] Take 500g of the reaction product from the previous step, add 9.0g of oxalic acid (analytical grade reagent from Aladdin Reagent Company, with a molar ratio of oxalic acid to NaOH of approximately 1.1), and place it in a reactor equipped with an electric stirrer and a thermometer. Stir at 40℃ for 1 hour. Separate the clear liquid using a German Eppendorf high-speed centrifuge and combine the samples. The analysis results are shown in Table 3.

[0057] (3) Molecular distillation

[0058] 300g of the reaction product from the previous step was subjected to first-stage molecular distillation using a VKL70-5FDRR fully heated gear pump molecular distillation apparatus from VTA GmbH, Germany (temperature 150℃, absolute pressure 0.5Pa). 258g of the heavy fraction from the molecular distillation was collected as the final product. The analytical results are shown in Table 3.

[0059] Table 3

[0060]

[0061] Example 3

[0062] (1) Esterification reaction

[0063] 1000g tall oil fatty acid (Arizonal brand 2LT product, cloud point -10℃), 359.6g glycerol, and 10.8g NaOH (NaOH accounts for 0.8% of the reactants) were placed in a reactor equipped with an electric stirrer, thermometer, reflux condenser, and reflux water separator. The mixture was heated and stirred to 140℃. Nitrogen gas was used to purge the water generated in the reaction and condense it into the water separator. After 8 hours of reaction, 55.7g of water was separated, and 1295.8g of reaction product was collected. The analytical results are shown in Table 4.

[0064] (2) Neutralization catalyst

[0065] Take 500g of the reaction product from the previous step, add 10.0g of maleic acid (analytical grade reagent from Aladdin Reagent Company, with a molar ratio of maleic acid to NaOH of approximately 1.1), and place it in a reactor equipped with an electric stirrer and a thermometer. Stir at 60℃ for 0.5h, let stand for 2h, and then take out the supernatant. Separate the turbid lower layer using a German Eppendorf high-speed centrifuge to obtain the supernatant and combine them. The sampling and analysis results are shown in Table 4.

[0066] (3) Molecular distillation

[0067] 400g of the reaction product from the previous step was subjected to first-stage molecular distillation using a VKL70-5FDRR fully heated gear pump molecular distillation apparatus from VTA GmbH (Germany), with the temperature controlled at 165℃ and the absolute pressure at 0.8 Pa. 358.6g of the heavy fraction from the first-stage molecular distillation was collected as the final product, and the analytical results are shown in Table 4.

[0068] Table 4

[0069]

[0070] Example 4

[0071] (1) Esterification reaction

[0072] 1000g of refined cottonseed oil fatty acids (cloud point -13℃), 351g of glycerol and 10.7g of NaOH were placed in a reactor equipped with an electric stirrer, thermometer, reflux condenser and reflux water separator. The mixture was heated and stirred to 150℃. Nitrogen gas was used to purge the water generated in the reaction and condense it into the water separator. After 7 hours of reaction, 50.2g of water was separated and 1257.8g of reaction product was collected. The analytical results are shown in Table 5.

[0073] (2) Neutralization catalyst

[0074] Take 500g of the reaction product from the previous step, add 12.4g of malonic acid (analytical grade reagent from Aladdin Reagent Company, with a molar ratio of malonic acid to NaOH of approximately 1.1.2), and place it in a reactor equipped with an electric stirrer and a thermometer. Stir at 50℃ for 1 hour. Separate the clear liquid using a German Eppendorf high-speed centrifuge and combine the samples. The results of the analysis are shown in Table 5.

[0075] (3) Molecular distillation

[0076] 300g of the reaction product from the previous step was subjected to first-stage molecular distillation using a VKL70-5FDRR fully heated gear pump molecular distillation apparatus from VTA GmbH, Germany (temperature 150℃, absolute pressure 0.5Pa). 258g of the heavy fraction from the molecular distillation was collected as the final product. The analytical results are shown in Table 5.

[0077] Table 5

[0078]

[0079] As can be seen from the above examples, after adding the polyacids shown in this invention to treat the esterification reaction products, the metal content can be greatly reduced, and after primary molecular distillation, the acid value and free glycerol of the final product can also meet the standard requirements.

[0080] Comparative Example 1

[0081] The esterification product from Example 2 was used, except that acetic acid was used instead of oxalic acid for neutralization catalyst treatment, and the molecular distillation conditions were the same as in Example 2. The analytical results of the neutralization catalyst product and the final product are shown in Table 6.

[0082] Table 6

[0083]

[0084] It is evident that the acid value and metal content of the final product did not meet the requirements of Sinopec Group's standards when using liquid monocarboxylic acid to neutralize the esterification product. This is because the generated monocarboxylic acid salt is soluble in the reaction system.

[0085] Comparative Example 2

[0086] The esterification product from Example 1 was used, except that solid monocarboxylic acid lauric acid was used instead of oxalic acid for neutralization catalyst treatment, and the molecular distillation conditions were the same as in Example 1. The analytical results of the neutralization catalyst product and the final product are shown in Table 7.

[0087] Table 7

[0088]

[0089] It is evident that the acid value and metal content of the final product did not meet the requirements of Sinopec Group's standards when using solid monocarboxylic acids to neutralize the esterification products. This is because the solid monocarboxylic acid or the generated monocarboxylic acid salt is soluble in the reaction system.

[0090] Test Example 1

[0091] This test example demonstrates the effectiveness of the unsaturated fatty acid ester diesel anti-wear additive prepared in the examples and comparative examples in diesel fuel A. The physicochemical properties of diesel fuel A are shown in Table 8, and the test results are shown in Table 9. Currently, most diesel fuel standards worldwide, such as European standard EN590, Chinese automotive diesel fuel standard GB / T19147, and Beijing municipal standard DB 11 / 239, use a wear mark diameter of less than 460 μm (60℃) as the criterion for acceptable diesel fuel lubricity. China Petrochemical Corporation's enterprise procurement standard Q / SHCG 57 requires that the wear mark diameter of diesel fuel with additives not exceed 420 μm (60℃).

[0092] Table 8 Basic Physical and Chemical Properties of Diesel A

[0093]

[0094]

[0095] Table 9. Effects of anti-wear agents on diesel fuel A

[0096]

[0097]

[0098] As can be seen from Table 9, the anti-wear effect of the final product obtained by the method of the present invention is better than that of the esterification reaction product and also better than the product after neutralizing the catalyst from the esterification reaction product.

[0099] The results of the above test examples show that the ester-type anti-wear agent of the present invention has readily available raw materials, low cost, and simple production. When used as a diesel anti-wear agent, it can significantly improve the lubricity of low-sulfur diesel at low temperatures.

[0100] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A method for preparing an unsaturated fatty acid glyceride diesel anti-wear agent, comprising: (1) An unsaturated fatty acid raw material containing 12-24 carbon atoms is subjected to esterification reaction with glycerol in the presence of an alkaline catalyst at 120-180℃; (2) Add a solid polyacid to the esterification product and carry out a neutralization reaction at 30~80℃. Then separate the generated solid polyacid salt and the excess solid polyacid. The solid polyacid is selected from one or more of oxalic acid, malonic acid, succinic acid, adipic acid, maleic acid, fumaric acid, and phthalic acid. (3) Perform primary molecular distillation on the product after step (2) to obtain a fatty acid glyceride type anti-wear agent product.

2. The method according to claim 1, wherein in step (1), the unsaturated fatty acid has 18-22 carbon atoms, and the unsaturated fatty acid raw material has an unsaturated fatty acid content of more than 90% by weight and a saturated fatty acid content of less than 2.5% by weight.

3. The method according to claim 1, wherein, The unsaturated fatty acids are selected from oleic acid, linoleic acid, linolenic acid, and ricinoleic acid.

4. The method according to claim 1, wherein, The alkaline catalyst is selected from one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, sodium methoxide, and potassium methoxide.

5. The method according to claim 1, wherein, The amount of alkaline catalyst used is 0.1% to 2% of the total amount of reactants.

6. The method according to claim 1, wherein, The amount of alkaline catalyst used is 0.5-1.2% of the total amount of reactants.

7. The method according to claim 1, wherein, The reaction temperature in step (1) is 140~160℃.

8. The method according to claim 1, wherein, The solid polyacids include the corresponding polyacid anhydrides.

9. The method according to claim 1, wherein, The amount of solid polybasic acid added is 0.5 to 4 times the molar amount of the base catalyst.

10. The method according to claim 1, wherein, After adding a solid polybasic acid, a neutralization reaction is carried out at 40-60℃ for 0.5-1h, after which the generated solid polybasic acid salt and excess solid polybasic acid are separated.

11. The method according to claim 1, wherein, In step (3), the temperature of molecular distillation is 120-200℃ and the absolute pressure of molecular distillation is 0.05-50Pa.

12. The method according to claim 1, wherein, In step (3), the temperature of molecular distillation is 140-180℃ and the absolute pressure of molecular distillation is 0.1-20Pa.

13. The unsaturated fatty acid glyceride diesel anti-wear agent prepared by the method according to any one of claims 1 to 12.

14. A diesel composition comprising the unsaturated fatty acid glyceride diesel anti-wear agent of claim 13.

15. The diesel composition according to claim 14, wherein, The anti-wear agent content is 10-1000g per ton of base diesel oil.

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