Method for efficiently preparing fatty acid type anti-wear agent based on biodiesel

Abstract

The invention discloses a method for efficiently preparing a fatty acid type anti-wear agent based on biodiesel, which comprises the following steps: freezing and crystallizing the raw material biodiesel, filtering, evaporating and dealcoholizing, carrying out enzyme hydrolysis, insulating and layering, and rectifying under reduced pressure to finally obtain the fatty acid type anti-wear agent. Wherein the fatty acid composition of the crude methyl ester can be directionally regulated and controlled through freezing crystallization and filtering processes; through the synergistic effect of enzyme hydrolysis reaction and high-vacuum rectification separation coupling, efficient production of the fatty acid anti-wear agent prepared from biodiesel is achieved, the production period is greatly shortened, and the product quality is improved. According to the technology disclosed by the invention, the high-quality fatty acid type anti-wear agent can be produced economically, greenly, efficiently and stably, and the acid value of the product is stabilized between 198-203mgKOH / g oil and meets the Q / SHCG 57-2017 standard. The method has the advantages of low raw material requirement, wide application range, high production efficiency, high product quality, reproducible and reusable catalyst and the like, and is suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of oleochemical production technology, specifically relating to a method for efficiently preparing fatty acid-based anti-wear agents based on biodiesel. Background Technology

[0002] During the hydrodesulfurization of diesel fuel, some natural lubricating substances are also removed, leading to decreased lubrication performance and consequently increased engine wear and shortened engine life. Adding diesel anti-wear agents is a highly effective way to improve the lubricity of low-sulfur diesel fuel. Fatty acid-based anti-wear agents are a type of green, renewable, bio-based anti-wear agent that can tightly adhere to metal surfaces, forming a dense organic film that slows down wear. Compared to fatty acid ester-based anti-wear agents, fatty acid-based anti-wear agents not only meet the blending requirements of diesel fuel but also offer lower performance and cost, making them popular among many oil refining companies. Currently, mixed oleic acid is commonly used industrially as a raw material to produce fatty acid-based anti-wear agents.

[0003] Chinese patent CN112745969B discloses a process for preparing fatty acid-based diesel anti-wear agents using low-temperature freezing. This process uses crude vegetable oleic acid as raw material, which is melted, pre-crystallized, and filtered before adding modified nano-SiO2 additives, followed by deep freezing crystallization to obtain the product. However, this method suffers from a long production cycle due to the cumbersome additive modification steps, the need for precise gradient temperature control during freezing, and the inclusion of multiple filtration steps, thus limiting its industrial efficiency.

[0004] Chinese patent CN118389190A discloses a production system and method for a fatty acid-based diesel anti-wear agent. The method involves mixing molten fatty acids with chilled water, emulsifier, and electrolyte in a certain proportion, followed by emulsification and crystallization. The emulsified and crystallized material is then separated by centrifugation to obtain a crude oleic acid phase and a mixed phase of solid acid crystals and water. After dehydration of the crude oleic acid, the fatty acid-based diesel anti-wear agent is obtained. However, this method has certain limitations on the initial fatty acid composition of the raw materials and still faces problems such as difficulty in separating saturated fatty acids.

[0005] Compared to using oleic acid as a raw material to produce fatty acid-based anti-wear agents, using biodiesel as a raw material offers advantages such as a wider range of raw material sources, greater applicability, lower production costs, and stronger market competitiveness. However, traditional biodiesel hydrolysis processes for fatty acid production mainly include saponification and acidification processes and inorganic acid-catalyzed hydrolysis processes such as sulfuric acid. These processes commonly suffer from problems such as equipment corrosion, wastewater pollution, low production efficiency, high industrial salt production, and low product quality, which are inconsistent with the current concept of sustainable development. Furthermore, the large amount of saturated fatty acids (esters) remaining after biodiesel hydrolysis, due to their lack of double bonds, weak polarity, and high freezing point, makes it difficult to form a stable adsorption layer on metal surfaces. This results in poor dispersibility in diesel fuel when used as an anti-wear agent at low temperatures, severely impacting the performance and application of fatty acid-based anti-wear agents. Therefore, using enzymatic catalysis to replace traditional biodiesel fatty acid production processes not only conforms to the principles of green chemistry and significantly reduces equipment corrosion, wastewater treatment costs, and the generation of waste gases, but also improves production efficiency, promoting the rapid and sustainable development of the biodiesel-based fatty acid anti-wear agent industry. Summary of the Invention

[0006] To address the aforementioned problems in the existing technology, the purpose of this invention is to provide a method for efficiently preparing fatty acid-based anti-wear agents based on biodiesel.

[0007] This invention discloses a method for efficiently preparing fatty acid-based anti-wear agents based on biodiesel. The method includes the following steps: raw biodiesel is subjected to cooling crystallization, filtration, evaporation and de-alcoholization, hydrolysis reaction, filtration sedimentation, and high-vacuum distillation to obtain fatty acid anti-wear agents; the cooling crystallization process uses methanol as a solvent; the hydrolysis reaction process uses a biological enzyme as a catalyst, and the reaction pressure is negative; the methanol byproduct generated in the hydrolysis reaction process is recovered as refined methanol in the methanol distillation process and reused as a solvent in the cooling crystallization process, while the alcohol-containing process water obtained from the methanol distillation process is reused in the hydrolysis reaction process; the filtrate obtained from the filtration process is further evaporated and de-alcoholized to obtain unsaturated methyl esters, and the collected solvent methanol is reused in the cooling crystallization process; the biological enzymes and process water obtained from the filtration and sedimentation processes are reused in the hydrolysis reaction process; a small amount of unsaturated methyl esters obtained from the high-vacuum distillation process are used as raw material oils in the hydrolysis reaction process.

[0008] The technical solution adopted in this invention is as follows:

[0009] A method for efficiently preparing fatty acid-based anti-wear agents based on biodiesel includes the following steps:

[0010] S1: Raw biodiesel is cooled and crystallized in methanol solvent;

[0011] S2: After freezing and crystallizing, the liquid is kept warm and filtered in layers to collect the filtrate containing unsaturated methyl ester and the filter cake containing saturated methyl ester respectively.

[0012] S3: The filtrate obtained in step S2 is rotary evaporated to remove methanol, and the resulting liquid after de-ethanolification is unsaturated methyl ester;

[0013] S4: The unsaturated methyl ester obtained in step S3 is added to water as a solvent and a biological enzyme is used as a catalyst to carry out a hydrolysis reaction under negative pressure, so that the unsaturated methyl ester is hydrolyzed into unsaturated fatty acids.

[0014] S5: The liquid after hydrolysis reaction in step S4 is first filtered to separate the catalyst, and then settled into an upper fatty acid oil phase and a lower aqueous phase.

[0015] S6: The fatty acid oil phase in step S5 is subjected to high-vacuum distillation to separate a small amount of unsaturated methyl esters, and the unsaturated fatty acids are obtained, which are the fatty acid type anti-wear agent products.

[0016] Furthermore, the biodiesel includes at least one of soybean oil, palm oil, cottonseed oil, safflower oil, rapeseed oil, sunflower oil, jatropha oil, rice bran oil, and peanut oil.

[0017] Furthermore, in step S1, the mass ratio of methanol to biodiesel is 2:1-4:1, the cooling crystallization temperature is controlled at -25℃ to -10℃, and the cooling crystallization time is 0.5-2h.

[0018] Further, in step S4, the biological enzyme is immobilized lipase FM-NE04, the amount of enzyme is 3-5% of the weight of unsaturated methyl ester, the mass ratio of water to unsaturated methyl ester is 2:1-4:1, the reaction temperature is 40-55℃, the reaction pressure is absolute pressure 5-15kPa, and the reaction time is 4-8h.

[0019] Furthermore, in step S4, methanol water vapor is distilled off during the hydrolysis reaction under negative pressure. The vapor is condensed to obtain methanol water condensate. After methanol distillation, the methanol obtained from the distillation is reused in the freeze crystallization process, and the water obtained from the distillation is reused in the hydrolysis reaction section.

[0020] Furthermore, the bio-enzymes and water obtained from the filtration and sedimentation processes in step S5 are reused in the hydrolysis reaction process.

[0021] Furthermore, in step S6, the pressure of the high-vacuum distillation process is absolute pressure of 100-1000 Pa, the temperature of the bottom of the column is 190-230℃, and the temperature of the top of the column is 170-200℃.

[0022] Furthermore, in step S6, a small amount of unsaturated methyl ester obtained through high-vacuum distillation is used as the raw material oil for the hydrolysis reaction process.

[0023] By employing the above-described technology, the beneficial effects achieved by the present invention compared to the prior art are as follows:

[0024] (1) This invention uses biodiesel as a raw material to replace traditional oleic acid raw material, which has the advantages of wide raw material source, good universality, low production cost and strong market competitiveness, and is suitable for industrial promotion.

[0025] (2) This invention utilizes the synergistic coupling of freeze crystallization technology, bio-enzymatic hydrolysis technology and high-vacuum distillation technology to achieve clean, efficient and high-quality production of fatty acid-based anti-wear agents from biodiesel: First, freeze crystallization technology is used to achieve efficient separation of saturated fatty acid methyl esters from raw oil; then, bio-enzymatic hydrolysis technology is used to achieve efficient conversion and clean preparation of unsaturated fatty acid methyl esters to unsaturated fatty acids; finally, high-vacuum distillation technology is used to achieve efficient separation of residual fatty acid methyl esters to obtain high-quality fatty acid-based anti-wear agents that meet the Q / SHCG 57-2017 standard, with an acid value stable at 198-203 mgKOH / g oil.

[0026] (3) In the freeze crystallization process, methanol, a hydrolysis byproduct, is selected as the solvent to ensure that no other chemical substances (except process water) are introduced into the system. At the same time, the fatty acid composition is controlled by adjusting the crystallization temperature to efficiently separate saturated fatty acid methyl esters from the biodiesel feedstock. After freeze crystallization, the saturated fatty acid methyl ester content in the biodiesel feedstock is less than 1.0%, providing a stable and high-quality hydrolysis feedstock for the subsequent bioenzyme hydrolysis section.

[0027] (4) In the hydrolysis process, acid-resistant immobilized lipase is introduced into the hydrolysis reaction of biodiesel. The reaction conditions are mild and the immobilized lipase can be recycled. This overcomes the problems of equipment corrosion, acidic wastewater pollution and large industrial salt production caused by traditional biodiesel fatty acid preparation processes. The process is green and environmentally friendly. At the same time, vacuum technology is used to separate the hydrolysis byproduct methanol in a timely manner, which promotes the hydrolysis reaction in the positive direction. The conversion rate of methyl ester hydrolysis reaction can reach more than 96.5% in one step.

[0028] (5) In the high vacuum distillation process, the boiling range difference between fatty acids and fatty acid methyl esters is cleverly used to achieve efficient separation of a small amount of residual unsaturated fatty acid methyl esters in the hydrolysis products. The unsaturated methyl esters obtained from the separation are recycled for the hydrolysis process. By cleverly combining the reaction separation of the hydrolysis reaction process and the high vacuum distillation process, the shortcomings of the slow reaction rate when the concentration effect dominates in the later stage of the hydrolysis reaction are overcome, the preparation cycle is greatly shortened, the production efficiency is improved, and the quality of fatty acid anti-wear agent is improved.

[0029] (6) This invention provides an economical, universally applicable, green, efficient and high-quality method for preparing fatty acid-based anti-wear agents, which has the advantages of low raw material requirements, simple process, no solid waste generation, recyclable catalyst, and suitability for industrial production. Attached Figure Description

[0030] Figure 1 This is a process flow diagram of the production of fatty acid-based anti-wear agents in this application example.

[0031] Figure 2 These are experimental results under different number of applications of the immobilized enzyme catalyst. Detailed Implementation

[0032] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0033] Example 1: The fatty acid composition of the soybean oil biodiesel feedstock used in Example 1 (acid value 0.35 mg KOH / g) is shown in Table 1.

[0034] Table 1. Fatty acid composition distribution in soybean oil biodiesel feedstock

[0035] Element <![CDATA[C 16:0 ]]> <![CDATA[C 18:0 ]]> <![CDATA[C 18:1 ]]> <![CDATA[C 18:2 ]]> <![CDATA[C 18:3 ]]> mass fraction % 8.15 5.19 25.85 55.75 5.06

[0036] The process flow for preparing biodiesel in this embodiment is as follows: Figure 1 As shown, the process for preparing biodiesel includes the following steps:

[0037] 1) Freezing and crystallization section: Raw materials soybean oil biodiesel and methanol (purity ≥99.5%) are mixed in a mass ratio of 1:2, the stirring speed is set to 100 rpm, the crystallization temperature is controlled at -20℃, and the crystallization time is 1 hour;

[0038] 2) Filtration section: The liquid after the freeze crystallization reaction is kept warm and filtered in layers, and the filtrate and filter cake are collected separately;

[0039] 3) Evaporation and de-alcoholization section: The filtered filtrate is subjected to rotary evaporation to remove methanol. The rotary evaporation temperature is 60℃ and the pressure is 15kPa. The resulting de-alcoholized liquid is unsaturated methyl ester. The crude methanol obtained by rotary evaporation can be reused in the freeze crystallization process.

[0040] 4) Hydrolysis reaction section: The unsaturated methyl ester obtained in step 3) is mixed with deionized water at a mass ratio of 1:3, and immobilized lipase FM-NE04 is added at a dosage of 5 wt% of the unsaturated methyl ester. The reaction mixture is heated to 50°C and stirred for 5 hours under an absolute pressure of 5 kPa. During the hydrolysis process under negative pressure, methanol and water vapor are distilled off. The vapor is condensed to obtain methanol-water condensate. The methanol-water condensate can be subjected to simple distillation at a column top temperature of 65°C. The methanol obtained from the distillation is recycled to the freeze crystallization process, and the water is recycled to the hydrolysis reaction section.

[0041] 5) Filtration and sedimentation section: After the hydrolysis reaction, the feed liquid is filtered through a Buchner funnel, and the filter cake catalyst and filtrate are collected separately. The filter cake catalyst can be reused in the hydrolysis reaction section. The filtrate is kept at 50°C for 1 hour to separate into layers. After separation, the upper layer is the fatty acid oil phase, and the lower layer is the aqueous phase. The aqueous phase is recovered and reused in the hydrolysis reaction section.

[0042] 6) High-vacuum distillation section: The fatty acid oil phase obtained after separation is distilled under absolute pressure of 100 Pa, bottom temperature of 190℃, and top temperature of 170℃ to obtain a fatty acid-type anti-wear agent. During this process, the unsaturated fatty acid methyl esters obtained from the separation are collected simultaneously.

[0043] The composition of fatty acids obtained from the raw biodiesel in Example 1 after passing through the freeze crystallization section is shown in Table 2, the quality results of each material are shown in Table 3, and the various indicators of the obtained anti-wear agent product are shown in Table 4.

[0044] Table 2. Methyl ester content of various fatty acids after freeze crystallization of soybean oil biodiesel.

[0045] Element <![CDATA[C 16:0 ]]> <![CDATA[C 18:0 ]]> <![CDATA[C 18:1 ]]> <![CDATA[C 18:2 ]]> <![CDATA[C 18:3 ]]> mass fraction % 0.48 0.5 31.97 60.93 6.12

[0046] In Table 3, the feed liquid before freeze crystallization refers to the sum of the masses of biodiesel and methanol feedstocks during the freeze crystallization reaction process. The output mass of immobilized enzyme (wet weight) refers to the mass of the filter cake obtained after filtration following the enzyme hydrolysis process. The output mass of recovered methanol refers to the sum of the masses of methanol obtained from the "evaporation and deethanolination process" and the "filtration process".

[0047] Table 3. Quality of each material in the process of preparing fatty acid-based anti-wear agent from biodiesel.

[0048]

[0049]

[0050] Table 4. Anti-wear agent quality analysis table

[0051]

[0052] Example 2: Example 2 aims to evaluate the universality of this process for different raw materials. The process steps for preparing biodiesel in Example 2 are the same as in Example 1, except that the source of raw materials is changed, while all other conditions remain the same. The specific composition of the cottonseed oil biodiesel feedstock (acid value of 0.41 mg KOH / g) used in Example 2 is shown in Table 5.

[0053] Table 5. Fatty acid composition distribution in cottonseed oil biodiesel feedstock

[0054] Element <![CDATA[C 16:0 ]]> <![CDATA[C 18:0 ]]> <![CDATA[C 18:1 ]]> <![CDATA[C 18:2 ]]> <![CDATA[C 18:3 ]]> mass fraction % 21.56 3.12 17.71 56.75 0.86

[0055] The composition of fatty acids obtained from the raw biodiesel in Example 2 after passing through the freeze crystallization section is shown in Table 6, the quality results of each material are shown in Table 7, and the various indicators of the obtained anti-wear agent product are shown in Table 8.

[0056] Table 6. Methyl ester content of various fatty acids after freeze crystallization of cottonseed oil biodiesel.

[0057] Element <![CDATA[C 16:0 ]]> <![CDATA[C 18:0 ]]> <![CDATA[C 18:1 ]]> <![CDATA[C 18:2 ]]> <![CDATA[C 18:3 ]]> mass fraction % 0.53 0.36 25.53 72.31 1.27

[0058] Table 7. Quality of each material in the cottonseed oil biodiesel production process.

[0059]

[0060]

[0061] Table 8. Anti-wear agent quality analysis table

[0062]

[0063] Example 3: Example 3 aims to evaluate the reusability of immobilized lipase in the hydrolysis reaction stage. The experiment used the same soybean oil biodiesel feedstock as Example 1 (acid value: 0.35 mg KOH / g), and its overall process flow was the same as in Example 1. Figure 1 The only variable was that the lipase FM-NE04 used each time was the immobilized lipase FM-NE04 recovered after the previous round of hydrolysis. The trend of hydrolysis conversion rate during the five reuses of the immobilized enzyme is shown below. Figure 2 As shown.

[0064] from Figure 2 It can be seen that the biodiesel products obtained after five consecutive reuses of the immobilized enzyme all meet the Q / SHCG57-2017 standard. The results indicate that the immobilized lipase FM-NE04 maintained effective catalytic activity within five cycles, demonstrating good potential for repeated use.

[0065] Example 4: This example aims to evaluate the performance of methanol reuse. The experiment used the same soybean oil biodiesel feedstock as in Example 1 (acid value: 0.35 mg KOH / g), and its overall process flow was the same as in Example 1. Figure 1 The process is consistent, with the only variable being that the methanol used in this freeze-crystallization process is the methanol recovered in Examples 1-2, with a methanol purity of ≥99.5%.

[0066] The logistics quality results in this implementation case are shown in Table 9, and the various indicators of the obtained anti-wear agent product are shown in Table 10.

[0067] Table 9. Quality of each material in the process of preparing fatty acid-based anti-wear agent from soybean oil biodiesel.

[0068]

[0069]

[0070] Table 10. Anti-wear agent quality analysis table

[0071]

[0072]

[0073] Comparative Example 1: Comparative Example 1 is mainly used for process comparison. The experiment used the same soybean oil biodiesel feedstock as Example 1 (acid value: 0.35 mg KOH / g), and its overall process flow was the same as that of Example 1. Figure 1 The process is consistent, except that the reaction time of the "hydrolysis reaction section" in Comparative Example 1 is extended to 12 hours. After the hydrolysis reaction is completed, the oil phase product is obtained directly through layer dehydration. As shown in Table 11, extending the reaction time to 12 hours only increases the conversion rate of fatty acid methyl esters from 96.61% to 98.26% due to the concentration effect limiting the hydrolysis reaction, but the overall process cycle is significantly extended.

[0074] Table 11. Relationship between reaction time and conversion rate in the hydrolysis reaction section

[0075]

[0076]

[0077] The comparison results of the process flow of Comparative Example 1 and Example 1 are shown in Table 12.

[0078] Table 12. Comparison of process flows between Example 1 and Comparative Example 1

[0079] Measurement items Example 1 Comparative Example 1 Hydrolysis conversion rate % 96.7 97.95 Hydrolysis reaction time (h) 5 12 Distillation / distillation time (h) 1 0 Acid value of fatty acid products 199.5 196.5 Productivity per unit time high Low

[0080] Table 13 shows a comparison of the various indicators of the anti-wear agent products obtained from the process flow of Comparative Example 1 and Example 1.

[0081] Table 13. Comparison of Anti-wear Agent Quality Analysis

[0082]

[0083] In summary, this invention employs freeze crystallization technology to directionally control the fatty acid composition of biodiesel feedstocks. It utilizes immobilized enzymes to catalyze the biodiesel hydrolysis reaction under mild conditions, and the immobilized enzymes are recyclable, overcoming the equipment corrosion and acidic wastewater pollution problems associated with traditional concentrated sulfuric acid-catalyzed hydrolysis. This process is green and environmentally friendly. Furthermore, this invention utilizes vacuum technology to achieve timely separation of the hydrolysis byproduct methanol, driving the reaction in the forward direction and ensuring a high first-pass conversion rate of over 96.5% for the biodiesel hydrolysis reaction. The combination of hydrolysis and high-vacuum distillation significantly shortens the production cycle of fatty acid anti-wear agents from biodiesel by approximately half, improving production efficiency and enhancing the quality of the anti-wear agent product, resulting in superior performance across various indicators. The fatty acid-based anti-wear agents prepared by this invention all meet the Q / SHCG 57-2017 standard.

[0084] The contents described in this specification are merely an enumeration of the implementation forms of the inventive concept, and the scope of protection of this invention should not be regarded as limited to the specific forms described in the embodiments.

Claims

1. A method for efficiently preparing fatty acid-based anti-wear agents based on biodiesel, characterized in that... Includes the following steps: S1: Raw biodiesel is cooled and crystallized in methanol solvent; S2: After freezing and crystallizing, the liquid is kept warm and filtered in layers to collect the filtrate containing unsaturated methyl ester and the filter cake containing saturated methyl ester respectively. S3: The filtrate obtained in step S2 is rotary evaporated to remove methanol, and the resulting liquid after de-ethanolification is unsaturated methyl ester; S4: The unsaturated methyl ester obtained in step S3 is added to water as a solvent and a biological enzyme is used as a catalyst to carry out a hydrolysis reaction under negative pressure, so that the unsaturated methyl ester is hydrolyzed into unsaturated fatty acids. S5: The liquid after hydrolysis reaction in step S4 is first filtered to separate the catalyst, and then settled into an upper fatty acid oil phase and a lower aqueous phase. S6: The fatty acid oil phase in step S5 is subjected to high-vacuum distillation to separate a small amount of unsaturated methyl esters, and the unsaturated fatty acids are obtained, which are the fatty acid type anti-wear agent products.

2. The method for efficiently preparing fatty acid-based anti-wear agents based on biodiesel as described in claim 1, characterized in that... The biodiesel includes at least one of soybean oil, palm oil, cottonseed oil, safflower oil, rapeseed oil, sunflower oil, jatropha oil, rice bran oil, and peanut oil.

3. The method for efficiently preparing fatty acid-based anti-wear agents based on biodiesel as described in claim 1, characterized in that... In step S1, the mass ratio of methanol to biodiesel is 2:1-4:1, the cooling crystallization temperature is controlled at -25℃ to -10℃, and the cooling crystallization time is 0.5-2h.

4. The method for efficiently preparing fatty acid-based anti-wear agents based on biodiesel as described in claim 1, characterized in that... In step S4, the biological enzyme is immobilized lipase FM-NE04, the amount of enzyme used is 3-5% of the weight of unsaturated methyl ester, the mass ratio of water to unsaturated methyl ester is 2:1-4:1, the reaction temperature is 40-55℃, the reaction pressure is absolute pressure 5-15kPa, and the reaction time is 4-8h.

5. The method for efficiently preparing fatty acid-based anti-wear agents based on biodiesel as described in claim 1, characterized in that... In step S4, methanol water vapor is distilled off during the hydrolysis reaction under negative pressure. The vapor is condensed to obtain methanol water condensate. After methanol distillation, the methanol obtained from the distillation is reused in the freeze crystallization process, and the water obtained from the distillation is reused in the hydrolysis reaction section.

6. The method for efficiently preparing fatty acid-based anti-wear agents based on biodiesel as described in claim 1, characterized in that... The bio-enzymes and water obtained in step S5 through filtration and sedimentation are reused in the hydrolysis reaction process.

7. The method for efficiently preparing fatty acid-based anti-wear agents based on biodiesel as described in claim 1, characterized in that... In step S6, the pressure of the high vacuum distillation process is absolute pressure of 100-1000 Pa, the temperature of the bottom of the column is 190-230℃, and the temperature of the top of the column is 170-200℃.

8. The method for efficiently preparing fatty acid-based anti-wear agents based on biodiesel as described in claim 1, characterized in that... In step S6, a small amount of unsaturated methyl ester obtained through high-vacuum distillation is used as the raw material oil for the hydrolysis reaction process.

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