Preparation method of high-purity diester oil

Abstract

The invention provides a preparation method of high-purity diester oil, and relates to the technical field of genetic engineering of enzymes. The preparation method of the high-purity diester oil comprises the steps that raw materials are selected and prepared, high-purity fatty acid and alcohol are selected as reaction raw materials, the fatty acid is generally derived from hydrolysis of vegetable oil or animal fat, the alcohol can be methyl alcohol or ethyl alcohol, it is ensured that the purity of the fatty acid and the purity of the alcohol are both higher than 99%, and the influence of impurities on the purity of a final product is reduced; the raw materials are pretreated, wherein dehydration and possible impurity removal are included; esterification reaction: under the anhydrous condition, fatty acid and alcohol are mixed according to a certain molar ratio, the esterification reaction is carried out in the presence of a catalyst, and the catalyst is preferably strongly acidic ion exchange resin. Through the steps of accurately controlling raw material selection, esterification reaction conditions, reduced pressure distillation, molecular sieve adsorption treatment and rectification, the purity of the diester oil can be effectively improved, and the strict requirement of specific application on the purity is met.

Description

Technical Field

[0001] The invention relates to the technical field of enzyme genetic engineering, in particular to a method for preparing high-purity diester oil. Background Art

[0002] Oil is one of the three major nutrients for the human body. Reasonable dietary oil provides energy for the human body, enhances immune function, and maintains nerve and physiological activity. Diacylcerol is a natural TAG substitute ester, which has been proven to have multiple nutritional functions. This paper aims to provide a theoretical basis for the application of DAG as a new type of healthy oil. The metabolic mechanism of DAG and the main nutritional functions of DAG are reviewed. DAG has similar physical and chemical properties to TAG. Due to the differences in metabolic pathways with TAG and the ability to regulate the expression of genes related to fat oxidation, DAG has multiple functions such as promoting fat oxidation, inhibiting body weight gain, reducing visceral fat content, improving serum cholesterol, regulating blood sugar, and lowering blood lipids.

[0003] In the existing preparation technology, the esterification reaction is usually carried out under normal pressure, which requires a higher reaction temperature, thereby increasing the possibility of side reactions such as thermal decomposition and polymerization reactions, resulting in a decrease in product purity. In addition, due to the high boiling point of diester oil, conventional distillation is difficult to effectively separate impurities, especially when removing trace impurities such as water and unreacted alcohol, conventional methods are often not efficient enough.

[0004] Although molecular sieve adsorption treatment can remove moisture and some organic impurities, its adsorption capacity is limited by the type of molecular sieve and the treatment conditions. In addition, in practical applications, the regeneration and reuse efficiency of molecular sieves is low, which increases operating costs and environmental burdens. Therefore, technicians in this field provide a method for preparing high-purity diester oil to solve the problems raised in the above background technology. Summary of the invention

[0005] 1. Technical issues to be solved

[0006] In view of the deficiencies in the prior art, the present invention provides a method for preparing high-purity diester oil, which solves the problem that conventional distillation is difficult to effectively separate impurities, especially when removing trace impurities such as water and unreacted alcohol, the conventional method is often not efficient enough.

[0007] (II) Technical solution

[0008] To achieve the above objectives, the present invention is implemented by the following technical scheme: A method for preparing high-purity diester oil, comprising:

[0009] Raw material selection and preparation: select high-purity fatty acids and alcohols as reaction raw materials. Fatty acids are usually derived from the hydrolysis of vegetable oils or animal fats, while alcohols can be methanol or ethanol. Ensure that the purity of fatty acids and alcohols is higher than 99% to reduce the impact of impurities on the purity of the final product. Pre-treat the raw materials, including dehydration and removal of possible impurities;

[0010] Esterification reaction, under anhydrous conditions, fatty acids and alcohols are mixed in a certain molar ratio, and the esterification reaction is carried out in the presence of a catalyst, the catalyst is preferably a strongly acidic ion exchange resin, the reaction is carried out at a controlled temperature, usually between 60 degrees Celsius and 80 degrees Celsius, and the reaction time is determined according to the specific reactants and the activity of the catalyst, generally 2-4 hours;

[0011] After the reaction is completed, unreacted alcohol and by-products are removed by vacuum distillation. Vacuum distillation can be carried out at a lower temperature to reduce the risk of thermal decomposition. The appropriate vacuum degree is controlled, generally in the range of 10-50 mmHg, to ensure effective separation;

[0012] Molecular sieve adsorption treatment: use molecular sieve to adsorb the reaction mixture to remove trace amounts of water and impurities. Select the appropriate type of molecular sieve, mix the molecular sieve with the reaction mixture, control the appropriate temperature and time, and generally treat at room temperature for 1-2 hours;

[0013] A distillation step, in which the adsorption-treated mixture is distilled to further improve the purity of the diester oil. During the distillation process, high-purity diester oil products within the boiling point range are collected. The temperature and pressure of the distillation tower are set according to the boiling point range of the diester oil, and the main fractions are collected as the final product;

[0014] Product analysis and purity testing: Use gas chromatography, high performance liquid chromatography or other analytical techniques to conduct purity testing and component analysis on the final product to ensure that the product meets high purity standards. According to the analysis results, adjust the key parameters in the preparation process, including reaction time, temperature and catalyst dosage, to ensure the consistency of product quality.

[0015] Preferably, the raw material selection and preparation comprises the following steps:

[0016] S1. Raw material selection: select fatty acids with stable sources and high purity. Fatty acids can be obtained from vegetable oils or animal fats through hydrolysis reactions. The selected fatty acids should have a high content of single or a few concentrated fatty acid components to simplify the subsequent purification process. Select appropriate alcohols, such as methanol or ethanol, based on the properties and application areas of the desired diester oil;

[0017] S2. Raw material purity requirements, ensuring that the purity of the selected fatty acids and alcohols is higher than 99%;

[0018] S3. Calculation of the raw material molar ratio, the esterification reaction of fatty acid and methanol can be expressed as:

[0019] Fatty acid + methanol → diester oil + water

[0020] The formula for calculating the number of moles of fatty acids is:

[0021]

[0022] The formula for calculating the mass of methanol required is:

[0023] m 甲醇 =n 甲醇 ×M 甲醇

[0024] S4. Raw material preparation, dehydration of alcohol to ensure that the reaction system is anhydrous, anhydrous magnesium sulfate or molecular sieve desiccant can be used, if the fatty acid contains water, it can be heated to a certain temperature and maintained for a period of time, or dehydrated using a desiccant;

[0025] S5. Experimental operation: accurately weigh the mass of the required fatty acid and methanol, and mix the fatty acid and methanol evenly under anhydrous conditions.

[0026] Preferably, the esterification reaction comprises the following steps:

[0027] S1. Prepare the reactants, ensure that the purity of fatty acids and alcohols meets the requirements, and accurately weigh them according to the molar ratio calculated previously, mix the fatty acids and alcohols, and add an appropriate amount of catalyst, which can be a strong acid ion exchange resin;

[0028] S2. Heating and stirring, heating the mixture to a suitable reaction temperature, generally between 60-80 degrees Celsius, stirring while heating to ensure that the reactants are fully mixed to improve the reaction efficiency;

[0029] S3. Reaction time control, control the reaction time, usually the esterification reaction takes several hours, the specific time depends on the reaction temperature, catalyst activity, the reaction can be judged by monitoring the amount of water generated in the reaction system;

[0030] S4. Reaction monitoring: The progress of the reaction can be monitored by sampling and analyzing the acid value in the reaction mixture. The decrease in the acid value indicates that the esterification reaction is proceeding. When the acid value no longer decreases significantly, it can be considered that the reaction is close to completion. The calculation formula for the acid value is:

[0031]

[0032] Where V is the volume of the consumed KOH standard solution (ml), N is the concentration of the KOH solution (mol / L), 56.1 is the molar mass of KOH (g / mol), and m is the mass of the sample (g);

[0033] S5. Post-treatment: After the reaction is completed, the reaction mixture is cooled to room temperature, filtered to remove the catalyst, and subjected to reduced pressure distillation to remove unreacted alcohol and by-products.

[0034] Preferably, the vacuum distillation comprises the following steps:

[0035] S1. Prepare the device, make sure the distillation device has been cleaned and dried, including the distillation flask, condenser, vacuum pump and vacuum gauge, and pour the reaction mixture into the distillation flask;

[0036] S2. Connect the device, distillation flask, condenser, vacuum pump and vacuum gauge to ensure the system is well sealed;

[0037] S3. Evacuate the system, turn on the vacuum pump, and slowly reduce the pressure in the system to the required vacuum degree. Usually, the vacuum degree of reduced pressure distillation ranges from 10 to 50 mmHg, depending on the boiling point and thermal stability of the compound.

[0038] S4. Heating: slowly heat the distillation flask to start the distillation process. The heating rate should not be too fast to avoid local overheating and decomposition.

[0039] S5. Collect the fractions. Different components will evaporate and condense in turn according to the difference in boiling points. After condensation in the condenser, collect them in different receiving bottles. Use a thermometer to monitor the temperature in the distillation bottle to determine the distillation status of different components.

[0040] S6. End the distillation. When the temperature displayed by the thermometer no longer rises, it indicates that all volatile components have been evaporated and the distillation process is over;

[0041] S7. Post-processing: turn off the vacuum pump and heating source, wait for the system to cool down, turn off the vacuum system, collect and analyze the fractions to ensure the purity of the desired product.

[0042] Preferably, the molecular sieve adsorption treatment comprises the following steps:

[0043] S1. Selection of molecular sieves: Select the appropriate type of molecular sieve according to the type of impurities to be removed;

[0044] S2. Activation of molecular sieves. Before use, molecular sieves are usually activated to remove moisture and other adsorbed impurities. Activation is usually carried out at high temperatures, such as 300-400°C, and in a vacuum or nitrogen flow for several hours.

[0045] S3. Adsorption treatment, mixing the activated molecular sieve with the liquid to be treated, the mixing ratio and time are determined according to the specific situation, generally it is necessary to ensure that the molecular sieve is in full contact with the liquid. For liquid treatment, the molecular sieve can be added to the liquid, stirred for a period of time and then filtered to remove the molecular sieve. For gas treatment, the gas can be passed through an adsorption column filled with molecular sieves;

[0046] S4. Filtration or separation: After adsorption treatment, the molecular sieve is separated from the liquid or gas by filtration or centrifugation;

[0047] S5. Regeneration and reuse. After a period of use, the adsorption capacity of the molecular sieve will decrease. It can be regenerated by heating. The regeneration temperature is usually close to the activation temperature, but care should be taken not to exceed the maximum operating temperature of the molecular sieve.

[0048] Preferably, the distillation step comprises the following steps:

[0049] S1. Prepare the device, ensure that the distillation device has been cleaned and dried, including the distillation column, heating device, condenser and receiving bottle, and pour the mixture treated with molecular sieve into the distillation bottle;

[0050] S2. Heating, slowly heating the distillation flask to start the distillation process. The heating rate should not be too fast to avoid local overheating and decomposition;

[0051] S3. Control the reflux ratio. During the distillation process, part of the steam will condense and flow back into the distillation column. The reflux ratio, the ratio of the reflux volume to the distillate volume, has an important influence on the distillation efficiency.

[0052] S4. Collect the fractions. According to the difference in boiling points of different components, they will evaporate and condense in sequence. After condensation in the condenser, they will be collected in different receiving bottles. A thermometer can be used to monitor the temperature in the distillation bottle to determine the distillation status of different components.

[0053] S5. End the distillation. When the temperature displayed by the thermometer no longer rises, it indicates that all volatile components have been evaporated and the distillation process is over;

[0054] S6. Post-processing: turn off the heating source, wait for the system to cool down, turn off the distillation system, collect and analyze the fractions to ensure the purity of the desired product.

[0055] Preferably, the product analysis and purity test comprises the following steps:

[0056] S1. Sample preparation: take an appropriate amount of diester oil sample collected in the distillation step to ensure sample representativeness and uniformity;

[0057] S2. Chromatographic analysis: Analyze the sample using gas chromatography (GC) or high performance liquid chromatography (HPLC). For GC, the sample is injected into the chromatographic column, and the different components are separated in the column according to the difference in boiling point or polarity. The signal is detected and recorded by the detector. For HPLC, the sample is pumped into the chromatographic column by a high pressure pump, and the components are separated according to the difference in interaction with the stationary phase.

[0058] S3. Purity calculation: Calculate the purity of the diester oil based on the chromatogram. The purity can be determined by the percentage of the peak area, that is, the ratio of the target peak area to the total peak area.

[0059] (III) Beneficial effects

[0060] The present invention provides a method for preparing high-purity diester oil, which has the following beneficial effects:

[0061] 1. In the present invention, by precisely controlling the raw material selection, esterification reaction conditions, vacuum distillation, molecular sieve adsorption treatment and rectification steps, the purity of the diester oil can be effectively improved to meet the strict purity requirements of specific applications.

[0062] 2. In the present invention, by optimizing the reaction conditions and using molecular sieve adsorption treatment, by-products and impurities generated during the reaction, such as water, unreacted alcohol and fatty acids, etc., can be effectively removed, thereby improving product quality.

[0063] 3. In the present invention, the steps involved in the technical solution are relatively simple and easy to operate, and are suitable for production from laboratory scale to industrial scale. The reduced pressure distillation is carried out under conditions below atmospheric pressure, which can reduce the boiling point and thus reduce energy consumption. The use of molecular sieve adsorption treatment can effectively remove organic solvent residues and moisture, reduce environmental pollution, and the molecular sieve can be regenerated and reused, reducing resource consumption and processing costs. DETAILED DESCRIPTION

[0064] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0065] Embodiment 1:

[0066] The embodiment of the present invention provides a method for preparing high-purity diester oil, comprising:

[0067] Raw material selection and preparation: select high-purity fatty acids and alcohols as reaction raw materials. Fatty acids are usually derived from the hydrolysis of vegetable oils or animal fats, while alcohols can be methanol or ethanol. Ensure that the purity of fatty acids and alcohols is higher than 99% to reduce the impact of impurities on the purity of the final product. Pre-treat the raw materials, including dehydration and removal of possible impurities;

[0068] Esterification reaction, under anhydrous conditions, fatty acids and alcohols are mixed in a certain molar ratio, and the esterification reaction is carried out in the presence of a catalyst, the catalyst is preferably a strongly acidic ion exchange resin, the reaction is carried out at a controlled temperature, usually between 60 degrees Celsius and 80 degrees Celsius, and the reaction time is determined according to the specific reactants and the activity of the catalyst, generally 2-4 hours;

[0069] After the reaction is completed, unreacted alcohol and by-products are removed by vacuum distillation. Vacuum distillation can be carried out at a lower temperature to reduce the risk of thermal decomposition. The appropriate vacuum degree is controlled, generally in the range of 10-50 mmHg, to ensure effective separation;

[0070] Molecular sieve adsorption treatment: use molecular sieve to adsorb the reaction mixture to remove trace amounts of water and impurities. Select the appropriate type of molecular sieve, mix the molecular sieve with the reaction mixture, control the appropriate temperature and time, and generally treat at room temperature for 1-2 hours;

[0071] A distillation step, in which the adsorption-treated mixture is distilled to further improve the purity of the diester oil. During the distillation process, high-purity diester oil products within the boiling point range are collected. The temperature and pressure of the distillation tower are set according to the boiling point range of the diester oil, and the main fractions are collected as the final product;

[0072] Product analysis and purity testing: Use gas chromatography, high performance liquid chromatography or other analytical techniques to conduct purity testing and component analysis on the final product to ensure that the product meets high purity standards. According to the analysis results, adjust the key parameters in the preparation process, including reaction time, temperature and catalyst dosage, to ensure the consistency of product quality.

[0073] The raw material selection and preparation comprises the following steps:

[0074] S1. Raw material selection: select fatty acids with stable sources and high purity. Fatty acids can be obtained from vegetable oils or animal fats through hydrolysis reactions. The selected fatty acids should have a high content of single or a few concentrated fatty acid components to simplify the subsequent purification process. Select appropriate alcohols, such as methanol or ethanol, based on the properties and application areas of the desired diester oil;

[0075] S2. Raw material purity requirements, ensuring that the purity of the selected fatty acids and alcohols is higher than 99%;

[0076] S3. Calculation of the raw material molar ratio, the esterification reaction of fatty acid and methanol can be expressed as:

[0077] Fatty acid + methanol → diester oil + water

[0078] The formula for calculating the number of moles of fatty acids is:

[0079]

[0080] The formula for calculating the mass of methanol required is:

[0081] M 甲醇 =n 甲醇 ×M 甲醇

[0082] S4. Raw material preparation, dehydration of alcohol to ensure that the reaction system is anhydrous, anhydrous magnesium sulfate or molecular sieve desiccant can be used, if the fatty acid contains water, it can be heated to a certain temperature and maintained for a period of time, or dehydrated using a desiccant;

[0083] S5. Experimental operation: accurately weigh the mass of the required fatty acid and methanol, and mix the fatty acid and methanol evenly under anhydrous conditions.

[0084] The esterification reaction comprises the following steps:

[0085] S1. Prepare the reactants, ensure that the purity of the fatty acid and the alcohol meets the requirements, and accurately weigh them according to the molar ratio calculated previously, mix the fatty acid and the alcohol, and add an appropriate amount of catalyst, which can be a strong acid ion exchange resin;

[0086] S2. Heating and stirring, heating the mixture to a suitable reaction temperature, generally between 60-80 degrees Celsius, stirring while heating to ensure that the reactants are fully mixed to improve the reaction efficiency;

[0087] S3. Reaction time control, control the reaction time, usually the esterification reaction takes several hours, the specific time depends on the reaction temperature, catalyst activity, the reaction can be judged by monitoring the amount of water generated in the reaction system;

[0088] S4. Reaction monitoring: The progress of the reaction can be monitored by sampling and analyzing the acid value in the reaction mixture. The decrease in the acid value indicates that the esterification reaction is proceeding. When the acid value no longer decreases significantly, it can be considered that the reaction is close to completion. The calculation formula for the acid value is:

[0089]

[0090] Where V is the volume of the consumed KOH standard solution (ml), N is the concentration of the KOH solution (mol / L), 56.1 is the molar mass of KOH (g / mol), and m is the mass of the sample (g);

[0091] S5. Post-treatment: After the reaction is completed, the reaction mixture is cooled to room temperature, filtered to remove the catalyst, and subjected to reduced pressure distillation to remove unreacted alcohol and by-products.

[0092] The vacuum distillation comprises the following steps:

[0093] S1. Prepare the device, make sure the distillation device has been cleaned and dried, including the distillation flask, condenser, vacuum pump and vacuum gauge, and pour the reaction mixture into the distillation flask;

[0094] S2. Connect the device, distillation flask, condenser, vacuum pump and vacuum gauge to ensure the system is well sealed;

[0095] S3. Evacuate the system, turn on the vacuum pump, and slowly reduce the pressure in the system to the required vacuum degree. Usually, the vacuum degree of reduced pressure distillation ranges from 10 to 50 mmHg, depending on the boiling point and thermal stability of the compound.

[0096] S4. Heating: slowly heat the distillation flask to start the distillation process. The heating rate should not be too fast to avoid local overheating and decomposition.

[0097] S5. Collect the fractions. Different components will evaporate and condense in turn according to the difference in boiling points. After condensation in the condenser, collect them in different receiving bottles. Use a thermometer to monitor the temperature in the distillation bottle to determine the distillation status of different components.

[0098] S6. End the distillation. When the temperature displayed by the thermometer no longer rises, it indicates that all volatile components have been evaporated and the distillation process is over;

[0099] S7. Post-processing: turn off the vacuum pump and heating source, wait for the system to cool down, turn off the vacuum system, collect and analyze the fractions to ensure the purity of the desired product.

[0100] The molecular sieve adsorption process comprises the following steps:

[0101] S1. Selection of molecular sieves: Select the appropriate type of molecular sieve according to the type of impurities to be removed;

[0102] S2. Activation of molecular sieves. Before use, molecular sieves are usually activated to remove moisture and other adsorbed impurities. Activation is usually carried out at high temperatures, such as 300-400°C, and in a vacuum or nitrogen flow for several hours.

[0103] S3. Adsorption treatment, mixing the activated molecular sieve with the liquid to be treated, the mixing ratio and time are determined according to the specific situation, generally it is necessary to ensure that the molecular sieve is in full contact with the liquid. For liquid treatment, the molecular sieve can be added to the liquid, stirred for a period of time and then filtered to remove the molecular sieve. For gas treatment, the gas can be passed through an adsorption column filled with molecular sieves;

[0104] S4. Filtration or separation: After adsorption treatment, the molecular sieve is separated from the liquid or gas by filtration or centrifugation;

[0105] S5. Regeneration and reuse. After a period of use, the adsorption capacity of the molecular sieve will decrease. It can be regenerated by heating. The regeneration temperature is usually close to the activation temperature, but care should be taken not to exceed the maximum operating temperature of the molecular sieve.

[0106] The distillation step comprises the following steps:

[0107] S1. Prepare the device, ensure that the distillation device has been cleaned and dried, including the distillation column, heating device, condenser and receiving bottle, and pour the mixture treated with molecular sieve into the distillation bottle;

[0108] S2. Heating, slowly heating the distillation flask to start the distillation process. The heating rate should not be too fast to avoid local overheating and decomposition;

[0109] S3. Control the reflux ratio. During the distillation process, part of the steam will condense and flow back into the distillation column. The reflux ratio, the ratio of the reflux volume to the distillate volume, has an important influence on the distillation efficiency.

[0110] S4. Collect the fractions. According to the difference in boiling points of different components, they will evaporate and condense in sequence. After condensation in the condenser, they will be collected in different receiving bottles. A thermometer can be used to monitor the temperature in the distillation bottle to determine the distillation status of different components.

[0111] S5. End the distillation. When the temperature displayed by the thermometer no longer rises, it indicates that all volatile components have been evaporated and the distillation process is over;

[0112] S6. Post-processing: turn off the heating source, wait for the system to cool down, turn off the distillation system, collect and analyze the fractions to ensure the purity of the desired product.

[0113] The product analysis and purity test includes the following steps:

[0114] S1. Sample preparation: take an appropriate amount of diester oil sample collected in the distillation step to ensure sample representativeness and uniformity;

[0115] S2. Chromatographic analysis: Analyze the sample using gas chromatography (GC) or high performance liquid chromatography (HPLC). For GC, the sample is injected into the chromatographic column, and the different components are separated in the column according to the difference in boiling point or polarity. The signal is detected and recorded by the detector. For HPLC, the sample is pumped into the chromatographic column by a high pressure pump, and the components are separated according to the difference in interaction with the stationary phase.

[0116] S3. Purity calculation: Calculate the purity of the diester oil based on the chromatogram. The purity can be determined by the percentage of the peak area, that is, the ratio of the target peak area to the total peak area.

[0117] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing high-purity diester oil, characterized in that: include: Raw material selection and preparation: select high-purity fatty acids and alcohols as reaction raw materials. Fatty acids are usually derived from the hydrolysis of vegetable oils or animal fats, while alcohols can be methanol or ethanol. Ensure that the purity of fatty acids and alcohols is higher than 99% to reduce the impact of impurities on the purity of the final product. Pre-treat the raw materials, including dehydration and removal of possible impurities; Esterification reaction, under anhydrous conditions, fatty acids and alcohols are mixed in a certain molar ratio, and the esterification reaction is carried out in the presence of a catalyst, the catalyst is preferably a strongly acidic ion exchange resin, the reaction is carried out at a controlled temperature, usually between 60 degrees Celsius and 80 degrees Celsius, and the reaction time is determined according to the specific reactants and the activity of the catalyst, generally 2-4 hours; After the reaction is completed, unreacted alcohol and by-products are removed by vacuum distillation. Vacuum distillation can be carried out at a lower temperature to reduce the risk of thermal decomposition. The appropriate vacuum degree is controlled, generally in the range of 10-50 mmHg, to ensure effective separation; Molecular sieve adsorption treatment: use molecular sieve to adsorb the reaction mixture to remove trace amounts of water and impurities. Select the appropriate type of molecular sieve, mix the molecular sieve with the reaction mixture, control the appropriate temperature and time, and generally treat at room temperature for 1-2 hours; A distillation step, in which the adsorption-treated mixture is distilled to further improve the purity of the diester oil. During the distillation process, high-purity diester oil products within the boiling point range are collected. The temperature and pressure of the distillation tower are set according to the boiling point range of the diester oil, and the main fractions are collected as the final product; Product analysis and purity testing: Use gas chromatography, high performance liquid chromatography or other analytical techniques to conduct purity testing and component analysis on the final product to ensure that the product meets high purity standards. According to the analysis results, adjust the key parameters in the preparation process, including reaction time, temperature and catalyst dosage, to ensure the consistency of product quality.

2. The method for preparing a high-purity diester oil according to claim 1, characterized in that: The raw material selection and preparation comprises the following steps: S1. Raw material selection: select fatty acids with stable sources and high purity. Fatty acids can be obtained from vegetable oils or animal fats through hydrolysis reactions. The selected fatty acids should have a high content of single or a few concentrated fatty acid components to simplify the subsequent purification process. Select appropriate alcohols, such as methanol or ethanol, based on the properties and application areas of the desired diester oil; S2. Raw material purity requirements, ensuring that the purity of the selected fatty acids and alcohols is higher than 99%; S3. Calculation of the raw material molar ratio, the esterification reaction of fatty acid and methanol can be expressed as: Fatty acid + methanol → diester oil + water The formula for calculating the number of moles of fatty acids is: The formula for calculating the mass of methanol required is: m 甲醇 =n 甲醇 ×m 甲醇 S4. Raw material preparation, dehydration of alcohol to ensure that the reaction system is anhydrous, anhydrous magnesium sulfate or molecular sieve desiccant can be used, if the fatty acid contains water, it can be heated to a certain temperature and maintained for a period of time, or dehydrated using a desiccant; S5. Experimental operation: accurately weigh the mass of the required fatty acid and methanol, and mix the fatty acid and methanol evenly under anhydrous conditions.

3. The method for preparing a high-purity diester oil according to claim 1, characterized in that: The esterification reaction comprises the following steps: S1. Prepare the reactants, ensure that the purity of fatty acids and alcohols meets the requirements, and accurately weigh them according to the molar ratio calculated previously, mix the fatty acids and alcohols, and add an appropriate amount of catalyst, which can be a strong acid ion exchange resin; S2. Heating and stirring, heating the mixture to a suitable reaction temperature, generally between 60-80 degrees Celsius, stirring while heating to ensure that the reactants are fully mixed to improve the reaction efficiency; S3. Reaction time control, control the reaction time, usually the esterification reaction takes several hours, the specific time depends on the reaction temperature, catalyst activity, the reaction can be judged by monitoring the amount of water generated in the reaction system; S4. Reaction monitoring: The progress of the reaction can be monitored by sampling and analyzing the acid value in the reaction mixture. The decrease in the acid value indicates that the esterification reaction is proceeding. When the acid value no longer decreases significantly, it can be considered that the reaction is close to completion. The calculation formula for the acid value is: Where V is the volume of the consumed KOH standard solution in ml, N is the concentration of the KOH solution in mol / L, 56.1 is the molar mass of KOH in g / mol, and m is the mass of the sample in g; S5. Post-treatment: After the reaction is completed, the reaction mixture is cooled to room temperature, filtered to remove the catalyst, and subjected to reduced pressure distillation to remove unreacted alcohol and by-products.

4. The method for preparing a high-purity diester oil according to claim 1, characterized in that: The vacuum distillation comprises the following steps: S1. Prepare the device, make sure the distillation device has been cleaned and dried, including the distillation flask, condenser, vacuum pump and vacuum gauge, and pour the reaction mixture into the distillation flask; S2. Connect the device, distillation flask, condenser, vacuum pump and vacuum gauge to ensure the system is well sealed; S3. Evacuate the system, turn on the vacuum pump, and slowly reduce the pressure in the system to the required vacuum degree. Usually, the vacuum degree of reduced pressure distillation ranges from 10 to 50 mmHg, depending on the boiling point and thermal stability of the compound. S4. Heating: slowly heat the distillation flask to start the distillation process. The heating rate should not be too fast to avoid local overheating and decomposition. S5. Collect the fractions. Different components will evaporate and condense in turn according to the difference in boiling points. After condensation in the condenser, collect them in different receiving bottles. Use a thermometer to monitor the temperature in the distillation bottle to determine the distillation status of different components. S6. End the distillation. When the temperature displayed by the thermometer no longer rises, it indicates that all volatile components have been evaporated and the distillation process is over; S7. Post-processing: turn off the vacuum pump and heating source, wait for the system to cool down, turn off the vacuum system, collect and analyze the fractions to ensure the purity of the desired product.

5. The method for preparing a high-purity diester oil according to claim 1, characterized in that: The molecular sieve adsorption process comprises the following steps: S1. Selection of molecular sieves: Select the appropriate type of molecular sieve according to the type of impurities to be removed; S2. Activation of molecular sieves. Before use, molecular sieves are usually activated to remove moisture and other adsorbed impurities. Activation is usually carried out at high temperature (such as 300-400°C) and in vacuum or nitrogen flow for several hours. S3. Adsorption treatment, mixing the activated molecular sieve with the liquid to be treated, the mixing ratio and time are determined according to the specific situation, generally it is necessary to ensure that the molecular sieve is in full contact with the liquid. For liquid treatment, the molecular sieve can be added to the liquid, stirred for a period of time and then filtered to remove the molecular sieve. For gas treatment, the gas can be passed through an adsorption column filled with molecular sieves; S4. Filtration or separation: After adsorption treatment, the molecular sieve is separated from the liquid or gas by filtration or centrifugation; S5. Regeneration and reuse. After a period of use, the adsorption capacity of the molecular sieve will decrease. It can be regenerated by heating. The regeneration temperature is usually close to the activation temperature, but care should be taken not to exceed the maximum operating temperature of the molecular sieve.

6. The method for preparing a high-purity diester oil according to claim 1, characterized in that: The distillation step comprises the following steps: S1. Prepare the device, ensure that the distillation device has been cleaned and dried, including the distillation column, heating device, condenser and receiving bottle, and pour the mixture treated with molecular sieve into the distillation bottle; S2. Heating, slowly heating the distillation flask to start the distillation process. The heating rate should not be too fast to avoid local overheating and decomposition; S3. Control the reflux ratio. During the distillation process, part of the steam will condense and flow back into the distillation column. The reflux ratio (the ratio of the reflux volume to the distillate volume) has an important influence on the distillation efficiency. S4. Collect the fractions. According to the difference in boiling points of different components, they will evaporate and condense in sequence. After condensation in the condenser, they will be collected in different receiving bottles. A thermometer can be used to monitor the temperature in the distillation bottle to determine the distillation status of different components. S5. End the distillation. When the temperature displayed by the thermometer no longer rises, it indicates that all volatile components have been evaporated and the distillation process is over; S6. Post-processing: turn off the heating source, wait for the system to cool down, turn off the distillation system, collect and analyze the fractions to ensure the purity of the desired product.

7. The method for preparing a high-purity diester oil according to claim 1, characterized in that: The product analysis and purity test includes the following steps: S1. Sample preparation: take an appropriate amount of diester oil sample collected in the distillation step to ensure sample representativeness and uniformity; S2. Chromatographic analysis: using gas chromatography (GC) or high performance liquid chromatography (HPLC) analysis techniques to analyze samples. For GC, the sample is injected into the chromatographic column, and the different components are separated in the column according to the difference in boiling point or polarity. The detector detects and records the signal. For HPLC, the sample is pumped into the chromatographic column by a high pressure pump, and the components are separated according to the difference in interaction with the stationary phase. S3. Purity calculation: Calculate the purity of the diester oil based on the chromatogram. The purity can be determined by the percentage of the peak area, that is, the ratio of the target peak area to the total peak area.

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