Preparation method and application of amphiphilic metal alkali composite catalyst for monoglyceride synthesis
By using amphiphilic metal base composite catalyst, the problems of poor dispersion and low mass transfer efficiency in monoglyceride synthesis were solved, and efficient and green monoglyceride synthesis was achieved, which improved product purity and conversion rate, and simplified the process flow.
Patent Information
- Application Number
- CN202510248528.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-04
- Publication Date
- 2025-05-27
AI Technical Summary
In the existing monoglyceride synthesis process, the catalyst dispersion is poor, the mass transfer efficiency is low and the by-product generation is large, resulting in low product purity and conversion rate, complex process and heavy environmental governance burden.
An amphiphilic metal-base composite catalyst is used to form an amphiphilic catalyst by mixing the polyol with the metal hydroxide at a specific temperature and pressure, and the catalyst is used in the reaction to improve the reaction efficiency.
The efficient synthesis of monoglyesters was achieved, with the monoglyester content reaching more than 56%, and the yield and conversion rate exceeded 50% and 96%. At the same time, the process flow was simplified and environmental pollution was reduced.
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of monoglyceride synthesis, and particularly relates to a preparation method and application of an amphiphilic metal base composite catalyst for monoglyceride synthesis. Background Art
[0002] As an important class of non-ionic surfactants, monoglycerides (mono-fatty acid glycerides) are widely used in the fields of food processing, daily chemical industry, and pharmaceutical preparations due to their excellent emulsifying properties and biological safety. Their characteristics as intermediate products of human metabolism enable them to have no limit on the daily intake (ADI value unrestricted), making them key additives with unrestricted usage in the food industry. However, the current industrial preparation process of monoglycerides still has significant technical bottlenecks, restricting production efficiency and environmental friendliness.
[0003] Currently, in industrial production, alkaline catalysts (such as sodium hydroxide, potassium hydroxide, or calcium hydroxide) are generally used to catalyze the transesterification reaction of oils and fats with glycerol to synthesize monoglycerides. Although such catalysts have the advantages of wide sources and low costs, they have the following inherent defects:
[0004] Low product purity and conversion rate
[0005] Under the alkaline catalytic system, the monoglyceride content in the single reaction product is only 30%-46%, and the generation amounts of by-products diglycerides and saponified products are relatively high. Since the saponified products need to be removed through subsequent inorganic acid neutralization processes, the post-treatment process of the reaction is complicated, and salty wastewater and waste residues (i.e., "three wastes") are generated, increasing the burden of environmental governance.
[0006] Limited catalyst action mechanism
[0007] Alkaline catalysts are only soluble in the glycerol phase at the initial stage of the reaction and are insoluble in the oil phase. As the reaction proceeds, the generated monoglycerides form micelle structures by wrapping the unreacted oils and diglycerides due to their surface activity, resulting in the catalyst in the glycerol phase being unable to effectively contact the reaction substrates, forming a mass transfer barrier. This phenomenon directly leads to a sharp drop in the catalytic efficiency in the later stage of the reaction, making it difficult to break through the thermodynamic equilibrium limit, and ultimately resulting in low yields and recoveries of monoglycerides.
[0008] Insufficient process economy
[0009] Low conversion rates force enterprises to adopt multi-stage reactions or complex purification processes (such as molecular distillation), significantly increasing energy consumption and equipment investment costs. At the same time, the saponified products generated by the neutralization reaction require additional separation steps, further reducing the overall process economy.
[0010] Prior art attempts to alleviate the above problems by optimizing reaction temperature, pressure, or catalyst concentration, but none have been able to break through the limitations of the inherent physical and chemical properties of alkaline catalysts. Therefore, there is an urgent need to develop a new catalytic system or process method to solve the core problems of poor catalyst dispersion, low mass transfer efficiency, and high by-product generation, and to achieve the efficient and green synthesis of monoglycerides. Summary of the Invention
[0011] The problems existing in the prior art are as follows: When using a conventional metal alkaline catalyst as the catalyst for monoglyceride synthesis, the catalytic efficiency is low and the yield of monoglyceride is not good. To address the above technical problems, the present invention provides a preparation method for an amphiphilic metal base composite catalyst for monoglyceride synthesis, and the preparation method includes the following steps:
[0012] Mix polyols evenly at 80 - 115°C, then add metal hydroxide, stir evenly at 120 - 150°C, then conduct a vacuum dehydration reaction at 100 - 300 Pa for 0.5 - 3 h. After that, the reaction product is washed with ethanol multiple times and filtered by suction. After the obtained solid product is dried under vacuum, the amphiphilic metal base composite catalyst is obtained.
[0013] The polyols include a combination of two or more of glycerol, erythritol, xylitol, or sorbitol.
[0014] The metal hydroxides include one or a combination of two or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, and zinc hydroxide.
[0015] The mass ratio between the polyols and the metal hydroxides is 76.5 - 170.4:30 - 48.
[0016] Preferably, the mass ratio between the polyols and the metal hydroxides is 76.5:30, the polyols are a mixture of glycerol and erythritol in a mass ratio of 46:30.5, and the metal hydroxide is sodium hydroxide.
[0017] Preferably, the mass ratio between the polyols and the metal hydroxides is 92.25:30, the polyols are a mixture of xylitol and erythritol in a mass ratio of 31.25:61, and the metal hydroxide is sodium hydroxide.
[0018] Preferably, the mass ratio between the polyols and the metal hydroxides is 121.5:30, the polyols are a mixture of xylitol and sorbitol in a mass ratio of 76:45.5, and the metal hydroxide is sodium hydroxide.
[0019] Preferably, the mass ratio between the polyol and the metal hydroxide is 134.4:48. The polyol is a mixture of xylitol, erythritol, and glycerol formed according to a mass ratio of 30.4:48.8:55.2, and the metal hydroxide is sodium hydroxide.
[0020] Preferably, the mass ratio between the polyol and the metal hydroxide is 170.4:48. The polyol is a mixture of xylitol, erythritol, and sorbitol formed according to a mass ratio of 60.8:73.2:36.4, and the metal hydroxide is sodium hydroxide.
[0021] Preferably, the mass ratio between the polyol and the metal hydroxide is 122:40. The polyol is a mixture of glycerol, erythritol, xylitol, and sorbitol formed according to a mass ratio of 36.8:36.6:30.4:18.2, and the metal hydroxide is sodium hydroxide.
[0022] A method for synthesizing monoglyceride uses the above amphiphilic metal base composite catalyst as a catalyst. The specific method is to add glycerol and fatty acid ester into a reactor, heat until the oil and fat are completely melted, then add the amphiphilic metal base composite catalyst and mix evenly. Under the protection of nitrogen or inert gas, heat to the reaction temperature, and stir the reaction at a constant temperature to obtain monoglyceride. The reaction temperature is 100 - 240 °C. The fatty acid ester can be hydrogenated palm oil, soybean oil, animal oil, or sesame oil.
[0023] The present invention has the following beneficial effects:
[0024] (1) The amphiphilic metal base composite catalyst provided by the present invention has amphiphilicity and has good compatibility with both oil and fat and glycerol, so that the reaction rate can be accelerated, the reaction time can be reduced, and the reaction temperature can be lowered;
[0025] (2) The amphiphilic metal base composite catalyst obtained by the present invention basically does not react with glycerol. After the reaction is completed and the mixture is allowed to stand and separate into layers, more of the catalyst enters the lower glycerol layer, which is more conducive to the recycling of the catalyst;
[0026] (3) The method for obtaining the amphiphilic metal base composite catalyst of the present invention is simple. In the synthesis reaction of monoglyceride catalyzed by this catalyst, the content of monoglyceride in the obtained product can reach more than 56%, the yield can reach more than 50%, and the conversion rate of oil and fat can reach more than 96%. Specific Embodiments
[0027] The present invention will be described in detail below with reference to embodiments. It should be understood that the following embodiments are only illustrative examples of the embodiments of the present invention, rather than limiting the scope of the present invention.
[0028] The hydrogenated palm oil in the following embodiments of the present invention has a CAS number of 68514-74-9.
[0029] The CAS number of erythritol in the following embodiments of the present invention is 149-32-6.
[0030] The CAS number of xylitol in the following embodiments of the present invention is 87-99-0.
[0031] The CAS number of sorbitol in the following embodiments of the present invention is 50-70-4.
[0032] The CAS number of maltitol in the following comparative examples of the present invention is 585-88-6.
[0033] The CAS number of lactitol in the following comparative examples of the present invention is 585-86-4.
[0034] The CAS number of isomaltitol in the following comparative examples of the present invention is 64519-82-0.
[0035] Example 1
[0036] Weigh 46 g of glycerol and 30.5 g of erythritol and add them to a four-necked flask. Stir and mix evenly at 100 °C. Then add 30 g of sodium hydroxide, and while stirring, heat up to 145 °C. Keep stirring at a constant temperature for 2 h. After that, the reaction product is dehydrated under vacuum for 2 h, washed three times with ethanol and filtered by suction. The obtained solid product is dried under vacuum at 80 °C to obtain an amphiphilic metal base composite catalyst, and the stirring speed is 200 rpm.
[0037] Weigh 60 g of hydrogenated palm oil and 25 g of glycerol and add them to a four-necked flask. Under nitrogen protection, heat up to 70 °C until the hydrogenated palm oil is completely melted. Then add 0.1275 g (0.15 wt%) of the amphiphilic metal base composite catalyst, continue to heat up to 175 °C, and keep stirring and reacting at a constant temperature for 30 min. After the reaction is completed, let it stand for stratification to obtain the upper product containing monoglyceride and the lower glycerol layer containing the base catalyst. Analyze the upper product by high performance liquid chromatography. The monoglyceride content is 56.81%, and the yield of monoglyceride is calculated to be 52.78%, and the conversion rate of the oil and fat is 96.27%.
[0038] Example 2
[0039] Weigh 31.25 g of xylitol and 61 g of erythritol and add them to a four-necked flask. Stir and mix evenly at 100 °C. Then add 30 g of potassium hydroxide, stir and heat up to 145 °C, and keep stirring at a constant temperature for 2 h. After that, the reaction product is dehydrated under vacuum for 2 h, washed three times with ethanol and filtered by suction. The obtained solid product is dried under vacuum at 80 °C to obtain an amphiphilic metal base composite catalyst, and the stirring speed is 200 rpm.
[0040] Weigh 60 g of hydrogenated palm oil and 25 g of glycerol into a four-necked flask, heat it to complete melting of the oil and fat under nitrogen protection at 70 °C, then add 0.1275 g (0.15 wt%) of the amphiphilic metal base composite catalyst, continue to heat up to 175 °C, and stir the reaction at a constant temperature for 30 min. After the reaction is completed, let it stand for stratification to obtain the upper product containing monoglyceride and the lower glycerol layer containing the base catalyst. Analyze the upper product by high performance liquid chromatography. The monoglyceride content is 57.11%, and the yield of monoglyceride is calculated to be 53.25%, and the conversion rate of the oil and fat is 96.45%.
[0041] Example 3
[0042] Weigh 76 g of xylitol and 45.5 g of sorbitol and add them to a four-necked flask, stir and mix evenly at 100 °C, then add 30 g of calcium hydroxide, and then heat up to 145 °C, stir the reaction at a constant temperature for 2 h. After that, the reaction product is dehydrated under vacuum for 2 h, washed three times with ethanol and filtered by suction. The obtained solid product is then dried under vacuum at 80 °C to obtain the amphiphilic metal base composite catalyst.
[0043] Weigh 60 g of hydrogenated palm oil and 25 g of glycerol into a four-necked flask, heat it to complete melting of the oil and fat under nitrogen protection at 70 °C, then add 0.1275 g (0.15 wt%) of the amphiphilic metal base composite catalyst, continue to heat up to 175 °C, and stir the reaction at a constant temperature for 30 min. After the reaction is completed, let it stand for stratification to obtain the upper product containing monoglyceride and the lower glycerol layer containing the base catalyst. Analyze the upper product by high performance liquid chromatography. The monoglyceride content is 58.45%, and the yield of monoglyceride is calculated to be 54.31%, and the conversion rate of the oil and fat is 96.98%.
[0044] Example 4
[0045] Weigh 30.4 g of xylitol, 48.8 g of erythritol and 55.2 g of glycerol and add them to a four-necked flask, stir and mix evenly at 100 °C, add 48 g of zinc hydroxide, heat up to 145 °C, stir at a constant temperature for 2 h, and then the reaction product is dehydrated under vacuum for 2 h, washed three times with ethanol and filtered by suction. The obtained solid product is then dried under vacuum at 80 °C to obtain the amphiphilic metal base composite catalyst.
[0046] Weigh 60 g of hydrogenated palm oil and 25 g of glycerol and add them to a four-necked flask. Under nitrogen protection, heat to 70 °C until the oil is completely melted. Add 0.1275 g (0.15 wt%) of the amphiphilic metal base composite catalyst. Then continue to heat up to 175 °C and stir at a constant temperature for 30 min. After the reaction is completed, let it stand for stratification to obtain the upper product containing monoglyceride and the lower glycerol layer containing the base catalyst. Analyze the upper product by high-performance liquid chromatography. The monoglyceride content is 60.32%, and the yield of monoglyceride is calculated to be 58.41%, and the conversion rate of the oil is 97.58%.
[0047] Example 5
[0048] Weigh 60.8 g of xylitol, 73.2 g of erythritol and 36.4 g of sorbitol and add them to a four-necked flask. Stir and mix evenly at 100 °C. Then add 48 g of sodium hydroxide, and then heat up to 145 °C. Stir and react at a constant temperature for 2 h. Then, after vacuum dehydration for 2 h, washing with ethanol three times and filtering, the obtained solid product is further dried in vacuo at 80 °C to obtain the amphiphilic metal base composite catalyst.
[0049] Weigh 60 g of hydrogenated palm oil and 25 g of glycerol and add them to a four-necked flask. Under nitrogen protection, heat to 70 °C until the oil is completely melted. Then add 0.1275 g (0.15 wt%) of the amphiphilic metal base composite catalyst. Continue to heat up to 175 °C and stir at a constant temperature for 30 min. After the reaction is completed, let it stand for stratification to obtain the upper product containing monoglyceride and the lower glycerol layer containing the base catalyst. Analyze the upper product by high-performance liquid chromatography. The monoglyceride content is 61.86%, and the yield of monoglyceride is calculated to be 59.44%, and the conversion rate of the oil is 97.98%.
[0050] Example 6
[0051] Weigh 36.8 g of glycerol, 36.6 g of erythritol, 30.4 g of xylitol and 18.2 g of sorbitol and add them to a four-necked flask. Stir and mix evenly at 100 °C. Add 40 g of sodium hydroxide, stir and heat up to 145 °C. Stir and react at a constant temperature for 2 h. Then, after vacuum dehydration for 2 h, washing with ethanol three times and filtering, the obtained solid product is further dried in vacuo at 80 °C to obtain the amphiphilic metal base composite catalyst.
[0052] Weigh 60 g of hydrogenated palm oil and 25 g of glycerol into a four-necked flask. Under nitrogen protection and at 70 °C, heat until the oil is completely melted. Then add 0.1275 g (0.15 wt%) of the amphiphilic metal base composite catalyst, continue to heat up to 175 °C, and stir at a constant temperature for 30 min. After the reaction is completed, let it stand for stratification to obtain the upper product containing monoglyceride and the lower glycerol layer containing the base catalyst. Then analyze the upper product by high performance liquid chromatography. The monoglyceride content is 65.81%, and the yield of monoglyceride is calculated to be 62.85%, and the conversion rate of the oil is 98.52%.
[0053] Comparative Example 1
[0054] Weigh 36.8 g of maltitol, 36.6 g of erythritol, 30.4 g of xylitol and 18.2 g of sorbitol and add them into a four-necked flask. Stir and mix evenly at 100 °C, add 40 g of sodium hydroxide, stir and heat up to 145 °C, and stir at a constant temperature for 2 h. Then, after vacuum dehydration for 2 h, washing with ethanol three times and filtering, the obtained solid product is further dried in vacuo at 80 °C to obtain the amphiphilic metal base composite catalyst.
[0055] Weigh 60 g of hydrogenated palm oil and 25 g of glycerol into a four-necked flask. Under nitrogen protection and at 70 °C, heat until the oil is completely melted. Then add 0.1275 g (0.15 wt%) of the amphiphilic metal base composite catalyst, continue to heat up to 175 °C, and stir at a constant temperature for 30 min. After the reaction is completed, let it stand for stratification to obtain the upper product containing monoglyceride and the lower glycerol layer containing the base catalyst. Then analyze the upper product by high performance liquid chromatography. The monoglyceride content is 30.54%, and the yield of monoglyceride is calculated to be 27.31%, and the conversion rate of the oil is 60.75%.
[0056] Comparative Example 2
[0057] Weigh 36.8 g of glycerol, 36.6 g of erythritol, 30.4 g of lactitol and 18.2 g of sorbitol and add them into a four-necked flask. Stir and mix evenly at 100 °C, add 40 g of sodium hydroxide, stir and heat up to 145 °C, and stir at a constant temperature for 2 h. Then, after vacuum dehydration for 2 h, washing with ethanol three times and filtering, the obtained solid product is further dried in vacuo at 80 °C to obtain the amphiphilic metal base composite catalyst.
[0058] Weigh 60 g of hydrogenated palm oil and 25 g of glycerol into a four-necked flask. Under nitrogen protection, heat it to 70 °C until the oil is completely melted. Then add 0.1275 g (0.15 wt%) of the amphiphilic metal base composite catalyst, continue to heat up to 175 °C, and stir at a constant temperature for 30 min. After the reaction is completed, let it stand for stratification to obtain the upper product containing monoglyceride and the lower glycerol layer containing the base catalyst. Then, analyze the upper product by high-performance liquid chromatography. The monoglyceride content is 32.42%, and the yield of monoglyceride is calculated to be 29.33%, and the conversion rate of the oil is 72.54%.
[0059] Comparative Example 3
[0060] Weigh 36.8 g of glycerol, 36.6 g of erythritol, 30.4 g of xylitol, and 18.2 g of isomaltulose into a four-necked flask, stir and mix evenly at 100 °C, add 40 g of sodium hydroxide, stir and heat up to 145 °C, and stir at a constant temperature for 2 h. Then, after vacuum dehydration for 2 h, washing three times with ethanol and filtering, the obtained solid product is further dried in vacuo at 80 °C to obtain the amphiphilic metal base composite catalyst.
[0061] Weigh 60 g of hydrogenated palm oil and 25 g of glycerol into a four-necked flask. Under nitrogen protection, heat it to 70 °C until the oil is completely melted. Then add 0.1275 g (0.15 wt%) of the amphiphilic metal base composite catalyst, continue to heat up to 175 °C, and stir at a constant temperature for 30 min. After the reaction is completed, let it stand for stratification to obtain the upper product containing monoglyceride and the lower glycerol layer containing the base catalyst. Then, analyze the upper product by high-performance liquid chromatography. The monoglyceride content is 25.74%, and the yield of monoglyceride is calculated to be 21.68%, and the conversion rate of the oil is 50.63%.
[0062] Comparative Example 4
[0063] Weigh 122 g of erythritol into a four-necked flask, stir and mix evenly at 100 °C, add 40 g of sodium hydroxide, stir and heat up to 145 °C, and stir at a constant temperature for 2 h. Then, after vacuum dehydration for 2 h, washing three times with ethanol and filtering, the obtained solid product is further dried in vacuo at 80 °C to obtain the amphiphilic metal base composite catalyst.
[0064] Weigh 60 g of hydrogenated palm oil and 25 g of glycerol into a four-necked flask. Under nitrogen protection, heat it to 70 °C until the oil is completely melted. Then add 0.1275 g (0.15 wt%) of the amphiphilic metal base composite catalyst, continue to heat up to 175 °C, and stir at a constant temperature for 30 min. After the reaction, let it stand for stratification to obtain the upper product containing monoglyceride and the lower glycerol layer containing the base catalyst. Then analyze the upper product by high-performance liquid chromatography. The monoglyceride content is 10.11%, and the yield of monoglyceride is calculated to be 8.51%, and the conversion rate of the oil is 25.77%.
[0065] Comparative Example 5
[0066] Weigh 122 g of xylitol into a four-necked flask, stir and mix evenly at 100 °C, add 40 g of sodium hydroxide, stir and heat up to 145 °C, and stir at a constant temperature for 2 h. Then, after vacuum dehydration for 2 h, washing with ethanol three times and filtering, the obtained solid product is further dried under vacuum at 80 °C to obtain the amphiphilic metal base composite catalyst.
[0067] Weigh 60 g of hydrogenated palm oil and 25 g of glycerol into a four-necked flask. Under nitrogen protection, heat it to 70 °C until the oil is completely melted. Then add 0.1275 g (0.15 wt%) of the amphiphilic metal base composite catalyst, continue to heat up to 175 °C, and stir at a constant temperature for 30 min. After the reaction, let it stand for stratification to obtain the upper product containing monoglyceride and the lower glycerol layer containing the base catalyst. Then analyze the upper product by high-performance liquid chromatography. The monoglyceride content is 11.52%, and the yield of monoglyceride is calculated to be 9.75%, and the conversion rate of the oil is 28.98%.
[0068] Comparative Example 6
[0069] Weigh 122 g of sorbitol into a four-necked flask, stir and mix evenly at 100 °C, add 40 g of sodium hydroxide, stir and heat up to 145 °C, and stir at a constant temperature for 2 h. Then, after vacuum dehydration for 2 h, washing with ethanol three times and filtering, the obtained solid product is further dried under vacuum at 80 °C to obtain the amphiphilic metal base composite catalyst.
[0070] Weigh 60 g of hydrogenated palm oil and 25 g of glycerol into a four-necked flask. Under nitrogen protection, heat it to 70 °C until the oil is completely melted. Then add 0.1275 g (0.15 wt%) of the amphiphilic metal base composite catalyst, continue to heat up to 175 °C, and stir at a constant temperature for 30 min. After the reaction, let it stand for stratification to obtain the upper product containing monoglyceride and the lower glycerol layer containing the base catalyst. Then analyze the upper product by high-performance liquid chromatography. The monoglyceride content is 15.56%, and the yield of monoglyceride is calculated to be 13.21%, and the conversion rate of the oil is 30.85%.
[0071] Comparative Example 7
[0072] Weigh 60 g of hydrogenated palm oil and 25 g of glycerol into a four-necked flask. Heat it to complete melting of the oil and fat under nitrogen protection at 70 °C, then add 0.1275 g (0.15 wt%) of sodium hydroxide, continue to heat up to 175 °C, and stir and react at a constant temperature for 30 min. After the reaction, let it stand for stratification to obtain the upper product containing monoglyceride and the lower glycerol layer containing the base catalyst. Then, analyze the upper product by high-performance liquid chromatography. The monoglyceride content is 36.38%, and the yield of monoglyceride is calculated to be 34.87%, and the conversion rate of the oil and fat is 75.92%.
[0073] Performance Comparison
[0074] Synthesize monoglyceride using the catalysts obtained in Example 6 and Comparative Examples 1-7 of the present invention respectively. The test comparison results of the monoglyceride content, the yield of monoglyceride, and the conversion rate of the oil and fat in the upper product are shown in Table 1 and the continued Table 1 as follows:
[0075] Table 1
[0076] Test items Content of monoglyceride (%) Yield of monoglyceride (%) Conversion rate of oil and fat (%) Example 1 56.81 52.78 96.27 Example 2 57.11 53.25 96.45 Example 3 58.45 54.31 96.98 Example 4 60.32 58.41 97.58 Example 5 61.86 59.44 97.98 Example 6 65.81 62.85 98.52 Comparative example 1 30.54 27.31 60.75 Comparative example 2 32.42 29.33 72.54 Comparative example 3 25.74 21.68 50.63
[0077] Continued Table 1
[0078] Test items Content of monoglyceride (%) Yield of monoglyceride (%) Conversion rate of oil and fat (%) Comparative example 4 10.11 8.51 25.77 Comparative example 5 11.52 9.75 28.98 Comparative example 6 15.56 13.21 30.85 Comparative example 7 36.38 34.87 75.92
[0079] Inspired by the ideal embodiments of the present invention described above, through the above description, relevant staff can make various changes and modifications completely within the scope of not deviating from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.
Claims
1. A method for preparing an amphiphilic metal base composite catalyst for the synthesis of monoglycerides, characterized in that: The preparation method comprises the following steps: The polyol is mixed uniformly at 80-115° C., and then a metal hydroxide is added and stirred uniformly at 120-150° C. The obtained product is then vacuum dehydrated, washed with ethanol and filtered, and the obtained solid product is vacuum dried to obtain an amphiphilic metal base composite catalyst; The polyol includes a combination of two or more of glycerol, erythritol, xylitol or sorbitol; The metal hydroxide includes one or a combination of two or more of sodium hydroxide, potassium hydroxide, calcium hydroxide and zinc hydroxide; The mass ratio between the polyol and the metal hydroxide is 76.5-170.4:30-48.
2. The method for preparing an amphiphilic metal base composite catalyst for monoglyceride synthesis according to claim 1, characterized in that: The mass ratio of the polyol to the metal hydroxide is 76.5:30, the polyol is a mixture of glycerol and erythritol in a mass ratio of 46:30.5, and the metal hydroxide is sodium hydroxide.
3. The method for preparing an amphiphilic metal base composite catalyst for monoglyceride synthesis according to claim 1, characterized in that: The mass ratio of the polyol to the metal hydroxide is 92.25:30, the polyol is a mixture of xylitol and erythritol in a mass ratio of 31.25:61, and the metal hydroxide is sodium hydroxide.
4. The method for preparing an amphiphilic metal base composite catalyst for monoglyceride synthesis according to claim 1, characterized in that: The mass ratio of the polyol to the metal hydroxide is 121.5:30, the polyol is a mixture of xylitol and sorbitol in a mass ratio of 76:45.5, and the metal hydroxide is sodium hydroxide.
5. The method for preparing an amphiphilic metal base composite catalyst for monoglyceride synthesis according to claim 1, characterized in that: The mass ratio of the polyol to the metal hydroxide is 134.4:48, the polyol is a mixture of xylitol, erythritol and glycerol in a mass ratio of 30.4:48.8:55.2, and the metal hydroxide is sodium hydroxide.
6. The method for preparing an amphiphilic metal base composite catalyst for monoglyceride synthesis according to claim 1, characterized in that: The mass ratio of the polyol to the metal hydroxide is 170.4:48, the polyol is a mixture of xylitol, erythritol and sorbitol in a mass ratio of 60.8:73.2:36.4, and the metal hydroxide is sodium hydroxide.
7. The method for preparing an amphiphilic metal base composite catalyst for monoglyceride synthesis according to claim 1, characterized in that: The mass ratio of the polyol to the metal hydroxide is 122:40, the polyol is a mixture of glycerol, erythritol, xylitol and sorbitol in a mass ratio of 36.8:36.6:30.4:18.2, and the metal hydroxide is sodium hydroxide.
8. A method for synthesizing monoglyceride, characterized in that: The amphiphilic metal base composite catalyst according to any one of claims 1 to 7 is used as a catalyst.
9. The method for synthesizing monoglyceride according to claim 8, characterized in that: Add glycerol and fatty acid ester into the reactor, heat until the oil is completely melted, then add the amphiphilic metal base composite catalyst and mix evenly, heat to the reaction temperature under the protection of nitrogen or inert gas, and stir the reaction at a constant temperature to obtain monoglyceride.
10. The method for synthesizing monoglyceride according to claim 8, characterized in that: The reaction temperature is 100-240°C.