Poly-polyamine modified chlorine ball loaded ionic liquid heteropolyacid catalyst as well as preparation and application thereof

Abstract

The invention discloses a polyamine modified chlorine ball loaded ionic liquid heteropolyacid catalyst and preparation and application thereof.The polyamine modified chlorine ball loaded ionic liquid heteropolyacid catalyst is prepared by mixing chlorine balls, potassium carbonate and polyamine substances in an organic solvent under the synergistic effect of microwaves and ultrasonic waves for reaction, then conducting sulfonation reaction on an obtained polyamine modified chlorine ball carrier and 1, 3-propane sultone, and after the reaction is finished, obtaining the polyamine modified chlorine ball loaded ionic liquid heteropolyacid catalyst. Filtering, washing and drying to obtain sulfonated polyamine modified chlorine balls; and reacting the sulfonated polyamine modified chlorine balls with heteropoly acid, and then concentrating, washing and drying to obtain the polyamine modified chlorine ball loaded ionic liquid heteropoly acid. The catalyst is used for synthesizing higher fatty acid, cooling is performed after the reaction is finished, the catalyst and a reaction system are layered, the solid catalyst is recycled through filtration, and the catalyst is directly reused for the next reaction after being washed and dried. The problems that a traditional heteropolyacid catalyst is easy to dissolve in a polar solvent, active ingredients are easy to lose, the preparation time of the catalyst is long and the like are solved.

Description

Technical Field

[0001] This application relates to the technical field of ester preparation, and more particularly to a polyamine-modified chloride-supported ionic liquid heteropolyacid catalyst, its preparation method, and its application in the esterification reaction of lauric acid and glycerol. Background Technology

[0002] Glycerol monolaurate (GML) is a widely used multifunctional chemical, employed as a natural food preservative, surfactant emulsifier, and emollient in cosmetics. Extraction of GML from natural plants is limited by technological constraints and high costs; currently, GML is primarily derived through chemical synthesis, often using the direct catalytic esterification of lauric acid and glycerol. Traditional catalytic preparation processes suffer from low selectivity and severe environmental pollution. Therefore, in today's society, which advocates sustainable development, research into green and efficient catalysts for GML preparation has significant economic value.

[0003] Heteropolyacids exhibit good catalytic performance in esterification reactions, but their inherent properties, such as high solubility and difficulty in separation, limit their application. To address this issue, heteropolyacid catalysts are often modified. Common modification methods include modification with metal ions or organic compounds, or modification through immobilization. The aim is to obtain better catalytic activity and stability while facilitating catalyst separation from the reaction system, simplifying the operation process, and broadening the application range of heteropolyacids.

[0004] In recent years, ionic liquids have been widely used in extraction, catalysis, and other fields due to their unique designable properties. However, their high viscosity and high cost limit their application. Ionic liquid heteropolyacids obtained by modifying heteropolyacids with designable ionic liquids exhibit good catalytic performance due to their inherent "self-separation" properties, while simultaneously solving the problems of high viscosity and high cost of ionic liquids. Although modifying heteropolyacids in the form of heteropolyacid salts achieves good catalytic performance, the resulting heteropolyacid particles are very fine, making separation difficult. Furthermore, the amount of heteropolyacid used is relatively large. To facilitate separation and reduce preparation costs, immobilization is a common method for modifying heteropolyacids.

[0005] The selection of the support is one of the key research focuses of supported catalysts. Different supports can directly affect the degree of immobilization of heteropolyacids on the support surface, thereby affecting the catalytic activity of the catalyst. For example, patent document CN202210060636.X discloses a heteropolyacid catalyst modified with amines supported on chlorinated spheres, its preparation and application, which improves the catalytic activity and stability of the catalyst to a certain extent. However, in practical applications, it has been found that its catalytic activity and stability still need to be further improved. Summary of the Invention

[0006] This application provides an ultrasonic-microwave preparation method for polyamine-modified chloride sphere-supported ionic liquid heteropolyacid catalysts and its application. While maintaining the high catalytic activity of ionic liquid heteropolyacids, the method solves the problems of traditional heteropolyacid catalysts such as easy solubility in polar solvents, easy loss of active components, low catalytic activity, and long catalyst preparation time through chemical bonds, the larger particle size of chloride spheres, and the synergistic effect of multiple nitrogen atoms.

[0007] A method for preparing polypolyamine-modified chloride-based supported ionic liquid heteropolyacids, characterized by comprising: (1) Polyamines, potassium carbonate, and chlorine spheres are mixed in an organic solvent and the carrier is synthesized under the synergistic effect of microwave and ultrasound. After the reaction is completed, the carrier is obtained by filtration, washing and drying. The polyamines are polyethyleneimine with a molecular weight of 1800. (2) The polyamine-modified chlorinated sphere carrier and 1,3-propanesulfonate lactone were added to toluene and sulfonated under the synergistic effect of microwave and ultrasonic waves. After the reaction was completed, the sulfonated polyamine-modified chlorinated spheres were obtained by filtration, washing and drying. (3) The obtained sulfonated polyamine modified chlorine spheres are reacted with heteropolyacids, and then concentrated, washed and dried in sequence to obtain the polyamine modified chlorine spheres loaded with ionic liquid heteropolyacids.

[0008] This application describes a reaction in which chlorine spheres, potassium carbonate, and polyamines are mixed in an organic solvent under the synergistic effect of microwave and ultrasound. The resulting polyamine-modified chlorine sphere carrier is then sulfonated with 1,3-propanesulfonate lactone. After the reaction, the sulfonated polyamine-modified chlorine spheres are obtained by filtration, washing, and drying. The obtained sulfonated polyamine-modified chlorine spheres are then reacted with a heteropolyacid, and after concentration, washing, and drying, a polyamine-modified chlorine sphere-loaded ionic liquid heteropolyacid is obtained.

[0009] Compared to the catalyst disclosed in patent document CN202210060636.X, the catalyst prepared in this application has a significantly improved yield of the target product. Furthermore, the catalyst prepared in this application is linked to silicotungstic acid via -SO3H groups, further enhancing the binding strength of the active components and exhibiting better reusability (see...). Figure 2 Meanwhile, the presence of sulfonic acid groups improves the acidity of the catalyst, thereby increasing the reaction rate; the multiple N atoms provided by the polyamine in the catalyst also promote the selectivity of the reaction, thus increasing the yield of the target product.

[0010] The preparation route of this catalyst is shown below:

[0011]

[0012]

[0013]

[0014] Indicates chlorine ball Several alternative methods are provided below, but they are not intended as additional limitations on the overall solution above. They are merely further additions or optimizations. Provided there are no technical or logical contradictions, each alternative method can be combined individually with respect to the overall solution above, or multiple alternative methods can be combined with each other.

[0015] In step (1): Optionally, the chlorine balls are commercially available products.

[0016] Optionally, the organic solvent is ethyl acetate or acetonitrile.

[0017] Optionally, the mixing ratio of the polyamine substance to the chlorine ball is calculated as 1-6 mmol:1g; the amount of potassium carbonate used is 5-10% of the mass of the chlorine ball.

[0018] More preferably, the mixing ratio of the polyamine substance to the chlorine ball is calculated as a mass ratio of 3 mmol:1g between the amount of the polyamine substance and the mass of the chlorine ball.

[0019] In this step, potassium carbonate acts as a catalyst for the reaction between the polyamine and the chloride spheres, promoting the formation of carbanions and thus facilitating the nucleophilic substitution reaction between the chloride spheres and the polyamines. Optionally, the amount of potassium carbonate used is 5-10% of the mass of the chloride spheres; further, it is 8% of the mass of the chloride spheres.

[0020] Optionally, the washing process is as follows: washing with ethyl acetate, water and methanol in sequence.

[0021] Optionally, the drying conditions are: vacuum drying at 75°C.

[0022] In step (2): Optionally, the mixing ratio of the polyamine-modified chloroform to 1,3-propanesulfonic acid lactone is calculated as 1-6 mmol:1g based on the molar amount of 1,3-propanesulfonic acid lactone to the mass ratio of the polyamine-modified chloroform; the solvent used is toluene.

[0023] Further preferably, the mixing ratio of the polyamine-modified chloroform to 1,3-propanesulfonic acid lactone is calculated as 4 mmol:1 g, where the amount of 1,3-propanesulfonic acid lactone is equal to the mass ratio of the polyamine-modified chloroform.

[0024] In step (3): Optionally, the ratio of the heteropolyacid to the sulfonated polyamine-modified chlorine beads is calculated as 1-5 mmol:1g.

[0025] Further preferably, the mixing ratio of the polyamine-modified chloroform to 1,3-propanesulfonic acid lactone is calculated as 2 mmol:1 g, where the amount of 1,3-propanesulfonic acid lactone is equal to the mass ratio of the polyamine-modified chloroform.

[0026] Optionally, the heteropoly acid is silicotungstic acid.

[0027] Regarding the control of conditions during catalyst preparation: Optionally, the reactions in steps (1) and (2) are both carried out in a microwave-ultrasound synthesizer.

[0028] Optionally, in step (1), the reaction temperature is 60-90℃, the ultrasonic power is 200-500W, the microwave power is 200-500W, and the reaction time is 2-4h. Further, in step (1), the microwave power is 300W and the ultrasonic power is 300-400W.

[0029] Optionally, in step (2), the reaction temperature is 70-110℃, the ultrasonic power is 200-500W, the microwave power is 100-400W, and the reaction time is 1-3 h; further, in step (2), the ultrasonic power is 300W and the microwave power is 200W-300W.

[0030] In step (3), the heteropolyacid modification reaction temperature is 70-100℃ and the reaction time is 6-18 h.

[0031] Preferably, in step (1), the reaction temperature is 80℃, the ultrasonic power is 300W, the microwave power is 300W, and the reaction time is 3h; in step (2), the reaction temperature is 90℃, the ultrasonic power is 300W, the microwave power is 200W, and the reaction time is 1h; in step (3), the heteropolyacid modification reaction temperature is 90℃, and the reaction time is 12h.

[0032] This application also provides a polyamine-modified chloride sphere supported ionic liquid heteropolyacid catalyst prepared by the method described above.

[0033] Specifically, the polyamine-modified chloride-supported ionic liquid silicotungstic acid (CP-PEI-SO3-SiW) catalyst has the structural formula shown in formula (1): (1).

[0034] Among them, m = 1~4, with the optimal value being m = 2.

[0035] This application also provides the use of the polypolyamine-modified chloride-supported ionic liquid heteropolyacid catalyst in the preparation of higher fatty acids.

[0036] This application also provides a method for preparing higher fatty acid esters, comprising: Using alcohols and carboxylic acids as raw materials, polyamine-modified chloride-supported ionic liquid heteropolyacids as catalysts, the reaction was carried out in an oil bath at 130-170℃ for 0.5-3 h; after the reaction, the catalyst was recovered and used for the next reaction. The preparation of the polyamine-modified chloride-supported ionic liquid heteropolyacid includes: (1) Polyamines, potassium carbonate, and chlorine spheres are mixed in an organic solvent and the carrier is synthesized under the synergistic effect of microwave and ultrasound. After the reaction is completed, the carrier is obtained by filtration, washing and drying. The polyamines are polyethyleneimine with a molecular weight of 1800. (2) The polyamine-modified chlorinated sphere carrier and 1,3-propanesulfonate lactone were added to toluene and sulfonated under the synergistic effect of microwave and ultrasonic waves. After the reaction was completed, the sulfonated polyamine-modified chlorinated spheres were obtained by filtration, washing and drying. (3) The obtained sulfonated polyamine modified chlorine spheres are reacted with heteropolyacids, and then concentrated, washed and dried in sequence to obtain the polyamine modified chlorine spheres loaded with ionic liquid heteropolyacids.

[0037] Optionally, the mass ratio of the carboxylic acid to the alcohol is 1:3-7.

[0038] Optionally, the amount of catalyst used is 1% to 6% of the mass of carboxylic acid.

[0039] Optionally, the carboxylic acid is one of C8-C20 unsaturated or saturated fatty acids.

[0040] Optionally, the alcohol is one of methanol, ethanol, ethylene glycol, or glycerol.

[0041] Optionally, the reaction temperature is 130-170℃; the reaction time is 1.0-3h.

[0042] The application of heteropolyacid catalysts is limited by their easy solubility in polar solvents and difficulty in separation. However, when using polyamine-modified chlorinated spheres to support ionic liquid silicotungstic acid as a catalyst, the effective dispersion of the active components on the support surface greatly increases the number of reactive sites, allowing the high catalytic activity of ionic liquid silicotungstic acid to be retained. This reduces the amount of ionic liquid heteropolyacid used, and the catalyst can be separated by simple filtration after the reaction, making the catalyst reusable. The steric hindrance effect and high nitrogen promoting effect of the chlorinated spheres improve the selectivity of the reaction between lauric acid and glycerol, promoting the formation of lauric acid monoglyceride. The catalyst preparation process is simple, and the introduction of ultrasonic-microwave technology greatly shortens the preparation time, reducing energy consumption and cost. Therefore, the research on the preparation and catalytic performance of polyamine-modified chlorinated sphere-supported heteropolyacids using ultrasonic-microwave assisted methods has promising application prospects.

[0043] Compared with the prior art, this application has at least one of the following beneficial effects: (1) This application uses polyamines, chlorinated spheres and heteropolyacids as raw materials to prepare polyamine-modified chlorinated sphere supported ionic liquid heteropolyacid catalysts. It retains the high catalytic activity of ionic liquid heteropolyacids, solves the problems of traditional heteropolyacid catalysts being easily soluble in polar solvents, easy loss of active components and long catalyst preparation time, reduces the amount of catalyst used, and is simple to prepare, with short preparation time and low cost. (2) This application solves the problem of difficult separation of traditional heteropolyacid catalysts (due to their fine particle size). When polyamine-modified chloride sphere supported ionic liquid heteropolyacid catalyst is used as the catalyst, the chloride sphere particles are relatively large, and separation can be achieved simply by filtration. The separation and purification are simple and can be reused. (3) The polyamine-modified chlorinated sphere supported ionic liquid heteropolyacid catalyst provided in this application has a steric hindrance effect, which not only improves the reaction activity, but also greatly improves the selectivity of the reaction between lauric acid and glycerol due to the presence of high N, thereby increasing the yield of lauric acid monoglyceride.

[0044] (4) This application solves the problems of complicated post-treatment of commonly used catalysts, environmental pollution and equipment corrosion. Attached Figure Description

[0045] Figure 1 The infrared spectrum of the polyamine-modified chloride sphere-supported ionic liquid silicotungstic acid catalyst (CP-PEI-SO3-SiW) in Example 1 is shown.

[0046] Figure 2 The graph shows the reusability results of the polyamine-modified chloride-supported ionic liquid silicotungstic acid (CP-PEI-SO3-SiW) catalyst in Example 8. Detailed Implementation

[0047] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0049] This application employs an ultrasonic-microwave-assisted solvothermal method to prepare the catalyst. The catalyst preparation process boasts advantages such as high efficiency, speed, environmental friendliness, controllability, and low cost. The catalyst is easily separated and purified, showing significant application potential. The specific steps include: (1) Using chlorinated spheres, polyamines, and potassium carbonate as raw materials, and ethyl acetate or acetonitrile as solvent, the reaction was carried out in a microwave-ultrasonic synthesizer to synthesize the carrier. After the reaction was completed, the carrier was filtered, washed with methanol, and dried under vacuum to obtain polyamine-modified chlorinated sphere carrier. In this step, the ultrasonic reaction temperature was 60-90℃, the ultrasonic power was 200-500W, the microwave power was 200-500W, and the reaction time was 2-4h.

[0050] (2) Polyamine-modified chlorosphere carrier and 1,3-propanesulfonate lactone were added to toluene, and sulfonation was carried out under the synergistic effect of microwave and ultrasound. After the reaction was completed, the mixture was filtered, washed with acetone, and vacuum dried to obtain sulfonated polyamine-modified chlorospheres. In this step, the ultrasonic reaction temperature was 70-110℃, the ultrasonic power was 200-500W, the microwave power was 100-400W, and the reaction time was 1-3 h.

[0051] (3) The obtained sulfonated polyamine-modified chlorine spheres are reacted with heteropolyacids, and then concentrated, washed and dried to obtain polyamine-modified chlorine spheres loaded with ionic liquid heteropolyacids. The heteropolyacid modification reaction temperature in this step is 70-100℃, and the reaction time is 6-18 h.

[0052] Based on the prepared catalyst, a method for preparing lauric acid monoglyceride using a polyamine-modified chloride-supported ionic liquid heteropolyacid catalyst is proposed, comprising the following steps: (1) Using the prepared polyamine-modified chloride sphere supported ionic liquid heteropolyacid as a catalyst, and using carboxylic acid (e.g., lauric acid) and alcohol (e.g., glycerol) as raw materials, the reaction is carried out in an oil bath; (2) After the reaction is completed, the catalyst is cooled and separated by simple filtration. The catalyst can be directly used in the next reaction after being washed with ethyl acetate and dried. (3) The reaction products were quantitatively analyzed using an Agilent 7890B gas chromatograph (FID detector, HP-5 capillary column), with methyl laurate as an internal standard; then, monoglyceride laurate was obtained by atmospheric distillation.

[0053] The molar ratio of lauric acid to glycerol is 1:3-7; the reaction temperature is 130-170℃; the reaction time is 0.5-3h; and the amount of catalyst used is 1%-6% of the mass of lauric acid.

[0054] The following are specific examples of preparation and application: All raw materials used in the following examples are commercially available products.

[0055] Example 1 This embodiment uses polypolyamine-modified chloride-supported ionic liquid silicotungstic acid (CP-PEI-SO3-SiW) catalyst as an example. The catalyst preparation method is as follows: (1) Under the conditions of reaction temperature of 80℃, ultrasonic power of 300W and microwave power of 300W, chlorine balls (1g) and polyethyleneimine 1800 (PEI-1800) (5.4g) were used as raw materials, potassium carbonate (0.8g) was used as catalyst, and acetonitrile (30mL) was used as solvent. The mixture was placed in a microwave-ultrasonic synthesizer and reacted for 3 h. After the reaction was completed, the mixture was filtered, washed with methanol, and dried under vacuum at 75℃ to obtain polyethyleneimine modified chlorine ball carrier (CP-PEI). (2) Under the conditions of reaction temperature of 90℃, ultrasonic power of 300W, microwave power of 200W and reaction time of 1h, polyethyleneimine modified chlorine ball carrier (1g) and 1,3-propanesulfonic acid lactone (0.49g) were added to 20 mL of toluene and placed in a reaction vessel for sulfonation reaction in a microwave-ultrasonic synthesizer. After the reaction was completed, the mixture was filtered, washed with acetone, and dried under vacuum at 75℃ to obtain sulfonated polyethyleneimine modified chlorine balls (CP-PEI-SO3). (3) Under the conditions of a reaction temperature of 90℃ and a reaction time of 12h, the obtained sulfonated polyethyleneimine modified chlorine balls (1g) were reacted with silicotungstic acid (H4SiW) 12 O 40 The reaction was carried out with 2 mmol, and then the polyamine-modified chloride sphere-supported ionic liquid heteropolyacid was obtained after concentration, washing and drying.

[0056] The infrared spectrum of the obtained CP-PEI-SO3-SiW catalyst is shown in the figure. Figure 1 As shown in d, Figure 1 In the image, a is the infrared spectrum of silicotungstic acid, b is the infrared spectrum of chlorobenzene, and c is the infrared spectrum of sulfonated polyethyleneimine-modified chlorobenzene. Figure 1 The results show that silicotungstic acid was successfully immobilized on sulfonated polyethyleneimine-modified chlorinated spheres via covalent bonds, while maintaining the stable structure of silicotungstic acid.

[0057] Example 2 The preparation of higher fatty acids using the above catalyst includes the following steps: (1) Using the polyamine-modified chloride-supported ionic liquid heteropolyacid prepared in Example 1 as a catalyst, lauric acid and glycerol were reacted in an oil bath. Specifically, 10g of lauric acid, 18.4g of glycerol (acid-alcohol molar ratio 1:4) and 0.4g of catalyst (prepared in Example 1) were added sequentially to a 100mL three-necked flask equipped with a reflux condenser, and the flask was heated in an oil bath at 150℃ for 2h.

[0058] (2) After the reaction is completed, the catalyst is cooled and separated by simple filtration. The catalyst can be directly used in the next reaction after being washed with ethyl acetate and dried. (3) The reaction products were quantitatively analyzed using an Agilent 7890B gas chromatograph (FID detector, HP-5 capillary column), with methyl laurate as an internal standard; then, monoglyceride laurate was obtained by atmospheric distillation.

[0059] Example 3 To verify the effect of different ultrasonic and microwave powers on the catalytic effect of the prepared catalyst, this embodiment investigates the effect of ultrasonic and microwave power in step (1) of Example 1 on the catalytic effect of the prepared catalyst. The preparation process is the same as in Example 1, with other conditions fixed, only the ultrasonic and microwave power in step (1) is changed, and polyamine-modified chloride sphere supported ionic liquid silicotungstic acid under different ultrasonic and microwave powers is prepared.

[0060] The polyamine-modified chloride-supported ionic liquid silicotungstic acid obtained under different ultrasonic and microwave powers catalyzed the esterification reaction of lauric acid and glycerol under the experimental conditions of Example 2. The results are shown in Table 1.

[0061] Table 1. Results of the preparation of lauric acid monoglyceride catalyzed by catalysts prepared with different ultrasonic and microwave powers.

[0062] As shown in Table 1, the yields of ultrasonic power in the range of 300-400 W and microwave power in the range of 300-400 W are all above 80%. The catalysts treated with ultrasonic power of 300 W and microwave power of 300 W have the highest yield of the target product during the catalytic reaction. From the perspective of saving energy, the ultrasonic power of step (1) is determined to be 300 W and the microwave power is 300 W.

[0063] Example 4 To verify the catalytic effect of different microwave and ultrasonic powers on the preparation of sulfonated polyamine-modified chlorinated sphere supported catalysts, this example investigated the effect of microwave and ultrasonic powers in step (2) of Example 1 on the preparation of the catalysts. The preparation process was the same as in Example 1, with other conditions fixed, only the microwave and ultrasonic powers in step (2) were changed to obtain polyamine-modified chlorinated sphere supported ionic liquid silicotungstic acid under different microwave and ultrasonic powers. Then, this series of catalysts catalyzed the esterification reaction of lauric acid and glycerol under the experimental conditions of Example 2. The results are shown in Table 2.

[0064] Table 2 Results of the preparation of lauric acid monoglyceride catalyzed by different microwave and ultrasonic powers

[0065] As shown in Table 2, the yield of the catalyst prepared by microwave power of 200W-300W and ultrasonic power of 300W in the sulfonation modification step is above 80%. The catalyst treated with microwave power of 200W and ultrasonic power of 300W has the highest yield of target product in the catalytic reaction. From the perspective of saving energy, the microwave power of step (2) is determined to be 200W and the ultrasonic power is 300W.

[0066] Example 5 To verify the effect of reaction time on the catalytic effect of the catalyst, in this example, 10g of lauric acid, 18.4g of glycerol (acid-to-alcohol molar ratio 1:4), and 0.4g of catalyst (prepared in Example 1) were added sequentially to a 100mL three-necked flask, and the flask was heated in an oil bath at 150℃. The product was sampled every half hour, and the conversion and yield of the reaction product were analyzed by gas chromatography. The results of the lauric acid monoglyceride reaction with varying reaction time are shown in Table 3.

[0067] Table 3. Results of lauric acid monoglyceride reaction at different reaction times.

[0068] As shown in Table 3, when the catalytic reaction is carried out for more than 2 hours, the yield is above 80%. Considering the overall reaction efficiency and the yield of the target product, the optimal reaction time is determined to be 2 hours.

[0069] Example 6 Referring to the catalytic reaction process of Example 2, only the molar ratio of acid to alcohol was changed to obtain the reaction results of lauric acid monoglyceride, as shown in Table 4.

[0070] Table 4. Results of the reaction of lauric acid monoglyceride with different molar ratios of acid and alcohol.

[0071] As shown in Table 4, the yield of acid-alcohol mixtures is above 80% in the range of 1:3-7, reaching the highest at 1:4, and then decreasing. Considering the need to save resources and the yield of the target product, the acid-alcohol mixture ratio is determined to be 1:4.

[0072] Example 7 Referring to the catalytic reaction process of Example 2, only the amount of catalyst was changed to obtain the reaction results of lauric acid monoglyceride, as shown in Table 5.

[0073] Table 5 Results of lauric acid monoglyceride reaction with different amounts of catalyst

[0074] As shown in Table 5, the yield is above 80% when the catalyst dosage is in the range of 3-5% of the lauric acid mass. Considering the conservation of resources and the yield of the target product, the optimal catalyst dosage is determined to be 4%.

[0075] Example 8 Referring to the catalytic reaction process of Example 2, the reaction results of lauric acid monoglyceride were obtained by only changing the reaction temperature, as shown in Table 6.

[0076] Table 6. Results of lauric acid monoglyceride reaction at different reaction temperatures

[0077] As shown in Table 6, the yield of the catalytic reaction is above 80% when the temperature is in the range of 140-150℃. Considering the need to save resources and the yield of the target product, the optimal reaction temperature is determined to be 150℃.

[0078] Example 9 Following the catalytic process of Example 2, after the reaction was completed and cooled, the polyamine-modified chloride-supported ionic liquid silicotungstic acid (CP-PEI-SO3-SiW) catalyst was separated from the reaction system by filtration, and the recovered catalyst was obtained after washing with ethyl acetate and drying.

[0079] To a 100 mL three-necked flask equipped with a reflux condenser, 10 g of lauric acid, 18.4 g of glycerol (acid-to-alcohol molar ratio 1:4), and 0.4 g of the recovered CP-PEI-SO3-SiW catalyst were added sequentially. The flask was then heated in an oil bath at 150 °C. The reaction was stopped after 2 h, and the yield and conversion of the reaction products were analyzed by gas chromatography.

[0080] The reusability of the CP-PEI-SO3-SiW catalyst in the reaction of laurate monoglyceride is as follows: Figure 2 As shown. By Figure 2It is known that the catalyst exhibits good stability and reusability when catalyzing selective esterification to prepare monoglyceride of laurate. After being reused 7 times, the yield of monoglyceride of laurate is still higher than 80%, which is better than the reusability of patent document CN202210060636.X.

[0081] Comparative Example 1 Following step (1) of Example 1, polyamine-modified chlorine balls (CP-PEI) were prepared.

[0082] Following steps (1)-(2) of Example 1, sulfonated polyamine modified chlorine balls (CP-PEI-SO3) were prepared.

[0083] The catalyst prepared in Example 1 is designated as CP-PEI(1800)-SO3-SiW.

[0084] Following the complete preparation steps of Example 1, with other reaction conditions fixed, the polyamines were changed to PEI-600, PEI-10000, and polyethyleneimine ethoxylate (PEO, 13000), and the resulting catalysts were denoted as CP-PEI(600)-SO3-SiW, CP-PEI(10000)-SO3-SiW, and CP-PEO-SO3-SiW, respectively.

[0085] To a 100mL three-necked flask equipped with a reflux condenser, 10g of lauric acid, 18.4g of glycerol (acid-to-alcohol molar ratio 1:4), and 0.4g of different catalysts were added sequentially. The flask was then heated in an oil bath at 150℃. The reaction was stopped after 2 hours. The yield and conversion of the reaction products were analyzed by gas chromatography. The results of obtaining lauric acid monoglyceride by changing different catalysts are shown in Table 7.

[0086] Table 7 Results of the reaction of lauric acid monoglyceride with different catalysts

[0087] As can be seen from the table, the PEI-modified chlorine-supported ionic liquid silicotungstic acid catalyst with a molecular weight of 1800 exhibits the best yield of the target product under the reaction conditions.

[0088] Comparative Example 2 Referring to patent document CN202210060636.X, Example 1 describes the preparation of the catalyst chlorosphere-piperazine-silicotungstic acid; referring to patent document CN201110346829.3s, Example 1 describes the preparation of the catalyst [HMIBS]3PW. 12 O 40 ;Refer to patent document CN112570022B Example 1 for the preparation of catalyst [QUPSH]1H3SiW 12 O 40 / SG-Fe3O4 (10%); Microsphere-type polymer solid esterification catalyst prepared according to patent document CN201010210613.X Example 1; Polydivinylbenzene-ionic liquid-polyacid catalyst PDVB-VIM-PS-HPW prepared according to patent CN201410004248.5 Example 1; QMCMCPA-TPA type catalyst prepared according to the preparation method of quaternary ammonium salt modified chloromethylated polystyrene resin supported phosphotungstic acid catalyst QMCMCPA-TPA in the paper "Preparation and Application of Polymer Supported Heteropolyacid Catalysts".

[0089] To a 100 mL three-necked flask equipped with a reflux condenser, 10 g of lauric acid, 18.4 g of glycerol (acid-to-alcohol molar ratio 1:4), and 0.4 g of different catalysts were added sequentially. The flask was then heated in an oil bath at 150 °C. The reaction was stopped after 2 h, and the yield and conversion of the reaction products were analyzed by gas chromatography. The results of obtaining lauric acid monoglyceride by changing different catalysts are shown in Table 8.

[0090] Table 8. Results of the reaction of lauric acid monoglyceride obtained by referring to patents and papers.

[0091] As shown in Table 8, under the same reaction conditions, the CP-PEI(1800)-SO3-SiW catalyst prepared in this application has the best yield of the target product.

[0092] The above examples demonstrate that the catalyst prepared in this application exhibits good catalytic activity and high yield of lauric acid monoglyceride even with a low catalyst dosage. Furthermore, the catalyst preparation time is short, energy consumption is low, post-processing is simple, and pollution is minimal, making it a green chemical technology.

[0093] It should be noted that common heteropolyacid catalysts are difficult to separate due to their fine particle size. However, when using sulfonated polyamine-modified chlorinated spheres supported on silicotungstic acid as a catalyst, the preparation is simple and low-cost, and the catalytic activity and target product yield are further improved. The ionic liquid heteropolyacid is widely dispersed on the surface of the chlorinated spheres, increasing the number of reactive sites and thus reducing the amount of ionic liquid heteropolyacid used. At the same time, the sulfonic acid groups in the catalyst are covalently bonded to the heteropolyacid, making the catalyst easy to separate after the reaction and greatly improving its reusability. The steric hindrance effect of the covalently bonded chlorinated spheres and the synergistic effect of the high-N support improve the selectivity of the reaction between lauric acid and glycerol, promoting the formation of lauric acid monoglyceride. Furthermore, the introduction of ultrasonic-microwave technology greatly shortens the catalyst preparation time and reduces energy consumption and cost.

[0094] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing a higher fatty acid ester, characterized in that, include: Using alcohols and carboxylic acids as raw materials, polyamine-modified chloride-supported ionic liquid heteropolyacids as catalysts, the reaction was carried out in an oil bath at 130-170℃ for 0.5-3 h; after the reaction, the catalyst was recovered and used for the next reaction. The preparation of the polyamine-modified chloride-supported ionic liquid heteropolyacid includes: (1) Polyamines, potassium carbonate, and chlorine spheres are mixed in an organic solvent and the carrier is synthesized under the synergistic effect of microwave and ultrasound. After the reaction is completed, the carrier is obtained by filtration, washing and drying. The polyamines are polyethyleneimine with a molecular weight of 1800. (2) The polyamine-modified chlorinated sphere carrier and 1,3-propanesulfonate lactone were added to toluene and sulfonated under the synergistic effect of microwave and ultrasonic waves. After the reaction was completed, the sulfonated polyamine-modified chlorinated spheres were obtained by filtration, washing and drying. (3) The obtained sulfonated polyamine modified chlorine spheres are reacted with heteropolyacids, and then concentrated, washed and dried in sequence to obtain the polyamine modified chlorine spheres loaded with ionic liquid heteropolyacids.

2. The preparation method according to claim 1, characterized in that the mass ratio of the carboxylic acid to the alcohol is 1:3-7; The amount of catalyst used is 1%-6% of the mass of carboxylic acid; The carboxylic acid is one of the C8-C20 unsaturated or saturated fatty acids; The alcohol is one of methanol, ethanol, ethylene glycol, or glycerol.

3. The preparation method according to claim 1, characterized in that the mixing ratio of the polyamine substance and the chlorine ball is based on a mass ratio of 1-6 mmol:1g of the polyamine substance to the chlorine ball; and the amount of potassium carbonate used is 5-10% of the mass of the chlorine ball.

4. The preparation method according to claim 1, characterized in that the mixing ratio of the polyamine-modified chlorospheres to 1,3-propanesulfonic acid lactone is calculated as 1-6 mmol:1g based on the molar amount of 1,3-propanesulfonic acid lactone to the mass ratio of the polyamine-modified chlorospheres.

5. The preparation method according to claim 1, characterized in that the ratio of the heteropolyacid to the sulfonated polyamine modified chlorine spheres is calculated as 1-5 mmol:1g based on the amount of heteropolyacid to the mass ratio of the sulfonated polyamine modified chlorine spheres.

6. The preparation method according to claim 1, wherein the heteropoly acid is silicotungstic acid.

7. The preparation method according to claim 1, characterized in that, The reactions in steps (1) and (2) are carried out in a microwave-ultrasound synthesizer; in step (1), the reaction temperature is 60-90℃, the ultrasonic power is 200-500W, the microwave power is 200-500W, and the time is 2-4h; in step (2), the reaction temperature is 70-110℃, the microwave power is 100-400W, the ultrasonic power is 200-500W, and the time is 1-3h; in step (3), the reaction temperature is 70-100℃, and the reaction time is 6-18h.

8. A method for preparing polyamine-modified chloride-supported ionic liquid heteropolyacids, characterized in that, include: (1) Polyamines, potassium carbonate, and chlorine spheres are mixed in an organic solvent and the carrier is synthesized under the synergistic effect of microwave and ultrasound. After the reaction is completed, the carrier is obtained by filtration, washing and drying. The polyamines are polyethyleneimine with a molecular weight of 1800. (2) The polyamine-modified chlorinated sphere carrier and 1,3-propanesulfonate lactone were added to toluene and sulfonated under the synergistic effect of microwave and ultrasonic waves. After the reaction was completed, the sulfonated polyamine-modified chlorinated spheres were obtained by filtration, washing and drying. (3) The obtained sulfonated polyamine modified chlorine spheres are reacted with heteropolyacids, and then concentrated, washed and dried in sequence to obtain the polyamine modified chlorine spheres loaded with ionic liquid heteropolyacids.

9. The polyamine-modified chloride-supported ionic liquid heteropolyacid catalyst prepared by the method described in claim 8.

10. The use of the polyamine-modified chloride-supported ionic liquid heteropolyacid catalyst as described in claim 9 in the preparation of higher fatty acids.

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