Preparation method of monoglyceride oleate and product thereof

Abstract

The invention provides a preparation method of monoglyceride oleate and a product thereof, and relates to the technical field of synthesis of ester compounds. The preparation method comprises the following steps: (1) mixing glycerol, oleic acid and a solvent, and adding a zeolite-p-toluenesulfonic acid catalyst for reaction to obtain an initial oleic acid monoglyceride mixture; the molar ratio of glycerol to oleic acid is (1-2.5): 1; the solvent is prepared from sulfolane and N, N-dimethylformamide in a mass ratio of 8: (1-5); the ratio of the total mass of the glycerol and the oleic acid to the mass of the solvent is 4: (1-3); and (2) carrying out three-stage molecular distillation treatment on the initial monoglyceride oleate mixture under the conditions of 100-200 Pa, 180-220 DEG C, 50-80 Pa, 180-220 DEG C, 0-10 Pa and 180-230 DEG C to obtain the monoglyceride oleate. According to the method, the yield and the purity of the monoglyceride oleate can be improved; and monoglyceride oleate is mixed with a specific antioxidant, so that the oxidation resistance of the product can be remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of ester compound synthesis, and particularly relates to a preparation method of oleic acid monoglyceride and a product thereof. Background Art

[0002] Fatty acid monoglycerides have emulsifying, lubricating, softening and wetting properties and are widely used in food processing and cosmetics preparation. For example, lauric acid monoglyceride can be used as a food emulsifier, and stearic acid monoglyceride can be used as a lubricant and antistatic agent for plastics.

[0003] The industrial production methods of fatty acid monoglycerides mainly include chemical synthesis and enzymatic methods; the enzymatic method generally uses lipase as a catalyst to synthesize monoglycerides at a relatively low temperature. Zeng Fankui used lipase to enzymatically hydrolyze triglycerides and glycerol in the article "Enzymatic Synthesis, Properties and Application of Monoolein in Low-Fat Ice Cream" at a reaction temperature of 50°C to obtain monoolein with a relatively high purity. However, the enzymatic method not only has high requirements on the reaction conditions and reaction system, but also requires the use of biological enzyme preparations, which are expensive and not suitable for large-scale production.

[0004] The chemical synthesis method utilizes glycerol and fatty acids to directly undergo an esterification reaction to produce fatty acid monoglycerides, as well as fatty acid diglycerides, fatty acid triglycerides and other components, resulting in a product that is a mixture; the content of fatty acid monoglycerides in the mixture is generally only 40%-50%, and the yield and purity of fatty acid monoglycerides are low, which is not conducive to its further application.

[0005] Chinese invention patent CN113264831A discloses a method for preparing fatty acid monoglyceride, comprising the following steps: S1, adding glycerol and fatty acid to a reactor, heating to 140℃-180℃ under the action of an alkaline catalyst, reacting for 3-8h under vacuum-0.096Mpa to obtain crude fatty acid monoglyceride; S2, the primary molecular distillation temperature is 100℃-130℃, the pressure is 0-100Pa, and the distillation time is 1-4h, removing crude fatty acids and glycerol and other components in the fatty acid monoglyceride to obtain distillate and steam residue, and the steam residue is fatty acid monoglyceride. The product obtained by this method has a fatty acid monoglyceride content of 50%-55%, a fatty acid diester content of 35%-45%, a fatty acid triglyceride content of <5%, a glycerol content of <10%, and an acid value of <1mgKOH / g. Although this method can increase the content of fatty acid monoglyceride accordingly, the improvement effect is limited, and the content of fatty acid monoglyceride in the product is still low. It is only suitable for industrial applications and cannot be used in the preparation of fine chemical products.

[0006] Chinese invention patent CN113698294A discloses a method for preparing oleic acid glyceride by reactive azeotropic distillation, wherein glycerol and oleic acid are used as reaction raw materials, N-methylpyrrolidone is used as reaction solvent, and toluene is used as water-carrying agent, and oleic acid glyceride is prepared under the catalysis of solid acid; toluene and water form an azeotropic system, and the temperature of the azeotropic system is 95-110°C; the reaction temperature is 190-200°C, and the esterification reaction time is 6-8h; the alcohol-acid molar ratio of the reaction raw material is 1:4-5; the amount of the solid acid is 2%-3% of the total mass of the reaction raw material; the mass ratio of N-methylpyrrolidone to glycerol is 5:1; the mass ratio of toluene to N-methylpyrrolidone is 1:1. Although this method can improve the conversion rate of the reaction process, the purity of fatty acid monoglyceride still needs to be improved.

[0007] In view of this, further exploration and research on the preparation method of fatty acid monoglycerides is needed in order to obtain a higher fatty acid monoglyceride content; at the same time, the reaction process should be further improved to solve the problem of insolubility and high viscosity of glycerol and fatty acids in the chemical synthesis method, which affects the purity and storage stability of the product. Summary of the invention

[0008] The invention aims at the problems existing in the prior art and provides a method for preparing oleic acid monoglyceride and a product thereof. Glycerol and oleic acid are used as reaction raw materials. In the presence of sulfolane and N,N-dimethylformamide, a zeolite-p-toluenesulfonic acid catalyst is added to carry out a reaction. The reaction product is subjected to a three-stage molecular distillation treatment to obtain high-purity oleic acid monoglyceride.

[0009] To achieve the above purpose, the technical solution adopted by the present invention is as follows: First, the present invention provides a method for preparing monooleylglycerol, comprising the steps of: (1) Glycerol, oleic acid and a solvent are mixed, and a zeolite-p-toluenesulfonic acid catalyst is added to react to obtain an initial oleic acid monoglyceride mixture; the molar ratio of glycerol to oleic acid is 1-2.5:1; the solvent is sulfolane and N,N-dimethylformamide in a mass ratio of 8:1-5; the ratio of the total mass of glycerol and oleic acid to the mass of the solvent is 4:1-3; (2) The initial monoglyceride oleate mixture obtained in step (1) is subjected to three-stage molecular distillation to obtain monoglyceride oleate; the conditions of the three-stage molecular distillation are: 100-200 Pa, 180-220° C. for the first stage molecular distillation treatment, 50-80 Pa, 180-220° C. for the second stage molecular distillation treatment, and 2-10 Pa, 180-230° C. for the third stage molecular distillation treatment.

[0010] Preferably, the preparation method is carried out in the presence of nitrogen or argon.

[0011] Preferably, in step (1), the mass ratio of sulfolane to N,N-dimethylformamide is 8:2-5.

[0012] Further preferably, in step (1), the mass ratio of sulfolane to N,N-dimethylformamide is 8:4.

[0013] Preferably, in step (1), the molar ratio of glycerol to oleic acid is 1.5-2:1.

[0014] Further preferably, in step (1), the molar ratio of glycerol to oleic acid is 1.8:1.

[0015] Preferably, in step (1), the ratio of the total mass of the glycerol and oleic acid to the mass of the solvent is 4:1-3.

[0016] Further preferably, in step (1), the ratio of the total mass of the glycerol and oleic acid to the mass of the solvent is 4:2.

[0017] Preferably, in step (1), the catalyst is used in an amount of 1%-3% of the total mass of glycerol and oleic acid.

[0018] Further preferably, in step (1), the amount of the catalyst used is 2% of the total mass of glycerol and oleic acid.

[0019] In the present invention, under the conditions of the dosage of the zeolite-toluenesulfonic acid catalyst, the technical effects described in the present application can be achieved; the dosage of the zeolite-toluenesulfonic acid catalyst is any endpoint value or intermediate value within the range, not limited to 1%-3%, 1%-2%, 2%-3%, 1%-2.5%, 1.5%-3%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, and 3%.

[0020] Preferably, in step (1), the preparation method of the zeolite-p-toluenesulfonic acid catalyst is as follows: the zeolite is crushed through a 50-200 mesh sieve, activated at 140-160°C for 1-3h, then immersed in a 40wt%-60wt% p-toluenesulfonic acid solution, pressurized at 5-10Pa for 4-6h, filtered, dried, and calcined at 120-140°C for 2-4h to obtain the zeolite-p-toluenesulfonic acid catalyst; the mass ratio of the zeolite to p-toluenesulfonic acid is 1:1-4.

[0021] Further preferably, in step (1), the preparation method of the zeolite-p-toluenesulfonic acid catalyst is as follows: the zeolite is crushed through a 100 mesh sieve, activated at 150°C for 2h, then immersed in a 50wt% p-toluenesulfonic acid solution, pressurized at 8-10Pa for 5h, filtered, dried, and calcined at 130°C for 3h to obtain the zeolite-p-toluenesulfonic acid catalyst.

[0022] More preferably, the mass ratio of the zeolite to p-toluenesulfonic acid is 1:3.

[0023] Preferably, in step (1), the reaction temperature is 130-150° C. and the reaction time is 3-6 h.

[0024] Further preferably, in step (1), the reaction temperature is 140° C. and the reaction time is 4 h.

[0025] Preferably, in step (1), after the reaction, the zeolite-p-toluenesulfonic acid catalyst is removed by filtration; and the excess solvents: sulfolane and N,N-dimethylformamide are removed by reduced pressure distillation.

[0026] Preferably, in step (2), the conditions for the three-stage molecular distillation are: 100-200Pa, 180-220°C, and a scraping speed of 500-700rpm for the first stage molecular distillation treatment; 50-80Pa, 180-220°C, and a scraping speed of 400-500rpm for the second stage molecular distillation treatment; 2-10Pa, 180-230°C, and a scraping speed of 400-500rpm for the third stage molecular distillation treatment.

[0027] Further preferably, in step (2), the conditions for the three-stage molecular distillation are: 150Pa, 200°C, and a scraping speed of 600rpm for the first stage molecular distillation treatment; 60Pa, 200°C, and a scraping speed of 400rpm for the second stage molecular distillation treatment; 8Pa, 220°C, and a scraping speed of 400rpm for the third stage molecular distillation treatment.

[0028] Then, the present invention provides oleic acid monoglyceride, which is prepared by the above preparation method; the purity of the oleic acid monoglyceride is 95%-99%.

[0029] Finally, the present invention provides a monoglyceride of oleic acid product with high antioxidant property, which is composed of the following components: the above-mentioned monoglyceride of oleic acid and an antioxidant; the antioxidant is a mixture of Vc palmitate, BHT (2,6-di-tert-butyl-p-cresol) and vitamin E in a mass ratio of 2:2-5:1-3.

[0030] Preferably, the mass ratio of Vc palmitate, BHT and vitamin E is 2:4:2.

[0031] Preferably, in the monoglyceride oleate product, the mass ratio of monoglyceride oleate to antioxidant is 3000-6000:1.

[0032] Further preferably, in the monoglyceride oleate product, the mass ratio of monoglyceride oleate to antioxidant is 5000:1.

[0033] Compared with the prior art, the present invention has the following beneficial effects: 1. The preparation method of the present invention uses sulfolane and N,N-dimethylformamide as solvents, which is conducive to the uniform mixing of glycerol and oleic acid, promotes the reaction under the action of the composite catalyst zeolite-p-toluenesulfonic acid, and improves the yield and purity of oleic acid monoglyceride; before molecular distillation, the oleic acid monoglyceride content in the initial oleic acid monoglyceride can reach 80%-87%, and the method of the present invention can significantly improve the yield and purity of oleic acid monoglyceride.

[0034] 2. In the preparation method of the present invention, zeolite can also be used as a dehydrating agent to absorb water generated during the reaction, promote the reaction, and improve the yield and purity of the product.

[0035] 3. In the preparation method of the present invention, oleic acid monoglyceride is purified by three-stage molecular distillation to improve the purity of the product.

[0036] 4. The oleic acid monoglyceride prepared by the present invention, under the synergistic effect of Vc palmitate, BHT and vitamin E, can significantly improve the antioxidant property of the product, thereby improving the storage stability and reducing the POV value. DETAILED DESCRIPTION

[0037] The following non-limiting examples can enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way. The following content is merely an exemplary description of the scope of the present invention, and those skilled in the art can make various changes and modifications to the present invention based on the disclosed content, which should also fall within the scope of the present invention.

[0038] When the embodiments give numerical ranges, it should be understood that, unless otherwise specified in the present invention, both endpoints of each numerical range and any numerical value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meanings as those generally understood by those of ordinary skill in the art to which the present invention belongs.

[0039] The present invention is further described below by way of specific examples. The various chemical reagents used in the examples of the present invention are obtained through conventional commercial channels unless otherwise specified. Products from different manufacturers have no significant effect on the effects.

[0040] In the present invention, the purity (content, %) of monooleylglycerol = mass of monooleylglycerol / total mass of product × 100%.

[0041] The total yield of monooleylglycerol (%) = actual mass of monooleylglycerol / theoretical mass of monooleylglycerol × 100%.

[0042] Example 1 A preparation method of monooleylglycerol is: Step (1), 88.8 g of glycerol, 151.2 g of oleic acid, 80 g of sulfolane, and 40 g of N,N-dimethylformamide are mixed, 4.8 g of zeolite-p-toluenesulfonic acid catalyst (2% of the total mass of glycerol and oleic acid) is added, and the mixture is reacted at 140° C. for 4 h to obtain an initial oleic acid monoglyceride mixture, wherein the content of oleic acid monoglyceride in the initial oleic acid monoglyceride mixture is 86.0%; the molar ratio of glycerol to oleic acid is 1.8:1; The preparation method of the zeolite-p-toluenesulfonic acid catalyst is as follows: the zeolite is crushed through a 100-mesh sieve, activated at 150° C. for 2 hours, then immersed in a 50wt% p-toluenesulfonic acid solution, pressurized at 9±1Pa for 5 hours, filtered, dried, and calcined at 130° C. for 3 hours to obtain the zeolite-p-toluenesulfonic acid catalyst; the mass ratio of zeolite to p-toluenesulfonic acid is 1:3; Step (2), subjecting the initial monoglyceride oleate mixture obtained in step (1) to three-stage molecular distillation: 150Pa, 200°C, and a film scraping speed of 600rpm for the first stage molecular distillation treatment; 60Pa, 200°C, and a film scraping speed of 400rpm for the second stage molecular distillation treatment; 8Pa, 220°C, and a film scraping speed of 400rpm for the third stage molecular distillation treatment to obtain monoglyceride oleate, the yield of monoglyceride oleate is 79.3%, and the purity of monoglyceride oleate is 98.9%.

[0043] Example 2 Different from Example 1, in step (1), the mass ratio of the solvent sulfolane and N,N-dimethylformamide is different, and the mass ratio of the total mass of glycerol and oleic acid to the solvent is different.

[0044] Step (1), 88.8 g of glycerol, 151.2 g of oleic acid, 144 g of sulfolane, and 36 g of N,N-dimethylformamide are mixed, 4.8 g of zeolite-p-toluenesulfonic acid catalyst (2% of the total mass of glycerol and oleic acid) is added, and the mixture is reacted at 140° C. for 4 h to obtain an initial oleic acid monoglyceride mixture, wherein the content of oleic acid monoglyceride in the initial oleic acid monoglyceride mixture is 85.9%; the molar ratio of glycerol to oleic acid is 1.8:1; The preparation method of the zeolite-p-toluenesulfonic acid catalyst and the three-stage molecular distillation in step (2) are the same as those in Example 1.

[0045] Example 3 Different from Example 1, in step (1), the mass ratio of the solvent sulfolane and N,N-dimethylformamide is different, and the mass ratio of the total mass of glycerol and oleic acid to the solvent is different.

[0046] Step (1), 88.8 g of glycerol, 151.2 g of oleic acid, 36.9 g of sulfolane, and 23.1 g of N,N-dimethylformamide are mixed, 4.8 g of zeolite-p-toluenesulfonic acid catalyst (2% of the total mass of glycerol and oleic acid) is added, and the mixture is reacted at 140° C. for 4 h to obtain an initial oleic acid monoglyceride mixture, wherein the content of oleic acid monoglyceride in the initial oleic acid monoglyceride mixture is 85.1%; the molar ratio of glycerol to oleic acid is 1.8:1; The preparation method of the zeolite-p-toluenesulfonic acid catalyst and the three-stage molecular distillation in step (2) are the same as those in Example 1.

[0047] Example 4 The difference from Example 1 is that the molar ratio of glycerol to oleic acid in step (1) is different, and the amount of catalyst used and the ratio of the catalyst components are different.

[0048] Step (1), 78.8 g of glycerol, 161.2 g of oleic acid, 80 g of sulfolane, and 40 g of N,N-dimethylformamide are mixed, 2.4 g of zeolite-p-toluenesulfonic acid catalyst (1% of the total mass of glycerol and oleic acid) is added, and the mixture is reacted at 140° C. for 4 h to obtain an initial oleic acid monoglyceride mixture, wherein the content of oleic acid monoglyceride in the initial oleic acid monoglyceride mixture is 80.2%; the molar ratio of glycerol to oleic acid is 1.5:1; The preparation method of the zeolite-p-toluenesulfonic acid catalyst is as follows: the zeolite is crushed through a 100-mesh sieve, activated at 150° C. for 2 hours, then immersed in a 50wt% p-toluenesulfonic acid solution, pressurized at 9±1Pa for 5 hours, filtered, dried, and calcined at 130° C. for 3 hours to obtain the zeolite-p-toluenesulfonic acid catalyst; the mass ratio of zeolite to p-toluenesulfonic acid is 1:1; The three-stage molecular distillation in step (2) is the same as that in Example 1.

[0049] Example 5 The difference from Example 1 is that the molar ratio of glycerol to oleic acid in step (1) is different, and the amount of catalyst used and the ratio of catalyst components are different.

[0050] Step (1), 94.7 g of glycerol, 145.3 g of oleic acid, 80 g of sulfolane, and 40 g of N,N-dimethylformamide are mixed, 7.2 g of zeolite-p-toluenesulfonic acid catalyst (3% of the total mass of glycerol and oleic acid) is added, and the mixture is reacted at 140° C. for 4 h to obtain an initial oleic acid monoglyceride mixture, wherein the content of oleic acid monoglyceride in the initial oleic acid monoglyceride mixture is 85.7%; the molar ratio of glycerol to oleic acid is 2:1; The preparation method of the zeolite-p-toluenesulfonic acid catalyst is as follows: the zeolite is crushed through a 100-mesh sieve, activated at 150° C. for 2 hours, then immersed in a 50wt% p-toluenesulfonic acid solution, pressurized at 9±1Pa for 5 hours, filtered, dried, and calcined at 130° C. for 3 hours to obtain the zeolite-p-toluenesulfonic acid catalyst; the mass ratio of zeolite to p-toluenesulfonic acid is 1:4; The three-stage molecular distillation in step (2) is the same as that in Example 1.

[0051] Example 6 The difference from Example 1 is that the molar ratio of glycerol to oleic acid in step (1) is different.

[0052] Step (1), 59 g of glycerol, 181 g of oleic acid, 80 g of sulfolane, and 40 g of N,N-dimethylformamide are mixed, 4.8 g of zeolite-p-toluenesulfonic acid catalyst (2% of the total mass of glycerol and oleic acid) is added, and the mixture is reacted at 140° C. for 4 h to obtain an initial oleic acid monoglyceride mixture, wherein the content of oleic acid monoglyceride in the initial oleic acid monoglyceride mixture is 82.8%; the molar ratio of glycerol to oleic acid is 1:1; The preparation method of the zeolite-p-toluenesulfonic acid catalyst and the three-stage molecular distillation in step (2) are the same as those in Example 1.

[0053] Example 7 The difference from Example 1 is that the molar ratio of glycerol to oleic acid in step (1) is different.

[0054] Step (1), 107.8 g of glycerol, 132.2 g of oleic acid, 80 g of sulfolane, and 40 g of N,N-dimethylformamide are mixed, 4.8 g of zeolite-p-toluenesulfonic acid catalyst (2% of the total mass of glycerol and oleic acid) is added, and the mixture is reacted at 140° C. for 4 h to obtain an initial oleic acid monoglyceride mixture, wherein the content of oleic acid monoglyceride in the initial oleic acid monoglyceride mixture is 86.3%; the molar ratio of glycerol to oleic acid is 2.5:1; The preparation method of the zeolite-p-toluenesulfonic acid catalyst and the three-stage molecular distillation in step (2) are the same as those in Example 1.

[0055] The specific reaction conditions of step (1) of Examples 1 to 7, the content of monoglyceride in the initial monoglyceride mixture obtained in step (1), and the total yield and purity of the final monoglyceride obtained after purification in step (2) are shown in Table 1.

[0056] Table 1

[0057] Example 8 The difference from Example 1 is that the reaction conditions of step (1) are different: the reaction is carried out at 150° C. for 3 hours to obtain an initial oleic acid monoglyceride mixture. The content of oleic acid monoglyceride in the initial oleic acid monoglyceride mixture obtained in step (1) is 84.6%.

[0058] Step (2) was the same as in Example 1, and the total yield of monooleylglycerol finally obtained was 77.9% and the purity was 97.1%.

[0059] Example 9 The difference from Example 1 is that the reaction conditions of step (1) are different: the reaction is carried out at 130° C. for 6 hours to obtain an initial oleic acid monoglyceride mixture. The content of oleic acid monoglyceride in the initial oleic acid monoglyceride mixture obtained in step (1) is 84.8%.

[0060] Step (2) was the same as in Example 1, and the total yield of monooleylglycerol finally obtained was 76.1% and the purity was 97.3%.

[0061] Example 10 Different from Example 1, the conditions of the tertiary molecular distillation in step (2) are different.

[0062] The preparation method of step (1) and zeolite-p-toluenesulfonic acid catalyst is the same as that of Example 1; Step (2), subjecting the initial monoglyceride oleate mixture obtained in step (1) to three-stage molecular distillation: 100Pa, 220°C, and a film scraping speed of 500rpm for the first stage molecular distillation treatment; 50Pa, 220°C, and a film scraping speed of 500rpm for the second stage molecular distillation treatment; 10Pa, 180°C, and a film scraping speed of 500rpm for the third stage molecular distillation treatment, to obtain a total yield of 76.6% of monoglyceride oleate and a purity of 96.8%.

[0063] Embodiment 11 Different from Example 1, the conditions of the tertiary molecular distillation in step (2) are different.

[0064] The preparation method of step (1) and zeolite-p-toluenesulfonic acid catalyst is the same as that of Example 1; Step (2), subjecting the initial monoglyceride oleate mixture obtained in step (1) to three-stage molecular distillation: 200Pa, 180°C, and a film scraping speed of 700rpm for the first stage molecular distillation treatment; 80Pa, 180°C, and a film scraping speed of 400rpm for the second stage molecular distillation treatment; 2Pa, 230°C, and a film scraping speed of 400rpm for the third stage molecular distillation treatment, the total yield of monoglyceride oleate obtained is 76.0%, and the purity is 96.1%.

[0065] Comparative Example 1 Olein was prepared according to the method described in Example 1 of Publication No. CN113698294A.

[0066] Solid acid catalyst SO4 2- The preparation method of / ZrO2-Al2O3 is as follows: dissolve zirconium oxychloride and aluminum nitrate in deionized water at a molar ratio of 3:1, and after uniform dissolution, vigorously stir at room temperature and drop 28% NH3·H2O to produce a white precipitate. After adjusting the pH of the system to 10, stop stirring and age the precipitate at room temperature for 24 hours. After aging, filter and wash with deionized water until there is no chloride ion in the filtrate. Use silver nitrate to test, and dry the filter cake at 110°C for 24 hours, grind it into powder, put it into 1mol / L ammonium sulfate solution, immerse and stir it for 24 hours, and then filter it. After drying for 24 hours, roast it at 550°C for 6 hours to obtain a solid acid catalyst SO4 2- / ZrO2-Al2O3.

[0067] Add 3.68g glycerol, 33.8g oleic acid, 18.41g N-methylpyrrolidone and 20g toluene into the reactor, then weigh 0.75g solid acid catalyst SO4 2- / ZrO2-Al2O3, the reaction temperature was controlled at 190°C, and the reaction was stirred and distilled for 6 hours. After the reaction was completed, the product was filtered to separate the catalyst, the solvent N-methylpyrrolidone was removed by water washing, and the water-carrying agent toluene was removed by vacuum rotary evaporation to obtain a crude oleic acid glyceride product. The content of oleic acid glyceride in the crude oleic acid glyceride product was 61.8%, and the total yield was 42.0%.

[0068] Comparative Example 2 The difference from Example 1 is that the sulfolane and N,N-dimethylformamide in step (1) are replaced by N-methylpyrrolidone, that is, the solvent is 120 g of N-methylpyrrolidone. The rest is the same as Example 1.

[0069] Comparative Example 3 The difference from Example 1 is that the sulfolane in step (1) is replaced by N,N-dimethylformamide; that is, the solvent is 120 g of N,N-dimethylformamide. The rest is the same as Example 1.

[0070] Comparative Example 4 The difference from Example 1 is that the N,N-dimethylformyl in step (1) is replaced by sulfolane; that is, the solvent is 120 g of sulfolane. The rest is the same as Example 1.

[0071] Comparative Example 5 Different from Example 1, in step (1), the mass ratio of the total mass of glycerol and oleic acid to the mass of the solvent is 1:4.

[0072] Step (1), 11.1 g of glycerol, 18.9 g of oleic acid, 80 g of sulfolane, and 40 g of N,N-dimethylformamide are mixed, 0.6 g of zeolite-p-toluenesulfonic acid catalyst (2% of the total mass of glycerol and oleic acid) is added, and the mixture is reacted at 140° C. for 4 h to obtain an initial oleic acid monoglyceride mixture, wherein the content of oleic acid monoglyceride in the initial oleic acid monoglyceride mixture is 39.5%; the molar ratio of glycerol to oleic acid is 1.8:1; The preparation method of the zeolite-p-toluenesulfonic acid catalyst and the three-stage molecular distillation in step (2) are the same as those in Example 1.

[0073] Comparative Example 6 Different from Example 1, the molar ratio of glycerol to oleic acid is 1:2.

[0074] 33.6g of glycerol, 206.4g of oleic acid, 80g of sulfolane, and 40g of N,N-dimethylformamide were mixed, 4.8g of zeolite-p-toluenesulfonic acid catalyst (2% of the total mass of glycerol and oleic acid) was added, and the mixture was reacted at 140°C for 4h to obtain an initial oleic acid monoglyceride mixture, wherein the content of oleic acid monoglyceride in the initial oleic acid monoglyceride mixture was 28.1%; the molar ratio of glycerol to oleic acid was 1.8:1; The preparation method of the zeolite-p-toluenesulfonic acid catalyst and the three-stage molecular distillation in step (2) are the same as those in Example 1.

[0075] Comparative Example 7 The difference from Example 1 is that the zeolite-p-toluenesulfonic acid catalyst in step (1) is replaced by zeolite (4.8 g) that has only passed through a 100-mesh sieve, and p-toluenesulfonic acid is not used. The rest is the same as Example 1.

[0076] Comparative Example 8 Different from Example 1, the zeolite-p-toluenesulfonic acid catalyst in step (1) is replaced by an activated carbon-p-toluenesulfonic acid catalyst.

[0077] Step (1), 88.8 g of glycerol, 151.2 g of oleic acid, 80 g of sulfolane, and 40 g of N,N-dimethylformamide are mixed, 4.8 g of activated carbon-toluenesulfonic acid catalyst (2% of the total mass of glycerol and oleic acid) is added, and the mixture is reacted at 140° C. for 4 h to obtain an initial oleic acid monoglyceride mixture; the molar ratio of glycerol to oleic acid is 1.8:1; The preparation method of the activated carbon-p-toluenesulfonic acid catalyst is as follows: the activated carbon is crushed through a 100-mesh sieve, activated at 150° C. for 2 hours, then immersed in a 50wt% p-toluenesulfonic acid solution, pressurized at 9±1Pa for 5 hours, filtered, dried, and calcined at 130° C. for 3 hours to obtain the activated carbon-p-toluenesulfonic acid catalyst; the mass ratio of the activated carbon to the p-toluenesulfonic acid is 1:3; Step (2), subjecting the initial monoglyceride oleate mixture obtained in step (1) to three-stage molecular distillation: 150Pa, 200°C, and a scraping speed of 600rpm for the first stage molecular distillation treatment; 60Pa, 200°C, and a scraping speed of 400rpm for the second stage molecular distillation treatment; 8Pa, 220°C, and a scraping speed of 400rpm for the third stage molecular distillation treatment to obtain monoglyceride oleate.

[0078] Comparative Example 9 The difference from Example 1 is that the molecular distillation in step (2) is only a first-stage molecular distillation: the initial monoglyceride mixture obtained in step (1) is subjected to molecular distillation at 150 Pa, 200° C., and a scraping speed of 600 rpm to obtain monoglyceride. Step (1) and the preparation method of the zeolite-p-toluenesulfonic acid catalyst are the same as those in Example 1.

[0079] Comparative Example 10 The difference from Example 1 is that the conditions for the three-stage molecular distillation of step (2) are different: the initial oleic acid monoglyceride mixture obtained in step (1) is subjected to a first-stage molecular distillation treatment at 80 Pa, 200° C., and a scraping speed of 600 rpm; a second-stage molecular distillation treatment is carried out at 40 Pa, 200° C., and a scraping speed of 400 rpm; and a third-stage molecular distillation treatment is carried out at 8 Pa, 220° C., and a scraping speed of 400 rpm.

[0080] Step (1) and the preparation method of the zeolite-p-toluenesulfonic acid catalyst are the same as those in Example 1.

[0081] In the technical schemes of Comparative Examples 2 to 10, the oleic acid monoglyceride content in the initial oleic acid monoglyceride mixture obtained in step (1), and the total yield and purity of the final oleic acid monoglyceride obtained after purification in step (2) are shown in Table 2.

[0082] Table 2

[0083] Application Examples Since monooleylglycerol is easily oxidized, antioxidants are usually added to improve its storage stability. This application example studies the stability of monooleylglycerol treated with different antioxidants, and the main indicator examined is the peroxide value (POV).

[0084] The monoglyceride of oleic acid finally obtained in Example 1 was mixed with different antioxidants to obtain products containing monoglyceride of oleic acid. The above products were stored under accelerated oxidation conditions at 63±1°C. The POV values ​​(meq / kg) of monoglyceride of oleic acid in each group of products after 36 days are shown in Table 3.

[0085] Table 3

[0086] The letters a, b, c, and d in Table 3 represent the results of significant differences: the same letters in different rows in the same column indicate no significant difference (P>0.05), and different letters indicate significant difference (P<0.05).

[0087] It can be seen from Table 3 that when a specific ratio of Vc palmitate, BHT (2,6-di-tert-butyl-p-cresol) and vitamin E is used as an antioxidant on monoglyceride, compared with other antioxidant ingredients, the antioxidant properties of monoglyceride can be significantly improved. The POV values ​​of monoglyceride in groups 1-3 are small and the oxidation rate is slow; the POV values ​​of groups 1-3 are significantly lower than those in groups 4-7. The comparison results of groups 1-3 and 4-5 show that the Vc palmitate, BHT and vitamin E of the present invention as a whole can bring synergistic antioxidant effects, and the POV value is significantly reduced; the results of groups 1-3 and 6 show that not all antioxidants can achieve the technical effects of the present application. When Vc palmitate, BHA (butylated hydroxyanisole) and TBHQ (tert-butylhydroquinone) act on monoglyceride of oleic acid, the POV value is higher than that of groups 1-3, and the antioxidants of the present application have substantial characteristics as a whole; the results of groups 1-3 and 7 show that only three antioxidants can bring about the effect of significantly reducing the POV value under a specific ratio.

[0088] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing monooleylglycerol, characterized in that: Includes steps: (1) Glycerol, oleic acid and a solvent are mixed, and a zeolite-p-toluenesulfonic acid catalyst is added to react to obtain an initial oleic acid monoglyceride mixture; the molar ratio of glycerol to oleic acid is 1-2.5:1; the solvent is sulfolane and N,N-dimethylformamide in a mass ratio of 8:1-5; the ratio of the total mass of glycerol and oleic acid to the mass of the solvent is 4:1-3; (2) The initial monoglyceride oleate mixture obtained in step (1) is subjected to three-stage molecular distillation to obtain monoglyceride oleate; the conditions of the three-stage molecular distillation are: 100-200 Pa, 180-220° C. for the first stage molecular distillation treatment, 50-80 Pa, 180-220° C. for the second stage molecular distillation treatment, and 2-10 Pa, 180-230° C. for the third stage molecular distillation treatment.

2. The preparation method according to claim 1, characterized in that: In step (1), the molar ratio of glycerol to oleic acid is 1.5-2:1; the mass ratio of sulfolane to N,N-dimethylformamide is 8:2-5.

3. The preparation method according to claim 2, characterized in that: In step (1), the molar ratio of glycerol to oleic acid is 1.8:1; and the mass ratio of sulfolane to N,N-dimethylformamide is 8:

4.

4. The preparation method according to claim 1, characterized in that: In step (1), the ratio of the total mass of the glycerol and oleic acid to the mass of the solvent is 4:

2.

5. The preparation method according to claim 1, characterized in that: In step (1), the catalyst is used in an amount of 1%-3% of the total mass of glycerol and oleic acid.

6. The preparation method according to claim 1, characterized in that: In step (1), the preparation method of the zeolite-p-toluenesulfonic acid catalyst is as follows: the zeolite is crushed through a 50-200 mesh sieve, activated at a temperature of 140-160° C. for 1-3 hours, then immersed in a 40wt%-60wt% p-toluenesulfonic acid solution, pressurized at 5-10Pa for 4-6 hours, filtered, dried, and calcined at 120-140° C. for 2-4 hours to obtain the zeolite-p-toluenesulfonic acid catalyst; the mass ratio of the zeolite to p-toluenesulfonic acid is 1:1-4.

7. The preparation method according to claim 1, characterized in that: In step (1), the reaction temperature is 130-150°C and the reaction time is 3-6h.

8. The preparation method according to claim 1, characterized in that: In step (2), the conditions of the three-stage molecular distillation are: 100-200Pa, 180-220°C, and a scraping speed of 500-700rpm for the first stage molecular distillation treatment; 50-80Pa, 180-220°C, and a scraping speed of 400-500rpm for the second stage molecular distillation treatment; 2-10Pa, 180-230°C, and a scraping speed of 400-500rpm for the third stage molecular distillation treatment.

9. A monoglyceride of oleic acid, characterized in that: Prepared by the preparation method according to any one of claims 1 to 8; the purity of the monoglyceride of oleic acid is 95%-99%.

10. A monoglyceride oleate product with high antioxidant properties, characterized in that: The invention is composed of the following components: the monoglyceride of oleic acid as claimed in claim 9 and an antioxidant; the antioxidant is a mixture of Vc palmitate, BHT and vitamin E in a mass ratio of 2:2-5:1-3; The mass ratio of oleic acid monoglyceride to the antioxidant is 3000-6000:1.

Images