阅读说明：本技术 一种反应共沸精馏制备油酸甘油酯的方法 (Method for preparing glyceryl oleate by reaction azeotropic distillation ) 是由 顾正桂 胡博 葛盛才 张佩祥 曹晓艳 沙玉英 于 2021-09-24 设计创作，主要内容包括：本发明公开了一种反应共沸精馏制备油酸甘油酯的方法,以甘油与油酸为反应原料,以N-甲基吡咯烷酮为反应溶剂、甲苯为带水剂,在固体酸的催化下制备油酸甘油酯。本发明通过添加N-甲基吡咯烷酮作为反应溶剂,改善反应前油酸与甘油不互溶问题,同时有利于降低反应体系粘度,便于反应产物与催化剂的分离；采用甲苯为带水剂,由于甲苯与水形成非均相最低共沸物,通过反应与共沸精馏结合的方式可有效脱除反应过程生成的水,从而提高反应过程的转化率。本发明工艺可以实现反应过程中甘油转化率达到90.5％以上,目标产物油酸甘油酯选择性达到74.5％以上。(The invention discloses a method for preparing glyceryl oleate by reaction azeotropic distillation, which takes glycerol and oleic acid as reaction raw materials, takes N-methyl pyrrolidone as a reaction solvent and toluene as a water-carrying agent, and prepares the glyceryl oleate under the catalysis of solid acid. According to the invention, N-methyl pyrrolidone is added as a reaction solvent, so that the problem of immiscible oleic acid and glycerol before reaction is solved, the viscosity of a reaction system is reduced, and the separation of a reaction product and a catalyst is facilitated; toluene is used as a water-carrying agent, and the toluene and water form a heterogeneous minimum azeotrope, so that water generated in the reaction process can be effectively removed in a mode of combining reaction and azeotropic distillation, and the conversion rate of the reaction process is improved. The process can realize that the conversion rate of the glycerol in the reaction process reaches more than 90.5 percent, and the selectivity of the target product, namely the glyceryl oleate reaches more than 74.5 percent.)

1. A method for preparing glyceryl oleate by reaction azeotropic distillation takes glycerol and oleic acid as reaction raw materials and is characterized in that N-methyl pyrrolidone is taken as a reaction solvent, toluene is taken as a water-carrying agent, and the glyceryl oleate is prepared under the catalysis of solid acid.

2. The method for preparing glycerol oleate through reaction azeotropic distillation according to claim 1, wherein the mass ratio of N-methyl pyrrolidone to glycerol is 4-8: 1.

3. The method for preparing glyceryl oleate through reactive azeotropic distillation as described in claim 1, wherein the mass ratio of the toluene to the N-methyl pyrrolidone is 1-2: 1.

4. The method for preparing glyceryl oleate through reaction azeotropic distillation according to claim 1, wherein the amount of the solid acid is 1-5% of the total mass of the reaction raw materials.

5. The method for preparing glyceryl oleate through reaction azeotropic distillation according to claim 1, wherein the molar ratio of the alcohol to the alcohol in the reaction raw materials is 1: 3-5.

6. The method for preparing glyceryl oleate through reactive azeotropic distillation according to claim 1, wherein the reaction temperature is 160-200 ℃, and the esterification reaction time is 4-8 h.

7. The method for preparing glycerol oleate through reaction azeotropic distillation as described in claim 1, wherein the toluene and water form an azeotropic system, and the temperature of the azeotropic system is 95-110 ℃.

8. The method for producing glyceryl oleate by azeotropic distillation in the reaction environment, as claimed in claim 1, wherein the solid acid is SO₄ ^2-/ZrO₂-Al₂O₃、SO₄ ^2-/ZrO₂Or SO₄ ^2-/TiO₂。

9. The method for preparing the glyceryl oleate by the reaction azeotropic distillation as described in claim 1, which is characterized by comprising the following specific steps: toluene and water form an azeotropic system, the azeotropic system is condensed at the top of the tower and then enters a water separator, the upper layer of toluene reflows and enters a reactor for recycling, and the lower layer of water is discharged; after the reaction is finished, the catalyst is separated out by filtering the tower bottom material, the reaction solvent N-methyl pyrrolidone is removed by washing, and the water-carrying agent is removed by reduced pressure rotary evaporation to obtain the crude product of the glyceryl oleate.

Technical Field

The invention relates to a method for preparing glyceryl oleate, in particular to a method for preparing glyceryl oleate by reaction azeotropic distillation.

Background

The glyceryl oleate is an unsaturated fatty glyceride, is used as a main raw material of clavulanic acid in the pharmaceutical industry, can be used as a smoothing agent for processing in the textile industry, and is often used as an emulsifier and a wetting agent in the daily chemical industry.

The method for producing the glyceryl oleate mainly comprises the following steps: alcoholysis method after acyl halogenation, biological enzyme catalysis method, ester exchange method and classical esterification method. In the classical esterification method, oleic acid and glycerol are used as reaction raw materials, and an acid catalyst is adopted for esterification synthesis of glyceryl oleate. The reaction is simple to operate, and the yield is high, so that the method is suitable for industrial large-scale production. However, the homogeneous inorganic acid catalysis has the defects of equipment corrosion, and waste acid needs to be neutralized after reaction to generate wastewater to pollute the environment.

The literature reports that benzene sulfonic acid is used as a catalyst, and a vacuum filtration mode is utilized to prepare oleate. Patent CN104262149 discloses that a self-made solid acid catalyst is used to catalyze the reaction of glycerol and oleic acid, and a vacuum dehydrator is used to dehydrate the glycerol oleate. However, the existing methods all have the problem that the reaction raw materials of oleic acid and glycerol are not mutually soluble.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to provide a method for preparing glyceryl oleate by azeotropic distillation of reaction, which can improve the insolubility of reaction raw materials and improve the conversion rate.

The technical scheme is as follows: the method for preparing the glyceryl oleate by the reaction azeotropic distillation takes the glycerol and the oleic acid as reaction raw materials, takes the N-methyl pyrrolidone as a reaction solvent and the toluene as a water-carrying agent, and prepares the glyceryl oleate under the catalysis of solid acid.

Wherein the mass ratio of the N-methylpyrrolidone to the glycerol is 4-8: 1.

Wherein the mass ratio of the toluene to the N-methyl pyrrolidone is 1-2: 1.

Wherein the dosage of the solid acid is 1-5% of the total mass of the reaction raw materials.

The molar ratio of the reaction raw materials to the alcohol acid is 1: 3-5.

Wherein the reaction temperature is 160-200 ℃, and the esterification reaction time is 4-8 h.

Wherein the toluene and water form an azeotropic system, and the temperature of the azeotropic system is 95-110 ℃.

Wherein the solid acid is SO₄ ^2-/ZrO₂-Al₂O₃、SO₄ ^2-/ZrO₂Or SO₄ ^2-/TiO₂。

The method comprises the following specific steps: toluene and water form an azeotropic system, the azeotropic system is condensed at the top of the tower and then enters a water separator, the upper layer of toluene reflows and enters a reactor for recycling, and the lower layer of water is discharged; after the reaction is finished, the catalyst is separated out by filtering the tower bottom material, the reaction solvent N-methyl pyrrolidone is removed by washing, and the water-carrying agent is removed by reduced pressure rotary evaporation to obtain the crude product of the glyceryl oleate.

Has the advantages that: compared with the prior art, the invention has the following remarkable effects: 1. by adding N-methyl pyrrolidone as a reaction solvent, the problem of immiscible oleic acid and glycerol before reaction is solved, the viscosity of a reaction system is reduced, and the separation of a reaction product and a catalyst is facilitated; toluene is used as a water-carrying agent, and the toluene and water form a heterogeneous minimum azeotrope, so that water generated in the reaction process can be effectively removed in a mode of combining reaction and azeotropic distillation, and the conversion rate of the reaction process is improved. 2. The process can realize that the conversion rate of the glycerol in the reaction process reaches more than 90.5 percent, and the selectivity of the target product, namely the glyceryl oleate reaches more than 74.5 percent.

Drawings

FIG. 1 is a graph of data comparing the effect of different processes on glycerol conversion and oleate selectivity;

FIG. 2 is a graph of data comparing the effect of different reaction solvents on glycerol conversion and oleate selectivity;

FIG. 3 is a graph of data comparing the effect of different water-carrying agents on glycerol conversion and oleate selectivity.

Detailed Description

The present invention is described in further detail below.

Example 1

Adding 3.68g of glycerol, 33.8g of oleic acid, 18.41g of solvent N-methyl pyrrolidone and 20g of water-carrying agent toluene into a reaction kettle, and then weighing 0.75g of solid acid catalyst SO₄ ^2-/ZrO₂-Al₂O₃The reaction temperature is controlled at 190 ℃, and the reaction and rectification are carried out for 6 hours under stirring. And (3) after the reaction is finished, filtering the product to separate out the catalyst, removing the solvent N-methyl pyrrolidone by washing, and removing toluene as a water-carrying agent by reduced pressure rotary evaporation to obtain a crude product of the glyceryl oleate.

Solid acid catalyst SO of this example₄ ^2-/ZrO₂-Al₂O₃The preparation method comprises the following steps:

dissolving zirconium oxychloride and aluminum nitrate in a molar ratio of 3:1 in deionized water, stirring strongly at room temperature after uniformly dissolving, and dripping 28% NH₃·H₂And O generates white precipitate, the stirring is stopped after the pH value of the system is adjusted to 10, the precipitate is aged at the normal temperature for 24 hours, the mixture is filtered after the aging is finished, deionized water is used for washing until no chloride ion exists in the filtrate, silver nitrate is used for testing, the filter cake is dried at 110 ℃ for 24 hours, the mixture is ground into powder, and the powder is put into 1mol/L ammonium sulfate solution to be soaked and stirred for 24 hours and then filtered. Drying for 24h, and calcining at 550 ℃ for 6h to obtain solid acid catalyst SO₄ ^2-/ZrO₂-Al₂O₃。

The conversion rate of the glycerol is calculated according to the national standard GB/T132166 titration method, and Agilent-1260 high performance liquid chromatography is adopted for detecting and calculating the selectivity of the oleate.

Meanwhile, 3 other methods for preparing glyceryl oleate were compared. The experimental results of 3 methods are shown in figure 1, wherein the reaction solvent N-methylpyrrolidone and toluene as a water-carrying agent are not added, the reaction solvent N-methylpyrrolidone is only added, and the water-carrying agent toluene is only added. Only adding a reaction solvent can improve the intersolubility of oleic acid and glycerol, but has little influence on the conversion rate and the selectivity; only adding toluene as a water-carrying agent can remove water generated in the reaction and promote the esterification reaction, thereby improving the conversion rate in the reaction process; and meanwhile, a reaction solvent and a water-carrying agent are added, so that the intersolubility of raw materials can be improved, the reaction conversion rate can be improved, the glycerin conversion rate is over 90.5%, and the selectivity of the target product, namely the glyceryl oleate is over 74.5%.

Example 2

The basic procedure was as in example 1, except that the reaction temperature was varied. The effect of each reaction temperature on glycerol conversion and glycerol oleate selectivity is shown in table 1.

TABLE 1 reaction temperature influence on conversion and selectivity of the synthesis of glyceryl oleate

Reaction temperature (. degree.C.)	Conversion (%)	Selectivity (%)	Yield (%)
				140.0	59.5	25.0	14.9
150.0	65.4	27.3	17.9
				160.0	74.4	28.1	20.9
170.0	83.8	32.7	27.4
				180.0	86.2	34.8	30.0
190.0	89.7	37.6	33.7
				200.0	90.1	36.5	32.9

As can be seen from Table 1, different reaction temperatures have a greater effect on the conversion rate and a lesser effect on the selectivity of the synthesis process of glyceryl oleate. The reaction rate can be accelerated by increasing the reaction temperature, and the reaction conversion rate is improved. However, when the reaction temperature is increased to more than 190 ℃, the conversion rate of the glycerol and the selectivity of the product are almost kept stable, and simultaneously, the color of the reaction system is deepened after the reaction temperature reaches 200 ℃, thereby affecting the quality of the product. Therefore, the optimal reaction temperature is 190 ℃, the highest glycerol conversion rate can reach 89.7 percent, the selectivity of oleate can reach 37.6 percent, and the total yield is 33.7 percent.

Example 3

This example was carried out using the same procedure as example 1 except that the molar ratio of the alkyd was different. The effect of each alkyd molar ratio on glycerol conversion and glycerol oleate selectivity is shown in table 2.

TABLE 2 alkyd molar ratio Effect on conversion and selectivity of synthetic glyceryl oleate

Alcohol to acid ratio	Conversion (%)	Selectivity (%)	Yield (%)
				1:3.01	89.7	37.6	33.7
1:3.22	91.3	46.5	42.5
				1:3.39	89.8	54.1	48.6
1:3.61	90.9	67.5	61.4
				1:3.82	90.8	73.0	66.3
1:4.00	90.5	74.5	67.4
				1:5.00	90.3	72.7	65.6

As can be seen from table 2, when the molar ratio of the alkyds was changed, the glycerol conversion rate was hardly changed, and the product selectivity was significantly improved. The esterification reaction of oleic acid and glycerol comprises the reaction of glycerol and oleic acid to generate monooleate, the monooleate and oleic acid continuously react to generate dioleate, and finally the dioleate and oleic acid react to generate triolein. The excess of oleic acid can promote the reaction of monooleate and dioleate, which is beneficial to the formation of glyceryl oleate and can promote the selectivity of products. However, when the molar ratio of the alkyd is increased to 1:4, the conversion rate and the selectivity are slowly increased, and excessive oleic acid increases the difficulty of refining the product at the later stage. Therefore, the molar ratio of the alkyd is most preferably 1:3.8, the glycerol conversion is 90.8%, the oleate selectivity is 73.0%, and the overall yield is 66.3%.

Example 4

This example was carried out using the same glycerol oleate as in example 1 except that the amount of catalyst used was different. The effect of each catalyst dosage on glycerol conversion and glycerol oleate selectivity is shown in table 3.

TABLE 3 influence of catalyst dosage on conversion and selectivity of the synthesis of glyceryl oleate

Amount of catalyst (%)	Conversion (%)	Selectivity (%)	Yield (%)
				1.0％	84.7	61.4	52.0
2.0％	90.8	73.0	66.3
				3.0％	91.4	72.6	66.4
4.0％	90.4	70.6	63.8
				5.0％	89.7	69.4	62.3

As can be seen from Table 3, as the amount of catalyst used increases, the conversion and selectivity increase, and as the amount of catalyst used increases, so does the acidic sites in the system, allowing the reactants to react on sufficient active sites. And when the dosage of the catalyst reaches 3 percent of the total mass of the raw materials, the conversion rate and the selectivity are basically equal. But the conversion and selectivity decreased as the catalyst dosage continued to increase. This is because an excess of catalyst also accelerates the hydrolysis of the reverse reaction glycerol oleate. Meanwhile, the preparation and separation cost of the catalyst is considered, so that the dosage of the catalyst is preferably 2% of the total mass of the raw materials, the conversion rate of the glycerol is 90.8%, the selectivity of the oleate is 73.0%, and the total yield is 66.3%.

Example 5

The procedure for the preparation of glyceryl oleate in this example was the same as in example 1, except that the reaction time was different. The effect of each reaction time on glycerol conversion and glycerol oleate selectivity is shown in table 4.

TABLE 4 reaction time effect on conversion and selectivity of the synthesis of glyceryl oleate

Reaction time (h)	Conversion (%)	Selectivity (%)	Yield (%)
				2	83.6	50.4	42.1
4	87.4	65.1	57.1
				6	91.4	74.5	68.1
8	91.6	75.6	69.2

The temperature in the reaction kettle is selected to be 190 ℃ as the reaction starting time, the conversion rate and the selectivity are rapidly increased within 2h of reaction according to the table 4, the increase rate of the conversion rate and the selectivity is slowed down after the reaction time reaches 4h, and the conversion rate of the glycerol and the selectivity of the product are basically kept unchanged after the reaction time reaches 6 h. Since the esterification reaction is substantially in equilibrium when the reaction time reaches 6 h. Therefore, the conversion and selectivity are less affected by the continuous extension of the reaction time. Therefore, the reaction time is most preferably 6 hours, the conversion of glycerol is 91.4%, the selectivity for oleate is 74.5%, and the total yield is 68.1%.

Example 6

The preparation procedure of glyceryl oleate in this example is substantially the same as that of example 1, with the addition of 3.74g of glycerol, 43.07g of oleic acid and 20g of toluene as a water-carrying agent.

Example 7

The basic procedure is as in example 1, except that 3.74g of glycerol, 43.07g of oleic acid and 20.1g of N-methylpyrrolidone are added.

Example 8

The basic procedure was the same as in example 6, except that the amount of the solvent used was different, and the influence of the amount of each solvent added on the conversion and selectivity of the reaction is shown in Table 5.

TABLE 5 influence of solvent dosage on conversion and selectivity of the synthesis of glyceryl oleate

m (N-methylpyrrolidone): m (Glycerol)	Conversion (%)	Selectivity (%)	Yield (%)
				4.3:1	79.4	60.3	47.9
5.1:1	89.8	73.6	66.1
				6.4:1	81.2	65.8	53.4
7.5:1	73.6	52.4	38.6
				8.6:1	51.2	39.4	20.2

As can be seen from Table 5, the conversion of glycerol and the selectivity for oleate increased with increasing solvent usage and then decreased. When the mass ratio of the N-methylpyrrolidone to the glycerol is 4:1, oleic acid and the glycerol which are used as reaction raw materials cannot be fully dissolved mutually, so that part of the glycerol is insoluble in a system, the reaction rate is reduced, and the conversion rate and the selectivity are reduced. And as the mass ratio of the N-methyl pyrrolidone to the glycerol is more than 6:1 as the using amount of the reaction solvent is increased, the reaction conversion rate and the selectivity are reduced because the concentration of the reaction raw materials is reduced along with the addition of the reaction solvent, thereby inhibiting the reaction to a certain extent. Therefore, the best effect is achieved when the mass ratio of the N-methyl pyrrolidone to the glycerol is 5:1, the glycerol conversion rate is 89.8%, the oleate selectivity is 73.6%, and the oleate yield is 66.1%.

Example 9

The basic procedure was as in example 7, except that the amount of water-carrying agent was varied. The effect of the amount of each water-carrying agent added on the conversion and selectivity of the reaction is shown in Table 6.

TABLE 6 influence of the amount of water-carrying agent on the conversion and selectivity of the synthesis of glyceryl oleate

m (toluene): m (N-methylpyrrolidone)	Conversion (%)	Selectivity (%)	Yield (%)
				1:2	83.8	65.4	54.8
1:1	90.3	71.5	64.6
				2:1	78.2	59.8	46.8
3:1	61.4	42.4	26.0

As can be seen from table 6, when the mass ratio of the water-carrying agent to the reaction solvent was 1:2, the reaction conversion was low. This is because toluene does not completely entrain and remove water produced by the reaction when the amount of the water-carrying agent used is small. When the mass ratio of the water-carrying agent to the reaction solvent is 1: l, water generated by the reaction can be effectively removed, and the reaction conversion rate and the selectivity reach the maximum value. The reaction conversion rate and selectivity are rather reduced with further increase of the amount of the water-carrying agent, because the reactant concentration is reduced due to excessive amount of the water-carrying agent, and the reaction temperature is reduced due to a large amount of heat absorbed by the boiling water-carrying agent. Therefore, the best effect is achieved when the mass ratio of the water-carrying agent to the solvent is 1: l, the glycerol conversion rate is 90.3%, the oleate selectivity is 71.5%, and the oleate yield is 64.6%.

Comparative example 1

The basic procedure was as in example 6, except that the solvent was dimethyl sulfoxide.

Comparative example 2

The basic procedure was as in example 6, except that the solvent was N, N-dimethylformamide.

The effect of different solvent types on reaction conversion and selectivity in example 6 and comparative examples 1 and 2 is shown in FIG. 2.

As can be seen from fig. 2, of the three solvents, the best effect was obtained using N-methylpyrrolidone as the reaction solvent, with a glycerol conversion of 90.5% and an oleate selectivity of 73.4%. The solvent is added to promote the reaction product glycerol and oleic acid to be dissolved mutually, so that the reaction rate can be accelerated to a certain extent. When dimethyl sulfoxide and N, N-dimethylformamide are used as reaction solvents, when the reaction temperature reaches 190 ℃, the dimethyl sulfoxide and the N, N-dimethylformamide and toluene are evaporated out together, and the mutual solubility of glycerol and oleic acid in a reaction system is reduced along with the reduction of the solvent amount. Meanwhile, when toluene contains a solvent, water generated in the reaction is difficult to separate from toluene, resulting in deterioration of reaction effect. Therefore, the optimal reaction solvent is N-methyl pyrrolidone.

Comparative example 3

The basic procedure was the same as in example 7, except that the water-carrying agent added was carbon tetrachloride.

Comparative example 4

The basic procedure was as in example 7, except that the water-carrying agent added was cyclohexane.

The effect of different water-carrying agents on the conversion and selectivity of the reaction in example 7 and comparative examples 3 and 4 is shown in FIG. 3.

As can be seen from fig. 3, the toluene effect is the best among the different water-carrying agents. Because the boiling points of cyclohexane and carbon tetrachloride which are water-carrying agents are lower, a large amount of heat is absorbed when the cyclohexane and the carbon tetrachloride are boiled in the reaction, so that the reaction temperature is reduced, and the reaction activation energy is not provided enough. Resulting in insufficient reaction of oleic acid with glycerol resulting in a decrease in reaction conversion and selectivity. Therefore, toluene is the most preferred water-carrying agent.