CN118852603A - Preparation method of fatty alcohol polyoxyethylene ether fatty acid ester - Google Patents

Abstract

The invention belongs to the technical field of fatty acid esters, and particularly relates to a preparation method of fatty alcohol polyoxyethylene ether fatty acid esters. The method comprises the following steps: (1) Mixing polyol with an alkaline catalyst, and then adding ethylene oxide to carry out ring-opening polymerization reaction to obtain a polyether polyol crude product; (2) Adding sulfuric acid aqueous solution into the polyether polyol crude product, and stirring for reaction to obtain an intermediate product; (3) Adding fatty acid into the intermediate product for esterification reaction, filtering after the reaction is finished, and obtaining fatty alcohol polyoxyethylene ether fatty acid ester after the filtering is finished. The invention converts the alkaline catalyst used for synthesizing polyether into the esterification catalyst used for synthesizing fatty acid ester by a chemical method, omits the polyether refining step, simplifies the synthetic process flow, shortens the production period, and reduces the energy consumption and the production cost. Meanwhile, after the reaction is finished, the catalyst can be removed only by filtration, and residues in the product can not be remained so as to influence downstream application.

Description

Preparation method of fatty alcohol polyoxyethylene ether fatty acid ester

Technical Field

The invention belongs to the technical field of fatty acid esters, and in particular relates to a method for preparing fatty alcohol polyoxyethylene ether fatty acid esters.

Background Art

As a polymer material widely used in many industries, polyether polyols are usually synthesized by ring-opening homopolymerization or copolymerization of active hydrogen-containing initiators (such as alcohols, amines, phenols, etc.) and alkylene oxides (such as ethylene oxide, propylene oxide, butylene oxide, etc.) in the presence of homogeneous alkali metal catalysts (such as potassium hydroxide, sodium hydroxide, etc.). Fatty alcohol polyoxyethylene ether fatty acid ester products are firstly obtained by ring-opening copolymerization of fatty alcohols and ethylene oxide to form polyether polyol products, and then esterification with fatty acids. Its molecular structure contains both the structure of fatty acid esters and the hydrophilic structure of polyoxyethylene ethers. It is non-toxic and low-irritating, and has good application prospects in the fields of food, medicine, lubricants, personal care, etc.

The esterification reaction of fatty alcohol polyoxyethylene ether and fatty acid can be carried out under the condition of concentrated sulfuric acid or p-toluenesulfonic acid as catalyst, which has the characteristics of fast reaction rate, low reaction temperature, low energy consumption, etc. However, since the synthesis of polyether polyol products usually uses alkali metal as catalyst, if the alkali metal is not neutralized and refined, it will poison the acid catalyst in the subsequent esterification process. At the same time, the terminal hydroxyl group of the polyether product is occupied by the alkali metal, and the electronic and structural effects will make the esterification difficult.

Chinese patent CN111040149A discloses a method for preparing a polyether ester defoamer, wherein the polyol is first mixed with an alkaline catalyst, and then pre-dried with propylene oxide and ethylene oxide and reacted with them, and after the reaction, the crude product is neutralized, refined, and filtered to obtain a polyether polyol; the polyether polyol and fatty acid undergo esterification reaction under the action of concentrated sulfuric acid or p-toluenesulfonic acid catalyst to obtain a polyether ester papermaking defoamer product. Chinese patent CN114805786B discloses a method for preparing a tannin-based polyether polyol fatty acid ester plasticizer, wherein the crude tannin extract is first used as a raw material, and an alkali metal catalyst is used to polymerize with alkylene oxide to generate a polyether polyol, and after acid neutralization and adsorbent refining to remove the alkali metal, the polyether polyol is esterified with fatty acid under any catalyst of sulfuric acid, p-toluenesulfonic acid, and activated carbon-supported sulfuric acid/p-toluenesulfonic acid to form a polyether polyol fatty acid ester product. In the production processes of the above patents, polyether is synthesized under alkali metal catalysis conditions, and after the alkali metal is removed, polyether polyol fatty acid ester is synthesized under acidic catalysis conditions. This type of process route usually requires multiple reaction vessels and production lines such as polyether synthesis kettles, polyether refining kettles and esterification kettles. Not only is the process lengthy and complicated, the production efficiency is low, and the production cost is high, but sulfuric acid and p-toluenesulfonic acid will remain in the product and are difficult to remove, which may affect the subsequent use of the product.

In addition, the synthesis of esters can also be carried out under alkaline conditions. Chinese patent CN115650846A discloses a method for synthesizing glycerol polyoxyethylene ether fatty acid esters, comprising the following steps: using glycerol polyoxyethylene ether and natural oils as raw materials, heating to a reaction temperature of 220-250°C under the action of an alkaline catalyst (NaOH or KOH) to obtain glycerol polyoxyethylene ether fatty acid esters. Although this method does not require the removal of alkali metals in the polyether before the esterification reaction, the catalytic efficiency of alkali metals is relatively low compared to acid catalysts, resulting in a higher temperature required for the esterification reaction, increased energy consumption and production costs.

Summary of the invention

In view of the deficiencies in the prior art, the object of the present invention is to provide a method for preparing fatty alcohol polyoxyethylene ether fatty acid ester, wherein the alkaline catalyst used for polyether synthesis is converted into an esterification catalyst used for fatty acid ester synthesis by a chemical method, thereby eliminating the polyether refining step, and the polyether polymerization reaction and esterification reaction can be completed in one or two production lines, thereby simplifying the synthesis process, shortening the production cycle, and reducing energy consumption and production costs. At the same time, after the reaction is completed, the catalyst can be removed by filtering only, and will not remain in the product to affect downstream applications. The solid acid catalyst after removal can also be used again for esterification reaction to achieve recycling.

The technical solution adopted by the present invention is as follows:

The preparation method of the fatty alcohol polyoxyethylene ether fatty acid ester comprises the following steps:

(1) Mixing a polyol with an alkaline catalyst, then adding ethylene oxide, and carrying out a ring-opening polymerization reaction at a temperature of 95 to 140° C. and a pressure of 0 to 0.5 MPa to obtain a crude polyether polyol;

(2) Cooling the mixture to below 90°C, adding an aqueous sulfuric acid solution to the crude polyether polyol, and stirring the mixture at a temperature of 85-90°C for 1-2 hours to obtain an intermediate product;

(3) Add fatty acids to the intermediate product and carry out esterification reaction at a temperature of 135-150°C and a pressure of -0.06-0.09MPa. When the esterification rate is greater than 95%, the reaction is completed. Remove the vacuum and filter. After filtration, fatty alcohol polyoxyethylene ether fatty acid ester is obtained.

The polyol is one of diethylene glycol, propylene glycol, glycerol, n-butanol, isooctyl alcohol or n-octanol.

The alkaline catalyst is one of potassium methoxide, sodium methoxide, sodium hydride, potassium hydroxide or sodium hydroxide.

The concentration of the aqueous sulfuric acid solution is 10-30wt.%.

The fatty acid is one of stearic acid, oleic acid or lauric acid.

In the step (1), the amount of the alkaline catalyst used is 0.1-0.5 wt.% of the total amount of the polyol and ethylene oxide.

In the step (2), the molar ratio of sulfuric acid to the alkaline catalyst is (0.9-1.1):1.

In the step (3), the ratio of the added molar amount of fatty acid to the molar amount of hydroxyl groups in the polyol is (0.9-1.1):1.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The method for preparing fatty alcohol polyoxyethylene ether fatty acid esters of the present invention directly converts the alkaline catalyst used in polyether synthesis into the esterification catalyst required for fatty acid ester synthesis by chemical means, which not only eliminates the complex refining steps of polyether in traditional processes, but also greatly simplifies the overall synthesis process, shortens the production cycle, improves production efficiency, and reduces energy consumption and production costs;

(2) In the preparation method of fatty alcohol polyoxyethylene ether fatty acid ester of the present invention, after the reaction is completed, the catalyst in the system is precipitated in the form of oil-insoluble and can be removed by simple filtering operation, thereby avoiding the catalyst residue in the fatty acid ester product. This not only ensures the purity of the fatty acid ester product, but also reduces the potential impact in downstream applications, and also realizes the effective recovery and reuse of the catalyst, further reducing the production cost.

(3) The esterification catalyst (potassium hydrogen sulfate or sodium hydrogen sulfate) used in the preparation method of fatty alcohol polyoxyethylene ether fatty acid ester of the present invention is milder than the traditional sulfuric acid catalyst, which reduces the corrosion to the production equipment, prolongs the service life of the equipment, and reduces the maintenance cost. At the same time, the residual amount of potassium and sodium ions in the fatty acid ester product is below 10ppm, which ensures the high quality of the fatty acid ester product and meets more stringent environmental protection standards and downstream application requirements.

DETAILED DESCRIPTION

The present invention is further described below with reference to the embodiments, but they do not limit the implementation of the present invention.

The raw materials used in the examples and comparative examples are conventional commercially available raw materials unless otherwise specified, and the process methods used in the examples and comparative examples are conventional methods in the art unless otherwise specified.

Example 1

The preparation method of the fatty alcohol polyoxyethylene ether fatty acid ester comprises the following steps:

(1) Add 400 g of n-butanol and 4.56 g of potassium hydroxide to a 5 L stainless steel reactor, replace the reactor with nitrogen until the oxygen content in the reactor is 80 ppm, heat to 90 ° C, wait for the potassium hydroxide to dissolve, then continuously add 1190 g of ethylene oxide, and carry out ring-opening polymerization at a temperature of 95 ° C and a pressure of 0.2 ± 0.2 MPa. After the reaction is completed, react at internal pressure for 1 hour and degas for 10 minutes to obtain a crude polyether polyol;

(2) Cooling to 90°C, adding 79.78 g of a 10 wt.% aqueous sulfuric acid solution to the crude polyether polyol, stirring and reacting at a temperature of 87.5±2.5°C for 1 h to obtain an intermediate product;

(3) Add 1473g of stearic acid to the intermediate product, stir for 1h at 87.5±2.5℃ until completely dissolved, then slowly open the vacuum, and carry out esterification reaction at 140℃ and -0.075±0.015MPa. Take samples every 0.5h to test the esterification rate. When the esterification rate is 97.6% (the esterification rate is greater than 95%), the reaction is over, remove the vacuum and filter, and obtain fatty alcohol polyoxyethylene ether fatty acid ester. The sample indicators are shown in Table 1.

Example 2

The preparation method of the fatty alcohol polyoxyethylene ether fatty acid ester comprises the following steps:

(1) Add 200 g of glycerol and 12.86 g of sodium hydroxide to a 5 L stainless steel reactor, replace the reactor with nitrogen until the oxygen content in the reactor is 80 ppm, heat it to 90 ° C, wait for the sodium hydroxide to dissolve, then continuously add 1913 g of ethylene oxide, and carry out ring-opening polymerization at a temperature of 115 ° C and a pressure of 0.2 ± 0.2 MPa. After the reaction is completed, react at internal pressure for 1 hour and degas for 10 minutes to obtain a crude polyether polyol;

(2) Cooling to 90°C, adding 99.87 g of 30 wt.% sulfuric acid aqueous solution to the crude polyether polyol, stirring and reacting at 87.5±2.5°C for 2 h to obtain an intermediate product;

(3) Add 1305 g of lauric acid to the intermediate product and stir at 87.5±2.5°C for 1 h until it is completely dissolved. Then slowly open the vacuum and carry out esterification reaction at a temperature of 150°C and a pressure of -0.075±0.015 MPa. Take samples every 0.5 h to test the esterification rate. When the esterification rate is 96.1% (the esterification rate is greater than 95%), the reaction is completed. Remove the vacuum and filter. After filtration, fatty alcohol polyoxyethylene ether fatty acid ester is obtained.

Example 3

The preparation method of the fatty alcohol polyoxyethylene ether fatty acid ester comprises the following steps:

(1) Add 530 g of isooctyl alcohol and 19.25 g of potassium methoxide to a 5 L stainless steel reactor, replace the reactor with nitrogen until the oxygen content in the reactor is 80 ppm, heat it to 90 ° C, wait for the potassium methoxide to dissolve, then continuously add 1617 g of ethylene oxide, and carry out ring-opening polymerization at a temperature of 140 ° C and a pressure of 0.3 ± 0.2 MPa. After the reaction is completed, react at internal pressure for 1 hour and degas for 10 minutes to obtain a crude polyether polyol;

(2) Cooling to 90°C, adding 105.55 g of 25 wt.% sulfuric acid aqueous solution to the crude polyether polyol, stirring and reacting at 87.5±2.5°C for 1 h to obtain an intermediate product;

(3) Add 793 g of lauric acid to the intermediate product and stir at 87.5±2.5°C for 1 h until it is completely dissolved. Then slowly open the vacuum and carry out esterification reaction at a temperature of 135°C and a pressure of -0.075±0.015 MPa. Take samples every 0.5 h to test the esterification rate. When the esterification rate measured by sampling is 98.3% (the esterification rate is greater than 95%), the reaction is completed. Remove the vacuum and filter to remove the solid catalyst. After filtration, fatty alcohol polyoxyethylene ether fatty acid ester is obtained.

Example 4

The preparation method of the fatty alcohol polyoxyethylene ether fatty acid ester comprises the following steps:

(1) Add 515 g of diethylene glycol and 18.99 g of sodium methoxide to a 5 L stainless steel reactor, replace the reactor with nitrogen until the oxygen content in the reactor is 80 ppm, heat it to 90 ° C, wait for the sodium methoxide to dissolve, then continuously add 1506 g of ethylene oxide, and carry out ring-opening polymerization at a temperature of 140 ° C and a pressure of 0.3 ± 0.2 MPa. After the reaction is completed, react at internal pressure for 1 hour and degas for 10 minutes to obtain a crude polyether polyol;

(2) Cooling to 90°C, adding 172.25 g of 20 wt.% sulfuric acid aqueous solution to the crude polyether polyol, stirring and reacting at a temperature of 87.5±2.5°C for 1 h to obtain an intermediate product;

(3) Add 2605 g of oleic acid to the intermediate product and stir at 87.5±2.5°C for 1 h until it is completely dissolved. Then slowly open the vacuum and carry out esterification reaction at a temperature of 145°C and a pressure of -0.075±0.015 MPa. Take samples every 0.5 h to test the esterification rate. When the esterification rate measured by sampling is 97.5% (the esterification rate is greater than 95%), the reaction is completed. Remove the vacuum and filter to remove the solid catalyst. After filtration, fatty alcohol polyoxyethylene ether fatty acid ester is obtained.

Example 5

The preparation method of the fatty alcohol polyoxyethylene ether fatty acid ester comprises the following steps:

(1) Add 639 g of propylene glycol and 5.35 g of sodium hydride to a 5 L stainless steel reactor, replace the nitrogen until the oxygen content in the reactor is 80 ppm, raise the temperature to 90 ° C, wait for the sodium hydride to dissolve, and then continuously add 1336 g of ethylene oxide to carry out ring-opening polymerization at a temperature of 130 ° C and a pressure of 0.2 ± 0.2 MPa. After the reaction is completed, react at internal pressure for 1 hour and degas for 10 minutes to obtain a crude polyether polyol;

(2) Cooling to 90°C, adding 72.87 g of 30 wt.% sulfuric acid aqueous solution to the crude polyether polyol, stirring and reacting at 87.5±2.5°C for 1 h to obtain an intermediate product;

(3) Add 3296 g of lauric acid to the intermediate product and stir at 87.5±2.5°C for 1 h until it is completely dissolved. Then slowly open the vacuum and carry out esterification reaction at a temperature of 145°C and a pressure of -0.075±0.015 MPa. Take samples every 0.5 h to test the esterification rate. When the esterification rate measured by sampling is 98.9% (the esterification rate is greater than 95%), the reaction is completed. Remove the vacuum and filter to remove the solid catalyst. After filtration, fatty alcohol polyoxyethylene ether fatty acid ester is obtained.

Comparative Example 1

The preparation method of the fatty alcohol polyoxyethylene ether fatty acid ester comprises the following steps:

(1) Add 400 g of n-butanol and 4.56 g of potassium hydroxide to a 5 L stainless steel reactor, replace the reactor with nitrogen until the oxygen content in the reactor is 80 ppm, heat to 90 ° C, wait for the potassium hydroxide to dissolve, then continuously add 1190 g of ethylene oxide, and carry out ring-opening polymerization at a temperature of 95 ° C and a pressure of 0.2 ± 0.2 MPa. After the reaction is completed, react at internal pressure for 1 hour and degas for 10 minutes to obtain a crude polyether polyol;

(2) After cooling to 90 ^° C, add 12.06 g of 70 wt.% phosphoric acid and 79.5 g of pure water to the crude polyether polyol, stir for 1 hour, then add 4.77 g of magnesium silicate adsorbent, continue stirring for 0.5 hour, then turn on the vacuum to slowly dehydrate until the water content is 500 ppm, and filter to obtain refined polyether;

(3) When the temperature of the refined polyether drops to 40°C, add 7.98 g of concentrated sulfuric acid to the refined polyether and stir for 0.5 h to obtain an intermediate product;

(4) Add 1473 g of stearic acid to the intermediate product and stir at 87.5±2.5°C for 1 h until it is completely dissolved. Then slowly open the vacuum and carry out esterification reaction at a temperature of 140°C and a pressure of -0.075±0.015 MPa. Take samples every 0.5 h to test the esterification rate. When the esterification rate measured by sampling is 96.5% (the esterification rate is greater than 95%), the reaction is completed. Remove the vacuum and filter. After filtration, fatty alcohol polyoxyethylene ether fatty acid ester is obtained.

Comparative Example 2

The difference from Comparative Example 1 is that the concentrated sulfuric acid in step (3) is replaced by an equal mass of p-toluenesulfonic acid, and the rest is the same as Comparative Example 1.

Comparative Example 3

The preparation method of the fatty alcohol polyoxyethylene ether fatty acid ester comprises the following steps:

(1) Add 200 g of glycerol and 12.86 g of sodium hydroxide to a 5 L stainless steel reactor, replace the reactor with nitrogen until the oxygen content in the reactor is 80 ppm, heat it to 90 ° C, wait for the sodium hydroxide to dissolve, then continuously add 1913 g of ethylene oxide, and carry out ring-opening polymerization at a temperature of 115 ° C and a pressure of 0.2 ± 0.2 MPa. After the reaction is completed, react at internal pressure for 1 hour and degas for 10 minutes to obtain a crude polyether polyol;

(2) After cooling to 90 ^° C, add 47.71 g of 70 wt.% phosphoric acid and 105.7 g of pure water to the crude polyether polyol, stir for 1 hour, then add 6.34 g of magnesium silicate adsorbent, continue stirring for 0.5 hour, then turn on the vacuum to slowly dehydrate until the water content is 500 ppm, and filter to obtain refined polyether;

(3) When the temperature of the refined polyether drops to 40°C, add 29.96 g of concentrated sulfuric acid to the refined polyether and stir for 0.5 h to obtain an intermediate product;

(4) Add 1305 g of lauric acid to the intermediate product and stir at 87.5±2.5°C for 1 h until it is completely dissolved. Then slowly open the vacuum and carry out esterification reaction at a temperature of 150°C and a pressure of -0.075±0.015 MPa. Take samples every 0.5 h to test the esterification rate. When the esterification rate is 95.7% (the esterification rate is greater than 95%), the reaction is completed. Remove the vacuum and filter. After filtration, fatty alcohol polyoxyethylene ether fatty acid ester is obtained.

The fatty acid esters prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were subjected to performance tests, and the test methods were as follows:

Acid value (mgKOH/g): Tested in accordance with GB 5009.229-2016;

Esterification rate (%): calculated according to the following formula:

;

Wherein, E is the esterification rate (%); AV1 is the acid value measured after the fatty acid is dissolved (mgKOH/g); AV2 is the acid value measured at the end of the esterification reaction (mgKOH/g).

Potassium/Sodium ions (ppm): Tested using a flame spectrophotometer.

The test results are shown in Table 1:

Table 1 Performance test results

As can be seen from Table 1, the preparation method of fatty alcohol polyoxyethylene ether fatty acid ester of the present invention can greatly shorten the synthesis cycle of fatty acid ester, and the finished product has no catalyst residue, and the catalyst activity is equivalent to that of traditional concentrated sulfuric acid and p-toluenesulfonic acid. Since sulfuric acid and p-toluenesulfonic acid remain in the product, under similar esterification rate conditions, the finished product of the present invention has a lower acid value, and the potassium and sodium ion contents are all less than 10ppm, which significantly reduces the production cost while ensuring the quality of the finished product.

Claims (10)

1. A method for preparing fatty alcohol polyoxyethylene ether fatty acid ester, characterized in that it comprises the following steps: (1) mixing a polyol with an alkaline catalyst, and then adding ethylene oxide to carry out a ring-opening polymerization reaction to obtain a crude polyether polyol; (2) adding a sulfuric acid aqueous solution to the crude polyether polyol, stirring and reacting, and obtaining an intermediate product; (3) Add fatty acid to the intermediate product for esterification reaction, filter after the reaction is completed, and obtain fatty alcohol polyoxyethylene ether fatty acid ester. 2. The method for preparing fatty alcohol polyoxyethylene ether fatty acid ester according to claim 1, wherein the polyol is one of diethylene glycol, propylene glycol, glycerol, n-butanol, isooctyl alcohol or n-octanol. 3. The method for preparing fatty alcohol polyoxyethylene ether fatty acid ester according to claim 1, wherein the alkaline catalyst is one of potassium methoxide, sodium methoxide, sodium hydride, potassium hydroxide or sodium hydroxide. 4. The method for preparing fatty alcohol-polyoxyethylene ether fatty acid ester according to claim 1, wherein the concentration of the aqueous sulfuric acid solution is 10-30wt.%. 5. The method for preparing fatty alcohol polyoxyethylene ether fatty acid ester according to claim 1, wherein the fatty acid is one of stearic acid, oleic acid or lauric acid. 6. The method for preparing fatty alcohol polyoxyethylene ether fatty acid ester according to claim 1, characterized in that, in the step (1), the mass of the alkali metal in the alkaline catalyst is 0.1-0.5wt.% of the total amount of the polyol and ethylene oxide. 7. The method for preparing fatty alcohol polyoxyethylene ether fatty acid ester according to claim 1, characterized in that, in the step (2), the molar ratio of sulfuric acid to the alkaline catalyst is (0.9-1.1):1. 8. The method for preparing fatty alcohol polyoxyethylene ether fatty acid ester according to claim 1, characterized in that in the step (2), the stirring reaction temperature is 85-90°C and the time is 1-2 hours. 9. The method for preparing fatty alcohol polyoxyethylene ether fatty acid ester according to claim 1, characterized in that, in the step (3), the ratio of the added molar amount of fatty acid to the molar amount of hydroxyl groups in the polyol is (0.9~1.1):1. 10. The method for preparing fatty alcohol polyoxyethylene ether fatty acid ester according to claim 1, characterized in that in the step (3), the temperature of the esterification reaction is 135-150°C and the pressure is -0.06--0.09MPa.