Preparation method of N-acylamino acid surfactant

Abstract

The invention discloses a preparation method of an N-acylamino acid surfactant, and belongs to the technical field of surfactants. The preparation method comprises the following steps: by taking alkylamide and fatty acid as raw materials and nano Cu as a catalyst, reacting at 200-350 DEG C for 3-5 hours, after the reaction is finished, filtering to remove the nano Cu, standing and layering filtrate, and taking subnatant, so as to obtain the N-acylamino acid surfactant, the alkyl amide is alkyl amide of C6 to C18; and the fatty acid is C6-C22 fatty acid. The preparation method disclosed by the invention is simple to operate, low in reaction temperature, free of generation of byproducts in the reaction and high in product yield, and the prepared N-acylamino acid surfactant has excellent emulsifying capacity and foam stabilizing performance. The nano Cu prepared by the method is regular in morphology, relatively small in grain size, relatively large in specific surface area and more in exposed catalytic active sites.

Description

Technical Field

[0001] The invention belongs to the technical field of surfactants, and particularly relates to a method for preparing an N-acyl amino acid surfactant. Background Art

[0002] Amino acid surfactants are surfactants with excellent properties such as low irritation, low toxicity, good biocompatibility, good biodegradability and environmental compatibility. Amino acid surfactants can be divided into N-acyl amino acid surfactants and N-alkyl amino acid surfactants according to the group type. Among them, N-acyl amino acid surfactants have the following characteristic structure: It is a category of amino acid surfactants that is currently widely used in daily chemical applications. Due to its excellent surface activity, safety, mildness and good biodegradability, it can partially or completely replace traditional anionic surfactants and is currently widely used in cleaning products. Summary of the invention

[0003] The object of the present invention is to provide a method for preparing an N-acyl amino acid surfactant. The amino acid surfactant prepared by the method has high yield and high purity.

[0004] The preparation method of N-acyl amino acid surfactant provided by the present invention uses alkyl amide and fatty acid as raw materials, nano Cu as catalyst, reacts at 200-350°C for 3-5h, and after the reaction, filters to remove nano Cu, and allows the filtrate to stand for stratification, and takes the lower layer liquid to obtain N-acyl amino acid surfactant; the alkyl amide is C6-C18 alkyl amide; the fatty acid is C6-C22 fatty acid. The reaction equation of the preparation method of the present invention is as follows:

[0005]

[0006] Among them, R1 is a C6-C18 straight-chain alkyl group, and R2 is a C4-C20 straight-chain alkyl group.

[0007] Furthermore, the preparation method of the nano Cu comprises the following steps:

[0008] Step (1), adding a soluble copper salt, an alkali, a template and deionized water into a supercritical reactor in a certain molar ratio, stirring at room temperature at a stirring rate of 80 to 120 r / min for 30 to 60 minutes, then introducing carbon dioxide gas into the reactor, then heating to 30 to 80° C., the pressure in the reactor is 7 to 10 MPa, and reacting for 15 to 60 minutes; during the reaction process, as the carbon dioxide participates in the reaction and is consumed, the pressure in the reactor decreases, and the pressure is supplemented by introducing nitrogen;

[0009] Step (2), filtering the product obtained in step (1), washing with deionized water until the pH value of the filtrate is 7.0, and then drying in an oven at 100-120° C. for 12-24 hours, cooling to room temperature, charging the cooled product into a tubular furnace, calcining and reducing at 200-250° C. for 1-3 hours in a hydrogen-nitrogen mixed atmosphere, and cooling to room temperature to obtain nano Cu.

[0010] Furthermore, in step (1), the molar ratio of the soluble copper salt, the base, the template, the deionized water and the carbon dioxide is 1:(2.0-2.5):(0.1-0.3):(15.0-25.0):(1.5-3.0).

[0011] Furthermore, in step (2), the volume content of hydrogen in the hydrogen-nitrogen mixed gas is 10%.

[0012] Furthermore, in step (1), the soluble copper salt is one of copper chloride, copper nitrate and copper sulfate; the base is one of sodium hydroxide and potassium hydroxide; and the template agent is sodium N-dodecyl-N-butyldodecanoate.

[0013] Beneficial effects: (1) The present invention prepares N-acyl amino acid surfactants by dehydrogenation reaction of alkylamide and fatty acid under the action of nano Cu catalyst. The method is simple to operate, has a low reaction temperature, no by-products are generated in the reaction, and the product yield is high. The prepared N-acyl amino acid surfactant has excellent emulsification ability and foam stabilization performance. (2) The nano Cu prepared by the present invention has a regular morphology and a small grain size, a large specific surface area, and many exposed catalytic active sites. When it is used as a catalyst to catalyze the synthesis of N-acyl amino acid surfactants, it has good catalytic activity, which is beneficial to improve the yield of N-acyl amino acid surfactants. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The SEM images of nano-Cu prepared in Example 3 and Comparative Example 1 are shown in FIG. 1 , (a) is the SEM image of nano-Cu prepared in Example 3, and (b) is the SEM image of nano-Cu prepared in Comparative Example 1. DETAILED DESCRIPTION

[0015] The technical solution of the present invention is described in detail below through embodiments, but the protection scope of the present invention is not limited to the embodiments.

[0016] Example 1

[0017] The embodiment provides a method for preparing an N-acyl amino acid surfactant, comprising the following steps:

[0018] Step 1: Preparation of nano Cu. The specific steps are as follows:

[0019] Step (1), add 6.7g copper chloride, 4.0g sodium hydroxide, 2.4g template and 22.5g deionized water into a supercritical reactor, stir at room temperature at a stirring rate of 80r / min for 30min, then introduce 1.7L carbon dioxide gas into the reactor, the molar ratio of soluble copper salt, alkali, template, deionized water and carbon dioxide is 1:2:0.1:25:1.5, then heat to 30°C, the pressure in the reactor is 7MPa, and react for 15min. During the reaction, the pressure in the reactor is maintained at 7MPa by introducing nitrogen;

[0020] Step (2), filtering the product obtained in step (1), washing with deionized water until the pH value of the filtrate is 7.0, and then drying in an oven at 100° C. for 24 h, cooling to room temperature, charging the cooled product into a tubular furnace, calcining and reducing it at 200° C. for 1 h in a hydrogen-nitrogen mixed atmosphere (hydrogen volume content is 10%), and cooling it to room temperature to obtain nano Cu with a yield of 99.5%.

[0021] Step 2, prepare N-acyl amino acid surfactant, preparation method: add 6.5g hexyl amide and 5.8g hexanoic acid into a reaction container, the molar ratio is 1:1; then add 0.01g of the above-mentioned nano Cu, the catalyst amount is 0.1wt% of the total mass of the raw materials; react at 200°C for 3.0h, after the reaction is completed, filter to remove the nano Cu, let the filtrate stand for stratification, take the lower layer liquid, and obtain the N-acyl amino acid surfactant, the yield is 99.1%.

[0022] Example 2

[0023] The embodiment provides a method for preparing an N-acyl amino acid surfactant, comprising the following steps:

[0024] Step 1: Preparation of nano Cu. The specific steps are as follows:

[0025] Step (1), add 6.7g copper chloride, 7.0g potassium hydroxide, 7.2g template and 13.5g deionized water into a supercritical reactor, stir at room temperature at a stirring rate of 100r / min for 60min, then introduce 3.4L carbon dioxide gas into the reactor, the molar ratio of soluble copper salt, alkali, template, deionized water and carbon dioxide is 1:2.5:0.3:15:3, then heat to 60°C, the pressure in the reactor is 9MPa, and react for 30min. During the reaction, the pressure in the reactor is maintained at 9MPa by introducing nitrogen;

[0026] Step (2), filtering the product obtained in step (1), washing with deionized water until the pH value of the filtrate is 7.0, and then drying in an oven at 120° C. for 12 h, cooling to room temperature, charging the cooled product into a tubular furnace, calcining and reducing it at 250° C. for 3 h in a hydrogen-nitrogen mixed atmosphere (hydrogen volume content is 10%), and cooling it to room temperature to obtain nano Cu with a yield of 99.7%.

[0027] Step 2, prepare N-acyl amino acid surfactant, preparation method: add 10.7g lauramide and 22.1g docosic acid into a reaction container, the molar ratio is 1:1.3; then add 0.16g of the above-mentioned nano Cu, the amount of catalyst is 0.5wt% of the total mass of the raw materials; react at 300°C for 4.0h, after the reaction is completed, filter to remove the nano Cu, let the filtrate stand for stratification, take the lower layer liquid, and obtain the N-acyl amino acid surfactant, the yield is 99.3%.

[0028] Example 3

[0029] The embodiment provides a method for preparing an N-acyl amino acid surfactant, comprising the following steps:

[0030] Step 1: Preparation of nano Cu. The specific steps are as follows:

[0031] (1) 9.4 g of copper nitrate, 6.2 g of potassium hydroxide, 4.8 g of template and 18.0 g of deionized water were added to a supercritical reactor, stirred at room temperature at a stirring rate of 120 r / min for 45 min, and then 2.2 L of carbon dioxide gas was introduced into the reactor, and the molar ratio of soluble copper salt, alkali, template, deionized water and carbon dioxide was 1:2.2:0.2:20:2, then the temperature was raised to 80°C, the pressure in the reactor was 10 MPa, and the reaction was carried out for 60 min. During the reaction, the pressure in the reactor was maintained at 10 MPa by introducing nitrogen;

[0032] (2) The product obtained in step (1) is filtered, washed with deionized water until the pH value of the filtrate is 7.0, and then dried in an oven at 120° C. for 24 h, cooled to room temperature, and the cooled product is placed in a tubular furnace, calcined and reduced at 220° C. for 2 h in a hydrogen-nitrogen mixed atmosphere (hydrogen volume content is 10%), and cooled to room temperature to obtain nano Cu with a yield of 99.5%.

[0033] Step 2, prepare N-acyl amino acid surfactant, preparation method: add 10.7g lauramide and 12.0g lauric acid into a reaction container, the molar ratio is 1:1.2; then add 0.07g of the above-mentioned nano Cu, the amount of catalyst is 0.3wt% of the total mass of the raw materials; react at 350°C for 5.0h, after the reaction is completed, filter to remove the nano Cu, let the filtrate stand for stratification, take the lower layer liquid, and obtain the N-acyl amino acid surfactant, the yield is 99.6%.

[0034] Example 4

[0035] The embodiment provides a method for preparing an N-acyl amino acid surfactant, comprising the following steps:

[0036] Step 1: Preparation of nano Cu. The specific steps are as follows:

[0037] (1) 8.0 g of copper sulfate, 4.8 g of sodium hydroxide, 2.4 g of template and 16.2 g of deionized water were added to a supercritical reactor, stirred at room temperature at a stirring rate of 100 r / min for 50 min, and then 2.8 L of carbon dioxide gas was introduced into the reactor, and the molar ratio of soluble copper salt, alkali, template, deionized water and carbon dioxide was 1:2.4:0.1:18:2.5, and then the temperature was raised to 50°C, the pressure in the reactor was 8 MPa, and the reaction was continued for 50 min. During the reaction, the pressure in the reactor was maintained at 8 MPa by introducing nitrogen;

[0038] (2) The product obtained in step (1) was filtered, washed with deionized water until the pH value of the filtrate was 7.0, and then dried in an oven at 120° C. for 12 h, cooled to room temperature, and the cooled product was placed in a tubular furnace, calcined and reduced at 210° C. for 3 h in a hydrogen-nitrogen mixed atmosphere (hydrogen volume content was 10%), and cooled to room temperature to obtain nano Cu with a yield of 99.8%.

[0039] Step 2, prepare N-acyl amino acid surfactant, preparation method: add 14.9g octadecylamide and 18.5g octadecanoic acid into a reaction container, the molar ratio is 1:1.3; then add 0.17g of the above-mentioned nano Cu, the amount of catalyst is 0.5wt% of the total mass of the raw materials; react at 300°C for 3.0h, after the reaction is completed, filter to remove the nano Cu, let the filtrate stand for stratification, take the lower layer liquid, and obtain the N-acyl amino acid surfactant, the yield is 99.2%.

[0040] Comparative Example 1

[0041] According to the molar ratio in Example 3, that is, the molar ratio of soluble copper salt, alkali, template and deionized water is 1:2.2:0.2:20, and the Cu catalyst is prepared without supercritical carbon dioxide conditions, including the following steps:

[0042] (1) 9.4 g of copper nitrate, 6.2 g of potassium hydroxide, 4.8 g of template and 18.0 g of deionized water were added to a supercritical reactor, stirred at room temperature at a stirring rate of 120 r / min for 45 min, then heated to 80° C. and reacted for 60 min;

[0043] (2) The product obtained in step (1) was filtered and washed with deionized water until the pH value of the filtrate was 7.0, and then dried in an oven at 120° C. for 24 h, cooled to room temperature, and the cooled product was placed in a tubular furnace, calcined and reduced at 220° C. for 2 h in a hydrogen-nitrogen mixed atmosphere (hydrogen volume content was 10%), and cooled to room temperature to obtain a Cu catalyst with a yield of 98.2%.

[0044] The preparation method of N-acyl amino acid surfactant is as follows: 10.7g of lauramide and 12.0g of lauric acid are added to a reaction container in a molar ratio of 1:1.2; then 0.07g of the above-mentioned Cu catalyst is added, and the amount of the catalyst is 0.3wt% of the total mass of the raw materials; the reaction is carried out at 350°C for 5.0h. After the reaction is completed, the Cu catalyst is filtered out, the filtrate is allowed to stand for stratification, and the lower layer liquid is taken to obtain the N-acyl amino acid surfactant, and the yield is 90.1%.

[0045] The products prepared in Examples 1 to 4 and the comparative examples were tested, and the results were as follows:

[0046] (1) Figure 1 The SEM images of the Cu catalysts prepared in Example 3 and Comparative Example 1 show that the Cu catalyst prepared in Example 3 has a regular crystal morphology and a small grain size of about 51 nm, while the Cu catalyst prepared in Comparative Example 1 has an irregular crystal morphology and a large grain size of about 102 nm, which illustrates that the addition of supercritical carbon dioxide in Example 3 is conducive to the formation of a nano Cu catalyst with a regular morphology and a small grain size. The supercritical carbon dioxide fluid has high solubility and high diffusivity, which is conducive to sufficient and rapid contact and reaction between the reactants, so that the product has a high degree of dispersibility, avoids the agglomeration phenomenon between the nanoparticles, and thus inhibits the increase of the grain size. In the operation process of the present invention, the supercritical carbon dioxide participates in the chemical reaction as a raw material, reacts with the copper source and the alkali source to generate basic copper carbonate (2Cu 2 ++4OH-+CO 2 =Cu 2 (OH) 2 CO 3 ↓+H 2 O), thereby promoting the reaction and ultimately promoting the increase in the yield of the nano Cu catalyst.

[0047] (2) Table 1 shows the specific surface areas of the Cu catalysts prepared in Examples 1-4 and Comparative Example 1 obtained by BET characterization. As shown in Table 1, the nano Cu catalysts with regular morphology and small grain size formed in supercritical carbon dioxide have large specific surface areas, high catalytic activity, and are conducive to the adsorption of the reaction raw materials, thereby producing excellent catalytic performance, and the yield of the obtained N-acylamino acid surfactant is high.

[0048] Table 1

[0049] sample <![CDATA[Specific surface area (m 2 / g)]]> Example 1 42 Example 2 40 Example 3 45 Example 4 43 Comparative Example 1 29

[0050] (3) Performance test:

[0051] The N-acyl amino acid surfactants synthesized in Examples 1-4 and Comparative Example 1 were tested for foam stabilization and emulsification properties, and compared with the performance of commercial surfactant sodium polyoxyethylene fatty acid ether sulfate (AES) currently on the market with excellent foam stabilization and emulsification properties.

[0052] Foam stability test method: prepare a surfactant solution with a mass fraction of 1% using deionized water, take 20 mL of the solution into a 100 mL stoppered measuring cylinder, ultrasonicate for 30 minutes, vibrate vigorously 20 times, and record the initial foam height (H 1 , cm) and the foam height after standing for 5 min (H 2 , cm), The larger this value is, the better the foam stabilization performance is.

[0053] Emulsification performance test method: Use deionized water to prepare a 1% surfactant solution, take 20mL of the solution into a 100mL stoppered measuring cylinder, then add 20mL of kerosene, shake vigorously for 50 seconds and let it stand, record the time it takes to separate 10mL of water phase (separation time), repeat the test three times and take the average value. The longer the separation time, the stronger the emulsification ability.

[0054] The test results are shown in Table 2:

[0055] Table 2

[0056] sample Foam stability (%) Separation time (s) Example 1 91.9 110.6 Example 2 92.0 111.1 Example 3 92.2 110.3 Example 4 92.0 111.0 Comparative Example 1 91.7 109.8 AES 91.5 102.4

[0057] It can be seen from the test results in Table 2 that the foam stabilizing performance and emulsifying ability of the N-acyl amino acid surfactants synthesized in Examples 1-4 of the present invention and Comparative Example 1 are better than those of AES.

[0058] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes in form and details may be made without departing from the spirit and scope of the present invention.

Claims

1. A method for preparing an N-acylamino acid surfactant, characterized in that: Alkylamide and fatty acid are used as raw materials, nano Cu is used as catalyst, and the reaction is carried out at 200-350°C for 3-5 hours. After the reaction is completed, the nano Cu is filtered out, the filtrate is allowed to stand for stratification, and the lower layer liquid is taken to obtain an N-acyl amino acid surfactant; the alkylamide is a C6-C18 alkylamide; and the fatty acid is a C6-C22 fatty acid.

2. The preparation method according to claim 1, characterized in that: The molar ratio of the alkylamide to the fatty acid is 1:(1.0-1.3).

3. The preparation method according to claim 1, characterized in that: The amount of the nano Cu is 0.1-0.5 wt % of the total mass of the alkyl amide and the fatty acid.

4. The preparation method according to claim 1, characterized in that: The preparation method of the nano Cu comprises the following steps: Step (1), adding a soluble copper salt, an alkali, a template and deionized water into a supercritical reactor in a certain molar ratio, stirring at room temperature at a stirring rate of 80 to 120 r / min for 30 to 60 minutes, then introducing carbon dioxide gas into the reactor, then heating to 30 to 80° C., the pressure in the reactor is 7 to 10 MPa, and reacting for 15 to 60 minutes; during the reaction process, when the pressure in the reactor drops, nitrogen is introduced to supplement the pressure; Step (2), filtering the product obtained in step (1), washing with deionized water until the pH value of the filtrate is 7.0, and then drying in an oven at 100-120° C. for 12-24 hours, cooling to room temperature, charging the cooled product into a tubular furnace, calcining and reducing at 200-250° C. for 1-3 hours in a hydrogen-nitrogen mixed atmosphere, and cooling to room temperature to obtain nano Cu.

5. The preparation method according to claim 4, characterized in that: In step (1), the molar ratio of soluble copper salt, alkali, template, deionized water and carbon dioxide is 1:(2.0-2.5):(0.1-0.3):(15.0-25.0):(1.5-3.0).

6. The preparation method according to claim 4, characterized in that: In step (2), the volume content of hydrogen in the hydrogen-nitrogen mixed gas is 10%.

7. The preparation method according to claim 4, characterized in that: In step (1), the soluble copper salt is one of copper chloride, copper nitrate and copper sulfate; the alkali is one of sodium hydroxide and potassium hydroxide; and the template agent is sodium N-dodecyl-N-butyl dodecanoate.

Images