An N-alkyl amino acid surfactant and a method for preparing the same

Abstract

The application provides an N-alkyl amino acid surfactant and a preparation method thereof, and belongs to the technical field of surfactants; sodium glycinate, aliphatic aldehyde and deionized water are added into a reactor according to a certain molar ratio, a certain amount of BaO-CeO2 catalyst is added, and the reaction is carried out under the conditions of a temperature of 65-85 DEG C and stirring for 1-2 hours; then, heating and stirring are stopped, and the temperature is reduced to room temperature; the filtrate is filtered, and the lower layer liquid is obtained after the filtrate is layered and left to stand, so that the amino acid surfactant is obtained. The sodium glycinate and the aliphatic aldehyde are subjected to a dehydration reaction under the action of the BaO-CeO2 catalyst to prepare the amino acid surfactant; the method is simple in operation, high in product yield, and the prepared amino acid surfactant has excellent foam stabilizing and emulsifying properties; the BaO-CeO2 catalyst is prepared by using a grinding method and a supercritical oxygen crystallization method, which is beneficial to forming the nano BaO-CeO2 catalyst with small crystal grain size, good dispersity and large specific surface area.

Description

Technical Field

[0001] This invention belongs to the field of surfactant technology, specifically relating to an N-alkyl amino acid surfactant and its preparation method. Background Technology

[0002] With the promotion of green chemistry concepts and the increasing demand from consumers for environmentally friendly daily chemical products, the limitations of traditional petroleum-based surfactants are becoming increasingly apparent. Problems such as poor biodegradability and high irritation are prompting the search for milder, renewable alternatives. Amino acid surfactants, possessing both excellent surface activity and environmentally friendly properties, have become a research hotspot. N-alkyl amino acid surfactants are a class of surfactants with long-chain alkyl groups as hydrophobic moieties and amino acid groups as hydrophilic moieties. They possess advantages such as being environmentally friendly, readily biodegradable, and mild in performance, exhibiting excellent foam stabilizing and emulsifying properties, and are widely used in daily chemical products. However, common preparation methods often face problems such as harsh reaction conditions, numerous side reactions, low product yield and purity, and insufficient catalyst activity or selectivity, limiting their industrial application. Summary of the Invention

[0003] The purpose of this invention is to provide an N-alkyl amino acid surfactant and its preparation method, which is simple to operate and yields a high yield of amino acid surfactant products.

[0004] This invention provides a method for preparing N-alkyl amino acid surfactants. The method comprises: adding sodium glycinate, fatty aldehyde, and deionized water into a reactor in a certain molar ratio, then adding a certain amount of BaO-CeO2 catalyst, reacting at a temperature of 65-85℃ with stirring for 1-2 h, then stopping heating and stirring, cooling to room temperature, filtering, allowing the filtrate to stand and separate into layers, and taking the lower layer to obtain the amino acid surfactant. The reaction equation is as follows:

[0005]

[0006] Wherein, R is a C3-C17 straight-chain alkyl group.

[0007] Furthermore, the molar ratio of sodium glycinate, fatty aldehyde, and deionized water is 1:(1.2~1.8):(60~120).

[0008] Furthermore, the stirring speed is 80–120 rpm.

[0009] Furthermore, the amount of BaO-CeO2 catalyst used is (1.5~3.0) wt% of the total mass of sodium glycinate and fatty aldehydes.

[0010] Furthermore, the preparation method of the BaO-CeO2 catalyst is as follows:

[0011] A certain molar ratio of cerium nitrate and barium hydroxide is added to a mill with a rotation speed of 600-800 r / min. After grinding and mixing for 30-60 min, the solid reaction product obtained by grinding is placed in a supercritical crystallization vessel, a certain amount of deionized water is added, oxygen is introduced, the temperature is raised to 50-80 ℃, the pressure is 8-10 MPa, the crystallization reaction time is 1-2 h, the obtained crystallized product is dried at a temperature of 100-120 ℃ for 12-24 h, and then calcined at a temperature of 550-600 ℃ for 1-3 h to obtain the BaO-CeO2 catalyst.

[0012] The chemical reaction that occurs in the grinder is as follows:

[0013]

[0014] The chemical reactions that occur in the supercritical crystallization reactor are as follows:

[0015] .

[0016] Furthermore, in the preparation method of the BaO-CeO2 catalyst, the molar ratio of cerium nitrate, barium hydroxide, oxygen, and deionized water is 1:(1.5~1.8):(0.25~0.5):(90~180).

[0017] The N-alkyl amino acid surfactants prepared by the above preparation method are also within the scope of protection of this invention.

[0018] Beneficial effects:

[0019] (1) In this invention, amino acid surfactants are prepared by dehydration reaction of sodium glycinate and fatty aldehyde under the action of BaO-CeO2 catalyst. The method is simple to operate, has high product yield and high purity, and the prepared amino acid surfactants have excellent foam stabilizing and emulsifying properties.

[0020] (2) The present invention uses grinding method + supercritical oxygen crystallization method to prepare BaO-CeO2 catalyst. Since supercritical oxygen has high solubility and high diffusivity, it is beneficial to fully dissolve, mix and react the raw materials, which is beneficial to form nano BaO-CeO2 catalyst with small crystal size, good dispersion and large specific surface area, and the yield is high. Attached Figure Description

[0021] Figure 1 SEM images of the BaO-CeO2 catalysts prepared in Example 4 and Comparative Example 1. Detailed Implementation

[0022] The technical solution of the present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited to the embodiments described. In the following embodiments, cerium nitrate refers to anhydrous cerium nitrate, and barium hydroxide refers to anhydrous barium hydroxide.

[0023] Example 1

[0024] Preparation of BaO-CeO2 catalyst: 6.52 g of cerium nitrate and 5.13 g of barium hydroxide were added to a mill with a rotation speed of 600 r / min and ground for 30 min. The resulting solid reaction product was then placed in a supercritical crystallization vessel, and 32.4 g of deionized water was added. 112 mL of oxygen was introduced, the temperature was raised to 50 ℃, the pressure was 8 MPa, and the crystallization reaction time was 1 h. The resulting crystallized product was dried at 100 ℃ for 24 h and then calcined at 550 ℃ for 3 h to obtain a BaO-CeO2 catalyst with a yield of 99.7%. The molar ratio of cerium nitrate, barium hydroxide, oxygen, and deionized water was 1:1.5:0.25:90.

[0025] Preparation of amino acid surfactant: 4.85 g sodium glycine, 16.08 g stearaldehyde and 54 g deionized water were added to a reactor (molar ratio of sodium glycine, stearaldehyde and deionized water was 1:1.2:60), and then 0.31 g BaO-CeO2 catalyst (accounting for 1.5 wt% of the total mass of sodium glycine and stearaldehyde) was added. The reaction was carried out at a temperature of 65℃ and a stirring rate of 80 rpm for 1 h. After heating and stirring were stopped, the mixture was cooled to room temperature, filtered, and the filtrate was allowed to stand and separate into layers. The lower layer was taken to obtain an amino acid surfactant with a yield of 95.5%.

[0026] Example 2

[0027] Preparation of BaO-CeO2 catalyst: 6.52 g of cerium nitrate and 6.16 g of barium hydroxide were added to a mill at 700 r / min and ground for 50 min. The resulting solid reaction product was then placed in a supercritical crystallization reactor, and 43.2 g of deionized water was added. 224 mL of oxygen was introduced, the temperature was raised to 70 °C, the pressure was 8.8 MPa, and the crystallization reaction time was 2 h. The resulting crystallized product was dried at 120 °C for 12 h and then calcined at 580 °C for 2 h to obtain a BaO-CeO2 catalyst with a yield of 99.5%. The molar ratio of cerium nitrate, barium hydroxide, oxygen, and deionized water was 1:1.8:0.5:120.

[0028] Preparation of amino acid surfactant: 4.85 g sodium glycine, 16.56 g lauraldehyde and 108 g deionized water were added to a reactor (molar ratio of sodium glycine, lauraldehyde and deionized water was 1:1.8:120), and then 0.64 g BaO-CeO2 catalyst (3.0 wt% of the total mass of sodium glycine and lauraldehyde) was added. The reaction was carried out at 85℃ and 100 rpm for 2 h. After heating and stirring were stopped, the mixture was cooled to room temperature, filtered, and the filtrate was allowed to stand and separate into layers. The lower layer was taken to obtain an amino acid surfactant with a yield of 95.8%.

[0029] Example 3

[0030] Preparation of BaO-CeO2 catalyst: 6.52 g of cerium nitrate and 5.81 g of barium hydroxide were added to a mill at 750 r / min and ground for 45 min. The resulting solid reaction product was then placed in a supercritical crystallization vessel, and 57.6 g of deionized water was added. 201.6 mL of oxygen was introduced, the temperature was raised to 75 °C, the pressure was 9.3 MPa, and the crystallization reaction time was 1.5 h. The resulting crystallized product was dried at 110 °C for 18 h and then calcined at 580 °C for 1.5 h to obtain a BaO-CeO2 catalyst with a yield of 99.8%. The molar ratio of cerium nitrate, barium hydroxide, oxygen, and deionized water was 1:1.7:0.45:160.

[0031] Preparation of amino acid surfactant: 4.85 g sodium glycine, 6.12 g n-butyraldehyde and 76.5 g deionized water were added to a reactor (molar ratio of sodium glycine, n-butyraldehyde and deionized water was 1:1.7:85), and then 0.25 g BaO-CeO2 catalyst (accounting for 2.3 wt% of the total mass of sodium glycine and n-butyraldehyde) was added. The reaction was carried out at 70 ℃ and 110 rpm for 1.5 h. After heating and stirring were stopped, the mixture was cooled to room temperature, filtered, and the filtrate was allowed to stand and separate into layers. The lower layer was taken to obtain an amino acid surfactant with a yield of 96.1%.

[0032] Example 4

[0033] Preparation of BaO-CeO2 catalyst: 6.52 g of cerium nitrate and 6.16 g of barium hydroxide were added to a mill with a rotation speed of 680 r / min and ground for 55 min. The resulting solid reaction product was then placed in a supercritical crystallization vessel, and 61.2 g of deionized water was added. 201.6 mL of oxygen was introduced, the temperature was raised to 65℃, the pressure was 8.8 MPa, and the crystallization reaction time was 1 h. The resulting crystallized product was dried at 120℃ for 24 h and then calcined at 550℃ for 3 h to obtain a BaO-CeO2 catalyst with a yield of 99.5%. The molar ratio of cerium nitrate, barium hydroxide, oxygen, and deionized water was 1:1.8:0.45:170.

[0034] Preparation of amino acid surfactant: 4.85 g sodium glycine, 8 g hexanal and 72 g deionized water were added to a reactor (molar ratio of sodium glycine, hexanal and deionized water was 1:1.6:80), and then 0.33 g BaO-CeO2 catalyst (accounting for 2.6 wt% of the total mass of sodium glycine and hexanal) was added. The reaction was carried out at 70 ℃ and 100 rpm for 2 h. After heating and stirring were stopped, the mixture was cooled to room temperature, filtered, and the filtrate was allowed to stand and separate into layers. The lower layer was taken to obtain an amino acid surfactant with a yield of 96.9%.

[0035] Example 5

[0036] Preparation of BaO-CeO2 catalyst: 6.52 g of cerium nitrate and 5.47 g of barium hydroxide were added to a mill at 800 r / min and ground for 55 min. The resulting solid reaction product was then placed in a supercritical crystallization vessel, and 55.8 g of deionized water was added. 215 mL of oxygen was introduced, the temperature was raised to 80 °C, the pressure was 9.5 MPa, and the crystallization reaction time was 1 h. The resulting crystallized product was dried at 120 °C for 20 h and then calcined at 550 °C for 3 h to obtain a BaO-CeO2 catalyst with a yield of 99.7%. The molar ratio of cerium nitrate, barium hydroxide, oxygen, and deionized water was 1:1.6:0.48:155.

[0037] Preparation of amino acid surfactant: 4.85 g sodium glycine, 10.92 g n-decanal and 85.5 g deionized water were added to a reactor (molar ratio of sodium glycine, n-decanal and deionized water was 1:1.4:95), and then 0.47 g BaO-CeO2 catalyst (accounting for 3.0 wt% of the total mass of sodium glycine and n-decanal) was added. The reaction was carried out at 85℃ and a stirring rate of 120 rpm for 2 h. After heating and stirring were stopped, the mixture was cooled to room temperature, filtered, and the filtrate was allowed to stand and separate into layers. The lower layer was taken to obtain an amino acid surfactant with a yield of 95.7%.

[0038] Example 6

[0039] Preparation of BaO-CeO2 catalyst: 6.52 g of cerium nitrate and 5.13 g of barium hydroxide were added to a mill with a rotation speed of 650 r / min and ground for 60 min. The resulting solid reaction product was placed in a supercritical crystallization vessel, and 39.6 g of deionized water was added. 156.8 mL of oxygen was introduced, the temperature was raised to 65℃, the pressure was 8.3 MPa, and the crystallization reaction time was 2 h. The resulting crystallized product was dried at 120 ℃ for 24 h and then calcined at 600 ℃ for 1 h to obtain a BaO-CeO2 catalyst with a yield of 99.4%. The molar ratio of cerium nitrate, barium hydroxide, oxygen, and deionized water was 1:1.5:0.35:110.

[0040] Preparation of amino acid surfactant: 4.85 g sodium glycine, 16.8 g palmital and 99 g deionized water were added to a reactor (molar ratio of sodium glycine, palmital and deionized water was 1:1.4:110), and then 0.43 g BaO-CeO2 catalyst (accounting for 2.0 wt% of the total mass of sodium glycine and palmital) was added. The reaction was carried out at 66 ℃ and 110 rpm for 2 h. After heating and stirring were stopped, the mixture was cooled to room temperature, filtered, and the filtrate was allowed to stand and separate into layers. The lower layer was taken to obtain an amino acid surfactant with a yield of 95.9%.

[0041] Comparative Example 1

[0042] The catalyst was prepared under normal pressure and oxygen conditions. The preparation conditions for the other catalysts and amino acid surfactants were the same as in Example 4. Preparation of the BaO-CeO2 catalyst: 6.52 g of cerium nitrate and 6.16 g of barium hydroxide were added to a mill with a rotation speed of 680 r / min and ground for 55 min. The resulting solid reaction product was placed in a supercritical crystallization reactor, and 61.2 g of deionized water was added. Oxygen was introduced through a vent pipe connected to the bottom of the reactor at a flow rate of 3.36 mL / min for 1 h, and then discharged from the exhaust port on the top of the reactor lid. A total of 201.6 mL of oxygen was consumed. The temperature was raised to 65 °C, and the crystallization reaction was carried out under normal pressure for 1 h. The resulting crystallized product was dried at 120 °C for 24 h and then calcined at 550 °C for 3 h to obtain a BaO-CeO2 catalyst with a yield of 99.4%. The molar ratio of cerium nitrate, barium hydroxide, oxygen, and deionized water was 1:1.8:0.45:170.

[0043] Preparation of amino acid surfactant: 4.85 g sodium glycine, 8 g hexanal and 72 g deionized water were added to a reactor (molar ratio of sodium glycine, hexanal and deionized water was 1:1.6:80), and then 0.33 g BaO-CeO2 catalyst (accounting for 2.6 wt% of the total mass of sodium glycine and hexanal) was added. The reaction was carried out at 70 ℃ and 100 rpm for 2 h. After heating and stirring were stopped, the mixture was cooled to room temperature, filtered, and the filtrate was allowed to stand and separate into layers. The lower layer was taken to obtain an amino acid surfactant with a yield of 89.4%.

[0044] Figure 1 The images show SEM images of the BaO-CeO2 catalysts prepared in Example 4 and Comparative Example 1. As can be seen from the images, the BaO-CeO2 catalyst prepared in Example 4 has a regular crystal morphology, good particle dispersion, and a small crystal size of about 12 nm. In contrast, the BaO-CeO2 catalyst prepared in Comparative Example 1 has severe particle packing and an irregular morphology. This indicates that the addition of supercritical oxygen in Example 4 is beneficial to the formation of a nano BaO-CeO2 catalyst with a regular morphology, good dispersion, and small crystal size.

[0045] Table 1 shows the specific surface areas of the BaO-CeO2 catalysts prepared in Examples 1-6 and Comparative Example 1, obtained by BET characterization. As shown in Table 1, the BaO-CeO2 catalyst formed in supercritical oxygen has a large specific surface area and high catalytic activity, which is beneficial for the adsorption of reactants, resulting in excellent catalytic performance and a high yield of amino acid surfactants. In contrast, the BaO-CeO2 catalyst prepared in Comparative Example 1 under atmospheric pressure oxygen conditions has a smaller specific surface area and lower catalytic activity.

[0046] The amino acid surfactants synthesized in Examples 1-6 and Comparative Example 1 were tested for foam stabilization and emulsification properties, and their performance was compared with that of sodium fatty acid polyoxyethylene ether sulfate (AES), a commercially available surfactant with excellent foam stabilization and emulsification properties.

[0047] Table 1

[0048]

[0049] 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 graduated cylinder, sonicate for 30 min, and then shake vigorously 20 times. Record the initial foam height (H1, cm) and the foam height (H2, cm) after standing for 5 min. The larger this value, the better its foam stabilization performance.

[0050] Emulsification performance 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 graduated cylinder, add 20 mL of kerosene, shake vigorously for 50 minutes, and let stand. Record the time it takes for 10 mL of aqueous phase to separate (separation time). Repeat the test three times and take the average value. The longer the separation time, the stronger the emulsification ability.

[0051] Table 2

[0052]

[0053] As can be seen from the test results in Table 2, the amino acid surfactants synthesized in Examples 1-6 and Comparative Example 1 of this invention have better foam stabilization and emulsifying properties than AES.

[0054] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention.

Claims

1. A method for preparing an N-alkyl amino acid surfactant, characterized in that, Sodium glycinate, fatty aldehyde, and deionized water were added to a reactor in a specific molar ratio, followed by a certain amount of BaO-CeO2 catalyst. The reaction was carried out at 65–85 °C with stirring for 1–2 h. After heating and stirring were stopped, the mixture was cooled to room temperature, filtered, and the filtrate was allowed to stand and separate into layers. The lower layer was then collected to obtain the amino acid surfactant. The reaction equation is as follows: ； Wherein, R is a C3-C17 straight-chain alkyl group.

2. The preparation method according to claim 1, characterized in that, The molar ratio of sodium glycinate, fatty aldehyde, and deionized water is 1:(1.2~1.8):(60~120).

3. The preparation method according to claim 1, characterized in that, Stirring speed: 80-120 rpm.

4. The preparation method according to claim 1, characterized in that, The amount of BaO-CeO2 catalyst used is (1.5~3.0) wt% of the total mass of sodium glycinate and fatty aldehydes.

5. The preparation method according to claim 1, characterized in that, The preparation method of BaO-CeO2 catalyst is as follows: A certain molar ratio of cerium nitrate and barium hydroxide is added to a mill with a rotation speed of 600-800 r / min. After grinding and mixing for 30-60 min, the solid reaction product obtained by grinding is placed in a supercritical crystallization vessel, a certain amount of deionized water is added, oxygen is introduced, the temperature is raised to 50-80 ℃, the pressure is 8-10 MPa, the crystallization reaction time is 1-2 h, the obtained crystallized product is dried at a temperature of 100-120 ℃ for 12-24 h, and then calcined at a temperature of 550-600 ℃ for 1-3 h to obtain the BaO-CeO2 catalyst. The chemical reaction that occurs in the grinder is as follows: ； The chemical reactions that occur in the supercritical crystallization reactor are as follows: 。 6. The preparation method according to claim 5, characterized in that, In the preparation method of the BaO-CeO2 catalyst, the molar ratio of cerium nitrate, barium hydroxide, oxygen and deionized water is 1:(1.5~1.8):(0.25~0.5):(90~180).

7. The N-alkyl amino acid surfactant prepared by the preparation method according to any one of claims 1-6.

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