Amino acid surfactant and preparation method thereof

Abstract

The invention discloses an amino acid surfactant and a preparation method thereof, and belongs to the technical field of surfactants, the preparation method comprises the following steps: adding tryptophan sodium, halogenated n-alkane, alkali and deionized water into a reactor according to a certain molar ratio, then adding a certain amount of nano nickel catalyst, reacting for 1-3 hours under the stirring condition at the temperature of 30-60 DEG C, filtering, washing, and drying to obtain the amino acid surfactant. And stopping heating and stirring, cooling to room temperature, filtering, standing and layering the filtrate, and taking the supernatant to obtain the amino acid surfactant. The preparation method disclosed by the invention is simple to operate, low in reaction temperature, high in product yield and high in purity, and the prepared amino acid surfactant has excellent hard water resistance and excellent foaming performance.

Description

Technical Field

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

[0002] Amino acid surfactants are a class of surfactants with advantages such as being environmentally friendly, readily biodegradable, and having mild properties. Based on their structural characteristics, amino acid surfactants can be divided into N-alkyl amino acid surfactants and N-acyl amino acid surfactants. Among them, N-alkyl amino acid surfactants have long-chain alkyl groups as their hydrophobic groups and are commonly used in products such as shampoos and toothpastes, exhibiting excellent hard water resistance and foaming properties. Summary of the Invention

[0003] This invention provides an amino acid surfactant and its preparation method, with the aim of providing a novel N-alkyl amino acid surfactant.

[0004] The method for preparing amino acid surfactants provided by this invention is as follows: Sodium tryptophan, haloalkanes, alkali, and deionized water are added to a reactor in a certain molar ratio, and a certain amount of nano-nickel catalyst is added. The reaction is carried out at a temperature of 30-60℃ and a stirring rate of 100-150 rpm for 1-3 hours. After heating and stirring are stopped, the mixture is cooled to room temperature, filtered, and the filtrate is allowed to stand and separate into layers. The upper layer is then collected to obtain the amino acid surfactant. The reaction equation for the preparation method of this invention is as follows:

[0005] Wherein, R is a C4-C18 straight-chain alkyl group, X is Cl or Br, and Y is Na or K.

[0006] Furthermore, the molar ratio of haloalkanes, sodium tryptophan, base, and deionized water is 1:(1.2~1.8):(1.1~1.5):(50~100), and the amount of nano-nickel catalyst is 0.8~1.5 wt% of the total mass of haloalkanes, sodium tryptophan, and base.

[0007] Furthermore, the preparation method of the nano-nickel catalyst is as follows: a nickel source and an alkali source are added to a grinder and ground and mixed to obtain a solid-phase reaction mixture; the solid-phase reaction mixture is placed in a supercritical crystallization vessel, oxygen is introduced, the temperature is maintained at 50-80 °C, the pressure is maintained at 8.5-10 MPa, and a crystallization reaction is carried out under supercritical conditions for 0.5-2 h to obtain a crystallized product; the crystallized product is cooled to room temperature, then washed with deionized water, and filtered to obtain a filter cake; it is dried at 100-120 °C for 12-24 h, cooled to room temperature, and then placed in a tube furnace and calcined and reduced at 300-350 °C for 1-3 h under a hydrogen-nitrogen mixed atmosphere, and then cooled to room temperature to obtain nano-Ni.

[0008] Specifically, the nickel source is either nickel nitrate or nickel chloride.

[0009] Specifically, the alkali source is either sodium hydroxide or potassium hydroxide.

[0010] Specifically, the molar ratio of the nickel source to the alkali source is 1:(2.5-3).

[0011] Specifically, the grinding and mixing process uses a grinding mill with a speed of 800–1000 r / min and a time of 30–45 min.

[0012] Specifically, the oxygen concentration introduced into the supercritical crystallization reactor is not less than 99.9%.

[0013] Specifically, the filtrate was washed with deionized water until the pH of the filtrate reached 7.0.

[0014] Specifically, in the hydrogen-nitrogen mixture, the hydrogen volume content is 10%. Beneficial effects

[0015] (1) In this invention, an amino acid surfactant is prepared by adding nano-Ni catalyst to sodium tryptophan and haloalkanes under alkaline conditions to carry out a nucleophilic substitution reaction. This method is simple to operate, has a low reaction temperature, and produces high product yield and high purity. The prepared amino acid surfactant has excellent hard water resistance and excellent foaming properties.

[0016] (2) The nano-Ni catalyst prepared by the present invention using the grinding method and the supercritical oxygen crystallization method has a regular morphology, small grain size, large specific surface area, and strong catalytic activity, which is beneficial to improving the yield of amino acid surfactants. Attached Figure Description

[0017] Figure 1 SEM images of the nano-Ni catalysts prepared in Example 3 and Comparative Example 1. Detailed Implementation

[0018] 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.

[0019] Example 1 Preparation of nano-Ni catalyst: 3.7 g of nickel nitrate and 2 g of sodium hydroxide (molar ratio of nickel nitrate to sodium hydroxide was 1:2.5) were added to a grinder and ground for 45 min (grinding speed was 800 r / min) to obtain a solid-phase reaction mixture. The solid-phase reaction mixture was placed in a supercritical crystallization reactor, oxygen was introduced, and the temperature was raised to 50 °C for crystallization reaction. The pressure inside the reactor was 8.5 MPa, and the crystallization reaction time was 0.5 h to obtain the crystallized product. The crystallized product was cooled to room temperature, then washed and filtered with deionized water until the pH of the filtrate was 7.0. The obtained filter cake was dried at 120 °C for 24 h, cooled to room temperature, and then placed in a tube furnace. Under a hydrogen-nitrogen mixed atmosphere (hydrogen volume content was 10%), it was calcined and reduced at 300 °C for 3 h. After cooling to room temperature, nano-Ni was obtained with a yield of 99.3%.

[0020] Preparation of amino acid surfactant: 1.8 g of n-butane chloride, 5.4 g of sodium tryptophan, 0.9 g of sodium hydroxide and 18 g of deionized water were added to a reactor in a molar ratio of 1:1.2:1.1:50; then 0.06 g of nano-nickel catalyst was added, which was 0.8 wt% of the total mass of n-butane chloride, sodium tryptophan and sodium hydroxide; the reaction was carried out at 30 ℃ and 100 rpm for 3 h, then heating and stirring were stopped, the mixture was cooled to room temperature, the catalyst was removed by filtration, the filtrate was allowed to stand and separate into layers, and the upper layer was taken to obtain the amino acid surfactant with a yield of 98.3%.

[0021] Example 2 Preparation of nano-Ni catalyst: 2.6 g of nickel chloride and 3.1 g of potassium hydroxide (molar ratio of nickel chloride to potassium hydroxide of 1:2.8) were added to a grinder and ground for 30 min (grinding speed of 1000 r / min) to obtain a solid-phase reaction mixture. The solid-phase reaction mixture was placed in a supercritical crystallization reactor, oxygen was introduced, and the temperature was raised to 80 °C for crystallization reaction. The pressure inside the reactor was 10 MPa, and the crystallization reaction time was 1 h to obtain the crystallized product. The crystallized product was cooled to room temperature, washed with deionized water, and filtered until the pH of the filtrate was 7.0. The obtained filter cake was dried at 100 °C for 12 h, cooled to room temperature, and then placed in a tube furnace. Under a hydrogen-nitrogen mixed atmosphere (hydrogen volume content of 10%), it was calcined and reduced at 350 °C for 1 h. After cooling to room temperature, nano-Ni was obtained with a yield of 99.6%.

[0022] Preparation of amino acid surfactant: 5 g of n-dodecane bromide, 8.1 g of sodium tryptophan, 3.6 g of potassium hydroxide and 36 g of deionized water were added to a reactor in a molar ratio of 1:1.8:1.3:100; then 0.3 g of nano-nickel catalyst was added, which was 1.5 wt% of the total mass of n-dodecane bromide, sodium tryptophan and potassium hydroxide; the reaction was carried out at 50℃ and 150 rpm for 1 h, then heating and stirring were stopped, the mixture was cooled to room temperature, the catalyst was removed by filtration, the filtrate was allowed to stand and separate into layers, and the upper layer was taken to obtain an amino acid surfactant with a yield of 98.5%.

[0023] Example 3 Preparation of nano-Ni catalyst: 3.7 g of nickel nitrate and 3.4 g of potassium hydroxide (molar ratio of nickel nitrate to potassium hydroxide 1:3) were added to a grinder and ground for 45 min (grinding speed of the grinder was 800 r / min) to obtain a solid-phase reaction mixture. The solid-phase reaction mixture was placed in a supercritical crystallization reactor, oxygen was introduced, and the temperature was raised to 75 ℃ for crystallization reaction. The pressure inside the reactor was 9.5 MPa, and the crystallization reaction time was 2 h to obtain the crystallized product. The crystallized product was cooled to room temperature, then washed and filtered with deionized water until the pH of the filtrate was 7.0. The obtained filter cake was dried at 120 ℃ for 24 h, cooled to room temperature, and then placed in a tube furnace. Under a hydrogen-nitrogen mixed atmosphere (hydrogen volume content of 10%), it was calcined and reduced at 350 ℃ for 3 h. After cooling to room temperature, nano-Ni was obtained with a yield of 99.3%.

[0024] Preparation of amino acid surfactant: 2.4 g of n-hexane chloride, 6.8 g of sodium tryptophan, 1.7 g of potassium hydroxide and 36 g of deionized water were added to a reactor in a molar ratio of 1:1.5:1.5:100; then 0.2 g of nano-nickel catalyst was added, which was 1.5 wt% of the total mass of n-hexane chloride, sodium tryptophan and potassium hydroxide; the reaction was carried out at 60℃ and 120 rpm for 3 h, then heating and stirring were stopped, the mixture was cooled to room temperature, the catalyst was removed by filtration, the filtrate was allowed to stand and separate into layers, and the upper layer was taken to obtain the amino acid surfactant with a yield of 99.2%.

[0025] Example 4 Preparation of nano-Ni catalyst: 3.7 g of nickel nitrate and 3.4 g of potassium hydroxide (molar ratio of nickel nitrate to potassium hydroxide was 1:3) were added to a grinder and ground for 40 min (grinding speed was 900 r / min) to obtain a solid-phase reaction mixture. The solid-phase reaction mixture was placed in a supercritical crystallization reactor, oxygen was introduced, and the temperature was raised to 60 °C for crystallization reaction. The pressure inside the reactor was 8.8 MPa, and the crystallization reaction time was 2 h to obtain the crystallized product. The crystallized product was cooled to room temperature, then washed and filtered with deionized water until the pH of the filtrate was 7.0. The obtained filter cake was dried at 120 °C for 18 h, cooled to room temperature, and then placed in a tube furnace. Under a hydrogen-nitrogen mixed atmosphere (hydrogen volume content was 10%), it was calcined and reduced at 330 °C for 2 h. After cooling to room temperature, nano-Ni was obtained with a yield of 99.5%.

[0026] Preparation of amino acid surfactant: 5.8 g of n-octadecane chloride, 7.2 g of sodium tryptophan, 3 g of sodium hydroxide and 28.8 g of deionized water were added to a reactor in a molar ratio of 1:1.6:1.5:80; then 0.2 g of nano-nickel catalyst was added, which was 1 wt% of the total mass of n-octadecane chloride, sodium tryptophan and sodium hydroxide; the reaction was carried out at 60℃ and 120 rpm for 3 h, then heating and stirring were stopped, the mixture was cooled to room temperature, the catalyst was removed by filtration, the filtrate was allowed to stand and separate into layers, and the upper layer was taken to obtain the amino acid surfactant with a yield of 99.0%.

[0027] Example 5 Preparation of nano-Ni catalyst: 2.6 g of nickel chloride and 2.2 g of sodium hydroxide (molar ratio of nickel chloride to sodium hydroxide 1:2.8) were added to a grinder and ground for 45 min (grinding speed of 850 r / min) to obtain a solid-phase reaction mixture. The solid-phase reaction mixture was placed in a supercritical crystallization reactor, oxygen was introduced, and the temperature was raised to 70 °C for crystallization reaction. The pressure inside the reactor was 9.1 MPa, and the crystallization reaction time was 1.5 h to obtain the crystallized product. The crystallized product was cooled to room temperature, then washed and filtered with deionized water until the pH of the filtrate was 7.0. The obtained filter cake was dried at 100 °C for 24 h, cooled to room temperature, and then placed in a tube furnace. Under a hydrogen-nitrogen mixed atmosphere (hydrogen volume content of 10%), it was calcined and reduced at 350 °C for 1 h. After cooling to room temperature, nano-Ni was obtained with a yield of 99.1%.

[0028] Preparation of amino acid surfactant: 6.1 g of hexadecane bromide, 7.2 g of sodium tryptophan, 1.7 g of potassium hydroxide and 25.2 g of deionized water were added to a reactor in a molar ratio of 1:1.6:1.5:70; then 0.2 g of nano-nickel catalyst was added, which was 1.3 wt% of the total mass of hexadecane bromide, sodium tryptophan and potassium hydroxide; the reaction was carried out at 60 ℃ and 130 rpm for 3 h, then heating and stirring were stopped, the mixture was cooled to room temperature, the catalyst was removed by filtration, the filtrate was allowed to stand and separate into layers, and the upper layer was taken to obtain the amino acid surfactant with a yield of 98.9%.

[0029] Comparative Example 1 Preparation of nano-Ni catalyst: 3.7 g nickel nitrate and 3.4 g potassium hydroxide (molar ratio of nickel nitrate to potassium hydroxide was 1:3) were added to a grinder and ground for 45 min (grinding speed was 800 r / min) to obtain a solid-phase reaction mixture. The solid-phase reaction mixture was washed with deionized water and filtered until the pH of the filtrate was 7.0. The obtained filter cake was dried at 120 ℃ for 24 h, cooled to room temperature, and then placed in a tube furnace. Under a hydrogen-nitrogen mixed atmosphere (hydrogen volume content was 10%), it was calcined and reduced at 350 ℃ for 3 h. After cooling to room temperature, nano-Ni was obtained with a yield of 61.1%.

[0030] Preparation of amino acid surfactant: 2.4 g of n-hexane chloride, 6.8 g of sodium tryptophan, 1.7 g of potassium hydroxide and 36 g of deionized water were added to a reactor in a molar ratio of 1:1.5:1.5:100; then 0.2 g of nano-nickel catalyst was added, which was 1.5 wt% of the total mass of n-hexane chloride, sodium tryptophan and potassium hydroxide; the reaction was carried out at 60℃ and 120 rpm for 3 h, then heating and stirring were stopped, the mixture was cooled to room temperature, the catalyst was removed by filtration, the filtrate was allowed to stand and separate into layers, and the upper layer was taken to obtain an amino acid surfactant with a yield of 75.7%.

[0031] The products prepared in Examples 1-5 and Comparative Example 1 were tested, and the results are as follows: (1) Figure 1The images show SEM images of the Ni catalysts prepared in Example 3 and Comparative Example 1. As can be seen from the images, the Ni catalyst prepared in Example 3 has a regular crystal morphology and a small grain size of about 35 nm, while the Ni catalyst prepared in Comparative Example 1 is sintered and has an irregular morphology. This indicates that the addition of supercritical oxygen in Example 3 is beneficial to the formation of a nano-Ni catalyst with a regular morphology and a small grain size. Supercritical oxygen fluid has high solubility and high diffusivity, which is conducive to the full and rapid contact and reaction between reactants, resulting in highly dispersed products and avoiding the agglomeration of nanoparticles, thereby inhibiting the increase of grain size. In Comparative Example 1, the catalyst was prepared by grinding only, and the final Ni catalyst was sintered and agglomerated.

[0032] (2) Table 1 shows the specific surface areas of the Ni catalysts prepared in Examples 1-5 and Comparative Example 1, obtained by BET characterization. As can be seen from Table 1, the nano-Ni catalysts with regular morphology and small grain size formed in supercritical oxygen have a large specific surface area, high catalytic activity, and excellent catalytic performance, resulting in a high yield of amino acid surfactants; while the Ni catalyst prepared in Comparative Example 1 undergoes sintering and agglomeration, resulting in a smaller specific surface area; Table 1

[0033] (3) Performance testing: The hard water resistance of the amino acid surfactants synthesized in Examples 1-5 and Comparative Example 1 was determined according to the method of national standard GB / T7381-2010 "Determination of Stability of Surfactants in Hard Water"; the foaming properties of the amino acid surfactants synthesized in Examples 1-5 and Comparative Example 1 were determined according to the method of national standard GB / T7462-1994 "Determination of Foaming Power of Surfactants - Modified Ross-Miles Method" and compared with those of sodium dodecylbenzenesulfonate, which is widely used in the market.

[0034] Table 2

[0035] As can be seen from the test data in Table 2, the amino acid surfactant prepared by the present invention has higher stability in hard water than sodium dodecylbenzenesulfonate, and its foaming performance is comparable to that of sodium dodecylbenzenesulfonate. This indicates that the amino acid surfactant prepared by the present invention has excellent hard water resistance and foaming performance.

[0036] 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 amino acid surfactant, characterized in that, Sodium tryptophan, haloalkanes, alkali, and deionized water were added to a reactor in a specific molar ratio. A certain amount of nano-nickel catalyst was then added. The reaction was carried out at 30–60 °C with stirring for 1–3 h. After stopping heating and stirring, the mixture was cooled to room temperature, filtered, and the filtrate was allowed to separate into layers. The upper layer was then collected to obtain the amino acid surfactant. The reaction equation is as follows: ； Wherein, R is a C4-C18 straight-chain alkyl group, X is Cl or Br, and Y is Na or K.

2. The preparation method according to claim 1, characterized in that, The molar ratio of the haloalkanes, sodium tryptophan, base and deionized water is 1:(1.2~1.8):(1.1~1.5):(50~100), and the amount of nano-nickel catalyst is 0.8~1.5 wt% of the total mass of haloalkanes, sodium tryptophan and base.

3. The preparation method according to claim 1, characterized in that, The stirring conditions are: stirring speed 100-150 rpm.

4. The preparation method according to claim 1, characterized in that, The preparation method of the nano-nickel catalyst is as follows: Nickel source and alkali source are added to a grinder and ground to obtain a solid-phase reaction mixture. The solid-phase reaction mixture is placed in a supercritical crystallization reactor, oxygen is introduced, and the temperature is maintained at 50-80 °C and the pressure at 8.5-10 MPa. The crystallization reaction is carried out under supercritical conditions for 0.5-2 h to obtain a crystallized product. The crystallized product is cooled to room temperature, washed with deionized water, and filtered to obtain a filter cake. It is dried at 100-120 °C for 12-24 h, cooled to room temperature, and then placed in a tube furnace. Under a hydrogen-nitrogen mixed atmosphere, it is calcined and reduced at 300-350 °C for 1-3 h. After cooling to room temperature, nano-Ni is obtained.

5. The preparation method according to claim 4, characterized in that, The nickel source is either nickel nitrate or nickel chloride; the alkali source is either sodium hydroxide or potassium hydroxide.

6. The preparation method according to claim 4, characterized in that, The molar ratio of the nickel source to the alkali source is 1:(2.5-3).

7. The preparation method according to claim 4, characterized in that, During grinding and mixing, the grinding mill speed is 800-1000 r / min, and the time is 30-45 min.

8. The preparation method according to claim 4, characterized in that, The oxygen concentration introduced into the supercritical crystallization reactor is not less than 99.9%; the hydrogen-nitrogen mixture contains 10% hydrogen by volume.

9. The preparation method according to claim 4, characterized in that, Wash with deionized water until the pH of the filtrate reaches 7.

0.

10. An amino acid surfactant prepared according to any one of claims 1-9.

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