Method for preparing alanine by using glyceric acid

Abstract

The invention discloses a method for preparing alanine by using glyceric acid, which comprises the following steps of: performing dehydration reaction on the glyceric acid under the combined action of sodium hydroxide and a catalyst to generate 2-hydroxy acrylic acid, isomerizing the 2-hydroxy acrylic acid into pyruvic acid, and reducing and ammonifying the generated pyruvic acid into the alanine under the action of ammonia water, the catalyst and hydrogen. According to the method, the glycerate is catalytically converted into the alanine through the two main steps of dehydration and reductive ammoniation, the green method for preparing the alanine by catalyzing the glycerate is provided, and the synthesis method has the advantages of low cost, excellent performance and high yield; the method overcomes the defects of serious environmental pollution and non-renewable raw materials of alanine synthesis by a chemical method at present, and is a potential method for improving the commercial value of glycerol and expanding the application range of glycerol.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts, and in particular relates to a method for preparing alanine by utilizing glyceric acid. Background Art

[0002] As the basic building blocks of proteins, amino acids play a vital role in life and are widely used in food, feed supplements, biodegradable plastics, pharmaceuticals, cosmetics and other fields. In industry, the synthesis methods of amino acids mainly include microbial fermentation, enzymatic, protein hydrolysis and chemical synthesis. Among them, microbial fermentation is the main production method at present, but it requires a long reaction time, involves complex separation procedures, and strict requirements for aseptic operation conditions. In addition, this method can only produce L-amino acids and cannot meet the current market demand. Chemical synthesis is a simple and effective method that can avoid the limitations of the above-mentioned biological methods, and the racemic mixture produced by chemical synthesis can provide D-amino acids and L-amino acids through chiral separation. However, in some current chemical synthesis methods, such as Strecke, Gabriel and Miller synthesis, they either use highly toxic cyanide and non-renewable aldehydes as substrates, or are limited by low yields and complex procedures, making them unsuitable for large-scale industrial applications. Therefore, the development of green and environmentally friendly amino acid synthesis processes will have important scientific significance and economic value.

[0003] Biomass-derived chemicals are usually obtained by biomass conversion and processing. They are widely available, low-cost, and renewable. They are also rich in oxygen-containing groups and are a suitable raw material for the synthesis of amino acids. At present, the strategies for producing amino acids from biomass are mainly divided into two categories. The first is to catalytically convert biomass-derived oxygen-containing raw materials into amino acids by introducing N-containing functional groups. The second category involves the use of chitin-derived nitrogen-containing raw materials as the starting material for the catalytic synthesis of amino acids. The strategy that is being studied more at this stage is mainly to introduce N-containing functional groups for conversion. Since Yan Ning's research group proposed in 2018 that the introduction of ammonia water into the system can convert biomass-derived α-hydroxy acids into α-amino acids, different types of biomass-derived chemicals have begun to be studied for conversion into amino acids, including α-hydroxy acids, furfural, glycerol and its derivatives, chitin and its derivatives, etc.

[0004] Glycerol and its derivatives are a class of biomass-derived chemicals with high potential. Glycerol is the main byproduct of biodiesel. During the production of biodiesel through transesterification of vegetable oil, about 100 kg of glycerol will be produced for every ton of biodiesel produced. In addition, with the expansion of the scale of the biodiesel industry, the output of glycerol has increased rapidly, far exceeding the current market demand capacity. Therefore, as a large-volume and low-cost biomass derivative chemical, glycerol can meet the requirements of amino acid synthesis process for raw materials. In addition, the polyhydroxy structure of glycerol makes it more possible in the conversion path. Studying its catalytic conversion is not only conducive to improving the value of glycerol, but also to increasing the profits of the biodiesel industry. At present, the process of glycerol conversion to alanine has been realized, and a variety of chemical catalytic methods such as oxidation / dehydrogenation, dehydration, hydrogenolysis, steam reforming, and transesterification have also been developed to convert glycerol into value-added products, such as glyceric acid, lactic acid, 1,3-propylene glycol, glycerol carbonate, etc. These glycerol-derived chemicals, like glycerol, contain rich oxygen-containing groups and are also potential raw materials for the synthesis of amino acids.

[0005] Glyceric acid is the oxidation product of primary glycerol alcohol. It is commonly found in various plants in nature and has wide applications in medicine and food industries. Compared with the oxidation of secondary hydroxyl groups of glycerol, the oxidation of primary hydroxyl groups is less affected by steric hindrance. Therefore, glyceric acid can be easily obtained by oxidation of glycerol. Its unique dihydroxyl and carboxylic acid structure allows it to be used as a multifunctional platform molecule to produce high value-added chemicals, so it is also a reliable raw material for the synthesis of amino acids. At present, there are few studies on its conversion and appreciation, mainly focusing on the production of valuable 1,3-substituted compounds such as 3-iodopropionic acid. Therefore. It will be of great significance to develop a green and efficient alanine synthesis process using glyceric acid as a raw material to replace the current high-risk and high-cost traditional chemical process. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a method for preparing alanine using glyceric acid, which uses glyceric acid as a raw material and synthesizes alanine through a chemical method via dehydration, isomerization, and reductive amination.

[0007] To achieve the above object, the present invention adopts the following technical solution: A method for preparing alanine using glyceric acid, which comprises mixing a glyceric acid aqueous solution, ammonia water, sodium hydroxide and a catalyst, and performing a heating reaction in a hydrogen atmosphere to generate alanine. The process includes two main steps of dehydration and reductive amination, wherein the glyceric acid is first dehydrated under the combined action of a catalyst and sodium hydroxide to generate 2-hydroxyacrylic acid, which is then isomerized to pyruvic acid; the pyruvic acid then reacts with ammonia water to generate an imine product, which is then reduced to alanine under the action of a catalyst and hydrogen. The reaction flow is as follows: .

[0008] Furthermore, the catalyst is a ruthenium-based catalyst, in which the mass percentage of metal Ru is 0.1% to 5%. Specifically, a ruthenium metal salt precursor and a carrier are mixed in water to obtain a mixed aqueous solution, stirred at room temperature for 10 hours, heated and stirred at 80°C until the solution is completely evaporated, and then the evaporated solid is dried in an oven at 70°C for 10 hours and then transferred to a crucible, and heated and reduced in a hydrogen atmosphere to obtain the catalyst.

[0009] Furthermore, the ruthenium metal salt precursor is specifically ruthenium chloride hydrate.

[0010] Furthermore, the carrier is activated carbon, anatase titanium dioxide, rutile titanium dioxide, zirconium dioxide or magnesium oxide.

[0011] Furthermore, the temperature rise rate of the temperature reduction is 5°C / min, the reduction temperature is 400°C, and the reduction time is 3h.

[0012] Furthermore, the concentration of the glyceric acid aqueous solution is 20wt%.

[0013] Furthermore, the purity of the aqueous ammonia is 25-28wt%.

[0014] Furthermore, the ratio of the molar amount of glyceric acid in the glyceric acid aqueous solution to the volume of the ammonia water used is 1 mmol:10 ml.

[0015] Furthermore, the molar ratio of glyceric acid to the sodium hydroxide used in the glyceric acid aqueous solution is 1:(1-10), preferably 1:5.

[0016] Furthermore, the molar ratio of glyceric acid in the glyceric acid aqueous solution to the mass ratio of the catalyst used is 1 mmol:(10-100) mg, preferably 1 mmol:60 mg.

[0017] Furthermore, the pressure of the hydrogen atmosphere is 1-5 MPa, preferably 1 MPa.

[0018] Furthermore, the heating reaction temperature is 210° C. and the time is 2 hours.

[0019] Furthermore, the reaction was carried out under stirring at a stirring rate of 500 rpm.

[0020] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention realizes the preparation of alanine through a series of steps such as glyceric acid dehydration, isomerization, amination, and reduction, which provides a new green method for preparing alanine; 2. Compared with the traditional method of synthesizing alanine, this method has less pollution, and metal salt catalysts are easily available. It has the advantages of low cost, excellent performance and high yield. It solves the current problems of high cost and high pollution in the production of amino acids. It is an effective way to increase the value of glycerol, the net profit of the biodiesel industry and accelerate energy transformation.

[0021] 3. Glyceric acid can be obtained by oxidizing glycerol, a byproduct of biodiesel. Converting it into amino acids further expands the application of glyceric acid and provides a theoretical basis and reference cases for the conversion of other polyhydroxy acids.

[0022] 4. Compared with other catalysts used in the reaction, the catalyst used in the present invention can achieve excellent catalytic effect at a lower loading amount and has a higher conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The chromatogram (A, RT=6.24) and hydrogen spectrum (B) of the standard alanine.

[0024] Figure 2 The chromatogram (A, RT=6.23) and hydrogen spectrum (B) of alanine prepared in Example 1.

[0025] Figure 3 The chromatogram (A, RT=6.27) and hydrogen spectrum (B) of alanine prepared in Example 2.

[0026] Figure 4 The chromatogram (A, RT=6.25) and hydrogen spectrum (B) of alanine prepared in Example 3.

[0027] Figure 5 The chromatogram (A, RT=6.23) and hydrogen spectrum (B) of alanine prepared in Example 4.

[0028] Figure 6 The chromatogram (A, RT=6.26) and hydrogen spectrum (B) of alanine prepared in Example 5.

[0029] Figure 7 0.2%Ru-TiO prepared in Example 6 2 TEM image (A) and particle size distribution diagram (B) of the catalyst.

[0030] Figure 8 The chromatogram (A, RT=6.25) and hydrogen spectrum (B) of alanine prepared in Example 6.

[0031] Fig. 9 The chromatogram (A, RT=6.25) and hydrogen spectrum (B) of alanine prepared in Example 7.

[0032] Fig.10The chromatogram (A, RT=6.26) and hydrogen spectrum (B) of alanine prepared in Example 8.

[0033] Fig.11 The chromatogram (A, RT=6.23) and hydrogen spectrum (B) of alanine prepared in Example 9.

[0034] Fig.12 The chromatogram (A, RT=6.22) and hydrogen spectrum (B) of alanine prepared in Example 10. DETAILED DESCRIPTION

[0035] A method for preparing alanine using glyceric acid comprises the following steps: 1) Ruthenium chloride hydrate and a carrier are mixed in water to obtain a mixed aqueous solution, stirred at room temperature for 10 hours, heated and stirred at 80°C until the solution is completely evaporated, and then the evaporated solid is dried in an oven at 70°C for 10 hours and then transferred to a crucible. In a hydrogen atmosphere, the temperature is raised to 400°C at a rate of 5°C / min and reduced for 3 hours to obtain a Ru-based catalyst, in which Ru accounts for 0.1 wt%~5 wt%; 2) Mix 20wt% aqueous glyceric acid solution, ammonia water (purity 25-28wt%), sodium hydroxide and the catalyst, and introduce H 2 The pressure is raised to 1-5 MPa, and then heated to 210°C and stirred at 500 rpm for 2 h to generate alanine.

[0036] Wherein, the carrier in step 1) is activated carbon, anatase titanium dioxide, rutile titanium dioxide, zirconium dioxide or magnesium oxide.

[0037] In step 2), the molar ratio of glyceric acid in the glyceric acid aqueous solution to the volume of ammonia water used is 1 mmol:10 ml; the molar ratio of glyceric acid to the sodium hydroxide used is 1:(1~10); the molar ratio of glyceric acid to the mass ratio of the catalyst used is 1 mmol:(10~100) mg.

[0038] During the experiment, the effects of different metal catalysts, different sodium hydroxide dosages and different reaction temperatures on alanine yield were also investigated. The results are shown in Tables 1-3.

[0039] Table 1 Comparison of reaction results using different metal catalysts

[0040] Table 2 Comparison of reaction results with different sodium hydroxide dosages

[0041] Table 3 Comparison of reaction results at different reaction temperatures

[0042] Table 4 Different loading amounts of Ru-TiO 2 TOF comparison of catalysts

[0043] In order to make the contents of the present invention easier to understand, the technical solution of the present invention is further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0044] The raw materials and purchase sources involved in the following embodiments are as follows: Glyceric acid aqueous solution, Aladdin Company; Ammonia water (concentration 25-28wt%), Aladdin Company; Sodium hydroxide, Shanghai Linen Technology Development Co., Ltd.; Hydrogen, Guangdong Huate Gas Co., Ltd.; Ruthenium chloride, Tianjin Xiensiopude Technology Co., Ltd.; Nano carbon powder, Aladdin Company; Titanium dioxide (anatase), Aladdin Corporation; Titanium dioxide (rutile), Aladdin Corporation; Zirconia, Aladdin Corporation; Magnesium oxide, Tianjin Xiensiopude Technology Co., Ltd.; Standard alanine, Tianjin Xiensiopude Technology Co., Ltd.

[0045] The test and quantitative methods of the samples in the following examples are as follows: The liquid product was characterized by liquid chromatography, and the chromatographic analysis conditions were as follows: the chromatographic column was C-18 (250nm×4.6nm, 5μm); the mobile phase was an organic mobile phase (sodium acetate: 55%; methanol: 22.5%, acetonitrile: 22.5%), with a flow rate of 0.8ml / min; the column temperature was 25°C; the detection wavelength was 338nm using an ultraviolet detector; and the quantitative method was amino acid pre-column derivatization + external standard method standard curve.

[0046] Select the standard alanine as the external standard and establish a standard curve of alanine standard concentration and response value: Y=k 1 X, the product is quantified by Y1 / Y=k 1 ×X1 / X, where Y1 and X1 are the peak area and concentration of the standard alanine, Y and X are the peak area and concentration of the product alanine, respectively. 1 is the correction factor.

[0047] The test and quantitative methods of glyceric acid in the following examples are as follows: The glyceric acid substrate was characterized by liquid chromatography, and the chromatographic analysis conditions were as follows: the chromatographic column was Sugar-H (300nm×7.8nm, 5μm); the mobile phase was dilute sulfuric acid solution (10mmol / L), and the flow rate was 0.8ml / min; the detector cell temperature was 30℃; the differential detector was RID-20A; and the quantitative method was external standard method standard curve.

[0048] Select standard glyceric acid as the external standard and establish a standard curve of glyceric acid standard concentration and response value: y=k 2 x, the product is quantified by Y2 / y=k 2 ×X2 / x, where Y2 and X2 are the peak area and concentration of standard glyceric acid, y and x are the peak area and concentration of substrate glyceric acid, and k 2 is the correction factor.

[0049] Example 1 A method for preparing alanine using glyceric acid comprises the following steps: S1, in a beaker, 2.7mg ruthenium chloride and 200mg titanium dioxide (anatase) were dissolved in 20ml water, stirred at room temperature for 10h, and then the beaker was transferred to a water bath, stirred in a water bath at 80℃ until the water in the beaker was completely evaporated, and then the evaporated product was placed in a 70℃ oven for 10h. The dried product was transferred to a crucible and placed in a tubular furnace, and hydrogen was introduced for reduction; the heating rate of the tubular furnace was 10℃ / min, and the temperature was raised to 400℃, and maintained for 3 hours to obtain a titanium dioxide (anatase)-loaded Ru metal catalyst, in which the loading amount of Ru metal was 0.5wt%.

[0050] S2, dissolve the aqueous solution containing 0.5mmol glyceric acid in 5ml ammonia water, add 30mg Ru metal catalyst supported by titanium dioxide (anatase) synthesized in step S1, 100mg sodium hydroxide, and then charge 1MPa H 2 The temperature was raised to 210°C using an automatic temperature controller and the reaction was stirred at 500 rpm for 2 h.

[0051] After comparing the chromatogram and H-NMR spectrum of alanine standards (such as Figure 1 ) comparison, it can be confirmed that the product is alanine (such as Figure 2 ). The glyceric acid conversion rate of this embodiment was measured to be 100%, the alanine yield was 52.5%, and the purity was 98%.

[0052] Example 2 The titanium dioxide (anatase) used in step S1 was replaced with 200 mg of carbon nanopowder, and the other operations were the same as in Example 1 to prepare a carbon nanopowder-supported Ru metal catalyst.

[0053] After comparing the chromatogram and H-NMR spectrum of alanine standards (such as Figure 1 ) comparison, it can be confirmed that the product is alanine (such as Figure 3 ). The glyceric acid conversion rate of this embodiment was measured to be 94%, the alanine yield was 4%, and the purity was 98%.

[0054] Example 3 The titanium dioxide (anatase) used in step S1 was replaced with 200 mg of titanium dioxide (rutile), and the other operations were the same as in Example 1 to prepare a titanium dioxide (rutile)-supported Ru metal catalyst.

[0055] After comparing the chromatogram and H-NMR spectrum of alanine standards (such as Figure 1 ) comparison, it can be confirmed that the product is alanine (such as Figure 4 ). The conversion rate of glyceric acid in this embodiment was measured to be 98%, the yield of alanine was 51.1%, and the purity was 98%.

[0056] Example 4 The titanium dioxide (anatase) used in step S1 was replaced with 200 mg of zirconium oxide, and the other operations were the same as in Example 1 to prepare a zirconium oxide-supported Ru metal catalyst.

[0057] After comparing the chromatogram and H-NMR spectrum of alanine standards (such as Figure 1 ) comparison, it can be confirmed that the product is alanine (such as Figure 5 ). The conversion rate of glyceric acid in this embodiment was measured to be 99%, the yield of alanine was 50.1%, and the purity was 98%.

[0058] Example 5 The titanium dioxide (anatase) used in step S1 was replaced with 200 mg of magnesium oxide, and the other operations were the same as in Example 1 to obtain a magnesium oxide-supported Ru metal catalyst.

[0059] After comparing the chromatogram and H-NMR spectrum of alanine standards (such as Figure 1 ) comparison, it can be confirmed that the product is alanine (such as Figure 6 ). The conversion rate of glyceric acid in this embodiment was measured to be 99%, the yield of alanine was 58.7%, and the purity was 98%.

[0060] Example 6 The amount of ruthenium chloride used in step S1 was replaced with 1.1 mg, and the other operations were the same as in Example 1 to prepare a Ru metal catalyst with a Ru metal loading of 0.2%.

[0061] Figure 7 For the preparation of 0.2%Ru-TiO 2TEM image (A) and particle size distribution (B) of the catalyst. It can be seen from the figure that Ru nanoparticles are dispersed and adsorbed on the surface of the carrier, and their average size is d=1.44 nm.

[0062] After comparing the chromatogram and H-NMR spectrum of alanine standards (such as Figure 1 ) comparison, it can be confirmed that the product is alanine (such as Figure 8 ). The conversion rate of glyceric acid in this embodiment was measured to be 100%, the yield of alanine was 58.9%, and the purity was 98%.

[0063] Example 7 The amount of ruthenium chloride used in step S1 was replaced with 5.4 mg, and the other operations were the same as in Example 1 to prepare a Ru metal catalyst with a Ru metal loading of 1%.

[0064] After comparing the chromatogram and H-NMR spectrum of alanine standards (such as Figure 1 ) comparison, it can be confirmed that the product is alanine (such as Fig. 9 ). The conversion rate of glyceric acid in this embodiment was measured to be 100%, the yield of alanine was 46.5%, and the purity was 98%.

[0065] Example 8 The amount of ruthenium chloride used in step S1 was replaced with 8.1 mg, and the other operations were the same as in Example 1 to prepare a Ru metal catalyst with a Ru metal loading of 1.5%.

[0066] After comparing the chromatogram and H-NMR spectrum of alanine standards (such as Figure 1 ) comparison, it can be confirmed that the product is alanine (such as Fig.10 ). The conversion rate of glyceric acid in this embodiment was measured to be 100%, the yield of alanine was 39.9%, and the purity was 98%.

[0067] Example 9 The amount of ruthenium chloride used in step S1 was replaced with 10.8 mg, and the other operations were the same as in Example 1 to prepare a Ru metal catalyst with a Ru metal loading of 2%.

[0068] After comparing the chromatogram and H-NMR spectrum of alanine standards (such as Figure 1 ) comparison, it can be confirmed that the product is alanine (such as Fig.11 ). The conversion rate of glyceric acid in this embodiment was measured to be 100%, the yield of alanine was 35.4%, and the purity was 98%.

[0069] Example 10 The amount of ruthenium chloride used in step S1 was replaced with 16.2 mg, and the other operations were the same as in Example 1 to prepare a Ru metal catalyst with a Ru metal loading of 3%.

[0070] After comparing the chromatogram and H-NMR spectrum of alanine standards (such as Figure 1 ) comparison, it can be confirmed that the product is alanine (such as Fig.12 ). The conversion rate of glyceric acid in this embodiment was measured to be 100%, the yield of alanine was 35.9%, and the purity was 98%.

[0071] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for preparing alanine using glyceric acid, characterized in that: A glyceric acid aqueous solution, ammonia water, sodium hydroxide and a catalyst are mixed and heated in a hydrogen atmosphere to react to produce alanine.

2. The method for preparing alanine using glyceric acid according to claim 1, characterized in that: The concentration of the glyceric acid aqueous solution is 20wt%; the purity of the ammonia water is 25-28wt%.

3. The method for preparing alanine using glyceric acid according to claim 1, characterized in that: The catalyst is a ruthenium-based catalyst, wherein the mass percentage of metal Ru is 0.1% to 5%.

4. The method for preparing alanine using glyceric acid according to claim 3, characterized in that: The catalyst is specifically prepared by mixing a ruthenium metal salt precursor and a carrier in water to obtain a mixed aqueous solution, stirring at room temperature for 10 hours, heating and stirring at 80° C. until the solution is completely evaporated, and then further drying the evaporated solid and reducing it at a high temperature in a hydrogen atmosphere.

5. The method for preparing alanine using glyceric acid according to claim 4, characterized in that: The ruthenium metal salt precursor is specifically ruthenium chloride hydrate.

6. The method for preparing alanine using glyceric acid according to claim 4, characterized in that: The carrier is activated carbon, anatase titanium dioxide, rutile titanium dioxide, zirconium dioxide or magnesium oxide.

7. The method for preparing alanine using glyceric acid according to claim 4, characterized in that: The temperature rise rate of the temperature reduction is 5°C / min, the reduction temperature is 400°C, and the reduction time is 3h.

8. The method for preparing alanine using glyceric acid according to claim 1, characterized in that: In the aqueous solution of glyceric acid, the molar ratio of glyceric acid to the sodium hydroxide used is 1:(1~10); the molar ratio of glyceric acid to the volume of ammonia water used is 1 mmol:10ml; the molar ratio of glyceric acid to the mass ratio of the catalyst used is 1 mmol:(10~100) mg.

9. The method for preparing alanine using glyceric acid according to claim 1, characterized in that: The pressure of the hydrogen atmosphere is 1-5 MPa.

10. The method for preparing alanine using glyceric acid according to claim 1, characterized in that: The heating reaction was carried out at a temperature of 210° C. and for a time of 2 h.

Images