A method for preparing highly stable L-aspartic acid by synergistic catalysis

Abstract

The present invention relates to the field of amino acid preparation, and in particular to a method for preparing highly stable L-aspartic acid by synergistic catalysis, which realizes efficient synergy by combining histidine-modified UiO-67 enzyme complex and amino acid-modified ZIF-8 / Pebax-1657 mixed matrix membrane technology. The coordination of histidine and UiO-67 enhances the stability and activity of the enzyme, and improves the yield and purity of L-aspartic acid. At the same time, the high selectivity and permeability of the modified ZIF-8 / Pebax-1657 membrane improve the separation efficiency, effectively purify L-aspartic acid, improve the preparation efficiency and product quality of L-aspartic acid, reduce environmental pollution, and realize green production and cost control.

Description

Technical Field

[0001] The invention relates to the technical field of amino acid preparation, and in particular to a method for preparing highly stable L-aspartic acid through synergistic catalysis. Background Art

[0002] As a multifunctional amino acid, L-aspartic acid has a wide range of applications, covering multiple industries such as food, medicine, and chemical industry. In the food industry, L-aspartic acid is mainly used as a nutritional supplement to enhance the nutritional value of food. In addition, L-aspartic acid is also used as a flavoring agent and added to various refreshing drinks to enhance the flavor of food. In the field of medicine, L-aspartic acid is also widely used. It can be used as a liver function promoter, ammonia detoxifier, and fatigue recovery agent. L-aspartic acid is also used to synthesize a variety of pharmaceutical intermediates. It is the main raw material for synthesizing L-alanine and plays an important role in the treatment of diseases such as heart disease. In the chemical industry, L-aspartic acid is the main raw material for synthesizing polymer material polyaspartic acid. In addition, L-aspartic acid also plays an important role in the agricultural field. As a fertilizer enhancer, it can promote the absorption of nutrients by crops, increase the germination rate of seeds, and enhance the stress resistance of crops, thereby improving agricultural production efficiency and reducing costs. With the development of agricultural science and technology, L-aspartic acid has broad application prospects in the agricultural field, providing strong support for the realization of efficient, green and sustainable development of agricultural production.

[0003] As an important amino acid, L-aspartic acid has a wide range of applications in many fields. At present, the production technology of L-aspartic acid is relatively mature, and the market demand is also growing. The domestic production scale is at the leading level internationally, but there are still some challenges and problems. First, in industrial production, the preparation of L-aspartic acid is mainly produced by chemical method and enzyme catalysis. The chemical method needs to be carried out under high temperature and high pressure, has high requirements for equipment, and is prone to environmental pollution. In addition, the traditional production process has problems such as high raw material purity requirements, many separation and purification steps, high energy consumption and large environmental pollution. Cost and pollution problems greatly limit the market application and value of L-aspartic acid. In the enzyme catalysis method, although the specificity is high, the whole cell catalysis of fumaric acid to L-aspartic acid consumes a large amount of bacteria, and the maximum catalytic efficiency cannot be exerted. Secondly, there are problems of enzyme imbalance and catalysis-extraction cycle process in the biosynthesis of L-aspartic acid. There are significant differences in the catalytic ability of maleate isomerase and aspartase, resulting in low synthesis efficiency.

[0004] In summary, the technical problems that need to be solved in the preparation process of L-aspartic acid include improving catalytic efficiency, reducing environmental pollution, and reducing production costs. Solving these challenges is crucial to achieving green and efficient production of L-aspartic acid. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing highly stable L-aspartic acid by synergistic catalysis, and the L-aspartic acid prepared by combining the histidine-modified UiO-67 enzyme complex and the amino acid-modified ZIF-8 / Pebax-1657 mixed matrix membrane technology has high yield and high purity. By using the histidine-modified UiO-67 enzyme complex, efficient conversion of fumaric acid to L-aspartic acid can be achieved, and the reaction solution can be recycled by membrane concentration technology, reducing production costs, improving raw material utilization, reducing environmental pollution, reducing production costs and other advantages.

[0006] In order to solve the above technical problems, the present invention provides a method for preparing highly stable L-aspartic acid by synergistic catalysis.

[0007] To achieve the above object, the present invention provides the following technical solution: a method for preparing highly stable L-aspartic acid by synergistic catalysis, comprising the following steps:

[0008] Step 1: adding the histidine modified UiO-67 enzyme complex to the fumaric acid solution, reacting at 400 r / min, 40-45° C., for 6-20 hours to obtain product 1, wherein the above raw materials are calculated by mass ratio, histidine modified UIO-67 enzyme complex: fumaric acid solution = 1:70-150;

[0009] Step 2: Filter the product 1, wherein the solid is the histidine modified UIO-67 enzyme complex, and the liquid washed with ultrapure water is the washing liquid 1. After the washed histidine modified UIO-67 enzyme complex is mixed with the aspartase solution, an ammonium sulfate solution is added, and the mixture is stirred for 15 minutes under ice bath conditions, glutaraldehyde is added at room temperature and stirred for 15 minutes, and then washed once with tris(hydroxymethyl)aminomethane hydrochloride buffer solution. After drying, the regenerated histidine modified UIO-67 enzyme complex is obtained, which can be further used in step 1. The above raw materials are calculated by mass ratio, and the washed histidine modified UIO-67 enzyme complex: aspartase solution: ammonium sulfate solution: glutaraldehyde = 1: 0.01~0.1: 0.8~1.2, wherein the mass of the tris(hydroxymethyl)aminomethane hydrochloride buffer solution used for washing is 15~35 times the mass of the histidine modified UiO-67;

[0010] Step three: heat the filtrate of product one to 75-90°C, adjust the pH to cool and precipitate crystals, wash and dry to obtain L-aspartic acid and washing solution two, concentrate the mother liquor after cooling and crystallization, washing solution one and washing solution two through an amino acid-modified ZIF-8 / Pebax-1657 mixed matrix membrane, adjust the pH of the concentrated mother liquor, cool and recrystallize to precipitate crystals, wash and dry to obtain L-aspartic acid and washing solution three, mix washing solution three with the mother liquor after recrystallization, add fumaric acid and use it in step one.

[0011] Furthermore, the preparation method of the histidine-modified UiO-67 enzyme complex comprises the following steps:

[0012] S1: dissolving zirconium tetrachloride in dimethylformamide, stirring at a speed of 600 r / min for 15 to 30 min, to prepare a metal ion solution, wherein the weight ratio of the above raw materials is zirconium tetrachloride: dimethylformamide = 1:35 to 63;

[0013] S2: 4,4-biphenyldicarboxylic acid is dissolved in dimethylformamide, stirred at a speed of 600 r / min for 15-30 min, and then histidine is added and stirred for 30 min to obtain a ligand solution. The above raw materials are calculated by mass ratio: 4,4-biphenyldicarboxylic acid: dimethylformamide: histidine = 1:45-72:0.8-2.3;

[0014] S3: Pour the ligand solution into a flask, place the flask in a preheated 75-80°C oil bath at a speed of 300 r / min, add the metal ion solution dropwise, and after the addition is completed, stir at a speed of 600 r / min for 2 hours, raise the temperature to 95-110°C, continue stirring for 5 hours, cool the flask to room temperature in air and filter, wash with ethanol three times, and dry the product in a drying oven at 70°C for 4-8 hours to obtain histidine-modified UiO-67;

[0015] S4: After mixing the histidine-modified UiO-67 with the aspartase solution, add ammonium sulfate solution, stir for 1 hour under ice bath conditions, let stand for 1 hour at room temperature, add glutaraldehyde and stir for 30 minutes, wash three times with tris(hydroxymethylaminomethane) hydrochloride buffer, and dry to obtain the histidine-modified UiO-67 enzyme complex. The above raw materials are calculated by mass ratio: histidine-modified UiO-67: aspartase solution: ammonium sulfate solution: glutaraldehyde = 1: 0.1~0.3: 1.5~4, wherein the mass of tris(hydroxymethylaminomethane) hydrochloride buffer used for a single wash is 15~35 times the mass of histidine-modified UiO-67.

[0016] Furthermore, the aspartase solution is prepared by dissolving aspartase in ultrapure water, and the mass ratio of aspartase to ultrapure water is 1:1-5.

[0017] Furthermore, the fumaric acid solution is prepared by dissolving fumaric acid in ultrapure water, and the mass ratio of fumaric acid to ultrapure water is 1:5-15.

[0018] Furthermore, the ammonium sulfate solution is prepared by dissolving ammonium sulfate in ultrapure water, wherein the concentration of the ammonium sulfate solution is 20% to 50%.

[0019] Furthermore, the preparation method of the amino acid modified ZIF-8 / Pebax-1657 mixed matrix membrane comprises the following steps:

[0020] Step 1: adding ZIF-8 nanoparticles to a methanol solution in which threonine is dissolved, with a mass ratio of ZIF-8 nanoparticles: threonine: methanol = 1: 0.75-1.55: 50-100, stirring at 40-80° C. for 2-4 hours, filtering, washing, and drying to obtain amino acid-modified ZIF-8 nanoparticles;

[0021] Step 2: After mixing anhydrous ethanol and ultrapure water, heat them to 80-85°C in an oil bath under stirring conditions, then add Pebax-1657 thereto and keep stirring at 80-85°C for 4-5 hours to completely dissolve them, thereby obtaining a Pebax-1657 solution, wherein the mass ratio of Pebax-1657: anhydrous ethanol: ultrapure water is 1:5-20:10-25;

[0022] Step 3: adding amino acid modified ZIF-8 nanoparticles to the Pebax-1657 solution prepared in step 2, and mixing by ultrasonic stirring to obtain a casting solution containing fillers, wherein the mass ratio of amino acid modified ZIF-8 nanoparticles to Pebax-1657 solution is 1:12-23;

[0023] Step 4: The casting solution obtained in step 3 is subjected to ultrasonic degassing for 10 to 30 minutes and allowed to stand for 4 to 10 minutes. It is then poured onto a clean polytetrafluoroethylene plate and placed in a constant temperature oven at 60 to 80°C to dry for 18 to 24 hours. It is then placed in a vacuum oven to continue to remove the solvent for 18 to 24 hours to obtain an amino acid modified ZIF-8 / Pebax-1657 mixed matrix membrane.

[0024] Furthermore, the preparation method of the Tris(hydroxymethyl)aminomethane hydrochloride buffer solution is that Tris(hydroxymethyl)aminomethane hydrochloride) is dissolved in ultrapure water, and the concentration of the Tris(hydroxymethyl)aminomethane hydrochloride buffer solution is 5% to 17%.

[0025] The beneficial effects of the present invention are as follows: a method for preparing highly stable L-aspartic acid by synergistic catalysis, combining histidine-modified UiO-67 enzyme complex and amino acid-modified ZIF-8 / Pebax-1657 mixed matrix membrane technology to prepare L-aspartic acid, has the advantage of synergistic effect. First, the addition of the histidine-modified UiO-67 enzyme complex can improve the selectivity and efficiency of the reaction. Histidine, as an amino acid, can form a stable coordination with UiO-67 through its amino group, thereby enhancing the stability and activity of the enzyme. This modified enzyme complex can more effectively catalyze the reaction during the fumaric acid conversion process, thereby improving the yield and purity of L-aspartic acid. At the same time, UiO-67 itself has a larger pore size and specific surface area, which can accommodate more guest molecules, thereby improving the reaction efficiency. Secondly, the amino acid-modified ZIF-8 / Pebax-1657 mixed matrix membrane is used for concentration, which can achieve an efficient and environmentally friendly separation process. This mixed matrix membrane combines the high selectivity of ZIF-8 and the high permeability of Pebax-1657, which can improve the self-diffusion of molecules while maintaining high selectivity, thereby improving separation efficiency. In the preparation process of L-aspartic acid, this membrane can effectively separate L-aspartic acid from the reaction solution, while removing unwanted byproducts and impurities, improving product purity, reducing subsequent purification steps, and reducing production costs.

[0026] In summary, this technology combining the histidine-modified UiO-67 enzyme complex and the amino acid-modified ZIF-8 / Pebax-1657 mixed matrix membrane not only improves the preparation efficiency and product quality of L-aspartic acid, but also reduces environmental pollution and achieves green production and cost control. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A flow chart of the method for preparing highly stable L-aspartic acid by synergistic catalysis provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0029] See also Figure 1 , an embodiment of the present invention provides a method for preparing highly stable L-aspartic acid through synergistic catalysis.

[0030] The following is a detailed description of the method for preparing a synergistic catalytic highly stable L-aspartic acid provided by the present invention through examples.

[0031] Example 1

[0032] Step 1: adding the histidine modified UiO-67 enzyme complex to a fumaric acid solution (the mass ratio of fumaric acid to ultrapure water is 1:10), reacting at 400 r / min, 45°C for 8 hours to obtain product 1, wherein the above raw materials are calculated by mass ratio, histidine modified UIO-67 enzyme complex: fumaric acid solution = 1:120;

[0033] Step 2: Filter the product 1, wherein the solid is the histidine modified UIO-67 enzyme complex, and the liquid washed with ultrapure water is the washing liquid 1. After the washed histidine modified UIO-67 enzyme complex is mixed with aspartase solution (the mass ratio of aspartase to ultrapure water is 1:3), 50% ammonium sulfate solution is added, and it is stirred for 15 minutes under ice bath conditions, glutaraldehyde is added at room temperature and stirred for 15 minutes, and then washed once with 10% tris(hydroxymethyl)aminomethane hydrochloride buffer solution. After drying, the regenerated histidine modified UIO-67 enzyme complex is obtained, which can be further used in step 1. The above raw materials are calculated by mass ratio, the washed histidine modified UIO-67 enzyme complex: aspartase solution: ammonium sulfate solution: glutaraldehyde = 1: 0.01~0.1: 0.8~1.2, wherein the mass of the 10% tris(hydroxymethyl)aminomethane hydrochloride buffer solution used for washing is 20 times the mass of the histidine modified UiO-67.

[0034] Step three: heat the filtrate of product one to 85°C, adjust the pH to cool and precipitate crystals, and obtain L-aspartic acid and washing liquid two after elution and drying. Concentrate the mother liquor after cooling and crystallization, washing liquid one and washing liquid two through an amino acid-modified ZIF-8 / Pebax-1657 mixed matrix membrane, adjust the pH of the concentrated mother liquor, cool and recrystallize the precipitated crystals, and obtain L-aspartic acid and washing liquid three after elution and drying. After this step, the total yield of L-aspartic acid reaches 89.9% and the purity reaches 98.6%. Mix washing liquid three with the mother liquor after recrystallization, add fumaric acid and use it in step one.

[0035] The preparation method of the histidine-modified UiO-67 enzyme complex comprises the following steps:

[0036] S1: dissolving zirconium tetrachloride in dimethylformamide, stirring at a speed of 600 r / min for 15 min, to prepare a metal ion solution, wherein the weight ratio of the above raw materials is zirconium tetrachloride: dimethylformamide = 1:40;

[0037] S2: 4,4-biphenyldicarboxylic acid was dissolved in dimethylformamide, stirred at a speed of 600 r / min for 20 min, and then histidine was added and stirred for 30 min to obtain a ligand solution. The above raw materials were calculated by mass ratio: 4,4-biphenyldicarboxylic acid: dimethylformamide: histidine = 1:45:1.2;

[0038] S3: Pour the ligand solution into a flask, place the flask in a preheated 80°C oil bath at a speed of 300 r / min, add the metal ion solution dropwise, and after the addition is completed, stir at a speed of 600 r / min for 2 hours, raise the temperature to 100°C, continue stirring for 5 hours, cool the flask to room temperature in air and filter, wash with ethanol three times, and dry the product in a drying oven at 70°C for 6 hours to obtain histidine-modified UiO-67;

[0039] S4: After mixing the histidine-modified UiO-67 with the aspartase solution (the mass ratio of aspartase to ultrapure water is 1:2), 40% ammonium sulfate solution was added, and the mixture was stirred in an ice bath for 1 hour, and allowed to stand at room temperature for 1 hour. After adding glutaraldehyde and stirring for 30 minutes, the mixture was washed three times with 10% tris(hydroxymethyl)aminomethane hydrochloride buffer and dried to obtain the histidine-modified UiO-67 enzyme complex. The above raw materials were calculated by mass ratio of histidine-modified UiO-67: aspartase solution: ammonium sulfate solution: glutaraldehyde = 1:0.2:2, wherein the mass of tris(hydroxymethyl)aminomethane hydrochloride buffer used for a single wash was 20 times the mass of histidine-modified UiO-67.

[0040] The preparation method of amino acid modified ZIF-8 / Pebax-1657 mixed matrix membrane comprises the following steps:

[0041] Step 1: adding ZIF-8 nanoparticles to a methanol solution in which threonine is dissolved, with a mass ratio of ZIF-8 nanoparticles: threonine: methanol = 1:1.25:50, stirring at 75°C for 24 hours, filtering, washing, and drying to obtain amino acid-modified ZIF-8 nanoparticles;

[0042] Step 2: After mixing anhydrous ethanol and ultrapure water, heat them to 85°C in an oil bath under stirring conditions, then add Pebax-1657 thereto and keep stirring at 80-85°C for 4-5 hours to completely dissolve them, thereby obtaining a Pebax-1657 solution having a mass ratio of Pebax-1657: anhydrous ethanol: ultrapure water = 1:8:15;

[0043] Step 3: Add the amino acid modified ZIF-8 nanoparticles to the Pebax-1657 solution prepared in step 2, and mix by ultrasonic stirring to obtain a casting solution containing fillers, wherein the mass ratio of the amino acid modified ZIF-8 nanoparticles to the Pebax-1657 solution is 1:18;

[0044] Step 4: The casting solution obtained in step 3 was subjected to ultrasonic degassing for 30 minutes and allowed to stand for 5 minutes. It was then poured onto a clean polytetrafluoroethylene plate and placed in a 75°C constant temperature oven to dry for 8 hours. It was then placed in a vacuum oven to continue to remove the solvent for 24 hours to obtain an amino acid modified ZIF-8 / Pebax-1657 mixed matrix membrane.

[0045] Embodiment 2:

[0046] Step 1: adding the histidine modified UiO-67 enzyme complex to a fumaric acid solution (the mass ratio of fumaric acid to ultrapure water is 1:15), reacting at 400 r / min, 45°C for 10 hours to obtain product 1, wherein the above raw materials are calculated by mass ratio, histidine modified UIO-67 enzyme complex: fumaric acid solution = 1:120;

[0047] Step 2: Filter the product 1, wherein the solid is the histidine modified UIO-67 enzyme complex, and the liquid washed with ultrapure water is the washing liquid 1. After the washed histidine modified UIO-67 enzyme complex is mixed with aspartase solution (the mass ratio of aspartase to ultrapure water is 1:4), 40% ammonium sulfate solution is added, and it is stirred for 15 minutes under ice bath conditions, glutaraldehyde is added at room temperature and stirred for 15 minutes, and then washed once with 12% tris(hydroxymethyl)aminomethane hydrochloride buffer solution. After drying, the regenerated histidine modified UIO-67 enzyme complex is obtained, which can be further used in step 1. The above raw materials are calculated by mass ratio, and the washed histidine modified UIO-67 enzyme complex: aspartase solution: 40% ammonium sulfate solution: glutaraldehyde = 1:0.1:1, wherein the mass of the 12% tris(hydroxymethyl)aminomethane hydrochloride buffer solution used for washing is 30 times the mass of the histidine modified UiO-67;

[0048] Step three: heat the filtrate of product one to 75°C, adjust the pH to cool and precipitate crystals, wash and dry to obtain L-aspartic acid and washing liquid two, concentrate the mother liquor after cooling and crystallization, washing liquid one and washing liquid two through an amino acid-modified ZIF-8 / Pebax-1657 mixed matrix membrane, adjust the pH of the concentrated mother liquor, cool and recrystallize the precipitated crystals, wash and dry to obtain L-aspartic acid and washing liquid three. After this step, the total yield of L-aspartic acid reaches 92% and the purity reaches 98.7%. Washing liquid three is mixed with the mother liquor after recrystallization, and fumaric acid is added to it and used in step one.

[0049] The preparation method of the histidine-modified UiO-67 enzyme complex is shown in Example 1.

[0050] The preparation method of amino acid modified ZIF-8 / Pebax-1657 mixed matrix membrane is shown in Example 1.

[0051] Embodiment 3:

[0052] Step 1: adding the histidine modified UiO-67 enzyme complex to a fumaric acid solution (the mass ratio of fumaric acid to ultrapure water is 1:12), reacting at 400 r / min, 45°C for 8 hours to obtain product 1, wherein the above raw materials are calculated by mass ratio, histidine modified UIO-67 enzyme complex: fumaric acid solution = 1:110;

[0053] Step 2: Filter the product 1, wherein the solid is the histidine modified UIO-67 enzyme complex, and the liquid washed with ultrapure water is the washing liquid 1. After the washed histidine modified UIO-67 enzyme complex is mixed with aspartase solution (the mass ratio of aspartase to ultrapure water is 1:3.5), 35% ammonium sulfate solution is added, and it is stirred for 15 minutes under ice bath conditions, glutaraldehyde is added at room temperature and stirred for 15 minutes, and then washed once with 15% tris(hydroxymethyl)aminomethane hydrochloride buffer solution. After drying, the regenerated histidine modified UIO-67 enzyme complex is obtained, which can be further used in step 1. The above raw materials are calculated by mass ratio, and the washed histidine modified UIO-67 enzyme complex: aspartase solution: 35% ammonium sulfate solution: glutaraldehyde = 1:0.08:0.9, wherein the mass of the 15% tris(hydroxymethyl)aminomethane hydrochloride buffer solution used for washing is 30 times the mass of the histidine modified UiO-67;

[0054] Step three: heat the filtrate of product one to 85°C, adjust the pH to cool and precipitate crystals, wash and dry to obtain L-aspartic acid and washing liquid two, concentrate the mother liquor after cooling and crystallization, washing liquid one and washing liquid two through an amino acid-modified ZIF-8 / Pebax-1657 mixed matrix membrane, adjust the pH of the concentrated mother liquor, cool and recrystallize the precipitated crystals, wash and dry to obtain L-aspartic acid and washing liquid three. After this step, the total yield of L-aspartic acid reaches 89.5% and the purity reaches 98.5%. Mix washing liquid three with the mother liquor after recrystallization, add fumaric acid and use it in step one.

[0055] The preparation method of the histidine-modified UiO-67 enzyme complex is shown in Example 1.

[0056] The preparation method of amino acid modified ZIF-8 / Pebax-1657 mixed matrix membrane is shown in Example 1.

[0057] Comparative Example 1

[0058] The UiO-67 enzyme complex was added to a fumaric acid solution (the mass ratio of fumaric acid to ultrapure water was 1:12), and the reaction was carried out at 400 r / min and 45°C for 8 hours to obtain product 1, and the pH was adjusted to cool and precipitate crystals, and L-aspartic acid was obtained after elution and drying. After this step, the total yield of L-aspartic acid reached 62%, and the purity reached 93.7%, wherein the above raw materials were calculated by mass ratio, UIO-67 enzyme complex: fumaric acid solution = 1:110;

[0059] The preparation method of the UiO-67 enzyme complex comprises the following steps:

[0060] S1: dissolving zirconium tetrachloride in dimethylformamide, stirring at a speed of 600 r / min for 15 min, to prepare a metal ion solution, wherein the weight ratio of the above raw materials is zirconium tetrachloride: dimethylformamide = 1:40;

[0061] S2: 4,4-biphenyldicarboxylic acid was dissolved in dimethylformamide, and stirred at a speed of 600 r / min for 30 min to obtain a ligand solution. The above raw materials were calculated by mass ratio: 4,4-biphenyldicarboxylic acid: dimethylformamide = 1:45;

[0062] S3: Pour the ligand solution into a flask, place the flask in a preheated 80°C oil bath at a speed of 300 r / min, add the metal ion solution dropwise, and after the addition is completed, stir at a speed of 600 r / min for 2 hours, raise the temperature to 100°C, continue stirring for 5 hours, cool the flask to room temperature in air and filter, wash with ethanol 3 times, and dry the product in a drying oven at 70°C for 6 hours to obtain UiO-67;

[0063] S4: After mixing UiO-67 with aspartase solution (the mass ratio of aspartase to ultrapure water is 1:2), add 40% ammonium sulfate solution, stir it in an ice bath for 1 hour, let it stand at room temperature for 1 hour, add glutaraldehyde and stir for 30 minutes, wash it three times with 10% tris(hydroxymethyl)aminomethane hydrochloride buffer, and then dry it to obtain the UIO-67 enzyme complex. The above raw materials are calculated by mass ratio: UiO-67: aspartase solution: ammonium sulfate solution: glutaraldehyde = 1:0.2:2, wherein the mass of tris(hydroxymethyl)aminomethane hydrochloride buffer used for a single wash is 20 times the mass of histidine-modified UiO-67.

[0064] Table 1 Summary of total yield and purity of L-aspartic acid according to Examples 1 to 3 and Comparative Example 1

[0065] ;

[0066] Summary: As shown in Table 1, the technologies of histidine-modified UiO-67 enzyme complex and amino acid-modified ZIF-8 / Pebax-1657 mixed matrix membrane can greatly improve the yield and product purity of L-aspartic acid, and also achieve green production and cost control through reuse.

[0067] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing highly stable L-aspartic acid by synergistic catalysis, characterized in that: The following steps are involved: Step 1: adding the histidine modified UiO-67 enzyme complex to the fumaric acid solution, reacting at 400 r / min, 40-45° C., for 6-20 hours to obtain product 1, wherein the above raw materials are calculated by mass ratio, histidine modified UIO-67 enzyme complex: fumaric acid solution = 1:70-150; Step 2: Filter the product 1, wherein the solid is the histidine modified UIO-67 enzyme complex, and the liquid washed with ultrapure water is the washing liquid 1. After the washed histidine modified UIO-67 enzyme complex is mixed with the aspartase solution, an ammonium sulfate solution is added, and the mixture is stirred for 15 minutes under ice bath conditions, glutaraldehyde is added at room temperature and stirred for 15 minutes, and then washed once with tris(hydroxymethyl)aminomethane hydrochloride buffer solution. After drying, the regenerated histidine modified UIO-67 enzyme complex is obtained, which can be further used in step 1. The above raw materials are calculated by mass ratio, and the washed histidine modified UIO-67 enzyme complex: aspartase solution: ammonium sulfate solution: glutaraldehyde = 1: 0.01~0.1: 0.8~1.2, wherein the mass of the tris(hydroxymethyl)aminomethane hydrochloride buffer solution used for washing is 15~35 times the mass of the histidine modified UiO-67; Step 3: heating the filtrate of product 1 to 75-90°C, adjusting the pH to cool and precipitate crystals, eluting and drying to obtain L-aspartic acid and washing solution 2, concentrating the mother liquor after cooling and crystallization, washing solution 1 and washing solution 2 through an amino acid-modified ZIF-8 / Pebax-1657 mixed matrix membrane, adjusting the pH of the concentrated mother liquor, cooling and recrystallizing the precipitated crystals, eluting and drying to obtain L-aspartic acid and washing solution 3, mixing washing solution 3 with the mother liquor after recrystallization, adding fumaric acid and using it in step 1; The preparation method of the histidine-modified UiO-67 enzyme complex comprises the following steps: S1: dissolving zirconium tetrachloride in dimethylformamide, stirring at a speed of 600 r / min for 15 to 30 min, to prepare a metal ion solution, wherein the weight ratio of the above raw materials is zirconium tetrachloride: dimethylformamide = 1:35 to 63; S2: 4,4-biphenyldicarboxylic acid is dissolved in dimethylformamide, stirred at a speed of 600 r / min for 15-30 min, and then histidine is added and stirred for 30 min to obtain a ligand solution. The above raw materials are calculated by mass ratio: 4,4-biphenyldicarboxylic acid: dimethylformamide: histidine = 1:45-72:0.8-2.3; S3: Pour the ligand solution into a flask, place the flask in a preheated 75-80°C oil bath at a speed of 300 r / min, add the metal ion solution dropwise, and after the addition is completed, stir at a speed of 600 r / min for 2 hours, raise the temperature to 95-110°C, continue stirring for 5 hours, cool the flask to room temperature in air and filter, wash with ethanol three times, and dry the product in a drying oven at 70°C for 4-8 hours to obtain histidine-modified UiO-67; S4: After mixing the histidine-modified UiO-67 with the aspartase solution, add the ammonium sulfate solution, stir for 1 hour under ice bath conditions, stand for 1 hour at room temperature, add glutaraldehyde and stir for 30 minutes, wash three times with tris(hydroxymethyl)aminomethane hydrochloride buffer, and dry to obtain the histidine-modified UiO-67 enzyme complex. The above raw materials are calculated by mass ratio: histidine-modified UiO-67: aspartase solution: ammonium sulfate solution: glutaraldehyde = 1: 0.1~0.3: 1.5~4, wherein the mass of tris(hydroxymethyl)aminomethane hydrochloride buffer used for a single wash is 15~35 times the mass of histidine-modified UiO-67; The preparation method of the amino acid modified ZIF-8 / Pebax-1657 mixed matrix membrane comprises the following steps: Step 1: adding ZIF-8 nanoparticles to a methanol solution in which threonine is dissolved, with a mass ratio of ZIF-8 nanoparticles: threonine: methanol = 1: 0.75-1.55: 50-100, stirring at 40-80° C. for 2-4 hours, filtering, washing, and drying to obtain amino acid-modified ZIF-8 nanoparticles; Step 2: After mixing anhydrous ethanol and ultrapure water, heat them to 80-85°C in an oil bath under stirring conditions, then add Pebax-1657 thereto and keep stirring at 80-85°C for 4-5 hours to completely dissolve them, thereby obtaining a Pebax-1657 solution, wherein the mass ratio of Pebax-1657: anhydrous ethanol: ultrapure water is 1:5-20:10-25; Step 3: adding amino acid modified ZIF-8 nanoparticles to the Pebax-1657 solution prepared in step 2, and mixing by ultrasonic stirring to obtain a casting solution containing fillers, wherein the mass ratio of amino acid modified ZIF-8 nanoparticles to Pebax-1657 solution is 1:12-23; Step 4: The casting solution obtained in step 3 is subjected to ultrasonic degassing for 10 to 30 minutes and allowed to stand for 4 to 10 minutes. It is then poured onto a clean polytetrafluoroethylene plate and placed in a constant temperature oven at 60 to 80°C to dry for 18 to 24 hours. It is then placed in a vacuum oven to continue to remove the solvent for 18 to 24 hours to obtain an amino acid modified ZIF-8 / Pebax-1657 mixed matrix membrane.

2. The method for preparing a synergistic catalytic highly stable L-aspartic acid according to claim 1, characterized in that: The aspartase solution is prepared by dissolving aspartase in ultrapure water, and the mass ratio of aspartase to ultrapure water is 1:1-5.

3. The method for preparing a synergistic catalytic highly stable L-aspartic acid according to claim 1, characterized in that: The fumaric acid solution is prepared by dissolving fumaric acid in ultrapure water, wherein the mass ratio of fumaric acid to ultrapure water is 1:5-15.

4. The method for preparing a synergistic catalytic highly stable L-aspartic acid according to claim 1 or 2, characterized in that: The ammonium sulfate solution is prepared by dissolving ammonium sulfate in ultrapure water, wherein the concentration of the ammonium sulfate solution is 20% to 50%.

5. The method for preparing a synergistic catalytic highly stable L-aspartic acid according to claim 2, characterized in that: The preparation method of the tris(hydroxymethyl)aminomethane hydrochloride buffer solution is that tris(hydroxymethyl)aminomethane hydrochloride) is dissolved in ultrapure water, and the concentration of the tris(hydroxymethyl)aminomethane hydrochloride buffer solution is 5% to 17%.

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