Preparation method of artificial nitrogen fixation nano-enzyme

Abstract

The invention provides a preparation method of a molybdenum-based artificial nitrogen-fixing nano enzyme and a process for quickly converting nitrogen into ammonia under the condition of low energy consumption. The inorganic nano-material mimic enzyme with nitrogenase activity is prepared from nano molybdenum oxide and metal carbonates of different species and is used for simulating nitrogen fixation of natural nitrogenase. The prepared artificial nitrogenase is applied to catalysis of nitrogen and water reaction, and ammonia can be rapidly prepared under the condition of low energy consumption. The artificial nitrogenase provided by the invention is simple in preparation method and low in cost, and can be stably stored at normal temperature and normal pressure; the provided nitrogen fixation technology is low in energy consumption and does not need specific equipment; after water is added, spontaneous reaction can be carried out at normal temperature and normal pressure, and extra energy is not needed; the reaction product only contains ammonia, so that the problem of difficult separation and purification does not exist; the prepared artificial nitrogenase is safe and non-toxic and can be widely applied to the fields of agriculture, chemical engineering and the like.

Description

Technical Field

[0001] The present invention is used in the field of nitrogen conversion into ammonia, and specifically relates to a method for preparing an artificial nitrogenase, as well as a process for rapidly converting nitrogen into ammonia by the artificial nitrogenase without energy consumption and its application in agriculture and industry. Background Art

[0002] As the main component of nitrogen fertilizer, ammonia significantly improves the yield and quality of crops. At the same time, in industry, ammonia is a key raw material for synthesizing products such as urea, nitric acid and plastics, supporting the development of the chemical industry. In addition, ammonia molecules contain high-density hydrogen, so they can be used as a storage and transportation medium for clean energy. At present, the main way to synthesize ammonia in industry is through the Haber-Bosch process. This method uses iron catalysts to synthesize ammonia from nitrogen and hydrogen under high temperature and high pressure. This method consumes a lot of energy and is extremely dependent on fossil fuels. Unlike traditional nitrogen fixation processes, natural nitrogenase can achieve efficient catalysis of nitrogen and water into ammonia at low energy consumption. However, natural enzymes are protein molecules, which are limited by their easy inactivation, short lifespan, and difficult preservation, making them difficult to produce and utilize on a large scale.

[0003] Using nanomaterials with nitrogenase-like activity to simulate nitrogenase is an effective way to replace natural nitrogenase and achieve nitrogen fixation to ammonia at room temperature and pressure. Artificial nitrogenase prepared using inorganic materials has a catalytic efficiency similar to that of natural enzymes, and can maintain high activity under extreme conditions, with stable performance and easy preservation. For artificial enzyme simulations, the key to improving and optimizing their activity is to reasonably design their active centers and coordination environments. The active centers of natural nitrogenase are metal iron and molybdenum, which provide a strong reference for the design of artificial nitrogenase. At the same time, there are currently no mature methods and technologies for preparing artificial nitrogenase.

[0004] Based on the above analysis, the industry is in urgent need of a new method for preparing artificial nitrogenase, a new technology for efficiently converting nitrogen based on the artificial enzyme, and a new process for its application in agriculture. Summary of the invention

[0005] In order to fill this gap, the present invention proposes a new method for low-energy rapid preparation of a novel artificial nitrogenase. The artificial nitrogenase prepared by this method can convert nitrogen into amines at low energy consumption and can be used to increase the yield and income of crops.

[0006] Through in-depth research on artificial nitrogenase materials, the present invention fills the gap in the application of existing nitrogen fixation technology in the field of increasing agricultural production and income, and provides a new technical path and theoretical support for the research and development of related industries in the future. With further research and experimental verification, the application of artificial nitrogenase materials will show great potential in promoting the increase of crop production and income, increasing crop yields, reducing the practical use of nitrogen fertilizers, and improving the ecological environment.

[0007] The present invention first discloses a preparation method and application scenario of an artificial nitrogenase material, including:

[0008] (1) A method for preparing a novel artificial nitrogenase material is provided, comprising: taking 1-10 mmol of molybdenum trioxide or molybdenum dioxide and 1-20 mmol of alkali metal carbonate or transition metal carbonate M x (CO 3 ) y (wherein 1≤x≤3, 1≤y≤4) in a certain ratio, stirring for more than 10 minutes to obtain a reaction mixture; after the mixture is loaded into a reaction kettle, it is transferred to an oven for heat preservation treatment, and after the reaction kettle is completely cooled, it is taken out to obtain powdered artificial nitrogenase;

[0009] (2) A method for preparing an artificial nitrogenase material is provided, wherein: the insulation treatment temperature is 300 to 700° C., and the insulation treatment time is 100 to 360 minutes.

[0010] (3) The artificial nitrogenase provided can catalyze the reaction of nitrogen and water to produce ammonia;

[0011] (4) The artificial nitrogenase provided catalyzes the nitrogen production ammonia reaction, and the ammonia content in the product is determined using the national standard HJ536-2009 (Determination of ammonia nitrogen in water quality - salicylic acid spectrophotometry) method.

[0012] (5) The artificial nitrogenase described above can be used in agriculture by diluting the obtained molybdenum-based artificial nitrogenase solution at a ratio of 1:100-1:10000 and spraying it on the leaves of crops at different stages of their growth and development.

[0013] (6) The application scope of the artificial nitrogenase in agriculture includes but is not limited to staple crops, fruits, vegetables, and forage.

[0014] The artificial nitrogenase described in the present invention is expected to become the core technology for the next generation of ammonia synthesis, providing key support for the green transformation of the chemical industry. (1) The artificial nitrogen-fixing nanozyme can efficiently catalyze the conversion of nitrogen into ammonia under milder conditions (such as room temperature and atmospheric pressure), significantly reducing energy consumption and carbon emissions, which is in line with the development of green chemical industry.

[0015] (2) The artificial nitrogen-fixing nanozyme can operate at normal temperature and pressure, and is more suitable for distributed ammonia production. The artificial nitrogen-fixing nanozyme can be used in areas lacking centralized chemical facilities to synthesize ammonia on-site as fertilizer or to quickly deploy ammonia production equipment.

[0016] (3) Traditional ammonia synthesis equipment is large in scale and difficult to miniaturize. The artificial nitrogen-fixing nanozyme described in the present invention is suitable for the development of small-scale synthesis equipment due to its material and catalytic characteristics.

[0017] (4) The artificial nitrogen-fixing nanozyme can be used to synthesize ammonia using industrial by-products (such as hydrogen-rich gas or waste gas), thereby improving resource utilization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 XRD characterization of nitrogenase nanozyme;

[0019] Figure 2 Raman spectroscopy characterization of nitrogenase nanozyme;

[0020] Figure 3 Colorimetric reaction for characterization of nitrogen fixation activity of nitrogenase nanozyme;

[0021] Figure 4 The total amount of ammonia produced by nitrogenase nanozyme vs time curve;

[0022] Figure 5 NMR characterization of nitrogen fixation and ammonia production by nitrogenase nanozymes;

[0023] Figure 6 The efficiency of nitrogenase nanozymes in increasing agricultural production and income;

[0024] Figure 7 Use nitrogenase nanozymes to reduce and replace nitrogen fertilizers in agriculture;

[0025] Figure 8 Real-time infrared characterization of nitrogenase nanozymes for industrial ammonia synthesis. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Embodiment 1:

[0028] This example provides a method for preparing a dry molybdenum-based artificial nitrogenase, and the specific steps are as follows:

[0029] (1) Take 1-10 mmol of molybdenum trioxide or molybdenum dioxide and 1-20 mmol of alkali metal carbonate or transition metal carbonate M x (CO 3 ) y (wherein 1≤x≤3, 1≤y≤4) in a certain ratio, stirring for more than 10 min to obtain a reaction mixture;

[0030] (2) The mixture is placed in a reaction kettle, transferred to an oven and heat treated at 300 to 700° C. for 100 to 360 minutes. After the reaction kettle is completely cooled, it is taken out to obtain powdered artificial nitrogenase.

[0031] Embodiment 2:

[0032] This example provides a method for preparing a wet-process molybdenum-based artificial nitrogenase, and the specific steps are as follows:

[0033] (1) adding 1-10 mmol of molybdenum trioxide or molybdenum dioxide into a reaction kettle, and adding 30-90 mL of deionized water to dissolve; the reaction kettle has stirring and heating functions, and the stirring and heating functions are started in sequence;

[0034] (2) Keep the temperature in the reactor at 50-90°C for 1-4 hours, and add 1-20 mmol of alkali metal carbonate or transition metal carbonate M in a certain proportion. x (CO 3 ) y (wherein 1≤x≤3, 1≤y≤4), to obtain a mixed solution;

[0035] (3) The mixed solution is heated and stirred at 50 to 90° C. for 0.5 to 2.5 hours, and after cooling, an aqueous solution of molybdenum-based artificial nitrogenase is obtained.

[0036] The XRD characterization results of the prepared artificial nitrogenase nanozyme are shown in Figure 1 The Raman spectroscopy results are shown in Figure 2 shown.

[0037] Embodiment 3:

[0038] This example provides a method for producing amines using the prepared artificial nitrogen-fixing nanozyme, and the specific steps are as follows:

[0039] (1) After adding 4-6 mL of artificial nitrogen-fixing nanozyme into a three-necked flask, the three-necked flask was sealed with a rubber stopper and stirred at a stirring rate of 100-800 r / min for 4-10 min;

[0040] (2) maintaining the stirring rate and the air pressure in the bottle constant, and continuously filling the system with high-purity nitrogen or air for 5-10 minutes, and then sealing the bottle again to achieve the artificial nitrogenase-catalyzed reaction of nitrogen and water to produce ammonia;

[0041] (3) During the reaction, different time points (such as 2 h, 4 h, 8 h, etc.) were selected and samples were taken using a gas-tight syringe. The products were subjected to nuclear magnetic resonance analysis to determine the type and yield of the amine products. The ammonia content in the products was determined using the national standard HJ536-2009 (Determination of ammonia nitrogen in water quality - salicylic acid spectrophotometry).

[0042] The concentration of amines detected by salicylic acid spectrophotometry at different reaction times is shown in the following figure. Figure 3-4 As shown, the results of nuclear magnetic resonance analysis to detect the production of amines are as follows Figure 5 shown.

[0043] Embodiment 4:

[0044] This embodiment provides a method for using the artificial nitrogen-fixing nanozyme to increase crop yield and income, and the specific steps are as follows:

[0045] (1) Add 0.8-1.8 g of molybdenum-based artificial nitrogenase to a reactor, add 4 mL of water, and add a dispersant in a certain proportion; the reactor is equipped with stirring and ultrasonic functions, and the ultrasonic and stirring functions are started in sequence;

[0046] (2) After being treated in the reactor for a certain period of time, an aqueous solution of molybdenum-based artificial nitrogenase is obtained;

[0047] (3) After diluting the obtained molybdenum-based artificial nitrogenase solution at a ratio of 1:100-1:10000, it is sprayed on the leaves of crops manually or by drone at different stages of crop growth and development.

[0048] (4) Through the effect testing of more than ten kinds of crops, including staple crops, fruits, vegetables, forage, etc., molybdenum-based artificial nitrogenase has shown good effects in increasing production and income. The results are as follows Figure 6 shown.

[0049] (5) The significance of nano-nitrogenase to modern agriculture is also reflected in protecting the ecological environment and maintaining the sustainable development of agriculture. Artificial nitrogenase can be used to reduce the amount of traditional nitrogen fertilizers. Figure 7 As shown in the figure, even when only 70% of nitrogen fertilizer was used, the experimental plants were still able to maintain a good condition and the nitrogen content of the leaves of the plants could still be doubled, which means that nitrogen-fixing nanozymes have the potential to replace nitrogen fertilizers by reducing the amount of nitrogen fertilizer.

[0050] Gradually improve the soil environment, realize the sustainable development of agriculture, and gradually achieve the national strategic goal of reducing nitrogen emissions.

[0051] Example 5

[0052] This embodiment provides a technical method for using the artificial nitrogen-fixing nanozyme for industrial nitrogen fixation. The specific steps are as follows:

[0053] (1) adding a certain amount of artificial nitrogen-fixing nanozyme into a reactor, adding water and stirring to completely dissolve it;

[0054] (2) maintaining the stirring rate and the air pressure in the bottle unchanged, and continuously filling the reactor system with high-purity nitrogen or air, and then sealing the reactor to achieve the production of ammonia by the reaction of nitrogen and water catalyzed by artificial nitrogenase;

[0055] (3) The reaction supernatant was collected at different reaction times, and the amine produced by the reaction solution was monitored in real time by infrared. The results were as follows: Figure 8 As shown;

[0056] (4) The artificial nitrogen-fixing nanozyme can efficiently catalyze the conversion of nitrogen into ammonia under milder conditions (such as room temperature and atmospheric pressure), significantly reducing energy consumption and carbon emissions, and is in line with the development of green chemical industry. In addition, traditional ammonia synthesis equipment is large in scale and difficult to miniaturize. The artificial nitrogen-fixing nanozyme of the present invention is suitable for the development of small equipment and rapid deployment of ammonia production equipment due to its material and catalytic characteristics.

Claims

1. A method for preparing a dry-process molybdenum-based artificial nitrogenase, comprising: (1) Take 1-10 mmol of molybdenum trioxide or molybdenum dioxide and 1-20 mmol of alkali metal carbonate or transition metal carbonate M x (CO3) y (wherein 1≤x ≤3, 1≤y ≤4) according to a certain ratio, stirring for more than 10 min to obtain a reaction mixture; (2) The mixture is placed in a reactor, transferred to an oven for heat preservation, and after the reactor is completely cooled, it is taken out to obtain powdered artificial nitrogenase.

2. The preparation method according to claim 1, wherein: The insulation treatment temperature in step (2) is 300-700° C., and the insulation treatment time is 100-360 minutes.

3. A molybdenum-based artificial nitrogenase prepared according to any one of claims 1 to 2.

4. A use of the molybdenum-based artificial nitrogenase according to claim 3 in a process for converting nitrogen into ammonia, comprising: (1) After adding 0.8-1.8 g of molybdenum-based artificial nitrogenase into a three-necked flask, add 4 mL of water, seal the three-necked flask with a rubber stopper and stir at a stirring rate of 100-800 r / min for 4-10 min; (2) After stirring evenly, maintain the stirring rate and the air pressure in the bottle unchanged, and continue to fill the system with high-purity nitrogen or air for 5-10 minutes, and then seal the bottle again to achieve the production of ammonia by the reaction of nitrogen and water catalyzed by artificial nitrogenase; (3) During the reaction, select multiple time points (such as 2 h, 4 h, 8 h, etc.), use a gas-tight syringe to take samples, perform nuclear magnetic resonance analysis on the product, and quantify the amine product yield; and use the national standard HJ536-2009 (Determination of ammonia nitrogen in water quality - salicylic acid spectrophotometry) method to determine the ammonia content in the product.

5. The application of the molybdenum-based artificial nanozyme in agriculture includes: (1) Add 0.8-1.8 g of molybdenum-based artificial nitrogenase into a reactor, add 4 mL of water, and add a dispersant in a certain proportion; the reactor is equipped with stirring and ultrasonic functions, and the ultrasonic and stirring functions are started in sequence; (2) After being treated in the reactor for a certain period of time, an aqueous solution of molybdenum-based artificial nitrogenase is obtained; (3) Diluting the obtained molybdenum-based artificial nitrogenase solution in a ratio of 1:100-1:10000, and spraying it on the leaves of crops at different stages of their growth and development.

6. The use of the molybdenum-based artificial nitrogenase in agriculture according to claim 5, comprising: The agricultural application scope of step (2) includes but is not limited to staple food crops, fruits, vegetables, and forage.

7. A method for preparing a wet-process molybdenum-based artificial nitrogenase, comprising: (1) 1-10 mmol of molybdenum trioxide or molybdenum dioxide is added to a reaction kettle, and 30-90 mL of deionized water is added to dissolve the mixture; the reaction kettle has stirring and heating functions, and the stirring and heating functions are started in sequence; (2) After the reactor is kept warm for a certain period of time, 1-20 mmol of alkali metal carbonate or transition metal carbonate M is added in a certain proportion. x (CO3) y (wherein 1≤x ≤3, 1≤y ≤4), to obtain a mixed solution; (3) The mixed solution is continued to be heated and stirred, and after cooling, an aqueous solution of molybdenum-based artificial nitrogenase is obtained.

8. The preparation method according to claim 6, wherein: The insulation temperature in step (2) is 50-90°C and the insulation time is 1-4 hours; The insulation temperature in step (3) is 50-90° C., and the insulation time is 0.5-2.5 hours.

9. A use of the liquid molybdenum-based artificial nitrogenase according to claim 10 in a process for converting nitrogen into ammonia, comprising: After adding 4-6 mL of molybdenum-based artificial nitrogenase into the three-necked flask, the three-necked flask was sealed with a rubber stopper and stirred at a stirring rate of 100-800 r / min for 4-10 min; The stirring rate and the air pressure in the bottle are maintained constant, and high-purity nitrogen or air is continuously charged into the system for 5-10 minutes, and then the bottle mouth is sealed again to achieve the artificial nitrogenase-catalyzed reaction of nitrogen and water to produce ammonia; During the reaction, multiple time points (such as 2 h, 4 h, 8 h, etc.) were selected, and samples were taken using a gas-tight syringe. Nuclear magnetic resonance analysis was performed on the product to determine the type and yield of the product. The ammonia content in the product was determined using the national standard HJ536-2009 (Determination of ammonia nitrogen in water quality - salicylic acid spectrophotometry) method.

10. The industrial applications of the molybdenum-based artificial nanozyme include but are not limited to: (1) The artificial nitrogen-fixing nanozyme can efficiently catalyze the conversion of nitrogen into ammonia under milder conditions (such as room temperature and normal pressure), significantly reducing energy consumption and carbon emissions, which is in line with the development of green chemical industry; (2) The artificial nitrogen-fixing nanozyme can operate at room temperature and pressure, and is more suitable for distributed ammonia production. The artificial nitrogen-fixing nanozyme can be used in areas lacking centralized chemical facilities to synthesize ammonia on-site as fertilizer or to quickly deploy ammonia production equipment; (3) Traditional ammonia synthesis equipment is large in scale and difficult to miniaturize. The artificial nitrogen-fixing nanozyme of the present invention is suitable for the development of small-scale synthesis equipment due to its material and catalytic characteristics; (4) The artificial nitrogen-fixing nanozyme can be used to synthesize ammonia from industrial by-products (such as hydrogen-rich gas or waste gas), thereby improving resource utilization efficiency.

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