Method for catalyzing chemical-looping synthesis of ammonia by using metal nitride catalyst at low temperature and normal pressure
By using metal nitride catalyst in the ball mill reactor to synthesize ammonia under low temperature and normal pressure, and through the recycling and regeneration of the catalyst, the problem of low nitrogen carrier efficiency is solved, and the efficient synthesis of ammonia under low temperature and normal pressure is achieved, reducing energy consumption and improving reaction efficiency.
Patent Information
- Application Number
- CN202510351581.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-24
- Publication Date
- 2025-07-01
AI Technical Summary
In the existing chemical chain ammonia synthesis technology, the nitrogen carrier nitriding and ammonia efficiency are low, and the high-temperature and high-pressure reaction conditions lead to prominent contradictions in thermodynamics and kinetics, and there is a lack of effective ammonia synthesis technology under low temperature and normal pressure.
Mechanical ball milling is performed in the ball mill reactor by alternately passing hydrogen and nitrogen into chemical chains under low temperature and normal pressure, and the catalyst is regenerated under the ball milling conditions to realize the recycling of the catalyst.
It effectively reduces the temperature and pressure of the synthetic ammonia reaction, improves the reaction efficiency, reduces energy consumption, and the catalyst exhibits excellent stability and durability under low temperature and normal pressure, and has good industrial application prospects.
Smart Images
Figure CN120229742A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of new chemical materials, and more specifically, relates to a method for catalytic chemical-looping ammonia synthesis using a metal nitride catalyst under low temperature and normal pressure. Background Art
[0002] With the large consumption of fossil fuels and the large emissions of greenhouse gases such as, the carbon-free fuel property of ammonia has attracted more and more attention of researchers. The development of low-energy-consumption and high-efficiency ammonia synthesis technology is the basis for realizing the fuel utilization of ammonia. The Haber-Bosch method proposed in the early 20th century is still the current industrial ammonia synthesis process basis, but this method has harsh reaction conditions, that is, in a high-temperature (300 - 500 °C) and high-pressure (20.26 - 30.39 MPa) environment, high-purity N2 and H2 react on an iron catalyst to synthesize ammonia. The high-temperature and high-pressure reaction conditions lead to prominent contradictions between thermodynamics and kinetics.
[0003] In recent years, with the development of chemical-looping technology, the chemical-looping ammonia synthesis technology that decomposes ammonia synthesis into two or more distributed reactions of nitrogen absorption and nitrogen release has gradually become the research focus. The chemical-looping ammonia synthesis process can effectively alleviate the contradiction between reaction thermodynamics and kinetics. And the way of alternating feeding of reactants avoids the problem of competitive adsorption of two reactants (N2 and H2) on the catalyst surface in catalytic ammonia synthesis.
[0004] At present, the nitridation and ammoniation efficiencies of nitrogen carriers in chemical-looping ammonia synthesis are still relatively low. As the core of the chemical-looping ammonia synthesis process, the performance of the nitrogen carrier directly affects the reaction efficiency. However, most of the current studies on the two-step reaction are relatively independent, and there are few applications of the nitrogen carrier cycle in the two-step reaction.
[0005] Therefore, developing a new type of mild, more environmentally friendly and sustainable ammonia synthesis process, breaking through the high-temperature and high-pressure limitations of the Haber-Bosch process, and exploring alternative ammonia synthesis routes under mild or ambient conditions are of great significance. Summary of the Invention
[0006] Aiming at the above problems existing in the prior art, the technical problem to be solved by the present invention is to provide a method for catalytic chemical-looping ammonia synthesis using a metal nitride catalyst under low temperature and normal pressure. Through mechanical ball milling, a series of unique properties are generated on the surface of the metal nitride catalyst, which can efficiently synthesize ammonia at lower temperatures and pressures, and the catalyst after the reaction can be directly recycled after in-situ regeneration.
[0007] To solve the above technical problems, the technical solutions adopted by the present invention are as follows:
[0008] A method for catalytic chemical-looping ammonia synthesis using a metal nitride catalyst under low temperature and atmospheric pressure, in which the metal nitride is used as the catalyst under low temperature and atmospheric pressure, and hydrogen and nitrogen are continuously and alternately introduced into a ball-milling reactor for chemical-looping ammonia synthesis.
[0009] Preferably, the metal element in the metal nitride is any one of La, V, Ce, Ti, Zn, Cu, Co, Cr, Ce, Ni, Fe, Mn, W, Tc, and Yb.
[0010] Preferably, the metal element in the metal nitride is any one of Zn, Cu, Ni, and Fe.
[0011] Preferably, the low temperature and atmospheric pressure are: temperature 20°C to 100°C, pressure 1 bar.
[0012] The method for catalytic chemical-looping ammonia synthesis using the metal nitride catalyst under low temperature and atmospheric pressure includes the following steps:
[0013] 1) Place the metal nitride in a ball-milling reactor for ball milling, and introduce hydrogen into the ball-milling reactor under atmospheric pressure to start the ammonia production reaction;
[0014] 2) After the reaction in step 1) is completed, introduce nitrogen into the ball-milling reactor, and perform nitrogen fixation reaction by ball milling under atmospheric pressure to regenerate and prepare the nitride catalyst;
[0015] 3) Repeat steps 1) and 2) for the nitride catalyst regenerated in step 2) to continuously synthesize ammonia.
[0016] Preferably, in step 1), the ball milling speed is 50 - 1500 r / min, the reaction temperature is 20 - 100°C, and the reaction time is 1 - 5 h.
[0017] Preferably, in step 1), the gas hourly space velocity of hydrogen is 1000 h -1 .
[0018] Preferably, in step 2), the ball milling speed is 50 - 1500 r / min, the reaction temperature is 20 - 100°C, and the reaction time is 2 - 10 h.
[0019] Preferably, in step 2), the gas hourly space velocity of nitrogen is 1000 h -1 .
[0020] An apparatus for the method of catalytic chemical-looping ammonia synthesis using a metal nitride catalyst under low temperature and atmospheric pressure, including a ball-milling reactor, a nitrogen gas inlet pipe, a hydrogen gas inlet pipe, a gas separator, and a motor.
[0021] Compared with the prior art, the beneficial effects of the present invention are:
[0022] 1) The present invention uses a ball-milling reactor. During the mechanical ball-milling process, the metal nitride catalyst can be refined to the nanoscale, and the locally instantaneous high temperature and high pressure generated by the collisions can break through the reaction activation energy barrier, effectively reducing the temperature and pressure of the ammonia synthesis reaction.
[0023] 2) The catalyst used in the present invention forms metal powder after the ammonia synthesis reaction. Under ball-milling conditions, it can react with nitrogen at normal pressure to be regenerated into a nitride catalyst, realizing the nitrogen fixation-ammonia production cycle reaction.
[0024] 3) Compared with the Haber-Bosch catalytic ammonia synthesis technology, the catalyst and ammonia production method adopted in the present invention have a simpler process, lower energy consumption, easily controllable reaction conditions, can significantly reduce production costs, and have good prospects for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 It is a schematic structural diagram of the device for chemical-looping ammonia synthesis at low temperature and normal pressure of the present invention; the reference numerals in the figure are: 1, ball-milling reactor; 2, nitrogen gas inlet pipe; 3, hydrogen gas inlet pipe; 4, gas separator; 5, motor. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described below in conjunction with specific embodiments. In the following embodiments, unless otherwise specified, the technical means used are all conventional means well-known to those skilled in the art. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.
[0027] In the following embodiments, zinc nitride, copper nitride, nickel nitride, and iron nitride selected are all purchased from Anhui Zesheng Technology Co., Ltd. The normal pressure in the following embodiments is 1 bar.
[0028] Example 1
[0029] In this embodiment, a device for catalytic chemical-looping ammonia synthesis with a metal nitride catalyst at low temperature and normal pressure is provided, as Figure 1 shown, including a ball-milling reactor 1, a nitrogen gas inlet pipe 2, a hydrogen gas inlet pipe 3, a gas separator 4, and a motor 5. The inlet end of the nitrogen gas inlet pipe 2 is connected to a nitrogen source, and the inlet end of the hydrogen gas inlet pipe 3 is connected to a hydrogen source. The motor 5 is electrically connected to the ball-milling reactor 1 and is used to drive the ball-milling medium in the ball-milling reactor 1 to rotate at a high speed, promoting the ammonia production and nitrogen fixation reactions and realizing efficient chemical-looping ammonia synthesis. The gas separator 4 is connected to the outlet of the ball-milling reactor 1. Under the action of low temperature, the ammonia gas generated by the reaction is liquefied and discharged separately from the tail gas after gas-liquid separation.
[0030] The working process of this device is as follows:
[0031] Place the metal nitride catalyst in the ball-milling reactor 1. Open the hydrogen gas supply pipe 3, and first introduce hydrogen into the ball-milling reactor 1 under atmospheric pressure. Then turn on the motor 5 to drive the ball-milling medium to rotate at high speed. After the reaction is completed, close the hydrogen gas supply pipe 3 and the motor 5. Collect the liquid ammonia generated in the ball-milling reactor 1 through the gas separator 4, and absorb and evacuate the reaction tail gas with an aqueous hydrochloric acid solution. Then open the nitrogen gas supply pipe 2, introduce nitrogen gas, and after the ball-milling reactor 1 is filled with nitrogen gas under atmospheric pressure, turn on the motor 5 and continue the ball-milling reaction. Repeat the above steps for the obtained nitride catalyst to continuously synthesize ammonia, with a total of 5 consecutive reactions.
[0032] The preparation processes of Examples 2-6 below are all carried out in the device of this example.
[0033] Example 2
[0034] A method for catalytic chemical-looping ammonia synthesis of a metal nitride catalyst at low temperature and atmospheric pressure, comprising the following steps:
[0035] 1) Place 10 g of zinc nitride powder catalyst in the ball-milling reactor for ball-milling. Under atmospheric pressure, introduce hydrogen into the ball-milling reactor for ammonia production reaction. The gas hourly space velocity (GHSV) of hydrogen is 1000 h -1 , the rotation speed of the ball mill is 50 r / min, the reaction temperature is 100 °C, and after reacting for 5 h, stop introducing hydrogen, and the reaction ends;
[0036] 2) After the reaction in step 1) is completed, introduce nitrogen gas into the ball-milling reactor. After the ball-milling reactor is filled with nitrogen gas under atmospheric pressure, carry out the nitrogen fixation reaction. The gas hourly space velocity (GHSV) of nitrogen is 1000 h -1 , the rotation speed of the ball mill remains 50 r / min, the reaction temperature is still 100 °C, and regenerate the nitride catalyst by ball-milling for 2 h under atmospheric pressure;
[0037] 3) Repeat step 1) and step 2) for the nitride catalyst obtained in step 2) to continuously synthesize ammonia.
[0038] Example 3
[0039] A method for catalytic chemical-looping ammonia synthesis of a metal nitride catalyst at low temperature and atmospheric pressure, comprising the following steps:
[0040] 1) Place 10 g of copper nitride powder catalyst in the ball-milling reactor for ball-milling. Under atmospheric pressure, introduce hydrogen into the ball-milling reactor for ammonia production reaction. The gas hourly space velocity of hydrogen is 1000 h -1 , the rotation speed of the ball mill is 300 r / min, the reaction temperature is 20 °C, and after reacting for 1 h, stop introducing hydrogen, and the reaction ends;
[0041] 2) After the reaction in step 1) is completed, nitrogen is introduced into the ball-milling reactor to make the ball-milling reactor in an environment filled with nitrogen at atmospheric pressure, and then the nitrogen fixation reaction is carried out. The gas hourly space velocity of nitrogen is 1000 h -1 , the rotation speed of the ball mill is maintained at 300 r / min, the reaction temperature is still 20 °C, and the ball milling is carried out for 10 h to regenerate and prepare the nitride catalyst;
[0042] 3) Repeat step 1) and step 2) for the nitride catalyst obtained in step 2) to continuously synthesize ammonia.
[0043] Example 4
[0044] A method for catalytic chemical-looping ammonia synthesis by a metal nitride catalyst at low temperature and atmospheric pressure, comprising the following steps:
[0045] 1) Place 10 g of nickel nitride powder catalyst in the ball-milling reactor for ball milling. Under atmospheric pressure, hydrogen is introduced into the ball-milling reactor for ammonia production reaction. The gas hourly space velocity of hydrogen is 1000 h -1 , the rotation speed of the ball mill is 1500 r / min, the reaction temperature is 60 °C, and after the reaction for 3 h, the introduction of hydrogen is stopped and the reaction ends;
[0046] 2) After the reaction in step 1) is completed, nitrogen is introduced into the ball-milling reactor to make the ball-milling reactor in an environment filled with nitrogen at atmospheric pressure, and then the nitrogen fixation reaction is carried out. The gas hourly space velocity of nitrogen is 1000 h -1 , the rotation speed of the ball mill is maintained at 1500 r / min, the reaction temperature is still 60 °C, and the ball milling is carried out for 6 h to regenerate and prepare the nitride catalyst;
[0047] 3) Repeat step 1) and step 2) for the nitride catalyst obtained in step 2).
[0048] Example 5
[0049] A method for catalytic chemical-looping ammonia synthesis by a metal nitride catalyst at low temperature and atmospheric pressure, comprising the following steps:
[0050] 1) Place 10 g of iron nitride powder catalyst in the ball-milling reactor for ball milling. Under atmospheric pressure, hydrogen is introduced into the ball-milling reactor for ammonia production reaction. The gas hourly space velocity of hydrogen is 1000 h -1 , the rotation speed of the ball mill is 1500 r / min, the reaction temperature is 30 °C, and after the reaction for 3 h, the introduction of hydrogen is stopped and the reaction ends;
[0051] 2) After the reaction in step 1) is completed, nitrogen is introduced into the ball-milling reactor to make the ball-milling reactor in an environment filled with nitrogen at atmospheric pressure, and then the nitrogen fixation reaction is carried out. The gas hourly space velocity of nitrogen is 1000 h -1 , the rotation speed of the ball mill is maintained at 1500 r / min, the reaction temperature is still 30 °C, and the ball milling is carried out for 6 h to regenerate and prepare the nitride catalyst;
[0052] 3) Repeat Steps 1) and 2) for the nitride catalyst obtained in Step 2).
[0053] Example 6
[0054] A method for catalytic chemical-looping ammonia synthesis using a metal nitride catalyst under low temperature and atmospheric pressure, comprising the following steps:
[0055] 1) Place 10 g of iron nitride powder catalyst in a ball-milling reactor for ball milling. Under atmospheric pressure, introduce hydrogen into the ball-milling reactor for ammonia production reaction. The gas hourly space velocity of hydrogen is 1000 h -1 , the rotation speed of the ball mill is 50 r / min, the reaction temperature is 80 °C, stop introducing hydrogen after reacting for 3 h, and the reaction ends;
[0056] 2) After the reaction in Step 1) is completed, introduce nitrogen into the ball-milling reactor. After the ball-milling reactor is in an environment filled with nitrogen under atmospheric pressure, carry out nitrogen fixation reaction. The gas hourly space velocity of nitrogen is 1000 h -1 , the rotation speed of the ball mill remains 50 r / min, the reaction temperature is still 80 °C, and ball mill for 8 h to regenerate and prepare the nitride catalyst;
[0057] 3) Repeat Steps 1) and 2) for the nitride catalyst obtained in Step 2) to continuously synthesize ammonia.
[0058] Example 7
[0059] Perform continuous reaction tests on Examples 2 - 6. After the catalyst is recycled 5 times, use the Nessler's reagent spectrophotometry method to analyze the ammonia yield (GB / T 14668 - 93). Ammonia generation rate = total amount of ammonia synthesis / total time of ammonia production reaction. The results are shown in Table 1.
[0060] Table 1 Reaction test results of Examples 2 - 6
[0061]
[0062] As can be seen from Table 1, there are significant differences in the ammonia generation rate and total synthesis amount of the catalyst under different conditions, indicating that the reaction conditions have a significant impact on the catalyst performance. Optimizing the parameters can improve the ammonia synthesis efficiency. Further experiments show that the catalyst exhibits excellent stability and durability in 5 consecutive reactions, providing reliable technical support for chemical-looping ammonia synthesis under low temperature and atmospheric pressure, and promoting the development of green ammonia synthesis technology.
[0063] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.
Claims
1. A method for synthesizing ammonia by chemical chain catalysis using a metal nitride catalyst at low temperature and normal pressure, characterized in that: At low temperature and normal pressure, metal nitride is used as a catalyst, and hydrogen and nitrogen are continuously and alternately introduced into a ball mill reactor to carry out chemical chain synthesis of ammonia.
2. The method for synthesizing ammonia by catalyzing chemical chaining with a metal nitride catalyst at low temperature and normal pressure according to claim 1, characterized in that: The metal element in the metal nitride is any one of La, V, Ce, Ti, Zn, Cu, Co, Cr, Ce, Ni, Fe, Mn, W, Tc, and Yb.
3. The method for synthesizing ammonia by catalyzing chemical chaining with a metal nitride catalyst at low temperature and normal pressure according to claim 2, characterized in that: The metal element in the metal nitride is any one of Zn, Cu, Ni and Fe.
4. The method for synthesizing ammonia by catalyzing chemical chaining with a metal nitride catalyst at low temperature and normal pressure according to claim 1, characterized in that: The low temperature and normal pressure are: temperature 20°C~100°C, pressure 1 bar.
5. The method for synthesizing ammonia by catalyzing chemical chaining with a metal nitride catalyst at low temperature and normal pressure according to claim 1, characterized in that: The following steps are involved: 1) placing the metal nitride in a ball mill reactor for ball milling, and introducing hydrogen into the ball mill reactor under normal pressure to start ammonia production reaction; 2) After the reaction in step 1) is completed, nitrogen is introduced into the ball milling reactor, and the ball milling is performed under normal pressure to carry out a nitrogen fixation reaction, thereby regenerating and preparing a nitride catalyst; 3) Repeating steps 1) and 2) with the nitride catalyst regenerated in step 2) to continuously synthesize ammonia.
6. The method for synthesizing ammonia by catalyzing chemical chaining with a metal nitride catalyst at low temperature and normal pressure according to claim 5, characterized in that: In the step 1), the ball milling speed is 50-1500 r / min, the reaction temperature is 20-100° C., and the reaction time is 1-5 h.
7. The method for synthesizing ammonia by catalyzing chemical chaining with a gold metal nitride catalyst at low temperature and normal pressure according to claim 5, characterized in that: In the step 1), the gas hourly space velocity of hydrogen is 1000 h -1 .
8. The method for synthesizing ammonia by catalyzing chemical chaining with a metal nitride catalyst at low temperature and normal pressure according to claim 5, characterized in that: In the step 2), the ball milling speed is 50-1500 r / min, the reaction temperature is 20-100° C., and the reaction time is 2-10 h.
9. The method for synthesizing ammonia by catalyzing chemical chaining with a metal nitride catalyst at low temperature and normal pressure according to claim 5, characterized in that: In step 2), the gas hourly space velocity of nitrogen is 1000 h -1 .
10. A device for catalyzing ammonia synthesis by chemical chaining at low temperature and normal pressure using the metal nitride catalyst according to any one of claims 1 to 9, characterized in that: It comprises a ball mill reactor (1), a nitrogen vent pipe (2), a hydrogen vent pipe (3), a gas separator (4), and a motor (5).