Method for synthesizing ammonia through lithium nitride catalyst chemical chain
By using lithium nitride catalyst in the ball mill reactor for chemical chain synthesis, the problem of high temperature and high pressure of Haber-Bosch process is solved, and an ammonia synthesis process with low energy consumption and low carbon emission is realized, with significant cost and environmental protection advantages.
Patent Information
- Application Number
- CN202510351577.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-24
- Publication Date
- 2025-06-10
AI Technical Summary
The existing Haber-Bosch ammonia synthesis process relies on high temperature and high pressure, resulting in high energy consumption and high carbon emissions. The catalyst costs are high and easy to be deactivated, making it difficult to achieve a sustainable synthetic ammonia process.
The lithium nitride catalyst is used to synthesize ammonia in a ball mill reactor, and the synthesis of ammonia and catalyst regeneration are achieved through the reaction of hydrogen and nitrogen under low temperature and normal pressure.
It reduces the temperature and pressure of the synthetic ammonia reaction, improves the activity and regeneration efficiency of the catalyst, simplifies the process flow, significantly reduces production costs, and has good industrial application prospects.
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of new chemical materials, and particularly relates to a method for chemically looping ammonia synthesis using a lithium nitride catalyst. Background Art
[0002] Ammonia is not only the main raw material for nitrogen fertilizers, but in recent years it has also been regarded as an "energy carrier" with important application prospects. The existing Haber-Bosch ammonia synthesis process is a process that highly depends on fossil energy, has high energy consumption, and high carbon emissions. Developing a new "green" ammonia synthesis process driven by renewable energy is an important topic for the sustainable development of human society. Decoupling the ammonia synthesis reaction into two or more stepwise reactions, namely the chemical looping ammonia synthesis process, has the characteristics of being easily coupled with renewable energy, operating at atmospheric pressure, and avoiding competitive adsorption of reactants.
[0003] Currently, the Haber-Bosch process is mainly used for ammonia synthesis in industry. This process uses an Fe-based catalyst, with a reaction temperature of 400 - 500 °C and a reaction pressure of 100 - 300 atm. Such harsh reaction conditions require high demands on equipment. Therefore, a large part of the investment in ammonia synthesis plants lies in high-pressure resistant equipment. This method has high energy consumption, consuming 1% - 2% of the total global energy consumption every year. According to statistics, 670 million tons are released globally every year by this process , accounting for about 2.4% of the global
[0004] Another ammonia synthesis catalyst used in industry, the Ru-based catalyst, although it has better activity than the Fe-based catalyst and relatively milder reaction conditions, has not been widely used because Ru is expensive and its carrier carbon is prone to methanation, resulting in deactivation. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to provide a method for chemically looping ammonia synthesis using a lithium nitride catalyst, which is simple, has low energy consumption, easy-to-control reaction conditions, and reduces production costs.
[0006] To solve the above technical problems, the technical solution adopted by the present invention is as follows:
[0007] A method for chemically looping ammonia synthesis using a lithium nitride catalyst, using lithium nitride as a catalyst, and respectively introducing hydrogen and nitrogen into a ball milling reactor under low-temperature and atmospheric-pressure conditions for chemically looping ammonia synthesis.
[0008] Further, the method for chemically looping ammonia synthesis using the lithium chloride catalyst includes the following steps
[0009] 1) Place lithium nitride in a ball-milling reactor for ball milling. Under normal pressure, introduce hydrogen into the ball-milling reactor to start the ammonia production reaction;
[0010] 2) After the reaction in step 1) is completed, introduce nitrogen into the ball-milling reactor, and carry out nitrogen fixation reaction by ball milling under normal pressure to regenerate and prepare a nitride catalyst;
[0011] 3) Repeat step 1) and step 2) for the nitride catalyst regenerated in step 2) to continuously synthesize ammonia.
[0012] Further, in step 1), the reaction time is 1 - 4 h.
[0013] Further, in step 1), the reaction temperature is 20 - 60 °C.
[0014] Further, in step 1), the rotation speed of the ball milling is 50 - 1500 r / min.
[0015] Further, in step 1), the reaction pressure is 1 bar.
[0016] Further, in step 2), the reaction time is 1 - 8 h.
[0017] Further, in step 2), the reaction temperature is 20 - 60 °C.
[0018] Further, in step 2), the rotation speed of the ball milling is 50 - 1500 r / min.
[0019] Further, in step 2), the reaction pressure is 1 bar.
[0020] Compared with the prior art, the present invention has the following advantages:
[0021] 1) The present invention uses a ball-milling reactor. The mechanical ball-milling process can refine the metal nitride catalyst to the nanoscale, and the locally instantaneous high temperature and high pressure generated by the collision can break through the reaction activation energy barrier, effectively reducing the temperature and pressure of the ammonia synthesis reaction;
[0022] 2) The lithium nitride catalyst adopted in the present invention has high reaction activity. After the ammonia production reaction, metallic lithium is more likely to react with nitrogen at low temperature to regenerate into a lithium nitride catalyst, realizing a low-temperature and normal-pressure nitrogen fixation - ammonia production cyclic reaction;
[0023] 3) The catalyst and ammonia production method adopted in the present invention are simpler in process, lower in energy consumption, easier to control reaction conditions, can significantly reduce production costs, and have good industrial application prospects compared with the Haber - Bosch catalytic ammonia synthesis technology. Detailed implementation manners
[0024] The present invention will be further illustrated below in conjunction with specific embodiments. The embodiments are implemented on the premise of the technical solution of the present invention. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention.
[0025] In the following embodiments, the Nessler reagent spectrophotometry was used to analyze the ammonia synthesis amount (GB / T 14668-93).
[0026] The atmospheric pressure in the following embodiments is 1 bar.
[0027] In the following embodiments, the calculation formula for the total amount of ammonia synthesis is: ammonia production rate = total amount of ammonia synthesis / total reaction time of ammonia production reaction.
[0028] Example 1
[0029] A method for chemical-looping ammonia synthesis using a lithium nitride catalyst includes the following steps:
[0030] (1) Weigh 10 g of lithium nitride powder catalyst. Use a ball mill reactor as the reaction device. The rotation speed of the ball mill is 50 r / min, the reaction temperature is 20 °C, and hydrogen is introduced at atmospheric pressure to start the ammonia production reaction. The gas hourly space velocity (GHSV) of hydrogen is 1000 h -1 , and after reacting for 1 h, stop introducing hydrogen, and the reaction ends;
[0031] (2) After the nitrogen production reaction ends, introduce nitrogen into the ball mill reactor. After the ball mill reactor is in an environment filled with nitrogen at 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 is 50 r / min, the reaction temperature is 20 °C, and ball mill for 2 h at atmospheric pressure to regenerate the by-product metal lithium and nitrogen in the ammonia production reaction in step 1) into a lithium nitride catalyst;
[0032] (3) Repeat step 1) and step 2) for the lithium nitride catalyst obtained in step 2), and cycle the ammonia production reaction. After the catalyst is cycled 5 times, use the Nessler reagent spectrophotometry to analyze the ammonia yield. The total amount of ammonia synthesis in 5 reactions is 8 mmol, and the ammonia production rate per gram of catalyst is 0.16 mmol / h.
[0033] Example 2
[0034] A method for chemical-looping ammonia synthesis using a lithium nitride catalyst includes the following steps:
[0035] (1) Weigh 10 g of lithium nitride powder catalyst. Use a ball mill reactor as the reaction device. The rotation speed of the ball mill is 150 r / min, the reaction temperature is 30 °C, and hydrogen is introduced at atmospheric pressure to start the ammonia production reaction. The gas hourly space velocity (GHSV) of hydrogen is 1000 h -1 , and after reacting for 4 h, stop introducing hydrogen, and the reaction ends;
[0036] After the ammonia production reaction ends, nitrogen is introduced into the ball milling reactor. After the ball milling reactor is in an environment filled with nitrogen at normal pressure, the nitrogen fixation reaction is carried out. The gas hourly space velocity (GHSV) of nitrogen is 1000 h -1 , the rotational speed of the ball mill is 150 r / min, the reaction temperature is 30 °C, and ball milling is carried out for 2 h at normal pressure. The reaction by-product metallic lithium from step 1) ammonia production is regenerated with nitrogen into a lithium nitride catalyst;
[0037] (3) Repeat step 1) and step 2) with the lithium nitride catalyst obtained in step 2), and carry out the cyclic ammonia production reaction. After the catalyst is recycled 5 times, the ammonia yield is analyzed by the Nessler reagent spectrophotometry method. The total amount of ammonia synthesis in 5 reactions is 42 mmol. After calculation, the ammonia generation rate per gram of catalyst is 0.21 mmol / h.
[0038] Example 3
[0039] A method for chemical looping ammonia synthesis with a lithium nitride catalyst includes the following steps:
[0040] (1) Weigh 10 g of the lithium nitride powder catalyst. Use the ball milling reactor as the reaction device. The rotational speed of the ball mill is 300 r / min, the reaction temperature is 30 °C, and hydrogen is introduced at normal pressure to start the ammonia production reaction. The gas hourly space velocity (GHSV) of hydrogen is 1000 h -1 , stop introducing hydrogen after reacting for 3 h, and the reaction ends;
[0041] After the ammonia production reaction ends, nitrogen is introduced into the ball milling reactor. After the ball milling reactor is in an environment filled with nitrogen at normal pressure, the nitrogen fixation reaction is carried out. The gas hourly space velocity (GHSV) of nitrogen is 1000 h -1 , the rotational speed of the ball mill is 300 r / min, the reaction temperature is 60 °C, and ball milling is carried out for 3 h at normal pressure. The reaction by-product metallic lithium from step 1) ammonia production is regenerated with nitrogen into a lithium nitride catalyst;
[0042] (3) Repeat step 1) and step 2) with the lithium nitride catalyst obtained in step 2), and carry out the cyclic ammonia production reaction. After the catalyst is recycled 5 times, the ammonia yield is analyzed by the Nessler reagent spectrophotometry method. The total amount of ammonia synthesis in 5 reactions is 34.5 mmol. After calculation, the ammonia generation rate per gram of catalyst is 0.23 mmol / h.
[0043] Example 4
[0044] A method for chemical looping ammonia synthesis with a lithium nitride catalyst includes the following steps:
[0045] (1) Weigh 10 g of lithium nitride powder catalyst. Use a ball-milling reactor as the reaction device. The rotation speed of the ball mill is 1500 r / min, the reaction temperature is 60 °C, and hydrogen is introduced at atmospheric pressure to start the ammonia production reaction. The gas hourly space velocity (GHSV) of hydrogen is 1000 h -1 , and stop introducing hydrogen after 4 h of reaction, and the reaction ends;
[0046] (2) After the ammonia production reaction ends, introduce nitrogen into the ball-milling reactor. After the ball-milling reactor is filled with nitrogen at 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 is 1500 r / min, the reaction temperature is 40 °C, and ball-mill for 8 h at atmospheric pressure to regenerate the by-product metallic lithium in the ammonia production reaction in step 1) and nitrogen into lithium nitride catalyst;
[0047] (3) Repeat step 1) and step 2) with the lithium nitride catalyst obtained in step 2) to carry out the cyclic ammonia production reaction. After the catalyst is recycled 5 times, use the Nessler reagent spectrophotometry to analyze the ammonia yield. The total amount of ammonia synthesis in 5 reactions is 68 mmol. After calculation, the ammonia generation rate per gram of catalyst is 0.34 mmol / h.
[0048] Example 5
[0049] A method for chemical-looping ammonia synthesis with lithium nitride catalyst, comprising the following steps:
[0050] (1) Weigh 10 g of lithium nitride powder catalyst. Use a ball-milling reactor as the reaction device. The rotation speed of the ball mill is 500 r / min, the reaction temperature is 50 °C, and hydrogen is introduced at atmospheric pressure to start the ammonia production reaction. The gas hourly space velocity (GHSV) of hydrogen is 1000 h -1 , and stop introducing hydrogen after 2 h of reaction, and the reaction ends;
[0051] (2) After the ammonia production reaction ends, introduce nitrogen into the ball-milling reactor. After the ball-milling reactor is filled with nitrogen at 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 is 500 r / min, the reaction temperature is 60 °C, and ball-mill for 1 h at atmospheric pressure to regenerate the by-product metallic lithium in the ammonia production reaction in step 1) and nitrogen into lithium nitride catalyst;
[0052] (3) Repeat step 1) and step 2) with the lithium nitride catalyst obtained in step 2) to carry out the cyclic ammonia production reaction. After the catalyst is recycled 5 times, use the Nessler reagent spectrophotometry to analyze the ammonia yield. The total amount of ammonia synthesis in 5 reactions is 24 mmol. After calculation, the ammonia generation rate per gram of catalyst is 0.24 mmol / h.
[0053] 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 using a lithium nitride catalyst chemical chain, characterized in that: Using lithium nitride as a catalyst, hydrogen and nitrogen are introduced into a ball mill reactor at low temperature and normal pressure to synthesize ammonia by chemical chain reaction.
2. The method for synthesizing ammonia using a lithium chloride catalyst chemical chain according to claim 1, characterized in that: The following steps are involved: 1) placing lithium 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.
3. The method for synthesizing ammonia using a lithium nitride catalyst chemical chain according to claim 2, characterized in that: In the step 1), the reaction time is 1-4 h.
4. The method for synthesizing ammonia using a lithium nitride catalyst chemical chain according to claim 2, characterized in that: In the step 1), the reaction temperature is 20-60°C.
5. The method for synthesizing ammonia by chemical chaining using lithium nitride catalyst according to claim 2, characterized in that: In the step 1), the rotation speed of the ball mill is 50-1500 r / min.
6. The method for synthesizing ammonia by chemical chaining using lithium nitride catalyst according to claim 2, characterized in that: In the step 1), the reaction pressure is 1 bar.
7. The method for synthesizing ammonia by chemical chaining using lithium nitride catalyst according to claim 2, characterized in that: In the step 2), the reaction time is 1-8 h.
8. The method for synthesizing ammonia by chemical chaining using lithium nitride catalyst according to claim 2, characterized in that: In the step 2), the reaction temperature is 20-60°C.
9. The method for synthesizing ammonia by chemical chaining using lithium nitride catalyst according to claim 2, characterized in that: In the step 2), the rotation speed of the ball mill is 50-1500 r / min.
10. The method for synthesizing ammonia by chemical chaining using lithium nitride catalyst according to claim 2, characterized in that: In the step 2), the reaction pressure is 1 bar.