Method and system for producing hydrogen through ammonia decomposition

Abstract

The invention discloses a method and system for producing hydrogen through ammonia decomposition, and the method comprises the steps: taking graphene as a microwave absorption medium, absorbing microwaves by the graphene under the irradiation of the microwaves, and rapidly raising the temperature to 1000 DEG C within 10 seconds to provide heat energy for ammonia decomposition; pi electrons moving almost freely in the graphene rapidly move under the action of a microwave field and collide with ammonia molecules to activate the ammonia molecules, and discharge plasma is generated; ammonia decomposition is realized under the synergistic effect of thermocatalysis and plasma catalysis; the system comprises an ammonia gas bottle, the ammonia gas bottle is communicated with an inlet of a quartz reactor through a gas mass flow meter, graphene is placed in the quartz reactor, the quartz reactor is placed in a microwave synthesis extraction instrument, an outlet of the quartz reactor is communicated with an inlet of a gas washing bottle, and an outlet of the gas washing bottle is communicated with an inlet of a gas collecting device; according to the invention, hydrogen is generated in an extremely short time, so that the starting time of the whole ammonia decomposition system is obviously shortened; the system is simple in structure, convenient to operate, lower in cost, more energy-saving and more environment-friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production by decomposing ammonia, and in particular to a method and system for hydrogen production by decomposing ammonia. Background Art

[0002] Hydrogen, as a highly promising clean energy carrier, has been widely used in many fields such as fuel cells and chemical industry due to its significant advantages such as zero carbon emissions after combustion and high energy density. However, traditional hydrogen production technologies, such as water electrolysis and natural gas reforming, have exposed many drawbacks. These methods are not only energy-intensive and costly, but also produce a large amount of carbon emissions, which seriously restricts the promotion and application of hydrogen in a wider range. Ammonia, as a common chemical raw material, shows unique potential for hydrogen production. Its decomposition products are only hydrogen and nitrogen. It has the outstanding advantages of huge potential for hydrogen production, extremely wide sources, and relatively convenient storage and transportation. In recent years, power generation systems based on ammonia decomposition to produce hydrogen have gradually attracted widespread attention from all walks of life.

[0003] However, it cannot be ignored that the traditional ammonia decomposition hydrogen production system has many problems that need to be solved. The existing ammonia decomposition hydrogen production system, such as the patent application named "An ammonia decomposition reaction device and system" (publication number CN116443813B), adopts the method of directly heating and decomposing ammonia. Although this method is simple and direct to operate, it has prominent problems such as high energy consumption and poor safety. On the other hand, starting from the system in a cold state until a stable hydrogen supply is achieved, this process often takes a long time, usually more than 30 minutes. The long startup time has brought many adverse effects to the entire system: first, it seriously affects the response speed of the system. When faced with changes in the external demand for hydrogen, it is unable to respond quickly and supply the required hydrogen in time. At the same time, the flexibility of the system is also greatly reduced, and it is difficult to quickly adjust the operating state according to the actual situation. Secondly, the long startup process means more energy consumption. In order to achieve and maintain the high temperature required for ammonia decomposition, various heating equipment needs to be continuously operated, which undoubtedly increases the energy cost. Moreover, the long startup time also prolongs the operating time of the equipment, aggravates the loss of the equipment, and further increases the production cost. Summary of the invention

[0004] In order to overcome the above-mentioned existing shortcomings, the purpose of the present invention is to provide a method and system for producing hydrogen by decomposing ammonia, which utilizes the interaction between microwaves and graphene to instantly generate high-temperature thermal energy and a plasma environment to start the ammonia decomposition process, produce hydrogen in a very short time, and significantly shorten the start-up time of the entire ammonia decomposition system; using a microwave synthesis extraction instrument, a high-temperature environment and a plasma environment can be provided simultaneously for the ammonia decomposition process, the system has a simple structure, is easy to operate, reduces costs, and is more energy-saving and environmentally friendly.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme:

[0006] A method for producing hydrogen by decomposing ammonia uses graphene as a microwave absorbing medium. Under microwave irradiation, the graphene absorbs microwaves and quickly heats up to 1000°C within 10 seconds, providing thermal energy for ammonia decomposition. The nearly freely moving π electrons in the graphene move rapidly under the action of the microwave field, collide with ammonia molecules to activate the ammonia molecules, and generate discharge plasma. Ammonia decomposition is achieved under the synergistic effect of thermal catalysis and plasma catalysis.

[0007] The graphene is one or more of mechanically exfoliated graphene, liquid-phase exfoliated graphene, redox graphene, chemical vapor deposited graphene, and epitaxially grown graphene in any ratio; the number of graphene layers is one or more of single layer and multilayer or any ratio combination; the graphene form is one or more of powder form, film form or fiber form.

[0008] A system for realizing the above-mentioned method of producing hydrogen by decomposing ammonia includes an ammonia cylinder 1, which is connected to the inlet of a quartz reactor 4 through a gas mass flowmeter 2, graphene 5 is placed in the quartz reactor 4, and the quartz reactor 4 is placed in a microwave synthesis extractor 3. The outlet of the quartz reactor 4 is connected to the inlet of a washing bottle 6, and the outlet of the washing bottle 6 is connected to the inlet of a gas collecting device 7.

[0009] Within 1-3 seconds after the microwave synthesis extractor 3 is turned on, ammonia molecules are decomposed under the synergistic effect of thermal catalysis and plasma catalysis; within 5-10 seconds after the microwave synthesis extractor 3 is turned on, ammonia flowing through the quartz reactor 4 is decomposed and converted into decomposition products to obtain hydrogen and nitrogen.

[0010] The microwave frequency range of the microwave synthesis extractor 3 is 1 GHz-10 GHz.

[0011] The microwave time of the microwave synthesis extractor 3 is controlled to be 1-20 minutes, and the power used is 100-1000 watts.

[0012] The quartz reactor 4 is filled with an ammonia decomposition catalyst between the graphene 5 and the outlet of the quartz reactor 4 to improve the ammonia decomposition efficiency.

[0013] The inlet of the quartz reactor 4 is connected to argon gas at the same time, and ammonia gas and argon gas flow through the quartz reactor 4 at the same time. Argon gas is used to enhance the effect of generating discharge plasma and improve the efficiency of ammonia decomposition.

[0014] The argon gas and the ammonia gas are mixed in any ratio.

[0015] The gas collection device 7 includes gas collection and gas detection. The gas collection device includes air bag collection and gas cylinder collection. The gas detection includes mass spectrometry detection and gas chromatography detection.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The invention provides a method for producing hydrogen by decomposing ammonia, wherein the interaction between microwaves and graphene is applied to the ammonia decomposition process. After a microwave synthesis extractor is turned on, within a very short time (within 1-3 seconds), the temperature of ammonia flowing through a quartz reactor is increased due to the rapid heating of graphene, and the ammonia flowing through the quartz reactor collides with nearly freely moving π electrons in the graphene to activate ammonia molecules, thereby providing reaction conditions for ammonia decomposition. Subsequently, within a very short time (within 5-10 seconds after the microwave synthesis extractor is turned on), the ammonia flowing through the quartz reactor is decomposed and converted into decomposition products to obtain hydrogen and nitrogen, thereby significantly shortening the start-up time of ammonia decomposition.

[0018] The interaction process between microwaves and graphene adopted in the present invention enables the system to start quickly. The system can respond to changes in hydrogen demand more quickly and make timely adjustments, which greatly enhances the flexibility of the system and enables it to better adapt to complex and changeable working environments. At the same time, the reliability of the system has also been significantly improved, providing a strong guarantee for its stability and sustainability in practical applications.

[0019] The system of the present invention has a simple structure, convenient operation, and can effectively reduce costs. It only uses a microwave synthesis extractor to create the two reaction conditions of high temperature and plasma required for ammonia decomposition. There is no consumption of additional fossil energy, no use of excessive equipment, and significantly improves energy-saving and environmental protection benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a system schematic diagram of a method for producing hydrogen by decomposing ammonia according to Example 1 of the present invention.

[0021] Figure 2 This is the mass spectrum of the gas product after ammonia decomposition in Example 1 of the present invention. DETAILED DESCRIPTION

[0022] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. 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.

[0023] Embodiment 1, a method for producing hydrogen by decomposing ammonia, using graphene as a microwave absorbing medium, under the irradiation of microwaves, the graphene absorbs microwaves and quickly heats up to 1000°C within 10 seconds, providing thermal energy for the decomposition of ammonia; the nearly freely moving π electrons in the graphene move rapidly under the action of the microwave field, collide with ammonia molecules to activate the ammonia molecules, and generate discharge plasma; the decomposition of ammonia is achieved under the synergistic effect of thermal catalysis and plasma catalysis.

[0024] like Figure 1 As shown, a system for realizing the above-mentioned method of decomposing ammonia to produce hydrogen includes an ammonia bottle 1, a gas mass flowmeter 2, a microwave synthesis extractor 3, a quartz reactor 4, graphene 5, a gas washing bottle 6, and a gas collecting device 7; the ammonia bottle 1 provides a source of ammonia, the ammonia bottle 1 is connected to the inlet of the quartz reactor 4 through the gas mass flowmeter 2, the gas mass flowmeter 2 controls the flow rate of ammonia, and the ammonia with controlled flow rate enters the inlet of the quartz reactor 4, the graphene 5 is placed in the quartz reactor 4, the quartz reactor 4 is placed in the microwave synthesis extractor 3, the ammonia enters the quartz reactor 4 and flows through the graphene 5, the outlet of the quartz reactor 4 is connected to the inlet of the gas washing bottle 6, the outlet of the gas washing bottle 6 is connected to the inlet of the gas collecting device 7, the reacted gas flows out from the outlet of the quartz reactor 4 and flows into the inlet of the gas washing bottle 6, the gas washing bottle 6 absorbs the unreacted ammonia, and the decomposed gas flows out from the outlet of the gas washing bottle 6 and enters the gas collecting device 7.

[0025] The microwave synthesis extractor 3 is used to provide a microwave source; the quartz reactor 4 containing graphene 5 is in the microwave synthesis extractor 3 and is in a microwave energy field; the graphene 5 absorbs microwave energy and converts it into thermal energy, and the thermal energy is transferred to nearby ammonia molecules to form plasma; the ammonia is decomposed into nitrogen and hydrogen under the synergistic effect of thermal catalysis and plasma catalysis.

[0026] The gas collection device 7 is used for gas collection and gas detection of ammonia decomposition products. The gas collection device includes air bag collection and gas cylinder collection; gas detection includes one or more of mass spectrometry detection and gas chromatography detection.

[0027] Mass spectrometry is used to detect the products of ammonia decomposition, such as Figure 2 As shown, the microwave synthesis extractor 3 is started, and the post-reaction gas passes through the washing bottle 6 to absorb the unreacted ammonia, and then the molecular peaks of nitrogen and hydrogen are detected on the mass spectrum. Through the ammonia decomposition hydrogen production method of embodiment 1, ammonia generates nitrogen and hydrogen through the ammonia decomposition hydrogen production system of this embodiment.

[0028] The microwave frequency of the microwave synthesis extractor 3 is 2.45 GHz; the microwave time is controlled to be 2 minutes, and the power used is 400 watts; during the microwave process of this embodiment, it can be clearly seen that the graphene turns red and generates heat, and the microwave graphene produces a discharge phenomenon; ammonia is decomposed under the synergistic effect of high temperature and microwave discharge plasma with graphene 5 as the medium, and mass spectrometry is performed on the reaction products nitrogen and hydrogen.

[0029] In order to improve the decomposition efficiency of an ammonia decomposition method for producing hydrogen, an ammonia decomposition catalyst is placed between the graphene 5 and the outlet of the quartz reactor 4. The graphene absorbs microwave energy and converts it into thermal energy to activate ammonia molecules. The graphene absorbs microwave energy and discharges to generate plasma to activate ammonia molecules. Subsequently, the activated ammonia molecules decompose around the graphene under the action of thermal catalysis and plasma catalysis. A small amount of undecomposed ammonia molecules continue to decompose when passing through the ammonia decomposition catalyst, thereby improving the ammonia decomposition efficiency.

[0030] In order to improve the decomposition efficiency of a method for producing hydrogen by decomposing ammonia, argon is simultaneously connected to the inlet of the quartz reactor 4, and ammonia and argon flow through the quartz reactor 4 at the same time. The microwave acts on the argon to enhance the effect of generating discharge plasma, which makes it easier to activate ammonia molecules and is more conducive to the decomposition process of ammonia, thereby improving the ammonia decomposition efficiency; argon and ammonia are mixed in any ratio.

[0031] Example 2 is the same as Example 1 except that: the microwave frequency of the microwave synthesis extractor 3 is 10 GHz; the microwave time is controlled to 1 minute, and the power used is 1000 watts; the rest is the same as Example 1. In the microwave process of this example, it can be clearly seen that the graphene turns red and generates heat, and the microwave graphene produces a discharge phenomenon; ammonia is decomposed under the synergistic effect of the high temperature and microwave discharge plasma with the graphene 5 as the medium, and the reaction products nitrogen and hydrogen are detected by mass spectrometry.

[0032] Example 3 is the same as Example 1 except that: the microwave frequency of the microwave synthesis extractor 3 is 1 GHz; the microwave time is controlled to 20 minutes, and the power used is 100 watts; the rest is the same as Example 1. In the microwave process of this example, it can be clearly seen that the graphene turns red and generates heat, and the microwave graphene produces a discharge phenomenon; ammonia is decomposed under the synergistic effect of the high temperature and microwave discharge plasma with the graphene 5 as the medium, and the reaction products nitrogen and hydrogen are detected by mass spectrometry.

[0033] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. However, the obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A method for producing hydrogen by decomposing ammonia, characterized in that: Graphene is used as a microwave absorbing medium. Under microwave irradiation, graphene absorbs microwaves and quickly heats up to 1000°C within 10 seconds, providing heat energy for the decomposition of ammonia. The nearly free-moving π electrons in graphene move rapidly under the action of the microwave field, collide with ammonia molecules, activate ammonia molecules, and generate discharge plasma. Ammonia decomposition is achieved under the synergistic effect of thermal catalysis and plasma catalysis.

2. The method for producing hydrogen by decomposing ammonia according to claim 1, characterized in that: The graphene is one or more of mechanically exfoliated graphene, liquid-phase exfoliated graphene, redox graphene, chemical vapor deposited graphene, and epitaxially grown graphene in any ratio; the number of graphene layers is one or more of single layer and multilayer or any ratio combination; the graphene form is one or more of powder form, film form or fiber form.

3. A system for implementing the method for producing hydrogen by decomposing ammonia according to any one of claims 1 to 2, characterized in that: The invention comprises an ammonia bottle (1), wherein the ammonia bottle (1) is connected to an inlet of a quartz reactor (4) via a gas mass flow meter (2), graphene (5) is placed in the quartz reactor (4), the quartz reactor (4) is placed in a microwave synthesis extractor (3), the outlet of the quartz reactor (4) is connected to an inlet of a gas washing bottle (6), and the outlet of the gas washing bottle (6) is connected to an inlet of a gas collecting device (7).

4. The system according to claim 3, characterized in that: Within 1 to 3 seconds after the microwave synthesis extraction device (3) is turned on, ammonia molecules are decomposed under the synergistic effect of thermal catalysis and plasma catalysis; within 5 to 10 seconds after the microwave synthesis extraction device (3) is turned on, ammonia gas flowing through the quartz reactor (4) is decomposed and converted into decomposition products to obtain hydrogen and nitrogen.

5. The system according to claim 3, characterized in that: The microwave frequency range of the microwave synthesis extraction apparatus (3) is 1 GHz-10 GHz.

6. The system according to claim 3, characterized in that: The microwave time of the microwave synthesis extraction apparatus (3) is controlled to be 1-20 minutes, and the power used is 100-1000 watts.

7. The system according to claim 3, characterized in that: The quartz reactor (4) is filled with an ammonia decomposition catalyst at the graphene (5) and at the outlet of the quartz reactor (4) to improve the ammonia decomposition efficiency.

8. The system according to claim 3, characterized in that: The inlet of the quartz reactor (4) is simultaneously connected to argon gas, and ammonia gas and argon gas flow through the quartz reactor (4) simultaneously. The argon gas is used to enhance the effect of generating discharge plasma and improve the efficiency of ammonia decomposition.

9. The system according to claim 8, characterized in that: The argon gas and the ammonia gas are mixed in any ratio.

10. The system according to claim 3, characterized in that: The gas collection device (7) includes gas collection and gas detection. The gas collection device includes gas bag collection and gas cylinder collection. The gas detection includes mass spectrometry detection and gas chromatography detection.

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