Method for synthesizing ammonia through chemical chain denitrification based on aluminum ash

Abstract

The invention aims to provide the aluminum ash-based chemical-looping denitrification ammonia synthesis method, active aluminum components, catalytic components and primary structures in the aluminum ash are fully utilized as nitrogen carrier raw materials, and aluminum ash denitrification and continuous ammonia synthesis are realized through ammonia release and nitrogen carrying respectively. The method specifically comprises the following steps: (1) grinding the aluminum ash to a required particle size range; (2) high-temperature water vapor is introduced into the aluminum ash which is placed in the ammonia release reactor and ground in the step (1), and primary ammonia release is carried out; (3) uniformly mixing the ammonia release reaction product obtained in the step (2) with a carbon source in proportion, introducing nitrogen into a nitrogen-carrying reactor, and realizing nitrogen fixation regeneration through carbon thermal reduction; (4) introducing an oxidizing agent into the product subjected to nitrogen fixation in the step (3) in a carbon removal reactor for carbon removal; and (5) conveying the nitrogen carrier decarbonized in the step (4) back into the ammonia release reactor, and repeating the steps (2), (3) and (4) to realize the aluminum ash-based chemical-looping ammonia synthesis circulation. Compared with the prior art, based on the aluminum ash, through the properties of a chemical looping technology, normal pressure, low consumption and elimination of aluminum ash harm, preparation of synthesis ammonia coupling synthesis gas is achieved, and a new way is provided for energy reform and development of a synthesis ammonia new technology and mining of aluminum ash recycling and energy regeneration.

Description

[0001] The invention relates to the field of synthetic ammonia and the field of resource recovery and harmless utilization of hazardous wastes, and in particular to a method for synthesizing ammonia through chemical chain denitrification based on aluminum ash. Background Art

[0002] my country's demand for synthetic ammonia is higher than 60 million tons per year, with an energy consumption of 73.67 million tons of standard coal, accounting for about 1.5% of total energy consumption, and direct carbon emissions of 200 million tons. Synthetic ammonia technology plays an important role in food security and social stability. It is also a new generation of hydrogen storage carrier and an important support for energy reform and achieving the "dual carbon" goal. However, the traditional Haber process has the disadvantages of high pressure and high consumption, so there is an urgent need to develop new technologies with high efficiency and high selectivity. Aluminum-based chemical chain ammonia synthesis has a high yield and has the potential to transfer carbon energy to ammonia, which can expand the clean utilization of fuels and is one of the most promising technologies for synthetic ammonia in the future.

[0003] The booming development of the aluminum industry has led to a continuous increase in the demand for aluminum resources. Based on the concept of mineral protection and recycling, it is bound to deeply tap the aluminum resources in waste. my country's annual production of hazardous waste aluminum ash exceeds 3 million tons, but active aluminum accounts for more than 65%. The disorderly and inefficient disposal of aluminum ash is not only a threat to the environment and human health, but also a huge waste of aluminum resources. It is a pain point problem that the aluminum industry urgently needs to solve. One of the dangerous properties of aluminum ash comes from the high reactivity of rich aluminum nitride, which happens to be the main active ingredient of aluminum-based nitrogen carriers. In addition, the original components of aluminum ash contain active aluminum phase components such as metallic aluminum and aluminum oxide, as well as alkali metals, flux, other metals, magnesium aluminum spinel and other catalytic components. In summary, there is an urgent need for a new technology that can deeply tap the aluminum resource characteristics of aluminum ash and achieve low-consumption synthetic ammonia. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a method for synthesizing ammonia by chemical chain denitrification based on aluminum ash. The purpose of the present invention is to convert aluminum nitride in aluminum ash into ammonia gas, and to achieve continuous, efficient and low-consumption synthesis of ammonia by cyclic nitrogen fixation based on the original structure and composition of aluminum ash.

[0005] The technical solution of the present invention comprises the following steps: (1) Grind aluminum ash to the required particle size range; (2) introducing high-temperature steam into the ground aluminum ash (1) placed in the ammonia release reactor to initially release ammonia; (3) after uniformly mixing the ammonia release reaction product obtained in (2) with the carbon source in proportion, introducing nitrogen into the nitrogen loading reactor to achieve nitrogen fixation regeneration by carbon thermal reduction; (4) introducing an oxidant into a carbon removal reactor to remove carbon from the product after nitrogen fixation in (3); (5) The nitrogen-carrying body after decarbonization in (4) is transported back to the ammonia release reactor, and steps (2), (3), and (4) are repeated to realize the chemical chain ammonia synthesis cycle based on aluminum ash.

[0006] Furthermore, the aluminum ash in step (1) includes but is not limited to low-aluminum secondary aluminum ash and high-aluminum secondary aluminum ash.

[0007] Furthermore, the particle size of the aluminum ash after grinding in step (1) is less than 0.3 mm.

[0008] Furthermore, the temperature range of the ammonia release reactor in step (2) is set to 600 o C~1000 o C, the water vapor concentration range is set to 40%~80%.

[0009] Furthermore, the ammonia release reaction product obtained in step (2) is transported from the ammonia release reactor to the nitrogen loading reactor through a return system.

[0010] Furthermore, the temperature of the nitrogen-loaded reactor in step (3) is 1200 o C~1600 o C. Heat sources include but are not limited to ammonia release heat transfer and solar energy.

[0011] Furthermore, the ratio of the aluminum base to the carbon source in step (3) is set in the range of 1:3 to 3:1.

[0012] Furthermore, the carbon source in step (3) includes but is not limited to carbon-containing fuels such as biomass, coal, and organic solid waste.

[0013] Furthermore, the carbon removal reactor described in step (4) receives the product after nitrogen fixation regeneration from the nitrogen loading reactor described in step (3) through the return pipe, and transports the nitrogen loading body after carbon removal back to the ammonia release reactor described in step (2) through the return pipe.

[0014] Furthermore, the oxidant in step (4) includes but is not limited to air, oxygen, water vapor, and carbon dioxide, and the decarbonization temperature range is 200 o C~600 o C.

[0015] Furthermore, the synthesis gas produced by carbon removal in step (4) includes but is not limited to being used for Fischer-Tropsch synthesis to produce high-value chemicals.

[0016] Furthermore, the nitrogen-carrying body after decarbonization in step (5) is transported back to the ammonia release reactor in step (2) through the return pipe to release ammonia, then enters the nitrogen-carrying reactor in step (3) through the return pipe to load nitrogen, then enters the carbon removal reactor in step (4) through the return pipe to remove carbon, and returns again to form a cyclic synthetic ammonia of ammonia release-nitrogen loading-carbon removal.

[0017] Furthermore, the chemical chain denitrification and ammonia synthesis method based on aluminum ash is applied in the resource-to-energy technology of hazardous waste.

[0018] Beneficial effects: Compared with the prior art, the present invention has the following beneficial effects: the method for synthesizing ammonia by chemical chain denitrification based on aluminum ash proposed in the present invention can not only harmlessly and greenly remove and utilize the highly active aluminum nitride in aluminum ash, but also improve the efficiency of ammonia production with the help of the native catalytic components in aluminum ash. It is a typical low-carbon approach that uses carbon without emitting carbon. It not only realizes the potential value of hazardous waste in high-value utilization, but also opens up a new path to ease energy reform and aluminum ash resource utilization and exploration, and is in line with the country's strategic goals of low consumption and low carbon, circular development, and turning waste into energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the method for synthesizing ammonia by chemical chain denitrification based on aluminum ash of the present invention; Figure 2 It is the X-ray diffraction spectrum of the product after aluminum ash releases ammonia and carries nitrogen; Figure 3 The ability to synthesize ammonia based on aluminum ash chemical chain denitrification under multiple cycles. DETAILED DESCRIPTION

[0020] The contents of the present invention are further described in detail below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0021] A method for synthesizing ammonia by chemical chain denitrification based on aluminum ash, the technical steps include: (1) Grinding: Grind high-aluminum aluminum ash, low-aluminum aluminum ash and other aluminum ash to make the particle size less than 0.3 mm; (2) Ammonia release: High-temperature steam is introduced into the ground aluminum ash (1) placed in the ammonia release reactor to perform preliminary ammonia release. The temperature range is set at 600 o C~1000 o C, the water vapor concentration range is set to 40%~80%; (3) Nitrogen loading: The ammonia release reaction product obtained in (2) is transported from the ammonia release reactor to the nitrogen loading reactor through the return system. After the ammonia release reaction product and the carbon source are evenly mixed in proportion, nitrogen is introduced into the nitrogen loading reactor to achieve nitrogen fixation regeneration through carbon thermal reduction at a temperature of 1200 o C~1600 o C, the ratio of aluminum base to carbon source is set to 1:3~3:1, the carbon source is not limited to biomass, coal, organic solid waste and other carbon-containing fuels, the heat source is not limited to ammonia release heat transfer, solar energy; (4) Carbon removal: The product after nitrogen fixation in (3) is transported to the carbon removal reactor through a return feeder, and an oxidant is introduced to remove carbon. The oxidant includes but is not limited to air, oxygen, water vapor, and carbon dioxide. The carbon removal temperature range is 200 o C~600 o C; (5) Circulation: The nitrogen-carrying body after decarbonization in step (5) is transported back to the ammonia release reactor in step (2) through the return pipe to release ammonia, then enters the nitrogen-carrying reactor in step (3) through the return pipe to carry nitrogen, then enters the carbon removal reactor in step (4) through the return pipe to remove carbon, and then returns again to form a cyclic synthesis of ammonia release-nitrogen loading-carbon removal. Example

[0022] This example implements a method for synthesizing ammonia by chemical chain denitrification based on aluminum ash, and the steps are as follows: The secondary aluminum ash is ground to a particle size of less than 0.15 mm and then heated to 80% water vapor concentration and 700°C ammonia release temperature. o C, the ammonia production efficiency of aluminum ash is 61%, which is higher than the ammonia production efficiency of AlN / Al2O3 as nitrogen carrier under the same working conditions. The nitrogen carrying temperature is 1400 o C. When the ratio of aluminum phase to activated carbon is 2:1, the characteristic peak of aluminum nitride can be detected by X-ray diffraction. Example

[0023] This example implements a method for synthesizing ammonia by chemical chain denitrification based on aluminum ash, and the steps are as follows: The alkali metal loaded secondary aluminum ash was ground to a particle size of less than 0.15 mm and heated to 700 °C at a water vapor concentration of 80%. o C to release ammonia, the temperature is 1400 o C. When the ratio of aluminum phase to activated carbon was 2:1, the aluminum nitride yield increased by 3.5 times and the ammonia yield increased by 3.4 times.

[0024] In summary, compared with other denitrification methods, the chemical chain denitrification and ammonia synthesis based on aluminum ash has a high reaction rate, a large denitrification treatment capacity, and high heat and energy utilization in the system; at the same time, it can recycle the synthetic ammonia energy and utilize carbon-containing fuels, but the product is synthesis gas, without carbon dioxide emissions, which broadens the low-carbon and high-value utilization of carbon-containing energy; compared with conventional aluminum-based nitrogen carriers, the native aluminum nitride in aluminum ash has extremely high reaction activity, and other native components play an in-situ catalytic role in ammonia release and nitrogen loading, and are highly competitive in ammonia production and energy consumption. It is a native and cheap nitrogen carrier, which is more suitable for the harmless treatment of aluminum ash and large-scale synthetic ammonia process, and has certain guiding significance for aluminum ash resource utilization and synthetic ammonia technology.

[0025] It is particularly noted that the specific embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by ordinary technicians in this field, various changes can be made to the specific operating steps and various reactants and reaction conditions can be changed and replaced without departing from the purpose of the present invention. Therefore, the direct or indirect application of the present invention in other related fields is included in the scope of the present invention.

Claims

1. In view of the problems existing in the prior art, the object of the present invention is to provide a method for synthesizing ammonia by chemical chain denitrification based on aluminum ash, characterized in that: The following steps are involved: (1) Grind aluminum ash to the required particle size range; (2) introducing high-temperature steam into the ground aluminum ash (1) placed in the ammonia release reactor to initially release ammonia; (3) after uniformly mixing the ammonia release reaction product obtained in (2) with the carbon source in proportion, introducing nitrogen into the nitrogen loading reactor to achieve nitrogen fixation regeneration by carbon thermal reduction; (4) introducing an oxidant into a carbon removal reactor to remove carbon from the product after nitrogen fixation in (3); (5) The nitrogen-carrying body after decarbonization in (4) is transported back to the ammonia release reactor, and steps (2), (3), and (4) are repeated to realize the chemical chain ammonia synthesis cycle based on aluminum ash.

2. The method for synthesizing ammonia by chemical chaining denitrification based on aluminum ash according to claim 1, characterized in that: The aluminum ash in step (1) includes but is not limited to low-aluminum secondary aluminum ash and high-aluminum secondary aluminum ash.

3. The method for synthesizing ammonia by chemical chaining denitrification based on aluminum ash according to claim 1, characterized in that: The particle size of the aluminum ash after grinding in step (1) is less than 0.3 mm.

4. The method for synthesizing ammonia by chemical chaining denitrification based on aluminum ash according to claim 1, characterized in that: The temperature range of the ammonia release reactor in step (2) is set to 600 o C~1000 o C, the water vapor concentration range is set to 40%~80%, and the obtained ammonia release reaction product is transported from the ammonia release reactor to the nitrogen loading reactor through the return system.

5. The method for synthesizing ammonia by chemical chaining denitrification based on aluminum ash according to claim 1, characterized in that: The temperature of the nitrogen-loaded reactor in step (3) is 1200 o C~1600 o C, the ratio of aluminum base to carbon source is set to 1:3~3:1, the carbon source includes but is not limited to biomass, coal, organic solid waste and other carbon-containing fuels, and the heat source includes but is not limited to ammonia release heat transfer and solar energy.

6. The method for synthesizing ammonia by chemical chaining denitrification based on aluminum ash according to claim 1, characterized in that: The carbon removal reactor in step (4) receives the product after nitrogen fixation regeneration from the nitrogen-carrying reactor in step (3) through the return pipe, and transports the decarbonized nitrogen-carrying body back to the ammonia release reactor in step (2) through the return pipe. The oxidant includes but is not limited to air, oxygen, water vapor, and carbon dioxide. The carbon removal temperature range is 200 o C~600 o C.

7. The method for synthesizing ammonia by chemical chaining denitrification from aluminum ash according to claim 1, characterized in that: The decarbonized nitrogen-carrying body described in step (5) is transported back to the ammonia release reactor described in step (2) through the return pipe to release ammonia, then enters the nitrogen loading reactor described in step (3) through the return pipe to load nitrogen, then enters the carbon removal reactor described in step (4) through the return pipe to remove carbon, and returns again to form a cyclic synthetic ammonia of ammonia release-nitrogen loading-carbon removal.

8. The method for synthesizing ammonia by chemical chain denitrification based on aluminum ash according to claim 1 is applied in the resource-energy technology of hazardous waste aluminum ash.

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