A supported ammonia adsorbent, its preparation method and use

Abstract

The application discloses a supported ammonia adsorbent and a preparation method and application thereof, and belongs to the technical field of chemical industry.The supported ammonia adsorbent is composed of at least one active metal chloride, a +2-valence metal oxide, a +3-valence metal oxide and a +4-valence metal oxide, wherein the active metal chloride accounts for 5-50% in mass percentage, the +2-valence metal oxide accounts for 24-60% in mass percentage, the +3-valence metal oxide accounts for 10-25% in mass percentage, and the +4-valence metal oxide accounts for 1-10% in mass percentage.The application improves the thermal stability of the carrier by introducing a dispersant into the carrier, optimizes the distribution of the active metal and improves the dispersion degree of the active component, further improves the ammonia removal rate and ammonia adsorption capacity of the adsorbent, and therefore the supported ammonia adsorbent has good adsorption performance.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology, specifically relating to a supported ammonia adsorbent, its preparation method, and its application. Background Technology

[0002] Hydrogen energy is a widely available, clean, carbon-free, flexible, efficient, and versatile alternative and sustainable clean energy source with excellent energy density and environmental friendliness. As one of the most feasible ways to achieve carbon peaking and carbon neutrality, it has attracted increasing attention from researchers. Ammonia, as an ideal hydrogen storage medium, has advantages such as mild liquefaction conditions, high safety, and high energy density (hydrogen storage density). It is easy to store and transport and produces no greenhouse gases, making it a feasible method to effectively solve the storage and transportation problems in the traditional hydrogen energy industry. However, although hydrogen production through ammonia decomposition can proceed smoothly at high temperatures and in the presence of a catalyst, the thermodynamic limitations of the reaction inevitably result in a small amount of residual ammonia in the products. This can cause performance degradation in PEM hydrogen fuel cells due to membrane material poisoning, greatly limiting its application in PEM fuel cells. Therefore, removing residual ammonia from ammonia decomposition products is of great significance for its application in the hydrogen energy field.

[0003] Currently, the publicly disclosed methods for removing ammonia from hydrogen are mainly divided into absorption and adsorption methods. Absorption methods generally use liquid absorbents, which are not suitable for large-scale applications. Adsorption methods, on the other hand, use solid adsorbents, where ammonia molecules in the gas undergo physical or chemical adsorption on their surface. Since this process is generally reversible, the adsorbent can be regenerated and reused after adsorption saturation and deactivation, thus having greater value for large-scale industrial applications. Existing ammonia adsorbents can be classified according to their principles into physical adsorbents (such as activated carbon) and chemical adsorbents (such as metal complexing agents). Physical adsorption is relatively weak, and while the former has milder adsorption and regeneration conditions, its adsorption effect is limited. Therefore, the latter is more suitable for scenarios requiring high ammonia removal efficiency. Numerous reports have been made on ammonia adsorbents with metal complexing agents as the active component (their active metal compositions include alkaline earth metals and transition metals). Because the contact between the active metal component and ammonia molecules has a significant impact on the adsorption process, the adsorption effect and adsorption capacity of existing supported metal complex ammonia adsorbents are very limited. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a supported ammonia adsorbent, its preparation method, and its application. By optimizing the distribution of active metals and improving the dispersion of active components, the adsorption performance of the ammonia adsorbent with metal complexing agents as active components is improved.

[0005] To achieve the above objectives, the technical solution of the present invention includes:

[0006] In a first aspect, the present invention provides a supported ammonia adsorbent, wherein the supported ammonia adsorbent is composed of at least one active metal chloride, a +2 valence metal oxide, a +3 valence metal oxide and a +4 valence metal oxide;

[0007] By mass percentage, the supported ammonia adsorbent contains 5-50% active metal chloride, 24-60% +2 valent metal oxide, 10-25% +3 valent metal oxide, and 1-10% +4 valent metal oxide.

[0008] Furthermore, in the above technical solution, the at least one active metal is one or a combination of two or more of Mg, Ca, Cr, Mn, Co, Ni, Cu, and Zn;

[0009] The +2 valence metal is Mg;

[0010] The +3 valence metal is Al;

[0011] The +4 valence metal oxide is a dispersant, and is one of Ti and Zr.

[0012] Furthermore, in the above technical solution, the specific surface area of ​​the supported ammonia adsorbent carrier is 100-500 m². 2 / g, pore volume 0.2-0.7cm 3 / g.

[0013] Secondly, the present invention provides a method for preparing the supported ammonia adsorbent, comprising the following steps:

[0014] S1. Dissolve the soluble salts of +2 valence metals and +3 valence metals in water to prepare solution A, dissolve the soluble precipitant in water to prepare solution B, and dissolve the soluble salts of +4 valence metals in water to prepare solution C.

[0015] S2. When solution B is added dropwise to solution A, precipitate X is formed.

[0016] S3. Immediately after the addition of solution B is completed, solution C is added dropwise to the turbid liquid containing precipitate X and subjected to constant temperature treatment. After the reaction is completed, a solid LDH precursor with a layered structure is obtained.

[0017] S4. Calcining the LDH precursor yields a composite oxide support;

[0018] S5. Dissolve at least one chloride salt of an active metal in water to prepare solution D, impregnate the composite oxide carrier, and dry it to obtain the supported ammonia adsorbent.

[0019] The mixed solution A of soluble salts of +2 valent metal Mg and +3 valent metal Al described in this invention can generate MgAl-LDH with a layered structure through a co-precipitation reaction under the action of a precipitant. In step S3, immediately after the addition of solution B, solution C is added to introduce the +4 valent metal component, causing it to deposit on the surface of the LDH particles. This aims to improve the high-temperature stability of the LDH material, inhibit the aggregation and growth of its particles during calcination, minimize the loss of surface area and pore volume during high-temperature treatment, optimize the distribution of active metals, and improve the dispersion of active components, thereby enhancing the performance of the adsorbent, including ammonia removal rate and ammonia adsorption capacity.

[0020] Furthermore, in the above technical solution, in step S3, after the reaction is completed, the solid obtained by filtering, washing and drying the precipitate is an LDH precursor with a layered structure.

[0021] Furthermore, in the above technical solution, the soluble salt of the +2 valence metal is one of magnesium nitrate, magnesium chloride, and magnesium sulfate.

[0022] Preferably, the soluble salt of the +2 valence metal is one of magnesium nitrate and magnesium chloride.

[0023] Furthermore, in the above technical solution, the soluble salt of the +3 valent metal is one of aluminum nitrate, aluminum chloride, and aluminum sulfate.

[0024] Preferably, the soluble salt of the +3 valent metal is one of aluminum nitrate and aluminum chloride.

[0025] Furthermore, in the above technical solution, the soluble salt of the +4 valence metal is one of titanium oxynitrate, titanium chloride, titanium oxysulfate, zirconium nitrate, zirconium chloride, and zirconium sulfate;

[0026] Preferably, the soluble salt of the +4 valence metal is one of titanium oxynitrate, titanium chloride, zirconium nitrate, and zirconium chloride.

[0027] In selecting the soluble salts of the +2 valence metal, the +3 valence metal, and the +4 valence metal, the present invention preferably uses salts whose anions are easily decomposed and volatilized during calcination (such as nitrates or chlorides), which can minimize the residue of their anionic components.

[0028] Furthermore, in the above technical solution, the soluble precipitant is one of sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium carbonate, potassium bicarbonate, potassium hydroxide, and ammonium carbonate.

[0029] Preferably, the soluble precipitant is one of sodium carbonate, potassium carbonate, and ammonium carbonate.

[0030] Regarding the selection of the soluble precipitant, since the obtained LDH is a layered material with anions between its layers, selecting carbonates or bicarbonates can yield LDH materials with carbonate or bicarbonate ions between the layers. During subsequent calcination, CO2 gas can be released, which is beneficial for reducing particle size. However, because bicarbonates are less basic, their precipitation effect is not as good as that of carbonates; therefore, carbonates are preferred.

[0031] Furthermore, in the above technical solution, the chloride salt of at least one active metal is one or a combination of two or more of magnesium chloride, calcium chloride, chromium chloride, manganese chloride, cobalt chloride, nickel chloride, copper chloride, and zinc chloride.

[0032] Preferably, the chloride salt of the at least one active metal is selected from one or a combination of two or more of magnesium chloride, calcium chloride, cobalt chloride, nickel chloride, copper chloride, and zinc chloride.

[0033] Furthermore, in the above technical solution, the concentration of the soluble salt of the +2 valence metal in solution A is 0.002-1 mol / L.

[0034] Preferably, the concentration of the soluble salt of the +2 valence metal in solution A is 0.002-0.5 mol / L.

[0035] Furthermore, in the above technical solution, the concentration of the soluble salt of the +3 valence metal in solution A is 0.01-0.3 mol / L.

[0036] Preferably, the concentration of the soluble salt of the +3 valence metal in solution A is 0.01-0.15 mol / L.

[0037] Al in solution 3+ The concentration may be one or two times the concentration of the corresponding salt, depending on the specific type of anion, while Mg 2 + The concentration of the ions is equal to the concentration of the corresponding salt; therefore, if expressed in terms of the concentration of metal ions, then:

[0038] The concentration of the +2 valence metal ions in solution A is 0.002-1 mol / L;

[0039] Preferably, the concentration of the +2 valence metal ions in solution A is 0.002-0.5 mol / L;

[0040] The concentration of the +3 valent metal ions in solution A is 0.02-0.6 mol / L;

[0041] Preferably, the concentration of the +3 valence metal ions in solution A is 0.02-0.3 mol / L;

[0042] The concentration of the soluble precipitant in solution B is 0.01-1 mol / L;

[0043] Preferably, the concentration of the soluble precipitant in solution B is 0.05-0.5 mol / L;

[0044] The concentration of the soluble salt of the +4 valence metal in solution C is 0.001-0.1 mol / L;

[0045] Preferably, the concentration of the soluble salt of the +4 valence metal in solution C is 0.01-0.1 mol / L;

[0046] The concentration of the chloride salt of at least one active metal in solution D is 0.1-1.0 mol / L;

[0047] Preferably, the concentration of the chloride salt of the at least one active metal in solution D is 0.2-1.0 mol / L.

[0048] Since the solubility of the chloride salt of the active metal is limited, multiple impregnations can be performed depending on the actual concentration of the specific salt solution.

[0049] Furthermore, in the above technical solution, in step S2, the reaction temperature is 50-100℃;

[0050] The precipitation temperature of LDH material has a significant impact on its particle nucleation rate. Preferably, the reaction temperature in step S2 is 80-100℃.

[0051] In step S3, the pH of the reaction system is 7-10 when the solution B is added.

[0052] The pH value of the solution determines the degree of precipitation of the metal components. Preferably, the pH of the reaction system is 8-10 when solution B is added dropwise in step S3.

[0053] In step S3, the temperature of the constant temperature treatment is 80-120℃, and the treatment time is 1-12h.

[0054] The conditions of the isothermal treatment step affect the crystallization effect of LDH material and also have an important impact on the deposition effect of +4 valence metal. Preferably, the isothermal treatment temperature in step S3 is 100-120℃ and the treatment time is 1-4h.

[0055] In step S4, the calcination temperature is 300-500℃ and the calcination time is 1-24h.

[0056] The purpose of the calcination step is to dehydrate the LDH material to generate a high-temperature stable composite oxide phase. In this step, carbonate ions will also decompose to produce gas, which is beneficial to reduce the particle size. The effect is affected by the calcination conditions. Preferably, the calcination temperature in step S4 is 300-500℃ and the calcination time is 1-24h.

[0057] In step S5, the drying temperature is 60-100℃ and the drying time is 1-24h.

[0058] The drying step in step S5 is to evaporate the excess moisture on the adsorbent. Since there is a possibility of hydrolysis of active metal chlorides, the temperature of this step must be strictly controlled to prevent it from being too high. Preferably, the drying temperature is 60-80℃ and the drying time is 6-24h.

[0059] Thirdly, the present invention provides the application of the supported ammonia adsorbent or the supported ammonia adsorbent prepared by the preparation method in the removal of ammonia from ammonia-containing gases.

[0060] Furthermore, in the above technical solution, the supported ammonia adsorbent needs to be ground, shaped, sieved, and dried before use;

[0061] Since the active metal chlorides on the adsorbent still carry a certain amount of water of crystallization, which will affect the ammonia removal effect, the ammonia adsorbent needs to undergo drying pretreatment to remove the water of crystallization before adsorbing ammonia-containing gases. The treatment conditions are as follows:

[0062] The drying conditions are as follows: the drying temperature is 100-200℃.

[0063] Preferably, the drying temperature is 100-150℃.

[0064] The dry atmosphere is N2, and the pressure is 0.05-1 MPa.

[0065] Preferably, the drying atmosphere is N2 and the pressure is 0.05-0.1 MPa.

[0066] The drying time is 1-24 hours.

[0067] Preferably, the drying time is 2-12 hours.

[0068] Because of the possibility of hydrolysis of active metal chlorides, the temperature of this drying pretreatment step must be strictly controlled to prevent it from getting too high. In addition, the drying purging atmosphere should be as anhydrous as possible to ensure the effectiveness of removing water of crystallization.

[0069] The supported ammonia adsorbent can adsorb and remove ammonia from ammonia-containing gases after drying pretreatment. The specific principle involves the complexation reaction between active metal ions and ammonia molecules. The conditions for the ammonia adsorption process are as follows:

[0070] Temperature range: 50-300℃;

[0071] The pressure is 0.05-1 MPa;

[0072] The volume content of ammonia in the ammonia-containing gas is 1-10000 ppm;

[0073] The ammonia-containing gas, excluding ammonia, consists of one or more of nitrogen, hydrogen, argon, and helium.

[0074] Due to the possibility of hydrolysis of active metal chlorides, the ammonia-containing gas introduced during the adsorption and deammoniation process needs to be as anhydrous as possible (and may need to undergo dehydration treatment if necessary) to prevent hydrolysis and deactivation of active metal chlorides.

[0075] The supported ammonia adsorbent can be regenerated after it becomes saturated.

[0076] When the ammonia adsorbent is saturated, it enters a deactivated state and becomes a deactivated adsorbent, which can be reused after regeneration.

[0077] Before regenerating the supported ammonia adsorbent after adsorption saturation, a purging pretreatment is required under the following conditions. The purpose of this pretreatment is to remove residual ammonia and trace amounts of water from the gas path and reactor. The treatment conditions are as follows:

[0078] The purging temperature is 50-300℃, which can generally be kept consistent with the adsorption deammoniation process.

[0079] The purging atmosphere is N2, and the pressure is 0.05-1 MPa, which can generally be consistent with the adsorption deammoniation process.

[0080] The purging time is 1-24 hours.

[0081] Preferably, the purging time is 2-12 hours.

[0082] After the purging step is completed, the deactivated ammonia adsorbent can be regenerated. The purpose of this regeneration is to decompose the ammonia complex of the active metal ions, release ammonia gas, and restore the adsorption capacity.

[0083] The conditions for the regeneration process are as follows:

[0084] The regeneration temperature is 600-800℃;

[0085] The regeneration atmosphere is N2, and the pressure is 0.05-1 MPa;

[0086] Since the regeneration step requires treating the deactivated adsorbent at high temperatures, in order to prevent the hydrolysis of active metal chlorides, it is necessary to ensure the effectiveness of the purging step before the regeneration step, and the regeneration atmosphere must be strictly kept anhydrous. If necessary, the regeneration atmosphere can be dehydrated.

[0087] Regeneration time is 1-48 hours;

[0088] Preferably, the regeneration time is 6-48 hours.

[0089] Beneficial effects

[0090] (1) The supported ammonia adsorbent is prepared by using LDH precursor as a carrier and the thermal stability of the material is improved by introducing a +4 valent metal dispersant. This effectively suppresses the particle aggregation problem caused by high-temperature thermal decomposition of LDH material, which is conducive to improving the dispersion of active species on the carrier surface. It can effectively increase the ammonia removal rate and ammonia adsorption capacity of the adsorbent. Therefore, the supported ammonia adsorbent exhibits good adsorption performance.

[0091] (2) The reaction between the supported ammonia adsorbent and ammonia is reversible, so it can be regenerated after adsorption saturation, enabling long-term cyclic use. The regeneration method is simple and easy to operate.

[0092] (3) The supported ammonia adsorbent uses inexpensive metal chlorides as active components, and all components do not contain precious metal components, resulting in low preparation costs.

[0093] (4) The supported ammonia adsorbent is prepared by co-precipitation and impregnation methods. The preparation methods are simple and easy to operate, and can be used for large-scale industrial production. Attached Figure Description

[0094] Figure 1 The images show the XRD patterns of the supported Mg-based adsorbent Ads-1 prepared in Example 1 and the supported Mg-based adsorbent Ads-1-1 prepared in Comparative Example 1. Detailed Implementation

[0095] To further illustrate the present invention, the following embodiments are listed based on experimental results, but these do not limit the scope of the invention as defined by the claims.

[0096] Example 1

[0097] This embodiment illustrates the preparation of the supported Mg-based adsorbent.

[0098] Weigh out 7.5 mmol magnesium nitrate hexahydrate and 2.5 mmol aluminum nitrate nonahydrate, add water to make 100 mL of solution, and denote this as solution a (where Mg... 2+ The concentration is 0.075 mol / L, Al 3+The concentration is 0.025 mol / L. Prepare a 0.2 mol / L sodium carbonate solution, denoted as solution b. Weigh 0.5 mmol of zirconium nitrate trihydrate and dissolve it in water to prepare a 10 mL solution, denoted as solution c (where Zr is present). 4+ The concentration is 0.05 mol / L. Weigh 2 mmol of magnesium chloride hexahydrate and add water to make 5 mL of solution, denoted as solution d (where Mg... 2+ (Concentration is 0.4 mol / L).

[0099] Solution a was heated to 90°C and kept at a constant temperature. Solution b was added dropwise to solution a until the pH reached 10. Then solution c was immediately added. The solution was then kept at 110°C for 2 hours. The solution was then filtered, washed, and dried to obtain the LDH precursor. The LDH precursor was then calcined at 400°C for 6 hours to obtain the composite oxide support.

[0100] Solution d was loaded onto the support in multiple stages using an impregnation method, and then dried at 60°C for 12 hours to obtain a supported Mg-based adsorbent, denoted as Ads-1.

[0101] XRD tests were performed on Ads-1, and the results are as follows: Figure 1 As shown.

[0102] Example 2

[0103] This embodiment illustrates the preparation of the supported Ca-based adsorbent.

[0104] Except that 2 mmol of calcium chloride hexahydrate was used instead of 2 mmol of magnesium chloride hexahydrate used in Example 1, the supported Ca-based adsorbent, denoted as Ads-2, was prepared by the same preparation method as in Example 1.

[0105] Example 3

[0106] This embodiment illustrates the preparation of the supported Cu-based adsorbent.

[0107] Except that 2 mmol of copper chloride dihydrate was used instead of 2 mmol of magnesium chloride hexahydrate used in Example 1, the supported Cu-based adsorbent, denoted as Ads-3, was prepared using the same preparation method as in Example 1.

[0108] Example 4

[0109] This embodiment illustrates the preparation of the supported Zn-based adsorbent.

[0110] Except that 2 mmol zinc chloride hexahydrate was used instead of 2 mmol magnesium chloride hexahydrate in Example 1, the supported Zn-based adsorbent, denoted as Ads-4, was prepared using the same preparation method as in Example 1.

[0111] Comparative Example 1

[0112] This comparative example illustrates the preparation of a supported Mg-based adsorbent without the addition of a dispersant, serving as a comparison with Example 1.

[0113] Weigh out 7.5 mmol magnesium nitrate hexahydrate and 2.5 mmol aluminum nitrate nonahydrate, add water to make 100 mL of solution, and denote this as solution a (where Mg... 2+ The concentration is 0.075 mol / L, Al 3+ The concentration is 0.025 mol / L. Prepare a 0.2 mol / L sodium carbonate solution, denoted as solution b. Weigh 2 mmol of magnesium chloride hexahydrate and add water to prepare a 5 mL solution, denoted as solution d (where Mg... 2+ (Concentration is 0.4 mol / L).

[0114] Solution a was heated to 90°C and kept at a constant temperature. Solution b was added dropwise to solution a until the pH reached 10. Then, the solution was kept at 110°C for 2 hours. After that, the solution was filtered, washed, and dried to obtain the LDH precursor. The obtained LDH precursor was then calcined at 400°C for 6 hours to obtain the composite oxide support.

[0115] Solution d was added to the support in multiple portions by impregnation and dried at 60°C for 12 hours to obtain a supported Mg-based adsorbent without dispersant, denoted as Ads-1-1.

[0116] XRD tests were performed on Ads-1-1, and the results are as follows: Figure 1 As shown.

[0117] The XRD results show that, compared with the supported Mg-based adsorbent Ads-1-1 prepared in Comparative Example 1, the supported Mg-based adsorbent Ads-1 prepared in Example 1 has a wider and weaker diffraction peak, indicating that the introduction of the +4 valence metal Zr can effectively reduce the grain size of the adsorbent support.

[0118] Comparative Example 2

[0119] This comparative example illustrates the preparation of a supported Ca-based adsorbent without the addition of a dispersant, serving as a comparison with Example 2.

[0120] Except that 2 mmol of calcium chloride hexahydrate was used instead of 2 mmol of magnesium chloride hexahydrate in Comparative Example 1, a supported Ca-based adsorbent, denoted as Ads-2-1, was prepared using the same preparation method as Comparative Example 1.

[0121] Comparative Example 3

[0122] This comparative example illustrates the preparation of a supported Cu-based adsorbent without the addition of a dispersant, serving as a comparison with Example 3.

[0123] Except that 2 mmol of copper chloride dihydrate was used instead of 2 mmol of magnesium chloride hexahydrate used in Comparative Example 1, a supported Cu-based adsorbent, denoted as Ads-3-1, was prepared using the same preparation method as Comparative Example 1.

[0124] Comparative Example 4

[0125] This comparative example illustrates the preparation of a supported Zn-based adsorbent without the addition of a dispersant, serving as a comparison with Example 4.

[0126] Except that 2 mmol zinc chloride hexahydrate was used instead of 2 mmol magnesium chloride hexahydrate in Comparative Example 1, a supported Zn-based adsorbent, denoted as Ads-4-1, was prepared using the same preparation method as Comparative Example 1.

[0127] Example 5

[0128] This embodiment illustrates the evaluation of the adsorption performance of the supported ammonia adsorbent.

[0129] The adsorbents obtained in Examples 1-4 and Comparative Examples 1-4 were ground, compressed into tablets, and sieved into 40-60 mesh particles, and then 1g was weighed and placed in a fixed bed reactor.

[0130] First, purge with N2 at a pressure of 0.05 MPa and a temperature of 120 °C for 2 hours. Then, purge with a space velocity of 12000 mL·h at a pressure of 0.05 MPa and a temperature of 50 °C. -1 ·gcat -1 A nitrogen-hydrogen mixture with an ammonia volume content of 1000 ppm (nitrogen:hydrogen volume ratio 1:3) was introduced for adsorption and deammoniation, and the ammonia content in the adsorption product gas was measured by gas chromatography.

[0131] When the ammonia content in the adsorbed product gas reaches 1 ppm, the gas inlet is stopped, the adsorption time is recorded, and the adsorption amount is calculated. The gas is then purged with N2 at a pressure of 0.05 MPa and a temperature of 50°C for 2 hours, and then regenerated by heating to 700°C for 24 hours.

[0132] After the regeneration process is completed, the temperature can be lowered to 50℃ before the next round of adsorption and deammoniation process can be carried out.

[0133] The experimental results show that the ammonia adsorbents in Examples 1-4 can all achieve an ammonia content in the adsorption product gas of no more than 1 ppm under the above conditions. The initial adsorption capacity and regeneration adsorption capacity of all adsorbents are shown in the table below:

[0134]

[0135] It can be seen that the adsorption capacities of adsorbents Ads-1, Ads-2, Ads-3, and Ads-4 obtained in Examples 1-4 with a tetravalent metal as a dispersant are significantly improved compared to the adsorbents Ads-1-1, Ads-1-2, Ads-1-3, and Ads-1-4 obtained in Comparative Examples 1-4 without a tetravalent metal as a dispersant. Therefore, the addition of the dispersant plays a key role in improving the adsorption capacity of the supported ammonia adsorbent, resulting in good ammonia adsorption capacity and regeneration performance recovery.

Claims

1. A supported ammonia adsorbent, characterized in that, The ammonia adsorbent is composed of at least one active metal chloride, a +2 valence metal oxide, a +3 valence metal oxide, and a +4 valence metal oxide; By mass percentage, the supported ammonia adsorbent contains 5-50% active metal chloride, 24-60% +2 valent metal oxide, 10-25% +3 valent metal oxide, and 1-10% +4 valent metal oxide. The preparation method of the ammonia adsorbent includes the following steps: S1. Dissolve the soluble salts of +2 valence metals and +3 valence metals in water to prepare solution A, dissolve the soluble precipitant in water to prepare solution B, and dissolve the soluble salts of +4 valence metals in water to prepare solution C. S2. Solution B is added dropwise to solution A, and the reaction yields a turbid liquid containing precipitate X; S3. Immediately after the addition of solution B is completed, add solution C to the turbid liquid containing precipitate X and perform constant temperature treatment. After the reaction is completed, the obtained solid is an LDH precursor with a layered structure. S4. Calcining the LDH precursor yields a composite oxide support; S5. Dissolve at least one active metal chloride salt in water to prepare solution D, impregnate the composite oxide carrier, and dry it to obtain the supported ammonia adsorbent. The metal in the at least one active metal chloride is one or a combination of two or more of Mg, Ca, Cr, Mn, Co, Ni, Cu, and Zn; The +2 valence metal is Mg; The +3 valence metal is Al; The +4 valence metal is one of Ti or Zr.

2. The supported ammonia adsorbent according to claim 1, characterized in that, The specific surface area of ​​the carrier in the supported ammonia adsorbent is 100-500 m². 2 / g, pore volume 0.2-0.7 cm³ 3 / g.

3. The method for preparing the supported ammonia adsorbent according to any one of claims 1-2, characterized in that, Includes the following steps: S1. Dissolve the soluble salts of +2 valence metals and +3 valence metals in water to prepare solution A, dissolve the soluble precipitant in water to prepare solution B, and dissolve the soluble salts of +4 valence metals in water to prepare solution C. S2. Solution B is added dropwise to solution A, and the reaction yields a turbid liquid containing precipitate X; S3. Immediately after the addition of solution B is completed, add solution C to the turbid liquid containing precipitate X and perform constant temperature treatment. After the reaction is completed, the obtained solid is an LDH precursor with a layered structure. S4. Calcining the LDH precursor yields a composite oxide support; S5. Dissolve at least one chloride salt of an active metal in water to prepare solution D, impregnate the composite oxide carrier, and dry it to obtain the supported ammonia adsorbent.

4. The preparation method according to claim 3, characterized in that, The soluble salt of the +2 valence metal is one of magnesium nitrate, magnesium chloride, and magnesium sulfate; The soluble salt of the +3 valent metal is one of aluminum nitrate, aluminum chloride, and aluminum sulfate. The soluble salt of the +4 valence metal is one of titanium oxynitrate, titanium chloride, titanium oxysulfate, zirconium nitrate, zirconium chloride, and zirconium sulfate. The soluble precipitant is one of sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium carbonate, potassium bicarbonate, potassium hydroxide, and ammonium carbonate. The chloride salt of the at least one active metal is one or a combination of two or more of magnesium chloride, calcium chloride, chromium chloride, manganese chloride, cobalt chloride, nickel chloride, copper chloride, and zinc chloride.

5. The preparation method according to claim 3, characterized in that, The concentration of the soluble salt of the +2 valence metal in solution A is 0.002-1 mol / L; The concentration of the soluble salt of the +3 valence metal in solution A is 0.01-0.3 mol / L; The concentration of the soluble precipitant in solution B is 0.01-1 mol / L; The concentration of the soluble salt of the +4 valence metal in solution C is 0.001-0.1 mol / L; The concentration of the chloride salt of at least one active metal in solution D is 0.1-1.0 mol / L.

6. The preparation method according to claim 3, characterized in that, In step S2, the reaction temperature is 50-100°C. o C; In step S3, the pH of the reaction system is 7-10 when the solution B is added dropwise. In step S3, the temperature of the isothermal treatment is 80-120°C. o C, the processing time is 1-12 hours; In step S4, the calcination temperature is 300-500°C. o C, the roasting time is 1-24 h; In step S5, the drying temperature is 60-100°C. o C, the drying time is 1-24 h.

7. The application of a supported ammonia adsorbent according to any one of claims 1-2 or a supported ammonia adsorbent prepared by any one of claims 3-6 in the removal of ammonia from ammonia-containing gas.

8. The application according to claim 7, characterized in that, The supported ammonia adsorbent needs to be ground, shaped, sieved, and dried before use; The drying conditions are as follows: the drying temperature is 100-200°C. o C, drying atmosphere is N2, pressure is 0.05-1 MPa; drying time is 1-24 h; The conditions for the ammonia adsorption process of the supported ammonia adsorbent in the ammonia removal of ammonia-containing gas are as follows: Temperature 50-300 o C; The pressure is 0.05-1 MPa; The volume content of ammonia in the ammonia-containing gas is 1-10000 ppm; The ammonia-containing gas, excluding ammonia, consists of one or more of nitrogen, hydrogen, argon, and helium.

9. The application according to claim 7, characterized in that, The supported ammonia adsorbent can be regenerated after it becomes saturated. Before regenerating the supported ammonia adsorbent after adsorption saturation, a purging pretreatment is required under the following conditions: The purging temperature is 50-300°C. o C; The purging atmosphere is N2, and the pressure is 0.05-1 MPa; The purging time is 1-24 hours; The conditions for the regeneration process are as follows: Regeneration temperature is 600-800 o C; The regeneration atmosphere is N2, and the pressure is 0.05-1 MPa; The regeneration time is 1-48 hours.

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