Ammonia combustion-supporting catalyst composition as well as preparation method and application thereof

Abstract

The invention discloses an ammonia combustion combustion-supporting catalyst composition as well as a preparation method and application thereof, and provides the ammonia combustion combustion-supporting catalyst composition which takes a perovskite type multi-element transition metal oxide as an active component, can reduce the activation energy of ammonia combustion reaction, and can improve the combustion efficiency under the operating condition of a CFB (Circulating Fluidized Bed) boiler. Combustion of ammonia, CO and carbon in fly ash is effectively promoted in the hearth; the inorganic filler with high pore volume and specific surface area and the pseudo-boehmite provide a good dispersion effect for the active component, so that the combustion-supporting function of the active component on ammonia, CO and carbon in fly ash is further improved; the strength of the catalyst composition is also improved due to the interaction of the pseudo-boehmite and the inorganic filler; the rare earth tailings contain high effective components such as Fe2O3 and rare earth, the effects of reducing cost and recycling waste can be achieved by adding the rare earth tailings, the content of the effective components can be further increased by conducting modification treatment on the rare earth tailings, and the micropore structure of the rare earth tailings is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to an ammonia combustion-supporting catalyst composition, a preparation method and an application thereof. Background Art

[0002] Circulating fluidized bed (CFB) boilers have seen rapid development due to their perceived advantages, including good fuel adaptability, excellent load regulation, and convenient ash and slag comprehensive utilization. However, they are also a major source of CO2 emissions. Energy conservation and emission reduction measures, including the use of renewable energy, can reduce or offset CO2 emissions from CFB boiler combustion. NH3, a hydrogen-rich, carbon-free fuel, offers advantages such as high energy density, low cost, and safe storage and transportation. Its combined combustion with coal is considered a rapid and effective method for reducing CO2 emissions.

[0003] The NH3 combustion process itself has defects such as high ignition temperature, slow combustion speed, low activation performance, and relatively low combustion efficiency. At the same time, when NH3 is added to the CFB boiler for combustion, especially when a high proportion of NH3 is added for combustion, it will affect the flow field in the furnace, increase the linear velocity, and shorten the residence time of volatile matter, NH3, CO and other gaseous substances and fly ash in the furnace, resulting in an increase in the CO content, NH3 escape and fly ash carbon content in the rear. To overcome the above defects, the following methods can be used: (1) plasma combustion-assisted combustion; (2) fuel optimization; (3) heat and mass transfer enhancement; (4) use of NH3 combustion-assisted catalysts. Plasma combustion-assisted combustion is to enhance combustion by using the special electrical, thermal, optical and chemical activities of plasma. Its essence is to use its high-energy electrons to collide with neutral molecules, causing the molecules to dissociate, excite and even ionize, generating a large number of active atoms and radicals, which ultimately affect the chemical equilibrium of the combustion system and accelerate the chemical kinetics of combustion. The activity and density of OH groups play a major role in plasma-assisted combustion. The NH3 combustion-supporting catalyst reduces the activation energy of the NH3 combustion reaction, thereby lowering the ignition temperature of NH3 and increasing the combustion rate of NH3.

[0004] Chinese patent 202210916289.6 discloses an engine system based on plasma-assisted ammonia combustion and ammonia catalytic cracking, primarily comprising a plasma-assisted ammonia combustion module, an ammonia catalytic thermal cracker module, and a hydrogen conditioning module. This invention utilizes plasma-assisted ammonia combustion to provide the heat required for ammonia cracking in the ammonia catalytic thermal cracker module, replacing traditional electric heating. This solves the current problem of requiring ammonia engines to be equipped with additional large-capacity battery systems or dual-fuel systems. Furthermore, the exhaust heat from the plasma-assisted ammonia combustion can provide heat for the vaporization of liquid ammonia, and the ammonia content in the exhaust is adjustable, allowing for a denitrification reaction with the engine exhaust.

[0005] The literature [HINOKUMA S, KIRITOSHI S, KAWABATA Y, et al. Catalytic ammonia combustion properties and operando characterization of copper oxides supported on aluminum silicates and silicon oxides [J]. Journal of Catalysis, 2018 (361): 267-277.] introduces the application of a porous media supported catalyst in NH3 catalytic combustion. The focus is on the research of the porous media supported catalyst on Al6O 13 Si2, 3Al2O3·2SiO2, 3A2S and CuO on SiO2 x The activity of NH3 catalytic combustion, the selectivity of NO and N2O were found to be similar to CuO x The reducibility, local structure around Cu, Cu 2+ The content is closely related to the composition of NH3 adsorption.

[0006] In the above studies, plasma NH3-assisted combustion is more suitable for NH3-assisted combustion in engines and steam turbines, while NH3 combustion-supporting catalysts are more suitable for CFB boiler combustion. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the purpose of the present invention is to provide an ammonia combustion-supporting catalyst composition, a preparation method and application thereof, and the combustion-supporting catalyst prepared by the present invention is added to the interior of the CFB furnace, and circulates with the circulating material in the furnace-separator-returner-furnace. The CFB boiler is mixed with NH3 for combustion, especially under the combustion condition of high proportion of NH3. By reducing the activation energy of the NH3 combustion reaction in the furnace, the ignition temperature of NH3 is reduced, the combustion rate of NH3 is increased, the burnout of NH3 is promoted, and the escape of NH3 is reduced. At the same time, the combustion-supporting components in the combustion-supporting catalyst can also promote the combustion of the CO content in the flue gas and the carbon content in the fly ash, thereby improving the combustion efficiency of the boiler.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] An ammonia combustion-supporting catalyst composition consists of the following raw materials, calculated by mass percentage: 20-55% of perovskite component, 5-25% of modified rare earth tailings, 10-35% of inorganic filler and 5-35% of pseudo-boehmite.

[0010] Preferably, the perovskite component is CeFe x Mn y Srz O3、LaFe x Mn y Sr z O3、PrFe x Mn y Sr z O3 and NdFe x Mn y Sr z One or more of O3, wherein x=0-0.9, z=0-0.6, 0≤y≤1-(x+z).

[0011] Preferably, the content of the perovskite component is 25-50 wt%.

[0012] Preferably, the content of the modified rare earth tailings is 10-20 wt%.

[0013] Preferably, the content of the inorganic filler is 15-30 wt%.

[0014] Preferably, the content of pseudo-boehmite is 10-30 wt%.

[0015] Preferably, the preparation method of the modified rare earth tailings is as follows:

[0016] (1) performing strong magnetic separation on the rare earth tailings to obtain magnetically separated rare earth tailings;

[0017] (2) grinding and roasting the magnetically separated rare earth tailings, and then washing and drying them to obtain pretreated rare earth tailings;

[0018] (3) Add the pretreated rare earth tailings to the mixed acid solution, stir for 6-12 hours, then let it stand, filter, and dry to obtain the modified rare earth tailings.

[0019] Preferably, in step (2), the calcination temperature is 700-800° C. and the calcination time is 6-8 hours.

[0020] Preferably, in step (3), the mixed acid consists of citric acid and lactic acid, and the mass ratio of citric acid to lactic acid is 2-3:1.

[0021] Preferably, the inorganic filler is one or more of kaolin, attapulgite, montmorillonite and cordierite.

[0022] Preferably, the specific surface area of ​​the ammonia combustion-supporting catalyst composition is not less than 50 m 2 / g, wear index is not higher than 1.0% / h.

[0023] The present invention provides a method for preparing the above-mentioned ammonia combustion-supporting catalyst composition, comprising the following steps:

[0024] S1. Mix the perovskite component, modified rare earth tailings and inorganic filler uniformly, then add distilled water, stir and mix uniformly to obtain a slurry;

[0025] S2, adding pseudo-boehmite to distilled water, adding dilute nitric acid dropwise while stirring to form a uniform sol, and then adding the slurry obtained in step S1 thereto under stirring, adding dilute nitric acid dropwise while stirring, then stirring for 6-12 hours, and standing for 16-24 hours to obtain a viscous slurry;

[0026] S3. Dry the viscous slurry in an oven at 120-140° C. for 4-8 hours, then calcine in a muffle furnace at 800-950° C. for 8-16 hours, and crush and sieve to obtain an ammonia combustion-supporting catalyst composition.

[0027] Preferably, in step S1, the solid content in the slurry is 40-50 wt%.

[0028] The present invention also provides application of the ammonia combustion-supporting catalyst composition in catalytic combustion of NH3 in a circulating fluidized bed boiler.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention provides an ammonia combustion-supporting catalyst composition, which uses a perovskite-type multinary transition metal oxide as an active component, can reduce the activation energy of the ammonia combustion reaction, and effectively promote the combustion of ammonia, CO and carbon in fly ash in the furnace under CFB boiler operating conditions. Inorganic fillers and pseudo-boehmite with high pore volume and specific surface area provide a good dispersion effect for the active components, further improving the combustion-supporting function of the active components on ammonia, CO and carbon in fly ash. The interaction between the pseudo-boehmite and the inorganic filler also improves the strength of the catalyst composition. Rare earth tailings contain relatively high levels of effective components such as Fe2O3 and rare earths. The addition of rare earth tailings can reduce costs and promote waste recycling. Modification of the tailings can further increase the content of effective components and improve the microporous structure. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0032] It should be noted that, unless otherwise specified, all chemical reagents involved in the present invention were purchased through commercial channels.

[0033] The rare earth tailings come from the waste after mineral processing of a rare earth company in Ganzhou, and contain 2-3wt% rare earth oxides and 12-13wt% iron oxides.

[0034] Example 1

[0035] A method for preparing an ammonia combustion-supporting catalyst composition comprises the following steps:

[0036] S1, 40.0g of CeFe 0.4 Mn 0.1 Sr 0.5 O3 perovskite (100 wt% on a dry basis), 15.0 g of modified rare earth tailings (100 wt% on a dry basis) and 25.6 g of kaolin (78 wt% on a dry basis) were mixed uniformly, and then 112.5 g of distilled water was added and stirred to mix uniformly to obtain a slurry;

[0037] The preparation method of modified rare earth tailings is as follows:

[0038] 1) Using a super-strong roller magnetic separator to perform strong magnetic separation on the rare earth tailings to obtain magnetically separated rare earth tailings;

[0039] 2) grinding the magnetically separated rare earth tailings, then roasting them at 750° C. for 6 h, and then washing and drying them to obtain pretreated rare earth tailings;

[0040] 3) adding 20 g of the pretreated rare earth tailings to 200 mL of a mixed acid solution containing 20 g of citric acid and 10 g of lactic acid, stirring for 6 h, then standing for 8 h, filtering, and drying to obtain modified rare earth tailings;

[0041] S2, 29.4g of pseudo-boehmite was added to 85g of distilled water, and 15g of 10wt% dilute nitric acid was added dropwise while stirring to form a uniform sol, and then the slurry was added thereto under stirring, and 10g of 10wt% dilute nitric acid was added dropwise while stirring, followed by stirring for 8h, homogenization, and standing for 18h to obtain a viscous slurry;

[0042] S3. Dry the viscous slurry in an oven at 120° C. for 6 h, then calcine it in a muffle furnace at 850° C. for 12 h, and crush and sieve it to obtain an ammonia combustion-supporting catalyst composition.

[0043] Example 2

[0044] A method for preparing an ammonia combustion-supporting catalyst composition comprises the following steps:

[0045] S1, 50.0g of LaFe 0.4 Mn 0.3 Sr 0.3 O3 perovskite (100 wt% on a dry basis), 10.0 g of modified rare earth tailings (100 wt% on a dry basis) and 32.1 g of attapulgite (78 wt% on a dry basis) were mixed uniformly, and then 127.5 g of distilled water was added and stirred to mix uniformly to obtain a slurry;

[0046] The preparation method of modified rare earth tailings is as follows:

[0047] 1) Using a super-strong roller magnetic separator to perform strong magnetic separation on the rare earth tailings to obtain magnetically separated rare earth tailings;

[0048] 2) grinding the magnetically separated rare earth tailings, then roasting them at 800° C. for 6 h, and then washing and drying them to obtain pretreated rare earth tailings;

[0049] 3) adding 20 g of the pretreated rare earth tailings to 200 mL of a mixed acid solution containing 30 g of citric acid and 10 g of lactic acid, stirring for 6 h, then standing for 8 h, filtering, and drying to obtain modified rare earth tailings;

[0050] S2, 22.1g of pseudo-boehmite was added to 50g of distilled water, and 15g of 10wt% dilute nitric acid was added dropwise while stirring to form a uniform sol, and then the slurry was added thereto under stirring, and 10g of 10wt% dilute nitric acid was added dropwise while stirring, followed by stirring for 10h, homogenization, and standing for 24h to obtain a viscous slurry;

[0051] S3. Dry the viscous slurry in an oven at 130° C. for 5 h, then calcine it in a muffle furnace at 900° C. for 10 h, and crush and sieve it to obtain an ammonia combustion-supporting catalyst composition.

[0052] Example 3

[0053] A method for preparing an ammonia combustion-supporting catalyst composition comprises the following steps:

[0054] S1, 45.0g of PrFe 0.7 Mn 0.2 Sr 0.1 O3 perovskite (100 wt% on a dry basis), 15.0 g of modified rare earth tailings (100 wt% on a dry basis) and 19.2 g of attapulgite (78 wt% on a dry basis) were mixed uniformly, and then 112.5 g of distilled water was added and stirred to mix uniformly to obtain a slurry;

[0055] The preparation method of modified rare earth tailings is as follows:

[0056] 1) Using a super-strong roller magnetic separator to perform strong magnetic separation on the rare earth tailings to obtain magnetically separated rare earth tailings;

[0057] 2) grinding the magnetically separated rare earth tailings, then roasting them at 700° C. for 8 h, and then washing and drying them to obtain pretreated rare earth tailings;

[0058] 3) adding 20 g of the pretreated rare earth tailings to 200 mL of a mixed acid solution containing 25 g of citric acid and 10 g of lactic acid, stirring for 6 h, then standing for 8 h, filtering, and drying to obtain modified rare earth tailings;

[0059] S2, 29.4g of pseudo-boehmite was added to 65g of distilled water, and 15g of 10wt% dilute nitric acid was added dropwise while stirring to form a uniform sol, and then the slurry was added thereto under stirring, and 10g of 10wt% dilute nitric acid was added dropwise while stirring, followed by stirring for 12h, homogenization, and standing for 20h to obtain a viscous slurry;

[0060] S3. Dry the viscous slurry in an oven at 140° C. for 5 h, then calcine it in a muffle furnace at 950° C. for 8 h, and crush and sieve it to obtain an ammonia combustion-supporting catalyst composition.

[0061] Example 4

[0062] A method for preparing an ammonia combustion-supporting catalyst composition comprises the following steps:

[0063] S1, 35.0g of NdFe 0.4 Mn 0.4 Sr 0.2 O3 perovskite (100 wt% on a dry basis), 20.0 g of modified rare earth tailings (100 wt% on a dry basis) and 38.5 g of cordierite (78 wt% on a dry basis) were mixed uniformly, and then 127.5 g of distilled water was added and stirred to mix uniformly to obtain a slurry;

[0064] The preparation method of modified rare earth tailings is as follows:

[0065] 1) Using a super-strong roller magnetic separator to perform strong magnetic separation on the rare earth tailings to obtain magnetically separated rare earth tailings;

[0066] 2) grinding the magnetically separated rare earth tailings, then roasting them at 750° C. for 8 h, and then washing and drying them to obtain pretreated rare earth tailings;

[0067] 3) adding 20 g of the pretreated rare earth tailings to 200 mL of a mixed acid solution containing 20 g of citric acid and 10 g of lactic acid, stirring for 6 h, then standing for 8 h, filtering, and drying to obtain modified rare earth tailings;

[0068] S2, 22.1g of pseudo-boehmite was added to 45g of distilled water, and 15g of 10wt% dilute nitric acid was added dropwise while stirring to form a uniform sol, and then the slurry was added thereto under stirring, and 10g of 10wt% dilute nitric acid was added dropwise while stirring, followed by stirring for 12h, homogenization, and standing for 18h to obtain a viscous slurry;

[0069] S3. Dry the viscous slurry in an oven at 120° C. for 6 h, then calcine it in a muffle furnace at 800° C. for 16 h, and crush and sieve it to obtain an ammonia combustion-supporting catalyst composition.

[0070] Example 5

[0071] A method for preparing an ammonia combustion-supporting catalyst composition comprises the following steps:

[0072] S1, 30.0g of CeFe 0.2 Mn 0.4 Sr 0.4 O3 perovskite (100 wt% on a dry basis), 20.0 g of modified rare earth tailings (100 wt% on a dry basis) and 25.6 g of kaolin (78 wt% on a dry basis) were mixed uniformly, and then 105 g of distilled water was added and stirred to mix uniformly to obtain a slurry;

[0073] The preparation method of modified rare earth tailings is as follows:

[0074] 1) Using a super-strong roller magnetic separator to perform strong magnetic separation on the rare earth tailings to obtain magnetically separated rare earth tailings;

[0075] 2) grinding the magnetically separated rare earth tailings, then roasting them at 750° C. for 8 h, and then washing and drying them to obtain pretreated rare earth tailings;

[0076] 3) adding 20 g of the pretreated rare earth tailings to 200 mL of a mixed acid solution containing 20 g of citric acid and 10 g of lactic acid, stirring for 6 h, then standing for 8 h, filtering, and drying to obtain modified rare earth tailings;

[0077] S2, 34.1g of pseudo-boehmite was added to 50g of distilled water, and 15g of 10wt% dilute nitric acid was added dropwise while stirring to form a uniform sol, and then the slurry was added thereto under stirring, and 10g of 10wt% dilute nitric acid was added dropwise while stirring, followed by stirring for 8h, homogenization, and standing for 18h to obtain a viscous slurry;

[0078] S3. Dry the viscous slurry in an oven at 130° C. for 6 h, then calcine it in a muffle furnace at 900° C. for 10 h, and crush and sieve it to obtain an ammonia combustion-supporting catalyst composition.

[0079] Example 6

[0080] A method for preparing an ammonia combustion-supporting catalyst composition comprises the following steps:

[0081] S1, 25.0g of LaFe 0.6 Mn 0.2 Sr 0.2 O3 perovskite (100 wt% on a dry basis), 20.0 g of modified rare earth tailings (100 wt% on a dry basis) and 38.5 g of montmorillonite (78 wt% on a dry basis) were mixed uniformly, and then 112.5 g of distilled water was added and stirred to mix uniformly to obtain a slurry;

[0082] The preparation method of modified rare earth tailings is as follows:

[0083] 1) Using a super-strong roller magnetic separator to perform strong magnetic separation on the rare earth tailings to obtain magnetically separated rare earth tailings;

[0084] 2) grinding the magnetically separated rare earth tailings, then roasting them at 750° C. for 8 h, and then washing and drying them to obtain pretreated rare earth tailings;

[0085] 3) adding 20 g of the pretreated rare earth tailings to 200 mL of a mixed acid solution containing 30 g of citric acid and 10 g of lactic acid, stirring for 6 h, then standing for 8 h, filtering, and drying to obtain modified rare earth tailings;

[0086] S2, 29.4g of pseudo-boehmite was added to 65g of distilled water, and 15g of 10wt% dilute nitric acid was added dropwise while stirring to form a uniform sol, and then the slurry was added thereto under stirring, and 10g of 10wt% dilute nitric acid was added dropwise while stirring, followed by stirring for 7h, homogenization, and standing for 18h to obtain a viscous slurry;

[0087] S3. Dry the viscous slurry in an oven at 130° C. for 6 h, then calcine it in a muffle furnace at 900° C. for 8 h, and crush and sieve it to obtain an ammonia combustion-supporting catalyst composition.

[0088] Comparative Example 1

[0089] A method for preparing an ammonia combustion-supporting catalyst composition comprises the following steps:

[0090] S1, 40.0g of CeFe 0.4 Mn 0.1 Sr 0.5 O3 perovskite (100 wt% on a dry basis), 15.0 g of rare earth tailings (100 wt% on a dry basis) and 25.6 g of kaolin (78 wt% on a dry basis) were mixed uniformly, and then 112.5 g of distilled water was added and stirred to mix uniformly to obtain a slurry;

[0091] S2, 29.4g of pseudo-boehmite was added to 85g of distilled water, and 15g of 10wt% dilute nitric acid was added dropwise while stirring to form a uniform sol, and then the slurry was added thereto under stirring, and 10g of 10wt% dilute nitric acid was added dropwise while stirring, followed by stirring for 8h, homogenization, and standing for 18h to obtain a viscous slurry;

[0092] S3. Dry the viscous slurry in an oven at 120° C. for 6 h, then calcine it in a muffle furnace at 850° C. for 12 h, and crush and sieve it to obtain an ammonia combustion-supporting catalyst composition.

[0093] Comparative Example 2

[0094] A method for preparing an ammonia combustion-supporting catalyst composition comprises the following steps:

[0095] S1, 40.0g of CeFe 0.4 Mn 0.1 Sr 0.5 O3 perovskite (100 wt% on a dry basis), 15.0 g of magnetically separated rare earth tailings (100 wt% on a dry basis) and 25.6 g of kaolin (78 wt% on a dry basis) were mixed uniformly, and then 112.5 g of distilled water was added and stirred to mix uniformly to obtain a slurry;

[0096] The preparation method of magnetically separated rare earth tailings is as follows: using a super-strong roller magnetic separator to perform strong magnetic separation on the rare earth tailings to obtain magnetically separated rare earth tailings;

[0097] S2, 29.4g of pseudo-boehmite was added to 85g of distilled water, and 15g of 10wt% dilute nitric acid was added dropwise while stirring to form a uniform sol, and then the slurry was added thereto under stirring, and 10g of 10wt% dilute nitric acid was added dropwise while stirring, followed by stirring for 8h, homogenization, and standing for 18h to obtain a viscous slurry;

[0098] S3. Dry the viscous slurry in an oven at 120° C. for 6 h, then calcine it in a muffle furnace at 850° C. for 12 h, and crush and sieve it to obtain an ammonia combustion-supporting catalyst composition.

[0099] Comparative Example 3

[0100] The blank control group did not add any ammonia combustion flame retardant catalyst.

[0101] The combustion-supporting performance of the ammonia combustion-supporting catalysts prepared in Examples 1-6 and Comparative Examples 1-2 was evaluated according to the following steps: The ammonia combustion-supporting evaluation test was conducted in a quartz tube fixed-bed reactor. The combustion-supporting catalyst was mixed with CFB boiler circulating ash at a content of 3.0 wt % of the circulating ash. The quartz tube reactor was loaded with 1.0 g of the catalyst mixture. The reaction gas was (30 vol % NH 3 , 5 vol % CO, 3.5 vol % O 2 , 61.5 vol % N 2 ) at a flow rate of 120 ml / min. The reaction temperature was 870° C. and the reaction pressure was atmospheric pressure. The NH 3 and CO contents in the reaction tail gas were analyzed. The combustion-supporting performance of the ammonia combustion-supporting catalyst was evaluated based on the NH 3 and CO conversion rates, as shown in Formulas (1) and (2).

[0102]

[0103] Where: η NH3 is the NH3 conversion rate, C NH3 is the NH3 concentration in the mixed gas after the reaction, vol%, C NH3ais the NH3 concentration in the mixed gas before the reaction (vol%).

[0104]

[0105] Where: η CO is the CO conversion rate, C CO is the CO concentration in the mixed gas after the reaction, vol%, C CO0 is the CO concentration in the mixed gas before the reaction (vol%).

[0106] The test results are shown in the following table:

[0107]

[0108] Finally, it should be noted that the above embodiments do not limit the present invention in any form. Those skilled in the art will appreciate that modifications and improvements can be made based on the present invention. Therefore, any modifications or improvements made without departing from the spirit of the present invention are intended to fall within the scope of protection claimed in the present invention.

Claims

1. An ammonia combustion-supporting catalyst composition, characterized in that: Calculated by mass percentage, the invention is composed of the following raw materials: 20-55% of perovskite component, 5-25% of modified rare earth tailings, 10-35% of inorganic filler and 5-35% of pseudo-boehmite.

2. The ammonia combustion-supporting catalyst composition according to claim 1, characterized in that: The perovskite component is CeFe x Mn y Sr z O3、LaFe x Mn y Sr z O3、PrFe x Mn y Sr z O3 and NdFe x Mn y Sr z One or more of O3, wherein x=0-0.9, z=0-0.6, 0≤y≤1-(x+z).

3. The ammonia combustion-supporting catalyst composition according to claim 1, characterized in that: The preparation method of the modified rare earth tailings is as follows: (1) performing strong magnetic separation on the rare earth tailings to obtain magnetically separated rare earth tailings; (2) grinding and roasting the magnetically separated rare earth tailings, and then washing and drying them to obtain pretreated rare earth tailings; (3) Add the pretreated rare earth tailings to the mixed acid solution, stir for 6-12 hours, then let it stand, filter, and dry to obtain the modified rare earth tailings.

4. The ammonia combustion-supporting catalyst composition according to claim 3, characterized in that: In step (2), the calcination temperature is 700-800° C. and the calcination time is 6-8 hours.

5. The ammonia combustion-supporting catalyst composition according to claim 3, characterized in that: In step (3), the mixed acid consists of citric acid and lactic acid, and the mass ratio of citric acid to lactic acid is 2-3:

1.

6. The ammonia combustion-supporting catalyst composition according to claim 1, characterized in that: The inorganic filler is one or more of kaolin, attapulgite, montmorillonite and cordierite.

7. The ammonia combustion-supporting catalyst composition according to claim 1, characterized in that: The specific surface area of ​​the ammonia combustion-supporting catalyst composition is not less than 50m 2 / g, wear index is not higher than 1.0% / h.

8. The method for preparing the ammonia combustion-supporting catalyst composition according to any one of claims 1 to 7, characterized in that: The steps include: S1. Mix the perovskite component, modified rare earth tailings and inorganic filler uniformly, then add distilled water, stir and mix uniformly to obtain a slurry; S2, adding pseudo-boehmite to distilled water, adding dilute nitric acid dropwise while stirring to form a uniform sol, and then adding the slurry obtained in step S1 thereto under stirring, adding dilute nitric acid dropwise while stirring, then stirring for 6-12 hours, and standing for 16-24 hours to obtain a viscous slurry; S3. Dry the viscous slurry in an oven at 120-140° C. for 4-8 hours, then calcine in a muffle furnace at 800-950° C. for 8-16 hours, and crush and sieve to obtain an ammonia combustion-supporting catalyst composition.

9. The method for preparing the ammonia combustion-supporting catalyst composition according to claim 8, characterized in that: In step S1, the solid content in the slurry is 40-50 wt%.

10. Use of the ammonia combustion-supporting catalyst composition according to any one of claims 1 to 7 in catalytic combustion of NH3 in a circulating fluidized bed boiler.

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