Application of binary aluminum-based layered double hydroxide in degradation of polycyclic aromatic hydrocarbons at low temperature

Abstract

The application discloses application of a binary aluminum-based layered double metal oxide in degradation of polycyclic aromatic hydrocarbons at low temperature, and degrades polycyclic aromatic hydrocarbons in boiler flue gas in a range of 240-300 DEG C with the binary aluminum-based layered double metal oxide as a catalyst; the content of polycyclic aromatic hydrocarbons in the boiler flue gas is 30000h ‑1 -60000h ‑1 The chemical formula of the binary aluminum-based layered double metal oxide is: wherein M is one of Cu, Mn and Co. The application is aimed at the treatment difficulty of boiler flue gas with only low concentration of PAHs but needing rapid treatment, and a binary aluminum-based layered double metal oxide is designed based on the characteristics of LDOs, which is used for efficient degradation of polycyclic aromatic hydrocarbons at low temperature and has excellent PAHs deep degradation capacity.

Description

Technical Field

[0001] This invention belongs to the field of catalytic degradation of polycyclic aromatic hydrocarbons, specifically relating to the application of a binary aluminum-based bimetallic oxide as a catalyst in the low-temperature and high-efficiency degradation of polycyclic aromatic hydrocarbons. Background Technology

[0002] While "co-firing of solid waste" alleviates the pressure of solid waste disposal and accelerates the green and low-carbon development of industry, the complex composition of solid waste leads to a significant increase in the concentration of organic matter in the resulting flue gas. Polycyclic aromatic hydrocarbons (PAHs) are a class of organic pollutants in flue gas that should be given special attention. PAHs have extremely high equivalent toxicity, and their treatment is one of the problems that enterprises urgently need to solve.

[0003] Biological methods, adsorption / absorption, photocatalysis, plasma catalysis, and thermocatalysis are important methods used in practical engineering to treat PAH pollution. Among these, biological methods have long cycles, and adsorption / absorption methods are costly, making them unsuitable for boiler flue gas with only low concentrations of PAHs requiring rapid treatment. Photocatalysis and plasma catalysis have been restricted in several Chinese cities, including Guangzhou and Xiamen, due to the ozone byproduct of current technologies. Therefore, thermocatalysis has become the primary method for treating PAHs in boiler flue gas.

[0004] In boiler flue gas purification systems, selective catalytic reduction (SCR) denitrification catalysts have the ability to remove NOx and some organic matter. However, due to the flue gas environment and the complex structure of PAHs, PAHs cannot be converted into harmless CO2 and H2O. Instead, they generate organic pollutants with higher toxicity equivalents. Summary of the Invention

[0005] To address the challenge of treating boiler flue gas containing only low concentrations of PAHs but requiring rapid processing, this invention provides a method for the low-temperature degradation of PAHs using a binary aluminum-based bimetallic oxide.

[0006] The applicant of this invention previously investigated the degradation of naphthalene, a typical PAH pollutant, by a commercial V2O5-WO3 / TiO2 (VWTi) catalyst under simulated flue gas composition of a coal-fired power plant boiler. It was found that naphthalene is converted into PAHs such as dibenzo(a,h)anthracene, benzo(g,h,i)perylene, and anthracene, which have higher equivalent toxicity, by the VWTi catalyst. After calculating and comparing the toxicity of 16 PAHs preferentially controlled by the toxicity equivalent factor, it was found that the PAHs in the flue gas are 27 times more toxic after conversion on the VWTi catalyst than before conversion.

[0007] The applicant of this invention discovered in their research that layered bimetallic hydroxides (LDHs) are a novel class of catalytic materials. The unique flower-like structure of LDHs gives them a high specific surface area, abundant surface acid-base sites, and better controllability, leading to their widespread application in adsorption, photocatalysis, and water chemistry. However, due to the poor thermal stability of LDHs, they are often calcined to prepare layered bimetallic oxides (LDOs) in the field of thermocatalysis. LDOs retain the advantages of LDHs while possessing highly dispersed active components and abundant metal ligands. Their surface readily generates oxygen holes, facilitating electron separation and migration, and can form redox centers. Furthermore, LDOs offer richer controllability, allowing for adjustments during synthesis to achieve specific needs. However, the research and application of LDO catalysts in PAH degradation are currently limited.

[0008] Layered bimetallic hydroxides (LDHs), benefiting from their unique 2D lamellar structure and high specific surface area and abundant acid-base sites, have been used in various research fields such as carbon dioxide capture and water pollutant degradation. Layered bimetallic oxides (LDOs), derived from LDHs through topological calcination, inherit the abundant acid-base sites and high specific surface area of ​​LDHs, while possessing more defect sites and excellent thermal stability. Therefore, research has been conducted on applying LDOx catalysts to NOx conversion and organic matter degradation. However, there is little exploration into the degradation of highly toxic and structurally complex polycyclic aromatic hydrocarbons (PAHs) present in the gas phase. Based on the characteristics of LDOs, this invention designs a binary aluminum-layered layered bimetallic oxide for the low-temperature and efficient degradation of PAHs.

[0009] An application of a binary aluminum-based bimetallic oxide in the low-temperature degradation of polycyclic aromatic hydrocarbons, characterized in that the chemical formula of the binary aluminum-based bimetallic oxide is:

[0010]

[0011] M is one of Cu, Mn, and Co.

[0012] The binary aluminum-based bimetallic oxide used in this invention uses divalent metals as the main redox reaction elements, among which Cu, Mn, and Co elements have good low-temperature catalytic oxidation activity; trivalent aluminum elements play a role in supporting the structure and improving thermal stability. At the same time, the high dispersion, abundant surface acid-base sites, and multiphase defect sites brought about by the LDO structure enhance the adsorption and activation of PAHs in the catalyst, thus giving the catalyst excellent PAH deep degradation ability.

[0013] Optionally, the application includes:

[0014] Using the aforementioned binary aluminum-based bimetallic oxide as a catalyst, polycyclic aromatic hydrocarbons in flue gas are degraded in the range of 240–300°C.

[0015] Optionally, the content of polycyclic aromatic hydrocarbons in the boiler flue gas is 10 μg / Nm³. 3 -10000μg / Nm 3 .

[0016] Optionally, the binary aluminum-based bimetallic oxide is used in the flue gas purification system as a solid catalyst.

[0017] Optionally, the binary aluminum-based bimetallic oxide is suitable for a volume hourly space velocity (VHSV) of 30,000 h⁻¹. -1 -60000h -1 Boiler operating environment.

[0018] Optionally, the polycyclic aromatic hydrocarbon is naphthalene.

[0019] Optionally, the binary aluminum-based bimetallic oxide is prepared by a co-precipitation method.

[0020] The present invention also provides a method for low-temperature degradation of polycyclic aromatic hydrocarbons, comprising the following steps:

[0021] Using the aforementioned binary aluminum-based bimetallic oxide as a catalyst, polycyclic aromatic hydrocarbons in flue gas are degraded in the range of 250–300°C.

[0022] The chemical formula of the binary aluminum-based bimetallic oxide is:

[0023]

[0024] M is one of Cu, Mn, and Co.

[0025] This invention also provides a binary aluminum-based bimetallic oxide, the chemical formula of which is:

[0026]

[0027] M is one of Cu, Mn, and Co.

[0028] The present invention also provides a method for preparing the aforementioned binary aluminum-based bimetallic oxide, comprising the following steps:

[0029] (1) Add the nitrate solution dropwise to the sodium carbonate solution at a constant temperature of 25-35℃, stirring continuously and adjusting the pH of the mixed solution to 10±0.3 during the dropwise addition; continue stirring and react for 6-12 hours.

[0030] (2) After the reaction is complete, let it stand at room temperature for 8-24 hours; then filter, wash, dry and calcin.

[0031] Optionally, the calcination temperature is 350–450°C; the calcination time is 4–8 hours.

[0032] The most preferred preparation method includes the following steps:

[0033] a. Weigh out nitrate M (M = Mn, Co, Mn) salt solution (M(NO3)2), aluminum nitrate (Al2(NO3)3·9H2O) and anhydrous sodium carbonate (Na2CO3) according to a mole fraction ratio of 2:1:2;

[0034] b. Dissolve M(NO3)2 and Al2(NO3)3·9H2O in deionized water and stir at 300r / min for 30-60min at a constant temperature of 30℃.

[0035] c. Dissolve Na2CO3 in deionized water and stir at 1200 r / min for 30-60 min at a constant temperature of 30℃.

[0036] d. Add 4 mol / L M(NO3)2 solution dropwise to the Na2CO3 solution at a constant temperature of 30℃ and a stirring speed of 1200 r / min, and adjust the pH value to be around 10±0.3 throughout the titration process by using 4 mol / L NaOH.

[0037] e. The mixed solution obtained after step e is aged at a constant temperature of 30℃ and stirred at 1200r / min, and then aged at room temperature.

[0038] f. Filter the aged mixed solution and wash it with deionized water 5-10 times to adjust the pH of the filtrate to 7.

[0039] g. The filtered solid was dried at 60°C for 24 hours to obtain a binary aluminum-based bimetallic hydroxide.

[0040] h. The binary aluminum-based bimetallic hydroxide from step g is calcined at 400°C to obtain a binary aluminum-based bimetallic oxide.

[0041] Optionally, the amount of deionized water used for dissolution in steps b and c, based on aluminum nitrate, shall not exceed 0.25 mol (aluminum nitrate) / L.

[0042] Optionally, the aging time in step e should be between 6 and 12 hours, and not less than 6 hours.

[0043] Optionally, the aging time in step e should be between 8 and 24 hours, and not less than 8 hours.

[0044] Optionally, the calcination time in step h should be between 4 and 8 hours, and not less than 4 hours.

[0045] Compared with existing technologies, it has at least one of the following beneficial effects:

[0046] (1) It has excellent ability to deeply degrade PAHs:

[0047] Total flow rate: 1000 ml / min; oxygen concentration: 10%; temperature: 300℃; volumetric hourly space velocity: 60000 h⁻¹ -1 The initial concentration of naphthalene was 10000 μg / Nm³. 3 In simulated flue gas environments, while the V2O5-WO3 / TiO2 (VWTi) catalyst can completely convert naphthalene, its overall COx selectivity is only 45%, of which 15% is CO. In contrast, the binary aluminum-based bimetallic oxide of this invention completely converts naphthalene while maintaining a COx selectivity of over 60% and generating no CO.

[0048] Furthermore, in the concentration detection of 16 PAHs in the exhaust gas, the equivalent toxicity of PAHs generated in the exhaust gas of V2O5-WO3 / TiO2 (VWTi) catalyst was much higher than that of PAHs generated in the exhaust gas of binary aluminum-based bimetallic oxide catalyst.

[0049] (2) It has good thermal stability:

[0050] The total flow rate was 1000 ml / min, the oxygen concentration was 10%, the temperature was 300℃, and the volumetric hourly space velocity was 60000 h⁻¹. -1 The initial concentration of naphthalene was 10000 μg / Nm³. 3 Under simulated flue gas conditions, binary aluminum-based bimetallic oxides, represented by MnAl-LDO, can maintain stable conversion rates and COx selectivity throughout the 5-hour testing period. Attached Figure Description

[0051] Figure 1 Comparison of the NAP degradation performance of V2O5-WO3 / TiO2 (VWTi) catalyst and binary aluminum-based bimetallic oxide prepared in the embodiments of the present invention;

[0052] Figure 2 The graph shows the thermal stability of the MnAl-LDO catalyst after 5 hours. Detailed Implementation

[0053] The technical solution of this application will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0055] Example 1: Preparation and Application of CuAl Layered Bimetallic Oxide (CuAl-LDO)

[0056] (1) Weigh 0.05 mol Cu(NO3)2 and 0.025 mol Al2(NO3)3·9H2O and dissolve them in 100 ml of deionized water. Keep the solution at 30 °C and stir at 1000 r / min for half an hour to obtain Cu(NO3)2 solution.

[0057] (2) Weigh 0.05 mol Na2CO3 and dissolve it in 100 ml of deionized water. Keep the temperature constant at 30℃ and stir at 1000 r / min for half an hour to obtain Na2CO3 solution.

[0058] (3) Cu(NO3)2 solution was added dropwise to the Na2CO3 solution which was kept at a constant temperature of 30℃ and stirred at 1000r / min at a titration rate of 3ml / min, and the pH value was adjusted to be around 10.30 throughout the titration process by using 4mol / LNaOH.

[0059] (4) After titration, the mixed solution was kept at 30°C and stirred at 1000r / min for 10 hours, and then allowed to stand at room temperature for 12 hours.

[0060] (5) The mixed solution after standing for 12 hours was filtered and washed 7 times with deionized water until pH=7. The filtered solid was dried at 60℃ for 24 hours to obtain CuAl layered bimetallic hydroxide. The CuAl layered bimetallic hydroxide was then calcined at 400℃ for 5 hours to obtain CuAl layered bimetallic oxide with the chemical formula [Cu2]. 2+ Al(OH)2](CO3 2- ) 1 / 6 ·H2O; denoted as CuAl-LDO.

[0061] The CuAl layered bimetallic oxide CuAl-LDO prepared by the above method was subjected to a simulated volume space velocity of 60,000 h⁻¹. -1 In an experiment on flue gas emitted from an actual waste incineration boiler power plant with an oxygen concentration of 10% and an initial naphthalene concentration of 10 ppm, CuAl layered bimetallic oxides achieved complete conversion of naphthalene at 300℃, with more than 60% being converted into CO2. The equivalent toxicity of the converted naphthalene was calculated using formula (1). Compared with the equivalent toxicity of inlet naphthalene, the equivalent toxicity of the 16 PAHs at the outlet decreased by nearly 70%.

[0062] Among them, 16 polycyclic aromatic hydrocarbons (NAPs) are defined by the following formula:

[0063] TEQ = ∑TEF × [PAHs] out (1)

[0064] In the formula: TEQ represents the total equivalent toxicity of 16 polycyclic aromatic hydrocarbons, ng·TEQ / Nm 3 The conversion between standard conditions and operating conditions was performed using the ideal gas equation (PV = nRT); TEF is the equivalent toxicity factor for each polycyclic aromatic hydrocarbon, derived from the article "Levels of PAHs in the soils of Belgrade and its environs," as detailed in Table 1; [PAHs] out For the outlet concentration of each polycyclic aromatic hydrocarbon, ng / Nm³ 3 .

[0065] Table 1 shows the relative atomic mass and toxicity equivalent factor of 16 PAHs.

[0066]

[0067] Example 2: Preparation and Application of MnAl Layered Bimetallic Oxide (MnAl-LDO)

[0068] (1) Weigh 0.05 mol Mn(NO3)2 and 0.025 mol Al2(NO3)3·9H2O, dissolve them in 100 ml of deionized water, keep the temperature constant at 30℃, and stir at 1000 r / min for half an hour to obtain Mn(NO3)2 solution.

[0069] (2) Weigh 0.05 mol Na2CO3 and dissolve it in 100 ml of deionized water. Keep the temperature constant at 30℃ and stir at 1000 r / min for half an hour to obtain Na2CO3 solution.

[0070] (3) Add Mn(NO3)2 solution dropwise to the Na2CO3 solution which is kept at a constant temperature of 30℃ and stirred at 1000r / min at a titration rate of 3ml / min, and adjust the pH value to be around 10.30 throughout the titration process by using 4mol / LNaOH.

[0071] (4) After titration, the mixed solution was kept at 30°C and stirred at 1000r / min for 10 hours. Then it was left to stand at room temperature for 12 hours.

[0072] (5) The mixed solution after standing for 12 hours was filtered and washed 7 times with deionized water until pH=7. The filtered solid was dried at 60℃ for 24 hours to obtain MnAl layered bimetallic hydroxide. The MnAl layered bimetallic hydroxide was then calcined at 400℃ for 5 hours to obtain MnAl layered bimetallic oxide with the chemical formula [Mn2]. 2+ Al(OH)2](CO3 2- ) 1 / 6 ·H2O; denoted as MnAl-LDO.

[0073] The MnAl layered bimetallic oxide prepared by the above method was subjected to a simulated volume space velocity of 60,000 h⁻¹. -1 In an experiment on flue gas emitted from an actual waste incineration boiler power plant with an oxygen concentration of 10% and an initial naphthalene concentration of 10 ppm, MnAl layered bimetallic oxides achieved complete conversion of naphthalene at 300℃, with more than 60% being converted into CO2. The equivalent toxicity of the converted naphthalene was calculated using Equation (1). Compared with the equivalent toxicity of inlet naphthalene, the equivalent toxicity of the 16 PAHs at the outlet decreased by nearly 95%.

[0074] Figure 2 The data shown is based on a total flow rate of 1000 ml / min, an oxygen concentration of 10%, a temperature of 300℃, and a volumetric hourly space velocity of 60000 h⁻¹. -1 The initial concentration of naphthalene was 10000 μg / Nm³. 3 Under simulated flue gas conditions, the binary aluminum-based bimetallic oxide, represented by MnAl-LDO prepared in this embodiment, can maintain a stable conversion rate and COx selectivity throughout the 5-hour test period.

[0075] Example 3: Preparation and Application of CoAl Layered Bimetallic Oxide (CoAl-LDO)

[0076] (1) Weigh 0.05 mol Co(NO3)2 and 0.025 mol Al2(NO3)3·9H2O and dissolve them in 100 ml of deionized water. Then, keep the temperature constant at 30 °C and stir at 1000 r / min for half an hour to obtain a Co(NO3)2 solution.

[0077] (2) Weigh 0.05 mol Na2CO3 and dissolve it in 100 ml of deionized water. Keep the temperature constant at 30℃ and stir at 1000 r / min for half an hour to obtain Na2CO3 solution.

[0078] (3) Add Co(NO3)2 solution dropwise to a Na2CO3 solution that is kept at a constant temperature of 30℃ and stirred at 1000r / min at a titration rate of 3ml / min, and adjust the pH value to be around 10.30 throughout the titration process by using 4mol / LNaOH.

[0079] (4) After titration, the mixed solution was kept at 30°C and stirred at 1000r / min for 10 hours. Then it was left to stand at room temperature for 12 hours.

[0080] (5) The mixed solution after standing for 12 hours was filtered and washed 7 times with deionized water until pH=7. The filtered solid was dried at 60℃ for 24 hours to obtain CoAl layered bimetallic hydroxide. The CoAl layered bimetallic hydroxide was then calcined at 400℃ for 5 hours to obtain CoAl layered bimetallic oxide, [Co2 2+ Al(OH)2](CO3 2- ) 1 / 6 ·H2O; denoted as CoAl-LDO.

[0081] The CoAl layered bimetallic oxide CoAl-LDO prepared by the above method was subjected to a simulated volume space velocity of 60,000 h⁻¹. -1 In an experiment on flue gas emitted from an actual waste incineration boiler power plant with an oxygen concentration of 10% and an initial naphthalene concentration of 10 ppm, the CoAl layered bimetallic oxide achieved complete conversion of naphthalene at 300℃, with more than 50% being converted into CO2. The equivalent toxicity of the converted naphthalene was calculated using Equation (1). Compared with the equivalent toxicity of inlet naphthalene, the equivalent toxicity of the 16 PAHs at the outlet decreased by nearly 65%.

[0082] Figure 1 The data shown is based on a total flow rate of 1000 ml / min, an oxygen concentration of 10%, a temperature of 300℃, and a volumetric hourly space velocity of 60000 h⁻¹. -1 The initial concentration of naphthalene was 10000 μg / Nm³. 3In a simulated flue gas environment, the conversion results of catalysts V2O5-WO3 / TiO2 (VWTi), CuAl-LDO (prepared in Example 1), MnAl-LDO (prepared in Example 2), and CoAl-LDO (prepared in Example 3) were compared. Figure A shows the naphthalene conversion result, and B shows the COx selectivity. As can be seen from the figure, although the V2O5-WO3 / TiO2 (VWTi) catalyst can completely convert naphthalene, the total COx selectivity is only 45%, of which 15% is CO. In contrast, the binary aluminum-based bimetallic oxide prepared in this embodiment of the invention completely converts naphthalene while maintaining a COx selectivity of over 60% and generating no CO. Meanwhile, Tables 2-5 show the concentrations of 16 PAHs collected from the tail gas during the reactions of VWTi, CuAl-LDO (prepared in Example 1), MnAl-LDO (prepared in Example 2), and CoAl-LDO (prepared in Example 3) catalysts, respectively. The equivalent toxicity was further calculated using the above formula (1). The equivalent toxicity of PAHs in the tail gas from the VWTi catalyst reached 2.67 × 10⁻⁶. 6 The equivalent toxicity of PAHs in the tail gas of CuAl-LDO, MnAl-LDO and CoAl-LDO catalysts is only 25%, 5% and 35% of that of VWTi catalysts, respectively.

[0083] Table 2 shows the concentrations of 16 PAHs collected from the tail gas during the VWTi catalyst reaction.

[0084]

[0085] Table 3. Concentrations of 16 PAHs collected from the tail gas during the CuAl-LDO catalyst reaction.

[0086]

[0087]

[0088] Table 4. Concentrations of 16 PAHs collected from the tail gas during the MnAl-LDO catalyst reaction.

[0089]

[0090] Table 5. Concentrations of 16 PAHs collected from the tail gas during the CoAl-LDO catalyst reaction.

[0091]

[0092] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. The application of a binary aluminum-based bimetallic oxide in the low-temperature degradation of polycyclic aromatic hydrocarbons, characterized in that, Using the aforementioned binary aluminum-based bimetallic oxide as a catalyst, polycyclic aromatic hydrocarbons (PAHs) in boiler flue gas are degraded within the temperature range of 240–300°C, wherein the PAH content in the boiler flue gas is 10 μg / Nm³. 3 -10000μg / Nm 3 The polycyclic aromatic hydrocarbon is naphthalene. The binary aluminum layered bimetallic oxide is one of CuAl layered bimetallic oxide, MnAl layered bimetallic oxide, and CoAl layered bimetallic oxide; The CuAl layered bimetallic oxide was prepared by the following method: (1) 0.05 mol Cu(NO3)2 and 0.025 mol Al(NO3)3·9H2O were weighed and dissolved in 100 mL of deionized water, and stirred at 1000 r / min for half an hour at a constant temperature of 30 °C to obtain a Cu(NO3)2 solution; (2) 0.05 mol Na2CO3 was weighed and dissolved in 100 mL of deionized water, and stirred at 1000 r / min for half an hour at a constant temperature of 30 °C to obtain a Na2CO3 solution; (3) Cu(NO3)2 solution was added dropwise to the Na2CO3 solution at a titration rate of 3 mL / min under constant temperature of 30 °C and stirring at 1000 r / min, and the solution was further prepared by 4 mol / L (4) After titration, the mixed solution was kept at 30°C and stirred at 1000r / min for 10 hours, and then left to stand at room temperature for 12 hours. (5) The mixed solution after standing for 12 hours was filtered and washed with deionized water 7 times until pH=7. The solid of the filter was placed at 60°C and dried for 24 hours to obtain CuAl layered bimetallic hydroxide. The CuAl layered bimetallic hydroxide was calcined at 400°C for 5 hours to obtain CuAl layered bimetallic oxide. The MnAl layered bimetallic oxide was prepared by the following method: (a) 0.05 mol Mn(NO3)2 and 0.025 mol Al(NO3)3·9H2O were weighed and dissolved in 100 ml of deionized water, and stirred at 1000 r / min for half an hour at 30 °C to obtain a Mn(NO3)2 solution; (b) 0.05 mol Na2CO3 was weighed and dissolved in 100 ml of deionized water, and stirred at 1000 r / min for half an hour at 30 °C to obtain a Na2CO3 solution; (c) Mn(NO3)2 solution was added dropwise to the Na2CO3 solution at 3 ml / min with stirring at 1000 r / min and at a constant temperature of 30 °C, and the solution was further prepared by 4 mol / L... (d) After titration, the pH value was maintained at 10.30 throughout the titration process with NaOH; after titration, the mixed solution was kept at 30℃ and stirred at 1000r / min for 10 hours, and then allowed to stand at room temperature for 12 hours; (e) The mixed solution after standing for 12 hours was filtered and washed 7 times with deionized water until pH=7. The solid of the filter was placed at 60℃ and dried for 24 hours to obtain MnAl layered bimetallic hydroxide; the MnAl layered bimetallic hydroxide was calcined at 400℃ for 5 hours to obtain MnAl layered bimetallic oxide. The CoAl layered bimetallic oxide was prepared by the following method: (i) 0.05 mol Co(NO3)2 and 0.025 mol Al(NO3)3·9H2O were weighed and dissolved in 100 ml of deionized water, and stirred at 1000 r / min for half an hour at a constant temperature of 30 °C to obtain a Co(NO3)2 solution; (ii) 0.05 mol Na2CO3 was weighed and dissolved in 100 ml of deionized water, and stirred at 1000 r / min for half an hour at a constant temperature of 30 °C to obtain a Na2CO3 solution; (iii) Co(NO3)2 solution was added dropwise to the Na2CO3 solution, which was stirred at 1000 r / min at a constant temperature of 3 ml / min, and the solution was further prepared by titrating with 4 mol / L... (iv) After titration, the mixed solution was kept at 30°C and stirred at 1000 r / min for 10 hours, and then allowed to stand at room temperature for 12 hours. (v) The mixed solution after standing for 12 hours was filtered and washed 7 times with deionized water until pH=7. The solid of the filter was placed at 60°C and dried for 24 hours to obtain CoAl layered bimetallic hydroxide. The CoAl layered bimetallic hydroxide was calcined at 400°C for 5 hours to obtain CoAl layered bimetallic oxide.

2. The application according to claim 1, characterized in that, The binary aluminum-based bimetallic oxide is used as a solid catalyst in the flue gas purification system.

3. The application according to claim 1, characterized in that, The binary aluminum-based bimetallic oxide is suitable for volumes with a space velocity of 30,000 h⁻¹. -1 -60000h -1 Boiler operating environment.

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