A multifunctional catalyst for medium and low temperature flue gas purification and its preparation method

Abstract

The invention discloses a multifunctional catalyst for medium and low temperature flue gas purification and a preparation method thereof, belonging to the technical field of environmental functional materials and atmospheric pollutant control. A multifunctional catalyst for medium and low temperature flue gas purification is composed of the following components: CuO, Co3O4 and MgO, wherein the mass of CuO accounts for 0.5%-10% of the mass of the CoMgO composite oxide carrier, and the molar ratio x of the Mg element to the total amount of Co-Mg metal elements in the CoMgO composite oxide carrier is 0.05-0.25. The invention also specifically discloses a preparation method of the multifunctional catalyst for medium and low temperature flue gas purification, and the multifunctional catalyst is simultaneously applied to CO catalytic oxidation and CO reduction NO reaction, and exhibits good medium and low temperature catalytic activity, long-term operation stability and water resistance, and can be applied to industrial flue gas treatment under different working conditions or flue gas composition changes.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental functional materials and air pollutant control, and particularly relates to a multifunctional catalyst used for medium and low temperature flue gas purification and a preparation method thereof. Background Art

[0002] In recent years, under the background of ultra-low emissions and coordinated pollution reduction and carbon reduction in the industrial sector, higher requirements have been put forward for the control of air pollutants. CO and NO, as two typical air pollutants, pose a serious threat to ecological environmental safety and human health. Therefore, how to efficiently eliminate CO and NO in flue gas has become an important research topic in the field of environment. CO catalytic oxidation can oxidize CO to CO under oxygen-rich conditions through the action of catalysts. 2 , while the CO reduction of NO reaction can achieve the synergistic elimination of the two pollutants under oxygen-deficient conditions. As the core of the catalytic reaction, the catalyst is crucial to the reaction performance. In the existing technical applications, different catalysts are usually required for medium and low temperature flue gases under different conditions, which cannot meet the application scenarios with different operating conditions and large changes in flue gas composition during operation. Therefore, there is an urgent need to develop multifunctional catalysts to adapt to their application under different operating conditions. Summary of the invention

[0003] Based on the above shortcomings of current catalysts, the present invention provides a multifunctional catalyst for medium and low temperature flue gas purification and a preparation method thereof. The multifunctional catalyst can be simultaneously used in CO catalytic oxidation and CO reduction of NO reactions, and exhibits good medium and low temperature catalytic activity, long-term operating stability and water resistance, and can be applied to industrial flue gas treatment under different operating conditions and with large changes in flue gas composition.

[0004] The present invention adopts the following technical solution to solve the above technical problems: a multifunctional catalyst for medium and low temperature flue gas purification, characterized in that the multifunctional catalyst is composed of the following components: CuO, Co 3 O 4 and MgO, of which the mass of CuO accounts for 2.3% of Co 3 O 4 -MgO (CoMgO) composite oxide carrier mass is 0.5%-10%, the molar ratio x of Mg element to the total amount of Co-Mg metal elements in the composite oxide carrier is 0.05-0.25. This multifunctional catalyst is simultaneously used in CO catalytic oxidation and CO reduction of NO reactions, and exhibits good medium and low temperature catalytic activity, long-term operation stability and water resistance, and can be used in industrial flue gas treatment under different operating conditions or with large changes in flue gas composition.

[0005] It is further defined that the multifunctional catalyst is used in low-temperature CO catalytic oxidation or medium-low temperature catalytic CO reduction NO reaction, and the specific process is: 2 The flue gas containing CO and NO is introduced into a fixed bed reactor loaded with a multifunctional catalyst to achieve full contact and reaction between the gas and solid phases.

[0006] It is further defined that the test temperature ranges for the low-temperature CO catalytic oxidation and the medium-low temperature catalytic CO reduction of NO are 30-150°C and 75-400°C, respectively.

[0007] The method for preparing the multifunctional catalyst for medium and low temperature flue gas purification of the present invention is characterized by the following specific steps:

[0008] Step S1, adding magnesium acetate and cobalt acetate into deionized water and stirring and mixing to obtain a clear and transparent purple solution, wherein the molar ratio x of the Mg element to the total amount of the Co-Mg metal element is 0.05-0.25;

[0009] Step S2, dissolving citric acid in deionized water to obtain a clear, transparent, colorless solution;

[0010] Step S3, adding the colorless solution obtained in step S2 to the purple solution obtained in step S1, continuously stirring to mix them evenly, and then adding nitric acid solution and stirring to mix them evenly to obtain a mixed solution;

[0011] Step S4, heating and stirring the mixed solution obtained in step S3 at 80-100° C. to concentrate it into a gel state, and then transferring it into an oven at 120-150° C. to foam it;

[0012] Step S5, grinding the foamed product obtained in step S4 and pre-decomposing it at 160-200° C., and calcining the pre-decomposed powder to obtain a CoMgO composite oxide carrier;

[0013] Step S6, dissolving copper nitrate trihydrate corresponding to a CuO loading mass fraction of 0.5wt%-10wt% in deionized water to obtain a copper nitrate solution, and then adding a corresponding weight of the CoMgO composite oxide support obtained in step S5 to the obtained copper nitrate solution, stirring to mix them evenly, then drying the mixture, and then calcining it to obtain a multifunctional catalyst.

[0014] It is further defined that the molar ratio of the total amount of Co-Mg metal elements in the purple solution to the citric acid in the colorless solution in step S3 is 1:1-1:3.

[0015] Further defined, the calcination process in step S5 is firstly carried out at 5 ℃·min -1 The heating rate was increased from room temperature to 250 °C and maintained for 1 hour, then increased at 10 °C min-1 The temperature was raised to 500-700 °C at a heating rate and maintained for 3 hours.

[0016] Further, the calcination process in step S5 is specifically to first heat at 5 °C·min -1 The heating rate was increased from room temperature to 250 °C and maintained for 1 hour, then increased at 10 °C min -1 The temperature was raised to 550 °C at a heating rate of 1000 ℃ and maintained for 3 hours.

[0017] It is further defined that the calcination process in step S6 is to raise the temperature to 400-600° C. and maintain it for 1-5 hours.

[0018] It is further defined that the calcination process in step S6 is to increase the temperature to 500° C. and maintain it for 3 hours.

[0019] Since existing catalysts usually require the use of different catalysts for different flue gas conditions, they cannot meet the requirements for efficient removal of pollutants in flue gas under different operating conditions and application scenarios with large changes in flue gas composition. The CuO / CoMgO multifunctional catalyst has good molecular oxygen activation and redox properties, and can eliminate CO and NO under medium and low temperature conditions. The present invention adopts citric acid complexation and wet impregnation to prepare a high-efficiency multifunctional catalyst, which can eliminate pollutants contained in flue gas through CO catalytic oxidation and CO reduction NO reaction under oxygen-rich and oxygen-poor conditions, respectively, and shows good removal efficiency and long-term operation stability under medium and low temperature conditions.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0021] 1. The preparation method of the multifunctional catalyst of the present invention is simple and low in cost, which is conducive to mass production and its practical application in medium and low temperature flue gas purification.

[0022] 2. The multifunctional catalyst of the present invention is 4000 ppm CO, 10% O 2 and gas space velocity of 30000h -1 and 1000 ppm CO, 1000 ppm NO and a gas space velocity of 50000 h -1 Under the simulated flue gas conditions, good medium and low temperature conversion efficiency can be achieved, and even the catalyst with a lower CuO loading ratio can still show good catalytic performance. In addition, the catalyst shows good long-term operation stability and can meet the medium and low temperature flue gas purification needs under different working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1The catalytic efficiency of CuO / CoMgO catalysts with different Mg-Co ratios in CO reduction of NO (a) and CO catalytic oxidation (b);

[0024] Figure 2 The catalytic efficiency of CuO / CoMgO catalysts with different CuO loading ratios in CO reduction of NO (a) and CO catalytic oxidation (b);

[0025] Figure 3 These are the long-term operation stability test results of CuO / CoMgO catalyst loaded with 5 wt% CuO in CO catalytic oxidation and CO reduction of NO reactions. DETAILED DESCRIPTION

[0026] The above contents of the present invention are further described in detail below through examples, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples, and all technologies implemented based on the above contents of the present invention belong to the scope of the present invention. Example

[0027] Preparation of catalyst: The total amount of metal elements is 15 mmol, and the molar ratio of metal elements is 0.75:14.25 ( x =0.05) The corresponding magnesium acetate and cobalt acetate were added to 50 mL of deionized water and stirred vigorously for 1 hour to obtain a clear and transparent purple solution. 22.5 mmol citric acid was dissolved in 50 mL of deionized water to obtain a clear and transparent citric acid solution. The citric acid solution was added to the purple metal ion solution and stirred continuously to mix it evenly. 10 mL of nitric acid solution was added to the obtained mixed solution and stirred thoroughly, then heated and stirred at 90 °C to concentrate the solution into a gel state. The gel was transferred to an oven and foamed at 140 °C for 10 hours, and then the temperature was raised to 180 °C for pre-decomposition for 10 hours. The pre-decomposed powder was first heated in a box furnace at 5 °C·min -1 The heating rate was increased from room temperature to 250 °C and maintained for 1 hour, then increased at 10 °C min -1 The temperature was raised to 550 °C at a heating rate and maintained for 3 hours, and the CoMgO composite oxide support was calcined. 0.46 g of copper nitrate trihydrate corresponding to 5wt% CuO loading mass fraction was dissolved in deionized water to obtain 10 mL of copper nitrate solution, and 3 g of CoMgO composite oxide support was added to the solution, and stirred for 12 hours to mix it evenly. The mixture was then dried and calcined at 500 °C for 3 hours to obtain a multifunctional catalyst for medium and low temperature flue gas purification. Among them, the mass of CuO accounts for 5% of the total mass of the CoMgO composite oxide support, and the molar ratio of Mg element to the total amount of Co-Mg metal elements in the CoMgO composite oxide support is x is 0.05.

[0028] Catalyst performance test: The simulated flue gas containing pollutants was passed into a fixed bed reactor loaded with the multifunctional catalyst prepared above to achieve full gas-solid phase contact and reaction. 2 and gas space velocity of 30000 h -1 and 1000 ppm CO, 1000 ppm NO and a gas space velocity of 50000 h -1 Under the simulated flue gas conditions, the CO catalytic oxidation and CO reduction NO reaction performance tests were carried out in the test temperature ranges of 30-150 ℃ and 75-400 ℃ respectively. Figure 1 As shown in Figure 2, the catalyst exhibits good CO reduction performance for NO, achieving 100% NO and CO conversion in the range of 125-400 °C and 200-400 °C ( Figure 1 (a)); the CO conversion rate can reach more than 100% in the temperature range of 110-150 °C ( Figure 1 (b)). Example

[0029] Preparation of catalyst: The total amount of metal elements is 15 mmol, and the molar ratio of metal elements is 2.25:12.75 ( x =0.15) The corresponding magnesium acetate and cobalt acetate were added to 50 mL of deionized water and stirred vigorously for 1 hour to obtain a clear and transparent purple solution. 22.5 mmol citric acid was dissolved in 50 mL of deionized water to obtain a clear and transparent citric acid solution. The citric acid solution was added to the purple metal ion solution and stirred continuously to mix it evenly. 10 mL of nitric acid solution was added to the obtained mixed solution and stirred thoroughly, then heated and stirred at 90 °C to concentrate the solution into a gel state. The gel was transferred to an oven and foamed at 140 °C for 10 hours, and then the temperature was raised to 180 °C for pre-decomposition for 10 hours. The pre-decomposed powder was first heated in a box furnace at 5 °C·min -1 The heating rate was increased from room temperature to 250 °C and maintained for 1 hour, then increased at 10 °C min -1 The temperature was raised to 550 °C at a heating rate and maintained for 3 hours, and the CoMgO composite oxide support was calcined. 0.46 g of copper nitrate trihydrate corresponding to 5wt% CuO loading mass fraction was dissolved in deionized water to obtain 10 mL of copper nitrate solution, 3 g of CoMgO composite oxide support was added to the solution, and stirred for 12 hours to mix it evenly. The mixture was then dried and calcined at 500 °C for 3 hours to obtain an efficient and multifunctional catalyst for medium and low temperature flue gas purification. Among them, the mass of CuO accounts for 5% of the total mass of the CoMgO composite oxide support, and the molar ratio of Mg element to the total amount of Co-Mg metal elements in the CoMgO composite oxide support is xis 0.15.

[0030] Catalyst performance test: The simulated flue gas containing pollutants was passed into a fixed bed reactor loaded with the multifunctional catalyst prepared above to achieve full gas-solid phase contact and reaction. 2 and gas space velocity of 30000 h -1 and 1000 ppm CO, 1000 ppm NO and a gas space velocity of 50000 h -1 Under the simulated flue gas conditions, the CO catalytic oxidation and CO reduction NO reaction performance tests were carried out in the test temperature ranges of 30-150 ℃ and 75-400 ℃ respectively. Figure 1 As shown in Figure 2, the catalyst exhibits good CO reduction performance for NO, achieving 100% NO and CO conversion in the range of 125-400 °C and 200-400 °C ( Figure 1 (a)); 100% CO conversion is achieved in the temperature range of 100-150 °C ( Figure 1 (b)). Example

[0031] Preparation of catalyst: The total amount of metal elements is 15 mmol, and the molar ratio of metal elements is 3.75:11.25 ( x =0.25) The corresponding magnesium acetate and cobalt acetate were added to 50 mL of deionized water and stirred vigorously for 1 hour to obtain a clear and transparent purple solution. 22.5 mmol of citric acid was dissolved in 50 mL of deionized water to obtain a clear and transparent citric acid solution. The citric acid solution was added to the purple metal ion solution and stirred continuously to mix it evenly. 10 mL of nitric acid solution was added to the obtained mixed solution and stirred thoroughly, then heated and stirred at 90 °C to concentrate the solution into a gel state. The gel was transferred to an oven and foamed at 140 °C for 10 hours, and then the temperature was raised to 180 °C for pre-decomposition for 10 hours. The pre-decomposed powder was first heated in a box furnace at 5 °C·min -1 The heating rate was increased from room temperature to 250 °C and maintained for 1 hour, then increased at 10 °C min -1The temperature was raised to 550 °C at a heating rate and maintained for 3 hours, and the CoMgO composite oxide support was calcined. 0.46 g of copper nitrate trihydrate corresponding to 5wt% CuO loading mass fraction was dissolved in deionized water to obtain 10 mL of copper nitrate solution, 3 g of CoMgO composite oxide support was added to the solution, and stirred for 12 hours to mix it evenly. The mixture was then dried and calcined at 500 °C for 3 hours to obtain an efficient and multifunctional catalyst for medium and low temperature flue gas purification. Among them, the mass of CuO accounts for 5% of the total mass of the CoMgO composite oxide support, and the molar ratio of Mg element to the total amount of Co-Mg metal elements in the CoMgO composite oxide support is x is 0.25.

[0032] Catalyst performance test: The simulated flue gas containing pollutants was passed into a fixed bed reactor loaded with the multifunctional catalyst prepared above to achieve full gas-solid phase contact and reaction. 2 and gas space velocity of 30000 h -1 and 1000 ppm CO, 1000 ppm NO and a gas space velocity of 50000 h -1 Under the simulated flue gas conditions, the CO catalytic oxidation and CO reduction NO reaction performance tests were carried out in the test temperature ranges of 30-150 ℃ and 75-400 ℃ respectively. Figure 1 As shown in Figure 2, the catalyst exhibits good CO reduction performance, achieving 100% NO and CO conversion in the range of 150-400 °C and 200-400 °C ( Figure 1 (a)); 100% CO conversion is achieved in the temperature range of 110-150 °C ( Figure 1 (b)). Example

[0033] Preparation of catalyst: The total amount of metal elements is 15 mmol, and the molar ratio of metal elements is 2.25:12.75 ( x =0.15) The corresponding magnesium acetate and cobalt acetate were added to 50 mL of deionized water and stirred vigorously for 1 hour to obtain a clear and transparent purple solution. 22.5 mmol citric acid was dissolved in 50 mL of deionized water to obtain a clear and transparent citric acid solution. The citric acid solution was added to the purple metal ion solution and stirred continuously to mix it evenly. 10 mL of nitric acid solution was added to the obtained mixed solution and stirred thoroughly, then heated and stirred at 90 °C to concentrate the solution into a gel state. The gel was transferred to an oven and foamed at 140 °C for 10 hours, and then the temperature was raised to 180 °C for pre-decomposition for 10 hours. The pre-decomposed powder was first heated in a box furnace at 5 °C·min -1The heating rate was increased from room temperature to 250 °C and maintained for 1 hour, then increased at 10 °C min -1 The temperature was raised to 550 °C at a heating rate of 100 °C and maintained for 3 hours, and the CoMgO composite oxide support was calcined. 0.046 g of copper nitrate trihydrate corresponding to 0.5wt% CuO loading mass fraction was dissolved in deionized water to obtain 10 mL of copper nitrate solution, 3 g of CoMgO composite oxide support was added to the solution, and stirred for 12 hours to mix it evenly. The mixture was then dried and calcined at 500 °C for 3 hours to obtain an efficient and multifunctional catalyst for medium and low temperature flue gas purification. Among them, the mass of CuO accounts for 0.5% of the total mass of the CoMgO composite oxide support, and the molar ratio of Mg element to the total amount of Co-Mg metal elements in the CoMgO composite oxide support is 0.5%. x is 0.15.

[0034] Catalyst performance test: The simulated flue gas containing pollutants was passed into a fixed bed reactor loaded with the multifunctional catalyst prepared above to achieve full gas-solid phase contact and reaction. 2 and gas space velocity of 30000 h -1 and 1000 ppm CO, 1000 ppm NO and a gas space velocity of 50000 h -1 Under the simulated flue gas conditions, the CO catalytic oxidation and CO reduction NO reaction performance tests were carried out in the test temperature ranges of 30-150 ℃ and 75-400 ℃ respectively. Figure 2 As shown in Figure 2, the catalyst exhibits good CO reduction performance for NO, achieving 100% NO and CO conversion in the range of 125-400 °C and 200-400 °C ( Figure 2 (a)); 100% CO conversion rate is achieved in the temperature range of 90-150 °C ( Figure 2 (b)). Example

[0035] Preparation of catalyst: The total amount of metal elements is 15 mmol, and the molar ratio of metal elements is 2.25:12.75 ( x=0.15) The corresponding magnesium acetate and cobalt acetate were added to 50 mL of deionized water and stirred vigorously for 1 hour to obtain a clear and transparent purple solution. 22.5 mmol citric acid was dissolved in 50 mL of deionized water to obtain a clear and transparent citric acid solution. The citric acid solution was added to the purple metal ion solution and stirred continuously to mix it evenly. 10 mL of nitric acid solution was added to the obtained mixed solution and stirred thoroughly, then heated and stirred at 90 °C to concentrate the solution into a gel state. The gel was transferred to an oven and foamed at 140 °C for 10 hours, and then the temperature was raised to 180 °C for pre-decomposition for 10 hours. The pre-decomposed powder was first heated in a box furnace at 5 °C·min -1 The heating rate was increased from room temperature to 250 °C and maintained for 1 hour, then increased at 10 °C min -1 The temperature was raised to 550 °C at a heating rate and maintained for 3 hours, and the CoMgO composite oxide support was calcined. 0.28 g of copper nitrate trihydrate corresponding to 3 wt% CuO loading mass fraction was dissolved in deionized water to obtain 10 mL of copper nitrate solution, 3 g of CoMgO composite oxide support was added to the solution, and stirred for 12 hours to mix it evenly. The mixture was then dried and calcined at 500 °C for 3 hours to obtain an efficient and multifunctional catalyst for medium and low temperature flue gas purification. Among them, the mass of CuO accounts for 3% of the total mass of the CoMgO composite oxide support, and the molar ratio of Mg element to the total amount of Co-Mg metal elements in the CoMgO composite oxide support is x is 0.15.

[0036] Catalyst performance test: The simulated flue gas containing pollutants was passed into a fixed bed reactor loaded with the multifunctional catalyst prepared above to achieve full gas-solid phase contact and reaction. 2 and gas space velocity of 30000 h -1 and 1000 ppm CO, 1000 ppm NO and a gas space velocity of 50000 h -1 Under the simulated flue gas conditions, the CO catalytic oxidation and CO reduction NO reaction performance tests were carried out in the test temperature ranges of 30-150 ℃ and 75-400 ℃ respectively. Figure 2 As shown in Figure 2, the catalyst exhibits good CO reduction performance, achieving 100% NO and CO conversion in the range of 150-400 °C and 200-400 °C ( Figure 2 (a)); 100% CO conversion is achieved in the temperature range of 110-150 °C ( Figure 2 (b)). Example

[0037] Preparation of catalyst: The total amount of metal elements is 15 mmol, and the molar ratio of metal elements is 2.25:12.75 ( x =0.15) The corresponding magnesium acetate and cobalt acetate were added to 50 mL of deionized water and stirred vigorously for 1 hour to obtain a clear and transparent purple solution. 22.5 mmol citric acid was dissolved in 50 mL of deionized water to obtain a clear and transparent citric acid solution. The citric acid solution was added to the purple metal ion solution and stirred continuously to mix it evenly. 10 mL of nitric acid solution was added to the obtained mixed solution and stirred thoroughly, then heated and stirred at 90 °C to concentrate the solution into a gel state. The gel was transferred to an oven and foamed at 140 °C for 10 hours, and then the temperature was raised to 180 °C for pre-decomposition for 10 hours. The pre-decomposed powder was first heated in a box furnace at 5 °C·min -1 The heating rate was increased from room temperature to 250 °C and maintained for 1 hour, then increased at 10 °C min -1 The temperature was raised to 550 °C at a heating rate and maintained for 3 hours, and the CoMgO composite oxide support was calcined. 0.92 g of copper nitrate trihydrate corresponding to a CuO loading mass fraction of 10wt% was dissolved in deionized water to obtain 10 mL of copper nitrate solution, 3 g of CoMgO composite oxide support was added to the solution, and stirred for 12 hours to mix it evenly. The mixture was then dried and calcined at 500 °C for 3 hours to obtain an efficient and multifunctional catalyst for medium and low temperature flue gas purification. Among them, the mass of CuO accounts for 10% of the total mass of the CoMgO composite oxide support, and the molar ratio of Mg element to the total amount of Co-Mg metal elements in the CoMgO composite oxide support is x is 0.15.

[0038] Catalyst performance test: The simulated flue gas containing pollutants was passed into a fixed bed reactor loaded with the multifunctional catalyst prepared above to achieve full gas-solid phase contact and reaction. 2 and gas space velocity of 30000 h -1 and 1000 ppm CO, 1000 ppm NO and a gas space velocity of 50000 h -1 Under the simulated flue gas conditions, the CO catalytic oxidation and CO reduction NO reaction performance tests were carried out in the test temperature ranges of 30-150 ℃ and 75-400 ℃ respectively. Figure 2 As shown in Figure 2, the catalyst exhibits good CO reduction performance, achieving 100% NO and CO conversion in the range of 150-400 °C and 200-400 °C ( Figure 2 (a)); 100% CO conversion is achieved in the temperature range of 110-150 °C ( Figure 2 (b)). Example

[0039] Preparation of catalyst: The preparation process of the catalyst in this example is consistent with that in Example 2.

[0040] Catalyst performance test: The simulated flue gas containing pollutants was passed into a fixed bed reactor loaded with the multifunctional catalyst prepared above to achieve full gas-solid phase contact and reaction. 2 and gas space velocity of 30000 h -1 and 1000 ppm CO, 1000 ppm NO and a gas space velocity of 50000 h -1 Under the simulated flue gas conditions, the catalyst was tested for its long-term performance in CO catalytic oxidation and CO reduction of NO. Figure 3 As shown in the figure, the CO conversion rate of the catalyst can be maintained above 79% (the initial CO conversion rate is 83.6%) in the long-term operation stability test of CO catalytic oxidation for 15 hours at 80 ℃; in addition, the NO and CO conversion rates of the catalyst are maintained above 85% and 59% respectively (the initial NO and CO conversion rates are 86.5% and 60.8%) in the long-term operation stability test of catalytic CO reduction of NO for 15 hours at 100 ℃. The above results show that the catalyst can show good long-term operation stability in both CO catalytic oxidation and catalytic CO reduction of NO reactions.

[0041] The above embodiments describe the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for illustrating the principles of the present invention. Without departing from the scope of the principles of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a multifunctional catalyst for medium and low temperature flue gas purification, characterized in that The specific steps are: Step S1, adding magnesium acetate and cobalt acetate into deionized water and stirring and mixing to obtain a clear and transparent purple solution, wherein the molar ratio x of the Mg element to the total amount of the Co-Mg metal element is 0.05-0.25; Step S2, dissolving citric acid in deionized water to obtain a clear, transparent, colorless solution; Step S3, adding the colorless solution obtained in step S2 to the purple solution obtained in step S1, continuously stirring to mix them evenly, then adding nitric acid solution and stirring to mix them evenly to obtain a mixed solution; the molar ratio of the total amount of Co-Mg metal elements in the purple solution to the citric acid in the colorless solution is 1:1-1:3; Step S4, heating and stirring the mixed solution obtained in step S3 at 80-100° C. to concentrate it into a gel state, and then transferring it into an oven at 120-150° C. to foam it; Step S5, grinding the foamed product obtained in step S4 and pre-decomposing it at 160-200°C, and calcining the pre-decomposed powder to obtain a CoMgO composite oxide carrier; the calcination process is first at 5°C·min -1 The heating rate was increased from room temperature to 250 °C and maintained for 1 hour, then increased at 10 °C min -1 The temperature is raised to 500-700 °C at a heating rate and maintained for 3 hours; Step S6, dissolving copper nitrate trihydrate corresponding to a CuO loading mass fraction of 0.5wt%-10wt% in deionized water to obtain a copper nitrate solution, and then adding a corresponding weight of the CoMgO composite oxide support obtained in step S5 to the obtained copper nitrate solution, stirring to mix them evenly, then drying the mixture, and then calcining it to obtain a multifunctional catalyst.

2. The method for preparing the multifunctional catalyst for medium and low temperature flue gas purification according to claim 1, characterized in that: The calcination process in step S5 is specifically to first heat at 5 °C·min -1 The heating rate was increased from room temperature to 250 °C and maintained for 1 hour, then increased at 10 °C min -1 The temperature was raised to 550 °C at a heating rate of 1000 ℃ and maintained for 3 hours.

3. The method for preparing the multifunctional catalyst for medium and low temperature flue gas purification according to claim 1, characterized in that: The calcination process in step S6 is to raise the temperature to 400-600° C. and maintain it for 1-5 hours.

4. The method for preparing the multifunctional catalyst for medium and low temperature flue gas purification according to claim 1, characterized in that: The calcination process in step S6 is to raise the temperature to 500° C. and maintain it for 3 hours.

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