CO-SCR catalyst with active site self-protection function and its preparation and application

Abstract

The present invention discloses a CO-SCR catalyst with an active site self-protection function, a preparation method thereof, and an application in CO-SCR denitration. The preparation method comprises: adding nano-activated carbon and ethyl silicate to nitric acid, stirring and activating, and then drying, adding the obtained dry product and a soluble salt of metal R to water, mixing, drying, and then calcining at 300-350°C to obtain an intermediate product; metal R is at least one of Co, Cu, Ce, Ni, Fe, and W; the intermediate product and a soluble salt containing ruthenium are mixed in water, dried, and then calcined at 300-350°C, followed by reduction with a hydrogen-containing atmosphere at 300-350°C to obtain a CO-SCR catalyst with an active site self-protection function. The present invention utilizes SiO2 to wrap nano-activated carbon. When applied to CO-SCR denitration in an oxygen-containing atmosphere, the internal activated carbon can be controllably reacted with oxygen to slowly release CO, protect the active site, and reduce the probability of the active site being inactivated by O2 attack.

Description

Technical Field

[0001] The present invention relates to the field of carbon monoxide selective catalytic reduction (CO-SCR) denitrification, and in particular to a CO-SCR catalyst with active site self-protection function, a preparation method thereof, and an application thereof, which is suitable for denitrification of coke oven flue gas, sintering flue gas, pelletizing flue gas, motor vehicle exhaust gas, etc. containing carbon monoxide (CO) and nitrogen oxides (NO x ) of flue gas denitrification. Background Art

[0002] Carbon monoxide and nitrogen oxides exist simultaneously in coke oven flue gas, sintering flue gas, pelletizing flue gas, and motor vehicle exhaust. Nitrogen oxides are one of the main pollutants causing air pollution, while carbon monoxide is a toxic gas and needs to be treated before flue gas is discharged.

[0003] Currently, the removal of nitrogen oxides mostly uses ammonia selective catalytic reduction (NH3-SCR) technology, while CO needs to be converted into carbon dioxide (CO2) under the action of a catalyst. It is difficult to achieve simultaneous removal of the two on the same catalyst.

[0004] CO-SCR technology uses CO as a reducing agent to remove NO x This technology can significantly reduce the use of reducing agent ammonia on the basis of achieving simultaneous removal of two pollutants, thereby saving flue gas treatment costs.

[0005] Currently reported CO-SCR denitrification catalysts under aerobic conditions mostly use iridium as the active component (Ji et al., Adv. Mater. 2022, 34, 2205703; Hamada et al., Appl. Catal. A-Gen., 2012, 421-422, 1-13). The high price of iridium has seriously hindered the industrial application and promotion of this type of catalyst.

[0006] Replacing iridium with other metals is an important approach to effectively reducing the production costs of CO-SCR denitrification catalysts and flue gas treatment costs. For example, patent specifications CN112316946A and CN112316943A disclose two copper-based catalysts for CO-SCR reactions. However, in actual flue gas atmospheres, which contain more than 5 vol% oxygen (O2) and catalyst-poisoning components such as chloride ions, the active sites on these copper-based catalysts, which use transition metals as their active phase, rapidly lose activity under attack by O2 and chloride ions, rendering them incapable of long-term stable operation in such flue gas environments.

[0007] For catalyst use environments such as coke oven flue gas, sintering flue gas, and pelletizing flue gas, which have high oxygen and chlorine content and complex and changeable flue gas components, the catalyst's tolerance to O2 and resistance to chlorine poisoning are crucial to the long-term stability of the catalyst. Summary of the Invention

[0008] In view of the above technical problems and the shortcomings in the art, the present invention provides a CO-SCR catalyst with active site self-protection function and its preparation method and application. The catalyst can be represented by Ru / RO x -AC@SiO2, including RO x Represents the oxide of metal R, AC represents activated carbon, and AC@SiO2 represents activated carbon wrapped in SiO2. The catalyst has excellent denitrification activity under oxygen-containing and chlorine-containing flue gas conditions. In an oxygen-containing atmosphere, the strong reducing property of AC@SiO2 itself and the CO slowly released through the mesoporous SiO2 shell can protect the active vacancies of the catalyst and prevent O atoms from attacking the active vacancies; the excellent C-Cl cleavage function and Deacon reaction performance of Ru elemental substance can achieve efficient conversion of chloride ions into Cl2 and HCl, protecting the active sites from the attack of chloride ions. The catalyst is suitable for coke oven flue gas, pelletizing flue gas, sintering flue gas and other flue gases containing CO, NO x It provides strong support for the treatment of flue gas containing chlorine pollutants and has good application prospects.

[0009] The specific technical solutions are as follows:

[0010] A method for preparing a CO-SCR catalyst having an active site self-protection function comprises the following steps:

[0011] (1) adding nano-activated carbon and ethyl silicate to nitric acid, stirring and activating, and then drying; adding the obtained dry product and a soluble salt of metal R to water, mixing, drying, and then calcining at 300-350° C. to obtain an intermediate product; the metal R is at least one of Co, Cu, Ce, Ni, Fe, and W;

[0012] (2) The intermediate product and a soluble salt containing ruthenium are mixed in water, dried, calcined at 300-350° C., and then reduced in a hydrogen-containing atmosphere at 300-350° C. to obtain the CO-SCR catalyst having the active site self-protection function.

[0013] In the preparation method of the CO-SCR catalyst with active site self-protection function, in step (1), the nano activated carbon can be at least one of coconut shell activated carbon, wood activated carbon, and coal-based activated carbon.

[0014] In one embodiment, in the method for preparing the CO-SCR catalyst with active site self-protection function, in step (1), the method for preparing the nano-activated carbon includes: adding activated carbon into a ball mill and ball milling to obtain the nano-activated carbon.

[0015] Furthermore, in the method for preparing nano-activated carbon, the ball mill can have an orbital speed of 50 to 300 rpm and an autorotational speed of 100 to 800 rpm. If the orbital and autorotational speeds of the ball mill are too low or too high, the prepared activated carbon particles will not reach the required nanoparticle size, which will directly lead to the inability to control the subsequent oxidation reaction rate and protect the active sites.

[0016] In one embodiment, in the method for preparing the CO-SCR catalyst with active site self-protection function, in step (1), the particle size of the nano-activated carbon is 200 to 1000 nm.

[0017] In one embodiment, the preparation method of the CO-SCR catalyst with active site self-protection function, the mass ratio of the nano-activated carbon to the ethyl silicate is 1:0.05-0.1, and the mass of the ethyl silicate is calculated as SiO2; the ratio of the nano-activated carbon to the ethyl silicate can form a porous SiO2 protective shell with a film thickness of 2-10 nm on the outer layer of the nano-activated carbon, thereby achieving control of the oxidation reaction rate and maintaining a slow release of 5-20 ppm of CO; if the porous SiO2 protective shell is too thick or too thin, it is not conducive to controlling the reaction rate and CO release rate;

[0018] The mass ratio of the nano-activated carbon to the soluble salt of the metal R is 10:1-5;

[0019] The mass ratio of the intermediate product to ruthenium is 100:0.1-3.

[0020] In one embodiment, in the method for preparing the CO-SCR catalyst having the active site self-protection function, in step (1), the mass concentration of HNO3 in the nitric acid is 1% to 5%.

[0021] In one embodiment, in the method for preparing the CO-SCR catalyst with active site self-protection function, in step (1), the stirring activation temperature is 55-65° C. and the time is 0.5-1.5 h.

[0022] In one embodiment, in the method for preparing a CO-SCR catalyst with active site self-protection function, in step (2), the hydrogen-containing atmosphere is a mixture of hydrogen and an inert gas. The inert atmosphere can be a noble gas and / or nitrogen. Furthermore, the volume percentage of hydrogen in the mixture can be 1% to 10%.

[0023] The present invention further provides a CO-SCR catalyst with active site self-protection function prepared by the preparation method.

[0024] The present invention also provides the use of the CO-SCR catalyst with active site self-protection function in CO-SCR denitration.

[0025] As a general inventive concept, the present invention also provides a CO-SCR denitration method, which uses the CO-SCR catalyst with active site self-protection function to perform CO-SCR denitration treatment on exhaust gas at a treatment temperature of 150-300° C. The exhaust gas may also contain oxygen, chlorine, chlorine-containing compounds, etc.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention first wraps the nano-activated carbon with a silica shell, then loads the metal oxide onto the surface of the activated carbon protected by SiO2, and then uses it as a carrier to load metal ruthenium to obtain the final Ru / RO x -AC@SiO2 catalyst.

[0028] Compared to directly using activated carbon as a carrier, the present invention uses SiO2 to wrap nano-activated carbon. When applied to CO-SCR denitrification in an oxygen-containing atmosphere, the internal activated carbon can be controlled to react with oxygen to slowly release CO, thereby protecting the active sites and reducing the probability of the catalyst active sites being inactivated by O2 attack. The amount of CO released by AC alone is uncontrollable, and the consumption of activated carbon is too high under the high-temperature environment of actual denitrification applications. The SiO2 shell of the present invention can effectively control the reaction rate and the amount of CO generated. The present invention wraps AC with silica with a core-shell structure to control the reaction rate of AC, thereby achieving controlled release of low-concentration CO and long-term protection of the catalyst active sites. At the same time, it will not cause the rapid release of excessive CO, avoiding the aggravated emission of pollutants. DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to specific examples. It should be understood that these examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention.

[0030] The catalytic performance test conditions of the catalysts prepared in the following examples and comparative examples are as follows:

[0031] The catalyst was placed in a fixed-bed quartz tube reactor for activity testing. The reaction temperature was 150-300°C, the inlet NO concentration was 200 ppm, the inlet CO concentration was 1000 ppm, the inlet HCl concentration was 20 ppm, the oxygen content was 5 vol%, and the rest was nitrogen. The space velocity was 10000 h -1 .

[0032] Example 1

[0033] Ru / CoO x -AC@SiO2 catalyst preparation:

[0034] 10g of coconut shell activated carbon was added to a ball mill, and the revolution speed was set to 100 rpm and the rotation speed was set to 100 rpm. The activated carbon material was ball-milled into nano-activated carbon with a particle size of 600nm. The nano-activated carbon and ethyl silicate were added to a 3wt% nitric acid solution. The mass ratio of ethyl silicate to nano-activated carbon was 0.05:1 based on the mass of SiO2. The mixture was continuously stirred at 60°C for 1 hour for activation, and then dried at 100°C for 12 hours. The dried sample and 3.0g of cobalt nitrate were added to 100mL of deionized water, stirred for 6 hours, and then dried at 100°C for 12 hours. The dried sample was then calcined at 350°C for 3 hours to obtain CoO x / AC@SiO2.

[0035] Weigh 5g of CoO x / AC@SiO2 was added to 50mL of deionized water, followed by a ruthenium trichloride solution containing 0.05g of ruthenium. After stirring for 6 hours, the sample was placed in an oven and dried at 100°C for 12 hours. Finally, the dried sample was calcined at 350°C for 3 hours and then reduced at 300°C with a H2 / N2 mixture with a hydrogen concentration of 5vol% for 2 hours to obtain Ru / CoO x -AC@SiO2. The catalytic performance test results of the catalyst are shown in Table 1.

[0036] Example 2

[0037] Ru / CuO x -AC@SiO2 catalyst preparation:

[0038] 10g of wood activated carbon was added to a ball mill, and the revolution speed was set to 150 rpm and the rotation speed was set to 200 rpm. The activated carbon material was ball-milled into nano-activated carbon with a particle size of 300nm. The nano-activated carbon and ethyl silicate were added to a nitric acid solution with a concentration of 3wt%. The amount of ethyl silicate added was calculated based on the mass of SiO2 and the mass ratio of the nano-activated carbon was 0.06:1. The mixture was continuously stirred at 60°C for 1 hour for activation, and then dried at 100°C for 12 hours. The dried sample and 2.0g of copper nitrate were added to 100mL of deionized water, stirred for 6 hours, and then dried at 100°C for 12 hours. The dried sample was then calcined at 350°C for 3 hours to obtain CuO x / AC@SiO2.

[0039] Weigh 5g of CuO x / AC@SiO2 was added to 50 mL of deionized water, followed by a ruthenium trichloride solution containing 0.06 g of ruthenium. After stirring for 6 hours, the sample was placed in an oven and dried at 100°C for 12 hours. Finally, the dried sample was calcined at 350°C for 3 hours and then reduced at 300°C with a H2 / N2 mixture with a hydrogen concentration of 5 vol% for 2 hours to obtain Ru / CuO x -AC@SiO2. The catalytic performance test results of the catalyst are shown in Table 1.

[0040] Example 3

[0041] Ru / CeO x -AC@SiO2 catalyst preparation:

[0042] 10g of coal-based activated carbon was added to a ball mill, and the revolution speed was set to 200 rpm and the rotation speed was set to 500 rpm. The activated carbon material was ball-milled into nano-activated carbon with a particle size of 300nm. The nano-activated carbon and ethyl silicate were added to a 3wt% nitric acid solution. The mass ratio of ethyl silicate to nano-activated carbon was 0.08:1 based on the mass of SiO2. The mixture was continuously stirred at 60°C for 1 hour and then dried at 100°C for 12 hours. The dried sample and 3.0g of cerium nitrate were added to 100mL of deionized water, stirred for 6 hours, and then dried at 100°C for 12 hours. The dried sample was then calcined at 350°C for 3 hours to obtain CeO x / AC@SiO2.

[0043] Weigh 5g of CeO x / AC@SiO2 was added to 50 mL of deionized water, followed by a ruthenium trichloride solution containing 0.10 g of ruthenium. After stirring for 6 hours, the sample was placed in an oven and dried at 100°C for 12 hours. Finally, the dried sample was calcined at 350°C for 3 hours and then reduced at 300°C with a H2 / N2 mixture with a hydrogen concentration of 5 vol% for 2 hours to obtain Ru / CeO x -AC@SiO2. The catalytic performance test results of the catalyst are shown in Table 1.

[0044] Example 4

[0045] Ru / NiO x -AC@SiO2 catalyst preparation:

[0046] 10g of coconut shell activated carbon was added to a ball mill, and the revolution speed was set to 200 rpm and the rotation speed was set to 600 rpm. The activated carbon material was ball-milled into nano-activated carbon with a particle size of 300nm. The nano-activated carbon and ethyl silicate were added to a nitric acid solution with a concentration of 3wt%. The mass ratio of ethyl silicate to nano-activated carbon was 0.08:1 based on the mass of SiO2. The mixture was continuously stirred and activated at 60°C for 1 hour, and then dried at 100°C for 12 hours. The dried sample and 3.5g of nickel nitrate were added to 100mL of deionized water, stirred for 6 hours, and then dried at 100°C for 12 hours. The dried sample was then calcined at 350°C for 3 hours to obtain NiO x / AC@SiO2.

[0047] Weigh 5g of NiO x / AC@SiO2 was added to 50mL of deionized water, followed by a ruthenium trichloride solution containing 0.10g of ruthenium. After stirring for 6 hours, the sample was placed in an oven and dried at 100°C for 12 hours. Finally, the dried sample was calcined at 350°C for 3 hours and then reduced at 300°C with a H2 / N2 mixture with a hydrogen concentration of 5vol% for 2 hours to obtain Ru / NiO x -AC@SiO2. The catalytic performance test results of the catalyst are shown in Table 1.

[0048] Example 5

[0049] Ru / FeO x -AC@SiO2 catalyst preparation:

[0050] 10g of wood activated carbon was added to a ball mill, and the revolution speed was set to 300 rpm and the rotation speed was set to 800 rpm. The activated carbon material was ball-milled into nano-activated carbon with a particle size of 200nm. The nano-activated carbon and ethyl silicate were added to a 3wt% nitric acid solution. The mass ratio of ethyl silicate to nano-activated carbon was 0.1:1 based on the mass of SiO2. The mixture was continuously stirred at 60°C for 1 hour for activation, and then dried at 100°C for 12 hours. The dried sample and 4.0g of ferric nitrate were added to 100mL of deionized water, stirred for 6 hours, and then dried at 100°C for 12 hours. The dried sample was then calcined at 350°C for 3 hours to obtain FeO x / AC@SiO2.

[0051] Weigh 5g of FeO x / AC@SiO2 was added to 50 mL of deionized water, followed by a ruthenium trichloride solution containing 0.08 g of ruthenium. After stirring for 6 hours, the sample was placed in an oven and dried at 100°C for 12 hours. Finally, the dried sample was calcined at 350°C for 3 hours and then reduced at 300°C with a H2 / N2 mixture with a hydrogen concentration of 5 vol% for 2 hours to obtain Ru / FeO x -AC@SiO2. The catalytic performance test results of the catalyst are shown in Table 1.

[0052] Example 6

[0053] Ru / WO x -AC@SiO2 catalyst preparation:

[0054] 10g of coal-based activated carbon was added to a ball mill, and the revolution speed was set to 250 rpm and the rotation speed was set to 600 rpm. The activated carbon material was ball-milled into nano-activated carbon with a particle size of 250nm. The nano-activated carbon and ethyl silicate were added to a 3wt% nitric acid solution. The mass ratio of ethyl silicate to nano-activated carbon was 0.09:1 based on the mass of SiO2. The mixture was continuously stirred at 60°C for 1 hour for activation, and then dried at 100°C for 12 hours. The dried sample and 1.0g of ammonium metatungstate were added to 100mL of deionized water, stirred for 6 hours, and then dried at 100°C for 12 hours. The dried sample was then calcined at 350°C for 3 hours to obtain WO x / AC@SiO2.

[0055] Weigh 5g of WO x / AC@SiO2 was added to 50 mL of deionized water, followed by a ruthenium trichloride solution containing 0.10 g of ruthenium. After stirring for 6 hours, the sample was placed in an oven and dried at 100°C for 12 hours. Finally, the dried sample was calcined at 350°C for 3 hours and then reduced at 300°C with a 5 vol% H2 / N2 mixture for 2 hours to obtain Ru / WO x -AC@SiO2. The catalytic performance test results of the catalyst are shown in Table 1.

[0056] Example 7

[0057] Ru / CoCeO x -AC@SiO2 catalyst preparation:

[0058] 10g of coal-based activated carbon was added to a ball mill, and the revolution speed was set to 150 rpm and the rotation speed was set to 300 rpm. The activated carbon material was ball-milled into nano-activated carbon with a particle size of 400nm. The nano-activated carbon and ethyl silicate were added to a 3wt% nitric acid solution. The amount of ethyl silicate added was calculated based on the mass of SiO2 and the mass ratio of the nano-activated carbon was 0.08:1. The mixture was continuously stirred and activated at 60°C for 1 hour, and then dried at 100°C for 12 hours. The dried sample, 1.5g of cobalt nitrate and 1.5g of cerium nitrate were added to 100mL of deionized water, stirred for 6 hours, and then dried at 100°C for 12 hours. The dried sample was then calcined at 350°C for 3 hours to obtain CoCeO x / AC@SiO2.

[0059] Weigh 5g of CoCeO x / AC@SiO2 was added to 50 mL of deionized water, followed by a ruthenium trichloride solution containing 0.05 g of ruthenium. After stirring for 6 hours, the sample was placed in an oven and dried at 100°C for 12 hours. Finally, the dried sample was calcined at 350°C for 3 hours and then reduced at 300°C with a H2 / N2 mixture with a hydrogen concentration of 5 vol% for 2 hours to obtain Ru / CoCeO x -AC@SiO2. The catalytic performance test results of the catalyst are shown in Table 1. Comparison of the results of this example with those of Example 1 and Example 3 shows that Co and Ce in the catalyst system of the present invention have a synergistic effect on denitration, significantly promoting the improvement of the catalyst's denitration performance.

[0060] The catalyst of this embodiment was tested for stability at 220°C for 48 hours and found that the NO x The conversion rate was always maintained above 95.0%, indicating that the catalyst had excellent stability.

[0061] Example 8

[0062] Ru / CuCeO x -AC@SiO2 catalyst preparation:

[0063] 10g of coconut shell activated carbon was added to a ball mill, and the revolution speed was set to 200 rpm and the rotation speed was set to 400 rpm. The activated carbon material was ball-milled into nano-activated carbon with a particle size of 350nm. The nano-activated carbon and ethyl silicate were added to a 3wt% nitric acid solution. The mass ratio of ethyl silicate to nano-activated carbon was 0.06:1 based on the mass of SiO2. The mixture was stirred continuously at 60°C for 1 hour and then dried at 100°C for 12 hours. The dried sample, 1.0g of copper nitrate and 1.5g of cerium nitrate were added to 100mL of deionized water, stirred for 6 hours, and then dried at 100°C for 12 hours. The dried sample was then calcined at 350°C for 3 hours to obtain CuCeO x / AC@SiO2.

[0064] Weigh 5g of CuCeO x / AC@SiO2 was added to 50 mL of deionized water, followed by a ruthenium trichloride solution containing 0.06 g of ruthenium. After stirring for 6 hours, the sample was placed in an oven and dried at 100°C for 12 hours. Finally, the dried sample was calcined at 350°C for 3 hours and then reduced at 300°C with a H2 / N2 mixture with a hydrogen concentration of 5 vol% for 2 hours to obtain Ru / CuCeO x -AC@SiO2. The catalytic performance test results of the catalyst are shown in Table 1. Comparison of the results of this example with those of Example 2 and Example 3 shows that Cu and Ce in the catalyst system of the present invention have a synergistic effect on denitration, significantly promoting the improvement of the catalyst's denitration performance.

[0065] Comparative Example 1

[0066] Ru / CoO x Catalyst preparation:

[0067] 20.0 g of cobalt nitrate was added to 100 mL of deionized water, stirred for 6 hours, and dried at 100 ° C for 12 hours. The dried sample was then calcined at 350 ° C for 3 hours to obtain CoO x .

[0068] Weigh 5g of CoO x Add to 50mL of deionized water, then add ruthenium trichloride solution containing 0.06g of ruthenium, continue stirring for 6 hours and then put it into an oven to dry at 100℃ for 12 hours. Finally, the dried sample was calcined at 350℃ for 3 hours and then reduced with H2 / N2 mixed gas with a hydrogen concentration of 5vol% at 300℃ for 2 hours to obtain Ru / CoO x .

[0069] Comparative Example 2

[0070] CoO x-AC@SiO2 catalyst preparation: The preparation method of the catalyst is shown in Example 1, and the denitrification activity of the catalyst is shown in Table 1.

[0071] Comparative Example 3

[0072] Ru / CoO x -AC catalyst preparation:

[0073] The only difference from Example 1 is that ethyl silicate is not added, and the rest are the same, and Ru / CoO x -AC catalyst. The catalytic performance test results of this catalyst are shown in Table 1. The catalyst's activity at 220°C was only 67.5%, and activity decreased rapidly as the reaction temperature increased. Comparison of this comparative example with Example 1 demonstrates that without controlling the reaction rate of the activated carbon using a SiO2 shell, the nano-activated carbon would rapidly combust at high temperatures, failing to achieve self-protection of the active sites.

[0074] Comparative Example 4

[0075] Ru / CoO x -AC-SiO2 catalyst preparation:

[0076] The only difference from Example 1 is that the same mass of unmilled coconut shell activated carbon is used instead of nano activated carbon. The rest is the same. The Ru / CoO x -AC-SiO2 catalyst. The catalytic performance test results of this catalyst are shown in Table 1. The catalyst's activity at 240°C was only 88.4%, and the active temperature window was limited to 240-260°C. Comparison of this comparative example with Example 1 shows that activated carbon that has not been ball-milled to an appropriate particle size generates the reducing shielding gas CO very slowly, failing to effectively protect the active sites at high temperatures.

[0077] Table 1 shows the temperature window where the denitration activity of the catalysts of various embodiments and comparative examples is not less than 80%, the optimal denitration activity temperature, and the corresponding maximum nitrogen oxide conversion rate.

[0078] Table 1

[0079]

[0080] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A method for preparing a CO-SCR catalyst with active site self-protection function, characterized in that: Including steps: (1) Adding nano-activated carbon and ethyl silicate to nitric acid, stirring and activating, and then drying, forming a porous SiO2 protective shell layer with a thickness of 2 to 10 nm on the outer layer of the nano-activated carbon, adding the obtained dry product and a soluble salt of metal R to water, mixing, drying, and then calcining at 300 to 350° C. to obtain an intermediate product; the metal R is at least one of Co, Cu, Ce, Ni, Fe, and W; the particle size of the nano-activated carbon is 200 to 1000 nm; the mass concentration of HNO3 in the nitric acid is 1% to 5%; (2) The intermediate product and a soluble salt containing ruthenium are mixed in water, dried, calcined at 300-350° C., and then reduced in a hydrogen-containing atmosphere at 300-350° C. to obtain the CO-SCR catalyst having the active site self-protection function.

2. The preparation method according to claim 1, characterized in that In step (1), the nano activated carbon is at least one of coconut shell activated carbon, wood activated carbon, and coal activated carbon.

3. The preparation method according to claim 1, characterized in that In step (1), the preparation method of the nano activated carbon comprises: adding activated carbon into a ball mill and performing ball milling to obtain the nano activated carbon; In the method for preparing nano-activated carbon, the revolution speed of the ball mill is 50-300 rpm, and the rotation speed is 100-800 rpm.

4. The preparation method according to claim 1, characterized in that The mass ratio of the nano-activated carbon to the ethyl silicate is 1:0.05-0.1, and the mass of the ethyl silicate is calculated as SiO2; The mass ratio of the nano-activated carbon to the soluble salt of the metal R is 10:1-5; The mass ratio of the intermediate product to ruthenium is 100:0.1-3.

5. The preparation method according to claim 1, characterized in that In step (1): The stirring activation temperature is 55-65° C., and the time is 0.5-1.5 h.

6. The preparation method according to claim 1, characterized in that In step (2): The hydrogen-containing atmosphere is a mixture of hydrogen and inert gas; The inert atmosphere is a rare gas and / or nitrogen; The volume percentage of hydrogen in the mixed gas is 1% to 10%.

7. A CO-SCR catalyst having an active site self-protection function, prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the CO-SCR catalyst with active site self-protection function according to claim 7 in CO-SCR denitration.

9. A CO-SCR denitrification method, characterized in that: The CO-SCR catalyst with active site self-protection function as claimed in claim 7 is used to carry out CO-SCR denitration treatment of exhaust gas at a treatment temperature of 150 to 300°C.

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