Multimetallic Ir-M@N-SAPO-RHO catalyst resistant to water and sulfur under oxygen-rich conditions and its preparation and application

Abstract

The present invention discloses a multi-metal Ir-M@N-SAPO-RHO catalyst that is resistant to water and sulfur under oxygen-rich conditions, a preparation method thereof, and an application in CO-SCR denitration. The active component iridium and at least one of the active auxiliary agents tin, samarium, and lead are encapsulated into the SAPO-RHO molecular sieve by a one-step hydrothermal method, and then the loaded SAPO-RHO molecular sieve is exchanged with alkali metal cations, and the skeleton molecules at the outer opening of the molecular sieve pores are replaced with alkali metal ions to construct an alkali metal cation hinge door; at least one auxiliary agent of tin, samarium, and lead is used to enhance the adsorption of the catalyst to the reactant nitrogen oxides and improve the thermal stability of the active component zero-valent Ir; thereby achieving better catalyst anti-poisoning ability and denitration performance, and finally obtaining a multi-metal Ir-M@N-SAPO-RHO catalyst with high denitration efficiency, wide active temperature window, good stability, and strong anti-poisoning ability.

Description

Technical Field

[0001] The present invention relates to the selective catalytic reduction of carbon monoxide (CO-SCR) to nitrogen oxides (NO x ) technical field, specifically relates to an oxygen-rich condition (O 2 The multi-metal Ir-M@N-SAPO-RHO catalyst with water and sulfur resistance and a content of more than 1 vol%) and its preparation method and application are suitable for motor vehicle exhaust and industrial waste gas containing both CO and NO x Denitrification of flue gas and flue gas with added CO. Background Art

[0002] The large amount of nitrogen oxide emissions has caused a series of environmental problems. Motor vehicle exhaust, coke oven flue gas, sintering flue gas, pelletizing flue gas, and boiler flue gas usually contain both CO and NO. x And other pollutants.

[0003] At present, three-way catalysts are mostly used to treat motor vehicle exhaust to remove NO in the exhaust gas. x To remove it, additional reducing agents are required; while industrial tail gas needs to be treated with two catalysts to remove CO and NO. x The above technologies have increased the cost of flue gas treatment to a certain extent.

[0004] The CO in motor vehicle exhaust / industrial flue gas can be used to reduce NO x If the reducing agent can be effectively used, it will greatly save the cost of tail gas treatment and reduce the energy consumption and carbon dioxide emission problems caused by the preparation of other reducing agents. Therefore, CO-SCR technology is an extremely economical and low-energy flue gas denitrification technology.

[0005] Since CO prefers to react with O under oxygen-rich conditions 2 The reaction produces CO 2 , resulting in poor denitrification activity, narrow active temperature window and poor stability of most reported CO-SCR catalysts (Song et al., Chem. Eng. J. 2023, 452, 139331; Heo et al., Environ. Sci. Technol. 2020, 54, 8344-8351). Due to the above problems, the practical application of CO-SCR catalysts is greatly limited. In addition, water and sulfur dioxide often present in flue gas will also cause the activity of the catalyst to change, so it is necessary to develop catalysts with good resistance to O 2 , water-resistant and sulfur-resistant CO-SCR catalysts are of great significance.

[0006] The patent specification with publication number CN113275008A discloses a method for selective catalytic reduction of NO with CO x SiO 2 Ball-loaded iridium potassium bimetallic catalyst and its preparation method and application. The catalyst is prepared by impregnation method, SiO 2 The ball is the carrier, the precious metal iridium is the active component, and potassium is the auxiliary agent. 2 and SO 2 Under the existing conditions, the airspeed is 20000h -1 When the catalyst is in the range of 225~350℃, NO x The conversion rate reached more than 70%, N 2 The selectivity is 100%, and it has good anti-oxidation and anti-sulfur properties. However, the denitration performance of the catalyst when the exhaust gas contains water is not given when the catalyst is used, that is, the water resistance of the catalyst is unknown. In addition, the denitration effect of the catalyst still needs to be improved. Summary of the invention

[0007] The present invention provides a multi-metal Ir-M@N-SAPO-RHO catalyst that is resistant to water and sulfur under oxygen-rich conditions, and a preparation method and application thereof.

[0008] The invention first loads the precious metal Ir and the active auxiliary agent M metal (at least one of tin, samarium and lead) inside the pores of the SAPO-RHO molecular sieve; then, the molecular barrier effect is used to perform ion exchange between N metal cations (at least one of potassium, sodium, rubidium and cesium) and molecular sieve framework ions at the pores of the molecular sieve to form an N metal cation hinge gate through which only polar gas molecules can pass; and the steric barrier performance of the alkali metal cation hinge gate on non-polar gas molecules and the steric hindrance performance of macromolecular gases are used to selectively separate gas molecules entering the pores of the N-SAPO-RHO molecular sieve, thereby preventing O 2 , H 2 O, SO 2 Enter the pores of N-SAPO-RHO molecular sieve and selectively allow polar small molecule gases CO and NO x (especially NO) passes through the molecular sieve channels of N-SAPO-RHO molecular sieve, isolating O in the flue gas 2 , H 2 O, SO 2 The catalyst has excellent denitrification activity and a wide active temperature window under real flue gas conditions. At the same time, the catalyst shows excellent stability and anti-poisoning ability. It is effective for motor vehicle exhaust, pelletizing flue gas, sintering flue gas, etc. containing a large amount of CO and NO x It provides catalyst support for tail gas treatment and has good application prospects.

[0009] The specific technical solutions are as follows:

[0010] A method for preparing a water-resistant and sulfur-resistant multi-metal Ir-M@N-SAPO-RHO catalyst under oxygen-rich conditions, comprising the steps of:

[0011] (1) adding chloroiridic acid and a soluble salt of M to a mixture of pseudo-boehmite, orthophosphoric acid and water, adding silica sol after mixing, adding cetyltrimethylammonium bromide (CTAB) after stirring for a period of time, adding diethylamine after continuing to stir for a period of time, and continuing to stir to obtain a gel;

[0012] (2) adding SAPO-RHO seed crystals to the gel, stirring for a period of time, loading the mixture into a hydrothermal reactor, performing a hydrothermal reaction at 160-200° C. for 42-54 hours, and calcining the obtained solid product at 500-700° C. to obtain an intermediate product Ir-M@SAPO-RHO of SAPO-RHO encapsulated Ir and additive M;

[0013] (3) adding the intermediate product Ir-M@SAPO-RHO to an ammonium nitrate solution for ion exchange, taking the solid and continuing to add it to a N nitrate solution for ion exchange, then washing and drying the ion exchange product, calcining it at 500-700° C., and then reducing it at 400-800° C. in a hydrogen-containing atmosphere to obtain the water-resistant and sulfur-resistant multimetallic Ir-M@N-SAPO-RHO catalyst under the oxygen-rich condition;

[0014] M is at least one of tin (Sn), samarium (Sm), and lead (Pb);

[0015] N is at least one of potassium (K), sodium (Na), rubidium (Rb), and cesium (Cs).

[0016] In the preparation method of the multi-metal Ir-M@N-SAPO-RHO catalyst that is resistant to water and sulfur under oxygen-rich conditions described in the present invention, the active component (iridium) and the auxiliary agent (at least one of tin, samarium, and lead) are encapsulated into the interior of the molecular sieve by a one-step hydrothermal method, and at least one cation among potassium, sodium, rubidium, and cesium that has a screening effect in the molecular sieve is exchanged into the framework structure of the molecular sieve by an ion exchange method.

[0017] In one embodiment, in the water- and sulfur-resistant multi-metal Ir-M@N-SAPO-RHO catalyst under oxygen-rich conditions, the mass percentage of Ir is 0.5% to 2%, the molar ratio of M to Ir is 0.4 to 5:1, and the molar ratio of N to Ir is 1 to 20:1.

[0018] In one embodiment, the preparation method of the water-resistant and sulfur-resistant multi-metal Ir-M@N-SAPO-RHO catalyst under oxygen-rich conditions, the ratio of pseudo-boehmite, orthophosphoric acid, water, chloroiridic acid, soluble salt of M, silica sol, hexadecyltrimethylammonium bromide, diethylamine, and SAPO-RHO seed crystals is 5-10g: 10-15g: 20-1000mL: 0.05-0.1g: 0.01-0.1g: 5-10g: 1-5g: 5-20g: 0.1-0.5g, wherein the chloroiridic acid is calculated by the mass of iridium;

[0019] The mass concentration of silicon dioxide in the silica sol is 30% to 50%.

[0020] In one embodiment, the method for preparing the water- and sulfur-resistant multi-metal Ir-M@N-SAPO-RHO catalyst under oxygen-rich conditions, in step (2), the method for preparing the SAPO-RHO seed crystals comprises: adding silica sol to a mixed system of pseudo-boehmite, orthophosphoric acid and water, adding hexadecyltrimethylammonium bromide after mixing, stirring for a period of time and then adding diethylamine, continuing to stir for a period of time and then loading into a hydrothermal reactor, hydrothermally reacting at 160-200° C. for 42-54 hours, and calcining the obtained hydrothermal product at 500-700° C. for 3-5 hours to obtain the SAPO-RHO seed crystals.

[0021] In the preparation method of the SAPO-RHO seed crystal:

[0022] The ratio of pseudo-boehmite, orthophosphoric acid, water, silica sol, hexadecyltrimethylammonium bromide and diethylamine is 5-10g:10-15g:20-1000mL:5-10g:1-5g:5-20g;

[0023] The mass concentration of silicon dioxide in the silica sol is 30% to 50%.

[0024] In one embodiment, in the method for preparing the water- and sulfur-resistant multi-metal Ir-M@N-SAPO-RHO catalyst under oxygen-rich conditions, in step (3), the temperature for exchanging the intermediate product Ir-M@SAPO-RHO with ammonium nitrate ions is 55-65° C. and the time is 2-4 hours.

[0025] In one embodiment, in the method for preparing the water-resistant and sulfur-resistant multi-metal Ir-M@N-SAPO-RHO catalyst under oxygen-rich conditions, in step (3), the ratio of the intermediate product Ir-M@SAPO-RHO to the ammonium nitrate solution is 1 g: 10-30 mL;

[0026] The concentration of ammonium nitrate in the ammonium nitrate solution is 0.01-0.5 mol / L.

[0027] In one embodiment, in the method for preparing the water-resistant and sulfur-resistant multi-metal Ir-M@N-SAPO-RHO catalyst under oxygen-rich conditions, in step (3), the ratio of the intermediate product Ir-M@SAPO-RHO to the N nitrate solution is 1 g: 15-25 mL;

[0028] The N nitrate concentration in the N nitrate solution is 0.01-0.5 mol / L.

[0029] In one embodiment, in the method for preparing the water- and sulfur-resistant multi-metal Ir-M@N-SAPO-RHO catalyst under oxygen-rich conditions, in step (3), the solid is continuously added to the N nitrate solution for ion exchange at a temperature of 55 to 65° C. for 2 to 4 hours.

[0030] In one embodiment, in the method for preparing the water-resistant and sulfur-resistant multimetallic Ir-M@N-SAPO-RHO catalyst under oxygen-rich conditions, in step (3), the hydrogen-containing atmosphere is a mixture of hydrogen and an inert gas. The inert atmosphere can be a rare gas and / or nitrogen. Furthermore, the volume percentage of hydrogen in the mixture can be 1% to 10%.

[0031] The present invention further provides a water-resistant and sulfur-resistant multi-metal Ir-M@N-SAPO-RHO catalyst prepared by the preparation method under oxygen-rich conditions.

[0032] In the multi-metal Ir-M@N-SAPO-RHO catalyst that is resistant to water and sulfur under oxygen-rich conditions of the present invention, the carrier is a SAPO-RHO molecular sieve, the active substance is metal iridium, the co-catalyst is at least one of metal tin, samarium, and lead, and at least one cation of potassium, sodium, rubidium, and cesium on the molecular sieve is a metal node that plays a screening role.

[0033] The present invention also provides the use of the water- and sulfur-resistant multi-metal Ir-M@N-SAPO-RHO catalyst in CO-SCR denitrification under oxygen-rich conditions.

[0034] The present invention encapsulates the catalyst active components and active additives into the SAPO-RHO molecular sieve, constructs an alkali metal cation hinge door at the molecular sieve pipe port by using secondary ion exchange, and selectively separates the gas molecules entering the N-SAPO-RHO molecular sieve pores by using the alkali metal salt ion hinge door's spatial barrier performance for non-polar gas molecules and the spatial steric hindrance performance for macromolecular gases, thereby reducing the catalyst active components and O 2 , H 2 O, SO 2 The catalyst can show excellent denitrification activity, good stability and H resistance in CO-SCR denitrification.2 O and SO 2 Poisoning ability. 0.98g Ir-Sn@Cs-SAPO-RHO catalyst (catalyst of Example 4 in the present application specification) contains 300ppm NO, 3000ppm CO, 5vol.%O at 300℃ 2 , 200ppm SO 2 and 5 vol.% H 2 After continuous testing for 20 hours under O conditions, the denitrification activity can be stabilized at more than 85%.

[0035] As a general inventive concept, the present invention also provides a CO-SCR denitrification method, using the water- and sulfur-resistant multi-metal Ir-M@N-SAPO-RHO catalyst under oxygen-rich conditions to treat waste gas containing CO and nitrogen oxides, the treatment temperature is 200-400°C, and the oxygen content in the waste gas is above 1 vol%.

[0036] In one embodiment, in the CO-SCR denitration method, the amount of the water-resistant and sulfur-resistant multi-metal Ir-M@N-SAPO-RHO catalyst under oxygen-rich conditions is 2000 to 80000 h-1 at a space velocity of 1.5 to 2.0 s.h. -1 .

[0037] In one embodiment, in the CO-SCR denitrification method, the exhaust gas also contains sulfur dioxide and water vapor.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The present invention provides a multi-metal Ir-M@N-SAPO-RHO denitration catalyst with excellent water and sulfur resistance under oxygen-rich conditions, and a preparation method and application thereof. The active component iridium (Ir) and at least one of active auxiliary agents tin, samarium and lead are encapsulated into the interior of a SAPO-RHO molecular sieve by a one-step hydrothermal method, and then the loaded SAPO-RHO molecular sieve is subjected to alkali metal (at least one of potassium, sodium, rubidium and cesium) cation exchange, the framework molecules at the outer opening of the molecular sieve pores are replaced with alkali metal ions, and an alkali metal cation hinge door is constructed to isolate non-polar gas molecules and macromolecular gases, thereby preventing O 2 , H 2 O, SO 2Enter the pores of the N-SAPO-RHO molecular sieve and selectively allow polar small molecule gases CO and NO to pass through the molecular sieve pores of the N-SAPO-RHO molecular sieve; at least one additive among tin, samarium, and lead is used to enhance the catalyst's adsorption of reactant nitrogen oxides and improve the thermal stability of the active component zero-valent Ir; thereby achieving better catalyst anti-poisoning ability and denitrification performance, and ultimately producing a multi-metal Ir-M@N-SAPO-RHO catalyst with high denitrification efficiency, wide active temperature window, good stability, and strong anti-poisoning ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a scanning electron microscope (SEM) photograph of the Ir-Sn@Cs-SAPO-RHO catalyst of Example 4. DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0042] The catalyst performance test conditions prepared in the following examples and comparative examples are as follows:

[0043] The catalyst activity was tested in a fixed bed reactor at a reaction temperature of 200-400°C. x The inlet concentration was set to 300ppm, the CO inlet concentration was set to 3000ppm, the oxygen content was 5vol%, and the SO 2 The concentration is 200ppm, H 2 The O content is 5 vol%, nitrogen is used as carrier gas, and the space velocity is 40000 h -1 .

[0044] The chloroiridic acid hydrate solutions (or chloroiridic acid solutions) used in the preparation of the catalysts in the following examples and comparative examples are all chloroiridic acid hydrate solutions with an iridium concentration of 0.008 g / mL.

[0045] The SAPO-RHO seeds used in the following examples and comparative examples were prepared by the following method:

[0046] 8.4 g of pseudo-boehmite, 13.8 g of orthophosphoric acid, and 36.0 mL of deionized water were stirred at room temperature for 2 hours, and then 6.86 g of silica sol with a silica concentration of 40 wt% was added and stirred for 30 minutes, followed by 2.0 g of CTAB and 10.5 g of diethylamine, which were stirred for 2 hours, and then loaded into a hydrothermal reactor, and hydrothermally reacted at 200° C. for 2 days to obtain a hydrothermal product. The hydrothermal product was calcined at 600° C. for 4 hours to obtain SAPO-RHO seed crystals.

[0047] Example 1

[0048] Preparation of Ir-Sn@SAPO-RHO and Ir-Sn@K-SAPO-RHO catalysts:

[0049] Step 1: 8.4 g of pseudo-boehmite, 13.8 g of orthophosphoric acid, and 36.0 mL of deionized water were stirred at room temperature for 2 hours, and then 0.075 g of iridium chloroiridic acid hydrate solution and 0.07 g of stannous chloride dihydrate were added thereto and stirred for 2 hours. Then 6.86 g of silica sol with a silica concentration of 40 wt% was added and stirred for 30 minutes, and then 2.0 g of CTAB was added and stirred for 30 minutes, and then 10.5 g of diethylamine was added and stirred for 2 hours, and then 0.22 g of pre-prepared SAPO-RHO seed crystals were added thereto and stirred for 30 minutes, and then the mixture was loaded into a hydrothermal reactor, and the mixture was hydrothermally reacted at 200° C. for 2 days to obtain a hydrothermal product.

[0050] Step 2: The hydrothermal product is washed and dried, and then calcined at 600° C. for 4 hours to obtain a SAPO-RHO encapsulated Ir and Sn bimetallic sample.

[0051] Step 3: 5g SAPO-RHO encapsulated Ir and Sn bimetallic samples were ion exchanged with 100mL of 0.1mol / L ammonium nitrate solution at 60℃ for 3 hours, and then the exchanged product was ion exchanged twice with 100mL of 0.05mol / L potassium nitrate solution, each ion exchange temperature was 60℃, and each ion exchange time was 3 hours. The ion exchanged samples were filtered, washed and dried at 100℃ for 12 hours. The dried samples were calcined at 600℃ for 4 hours and then heated at 600℃ with 5vol%H 2 / 95vol%N 2 The mixed gas was reduced for 3 hours to obtain the final catalyst (Ir-Sn@K-SAPO-RHO). The mass percentage of Ir in the catalyst was 0.53% by ICP, the molar ratio of Sn to Ir was 0.78:1, and the molar ratio of K to Ir was 5.70:1.

[0052] The SAPO-RHO encapsulated Ir and Sn bimetallic samples obtained in step 2 were heated at 600 °C with 5 vol% H 2 / 95vol%N 2 The catalyst Ir-Sn@SAPO-RHO was obtained by mixed gas reduction for 3 hours. Ir-Sn@SAPO-RHO has NO x The conversion rate remained above 60.0%.

[0053] Ir-Sn@K-SAPO-RHO NO in the range of 275~350℃ xThe conversion rate remained above 75.0%.

[0054] Comparative Example 1

[0055] Preparation of Ir@SAPO-RHO catalyst:

[0056] Step 1: The same as step 1 of Example 1, except that stannous chloride dihydrate is not added, and the rest are the same;

[0057] Step 2: Same as step 2 in Example 1.

[0058] Step 3: Place the sample obtained in step 2 in a reducing atmosphere of 5 vol% H 2 / 95vol%N 2 The Ir@SAPO-RHO catalyst was obtained by reduction under mixed atmosphere and 600℃ for 3 hours. x The conversion rate remained above 30.0%.

[0059] Example 2

[0060] Preparation of Ir-Sn@Na-SAPO-RHO catalyst: The only difference from Example 1 is that the potassium nitrate solution is replaced by an equal volume and equimolar concentration of sodium nitrate solution, and the rest is the same to obtain Ir-Sn@Na-SAPO-RHO catalyst. The catalyst has a NO x The conversion rate remained above 60.0%.

[0061] Example 3

[0062] Preparation of Ir-Sn@Rb-SAPO-RHO catalyst: The only difference from Example 1 is that the potassium nitrate solution is replaced by an equal volume of rubidium nitrate solution of equal molar concentration, and the rest is the same to obtain Ir-Sn@Rb-SAPO-RHO catalyst. The catalyst has a NO x The conversion rate remained above 80.0%.

[0063] Example 4

[0064] Preparation of Ir-Sn@Cs-SAPO-RHO catalyst: The only difference from Example 1 is that the potassium nitrate solution is replaced by an equal volume of cesium nitrate solution of equal molar concentration, and the rest is the same to obtain an Ir-Sn@Cs-SAPO-RHO catalyst, the morphology of which is as follows Figure 1 As shown in Figure 2, the catalyst has a regular dodecahedral structure with a size of about 1.5 microns, indicating that the catalyst can still maintain a good structure after ion exchange. x The conversion rate remained above 85.0%.

[0065] Example 5

[0066] Preparation of Ir-Sm@Cs-SAPO-RHO catalyst: The only difference from Example 4 is that 0.14 g of samarium nitrate hexahydrate is used to replace 0.07 g of stannous chloride dihydrate (to ensure the molar ratio of M metal to Ir is consistent), and the rest is the same to obtain Ir-Sm@Cs-SAPO-RHO catalyst. The catalyst has NO in the range of 275-350 °C. x The conversion rate remained above 80.0%.

[0067] Example 6

[0068] Preparation of Ir-Pb@Cs-SAPO-RHO catalyst: The only difference from Example 4 is that 0.10 g of lead nitrate is used to replace 0.07 g of stannous chloride dihydrate (to ensure the molar ratio of M metal to Ir is consistent), and the rest is the same to obtain Ir-Pb@Cs-SAPO-RHO catalyst. The catalyst has a NO x The conversion rate remained above 75.0%.

[0069] Table 1 shows the test results of the denitration activity of the catalysts prepared in the examples and comparative examples.

[0070] Table 1

[0071]

[0072] 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 multi-metal Ir-M@N-SAPO-RHO catalyst that is resistant to water and sulfur under oxygen-rich conditions. It is characterized in that Includes steps: (1) Adding chloroiridic acid and a soluble salt of M to a mixture of pseudo-boehmite, orthophosphoric acid and water, adding silica sol after mixing, adding hexadecyltrimethylammonium bromide after stirring for a period of time, adding diethylamine after continuing to stir for a period of time, and continuing to stir to obtain a gel; (2) Adding SAPO-RHO seed crystals to the gel, stirring for a period of time, loading the mixture into a hydrothermal reactor, and subjecting the mixture to a hydrothermal reaction at 160-200° C. for 42-54 h. The obtained solid product is calcined at 500-700° C. to obtain an intermediate product Ir-M@SAPO-RHO of SAPO-RHO encapsulated Ir and additive M; (3) adding the intermediate product Ir-M@SAPO-RHO into an ammonium nitrate solution for ion exchange, taking the solid and continuing to add it into a N nitrate solution for ion exchange, then washing and drying the ion exchange product, calcining it at 500-700° C., and then reducing it at 400-800° C. in a hydrogen-containing atmosphere to obtain the water-resistant and sulfur-resistant multi-metal Ir-M@N-SAPO-RHO catalyst under the oxygen-rich condition; M is at least one of tin, samarium and lead; N is at least one of potassium, sodium, rubidium and cesium.

2. The preparation method according to claim 1, It is characterized in that In the water- and sulfur-resistant multimetallic Ir-M@N-SAPO-RHO catalyst under oxygen-rich conditions, the mass percentage of Ir is 0.5%-2%, the molar ratio of M to Ir is 0.4-5:1, and the molar ratio of N to Ir is 1-20:

1.

3. The preparation method according to claim 1, It is characterized in that The ratio of pseudo-boehmite, orthophosphoric acid, water, chloroiridic acid, soluble salt of M, silica sol, hexadecyltrimethylammonium bromide, diethylamine, and SAPO-RHO seed crystals is 5-10 g:10-15 g:20-1000 mL:0.05-0.1 g:0.01-0.1 g:5-10 g:1-5 g:5-20 g:0.1-0.5 g, wherein the chloroiridic acid is calculated based on the mass of iridium; The mass concentration of silicon dioxide in the silica sol is 30% to 50%.

4. The preparation method according to claim 1, It is characterized in that In step (2), the preparation method of the SAPO-RHO seed crystal comprises: adding silica sol to a mixed system of pseudo-boehmite, orthophosphoric acid and water, adding hexadecyltrimethylammonium bromide after mixing, stirring for a period of time and then adding diethylamine, continuing to stir for a period of time and then loading into a hydrothermal reaction kettle, performing a hydrothermal reaction at 160-200° C. for 42-54 hours, and calcining the obtained hydrothermal product at 500-700° C. for 3-5 hours to obtain the SAPO-RHO seed crystal; In the preparation method of the SAPO-RHO seed crystals, the ratio of pseudo-boehmite, orthophosphoric acid, water, silica sol, hexadecyltrimethylammonium bromide and diethylamine is 5-10 g: 10-15 g: 20-1000 mL: 5-10 g: 1-5 g: 5-20 g; and the mass concentration of silicon dioxide in the silica sol is 30%-50%.

5. The preparation method according to claim 1, It is characterized in that In step (3): The temperature of the intermediate product Ir-M@SAPO-RHO and the ammonium nitrate ion exchange is 55-65° C. and the time is 2-4 hours; The ratio of the intermediate product Ir-M@SAPO-RHO to the ammonium nitrate solution is 1 g: 10-30 mL; The concentration of ammonium nitrate in the ammonium nitrate solution is 0.01-0.5 mol / L; The ratio of the intermediate product Ir-M@SAPO-RHO to the N nitrate solution is 1 g: 15-25 mL; The N nitrate concentration in the N nitrate solution is 0.01-0.5 mol / L; The solid is continuously added to the N nitrate solution for ion exchange at a temperature of 55-65° C. for 2-4 hours.

6. The preparation method according to claim 1, It is characterized in that In step (3): The hydrogen-containing atmosphere is a mixture of hydrogen and an inert atmosphere; 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 multi-metal Ir-M@N-SAPO-RHO catalyst that is resistant to water and sulfur under oxygen-rich conditions, prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the multi-metal Ir-M@N-SAPO-RHO catalyst resistant to water and sulfur under oxygen-rich conditions according to claim 7 in CO-SCR denitrification.

9. A CO-SCR denitrification method, It is characterized in that The water- and sulfur-resistant multi-metal Ir-M@N-SAPO-RHO catalyst according to claim 7 is used to treat waste gas containing CO and nitrogen oxides at a treatment temperature of 200-400°C, and the oxygen content in the waste gas is above 1 vol%.

10. The CO-SCR denitration method according to claim 9, It is characterized in that The amount of the water- and sulfur-resistant multimetallic Ir-M@N-SAPO-RHO catalyst under the oxygen-rich condition is 2000-80000 h-1 at a space velocity. -1 ; The exhaust gas also contains sulfur dioxide and water vapor.

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