A N2O decomposition catalyst for hydrogen engines, its preparation method and application

Abstract

A hydrogen engine N2O decomposition catalyst, its preparation method, and its application are disclosed. The N2O decomposition catalyst includes a straight-through support, a first material coating coated on the straight-through support, and a second material coating coated on the first material coating. The first material coating is a passively heated coating containing 0.1-1 wt.% Pt, 0.2-2 wt.% Cu, the balance being cobalt oxide and unavoidable impurities. Heat is released by oxidizing H2 in the exhaust gas, which heats the second material coating located on the passively heated coating, accelerating the attainment of the N2O decomposition temperature. The second material coating is a highly water-resistant N2O decomposition coating containing 0.5-4 wt.% Rh, 1-10 wt.% alkali metal / alkaline earth metal, the balance being cobalt oxide and unavoidable impurities. This coating reduces the adsorption selectivity of the catalyst surface for H2O, prevents H2O from covering the active sites, facilitates N2O adsorption on the active sites, and promotes N2O decomposition, while also exhibiting high water resistance. This invention enables low-temperature N2O decomposition and high water resistance, solving the problem of uncontrollable N2O emissions in high water vapor environments under hydrogen engine exhaust.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen engine exhaust catalytic purification technology, specifically relating to an N2O decomposition catalyst, its preparation method, and its application. Background Technology

[0002] Nitrogen (N2O) is the third largest greenhouse gas. It is chemically stable at room temperature and can persist stably in the troposphere for extended periods. Its greenhouse effect is 298 times that of CO2. Hydrogen engines using zero-carbon fuels represent a crucial direction for the future development of the internal combustion engine industry.

[0003] The main pollutant emitted by hydrogen engines is NOx, while a large amount of N2O is generated when NOx is removed using aftertreatment catalysts. The most economical and effective technology for N2O control is direct catalytic decomposition, in which N2O can be directly decomposed into N2 and O2 under the action of a catalyst. However, existing N2O decomposition catalysts have the following main problems: (1) The N2O decomposition temperature is too high. The conventional aftertreatment system is DOC+SCR+ASC. During the exhaust gas purification process, a large amount of N2O will be generated at around 250℃ by DOC, SCR, and ASC catalysts. The best N2O decomposition catalyst reported so far has the best N2O decomposition activity (T) 50 (1) The temperature is approximately 300℃ or even higher, making N2O emission control difficult; (2) High water content severely reduces N2O decomposition activity. Hydrogen engine exhaust contains a large amount of water vapor, with a water content reaching up to 30%. The water in the exhaust can largely cover the active sites for N2O decomposition, making it difficult for N2O to be effectively adsorbed onto these sites, thus severely reducing N2O decomposition activity. Therefore, there is an urgent need for a low-temperature decomposition catalyst for N2O that is highly water-resistant and suitable for hydrogen engine emissions. Summary of the Invention

[0004] The purpose of this invention is to address the problems existing in the prior art and provide an N2O decomposition catalyst for hydrogen engines, enabling low-temperature N2O decomposition and possessing high water resistance, thereby solving the problem of difficult-to-control N2O emissions in high-moisture environments in hydrogen engine exhaust. This invention also provides a method for preparing the catalyst and its applications.

[0005] The technical solution adopted in this invention is as follows:

[0006] A hydrogen engine N2O decomposition catalyst includes a straight-through support, a first material coating coated on the straight-through support, and a second material coating coated on the first material coating.

[0007] The first layer of material coating is a passive heating coating, containing Pt, Cu and cobalt oxide. The mass content of Pt is 0.1-1%, the mass content of Cu is 0.2-2%, and the balance is cobalt oxide and unavoidable impurities. The passive heating coating releases heat from H2 in the oxidizing waste gas to heat the second layer of material coating located on the passive heating coating, thereby increasing the bed temperature of the second layer of material coating and accelerating the attainment of the decomposition temperature of N2O.

[0008] The second layer of material coating is a highly water-resistant N2O decomposition coating, containing Rh, alkali metal / alkaline earth metal and cobalt oxide. The mass content of Rh is 0.5-4%, the mass content of alkali metal / alkaline earth metal is 1-10%, and the balance is cobalt oxide and unavoidable impurities. The water-resistant N2O decomposition coating is used to reduce the adsorption selectivity of H2O on the catalyst surface, prevent H2O from covering the active sites, facilitate the adsorption of N2O on the active sites, decompose N2O and have high water resistance.

[0009] Furthermore, the loading of the first material coating accounts for 15% to 25% of the total coating loading on the N2O decomposition catalyst, with the remainder being the second material coating.

[0010] Furthermore, the length of the first layer of material coating covers 50% to 100% of the length of the through-type carrier, and the length of the second layer of material coating covers 100% of the length of the through-type carrier.

[0011] Furthermore, the particle size of the first layer of material coating D 90 The particle size of the second layer of material coating is 3.0–5.0 μm. D 90 The thickness is 6.0–8.0 μm.

[0012] Furthermore, the alkali metal / alkaline earth metal precursor is one or more of potassium acetylacetonate, sodium acetylacetonate, magnesium acetylacetonate, calcium acetylacetonate, barium acetylacetonate, and strontium acetylacetonate.

[0013] The preparation method of the N2O decomposition catalyst for hydrogen engines described in this invention is as follows:

[0014] (1) Preparation of the first material coating:

[0015] The organosilicon compound was added to acetone and dissolved completely to obtain an organosilicon compound solution. Cobalt oxide was added to the organosilicon compound solution, stirred evenly in a water bath at 50℃~70℃, allowed to stand for reaction, washed with deionized water, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain cobalt oxide A.

[0016] After uniformly mixing platinum and copper precursors, the mixture is fully dissolved in acetone to obtain a platinum-copper mixed solution. Cobalt oxide A is added to the platinum-copper mixed solution, and the mixture is centrifuged. The solid fraction obtained by centrifugation is freeze-dried to obtain a dry mixture. The dry mixture is calcined at 300℃~350℃ for 1~2 hours under static air conditions, cooled to below 50℃, and then H2 is introduced. The mixture is calcined at 400℃~500℃ for 2~4 hours to obtain a passively heated coating powder. The powder is further prepared into a slurry, ground to the required particle size, and then coated onto a direct-flow carrier to form the first layer of material coating.

[0017] (2) Preparation of the second material coating:

[0018] The organosilicon compound was added to acetone and dissolved completely to obtain an organosilicon compound solution. Cobalt oxide was added to the organosilicon compound solution, stirred evenly in a water bath at 50℃~70℃, allowed to stand for reaction, washed with deionized water, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain cobalt oxide A.

[0019] After uniformly mixing the rhodium precursor and the alkali metal / alkaline earth metal precursor, the mixture is fully dissolved in acetone to obtain a rhodium-alkali metal / alkaline earth metal mixed solution. Cobalt oxide A is added to the rhodium-alkali metal / alkaline earth metal mixed solution, and the mixture is centrifuged. The solid part obtained by centrifugation is freeze-dried to obtain a dried mixture. The dried mixture is calcined at 300℃~350℃ for 1~2 hours under static air conditions, cooled to below 50℃, and then O2 is introduced. The mixture is then calcined at 400℃~500℃ for 2~4 hours to obtain a coating powder.

[0020] The organosilicon compound is added to acetone and fully dissolved to obtain an organosilicon compound solution. The above coating powder is added to the organosilicon compound solution, ultrasonically stirred and centrifuged. The solid part obtained is prepared into a slurry, ground to the required particle size, and then coated on the first material coating to form the second material coating.

[0021] (3) The straight-through carrier after the first and second material coatings are applied is dried at 70~100℃ to prepare the N2O decomposition catalyst;

[0022] In the above steps, the organosilicon compound is one or more of polydimethylsiloxane, trimethylsilylacetylene, hexamethyldisilaneamine, vinyltriethoxysilane, diethoxydimethylsilane, tetraethyl orthosilicate, vinyltriethoxysilane, and 3-glycidoxypropyltrimethoxysilane.

[0023] Furthermore, the platinum precursor is one or more of platinum acetylacetonate, fluoroplatinum acetylacetonate, dipentenylplatinum, and cyclopentadienyltrimethylplatinum.

[0024] Furthermore, the copper precursor is one or more of copper acetylacetonate, phenylacetyl copper, bis(hexafluoroacetylacetonate)copper, and copper trifluoroacetylacetonate.

[0025] Furthermore, the rhodium precursor is one or more of rhodium acetylacetonate, rhodium acetylacetonate dicarbonyl, rhodium acetylacetonate triphenylphosphine carbonyl, and (1,5-cyclooctadiene) rhodium chloride dimer.

[0026] The N2O decomposition catalyst of the present invention is used for the after-treatment of pollutants emitted by hydrogen engines.

[0027] The preparation mechanism of the N2O decomposition catalyst of the present invention is as follows:

[0028] In the preparation of passively heated coating powder, cobalt A modified with organosilicon compounds is lipophilic. A mixed solution of lipophilic precursors platinum and copper can form a strong interaction with cobalt A through lipophilicity, which can fix the active species. Under static air at 300℃~350℃, the lipophilic group can be decomposed, and the active species platinum and copper can fall uniformly and orderly onto the surface of cobalt A. Then, H2 is introduced and calcined at 400℃~500℃ to form a platinum-copper alloy, which improves the catalytic oxidation ability.

[0029] In the preparation of a highly water-resistant N2O decomposition coating, cobalt oxide A modified with organosilicon compounds exhibits lipophilicity. A mixed solution of rhodium and alkali / alkaline earth metal precursors, both lipophilic, forms a strong interaction with cobalt oxide A, which can immobilize active species. Under static air at 300°C, the lipophilic groups decompose, allowing the active species rhodium and alkali / alkaline earth metals to uniformly and orderly settle on the surface of cobalt oxide A. Then, O2 is introduced, and the mixture is calcined at 400°C to 500°C to form rhodium oxide and alkali / alkaline earth metal oxides. Rhodium oxide is the key active species for improving N2O decomposition; increasing the amount of rhodium oxide effectively enhances the catalyst's N2O decomposition activity. The formed alkali / alkaline earth metal oxides enrich the alkaline centers on the catalyst surface, allowing O2 to desorb from the catalyst at lower temperatures, thus improving the catalyst's N2O decomposition performance. Simultaneously, N2O decomposition coating powder is added to an organosilicon compound solution, and the powder is brought into full contact with the organosilicon compound by ultrasound to prepare a highly water-resistant N2O decomposition coating slurry. This slurry is then coated onto a passively heated coating and dried to obtain an oleophilic N2O decomposition monolithic catalyst.

[0030] The present invention has the following beneficial effects:

[0031] (1) This invention solves the problem of severely reduced N2O decomposition activity of catalysts in high water vapor environments in hydrogen engine exhaust. This invention utilizes organosilicon compounds to make the highly water-resistant N2O decomposition coating oleophilic, making it easier for N2O to act on the catalytic active sites, preventing H2O from occupying the active sites, and effectively improving the low-temperature N2O decomposition performance and water resistance of the catalyst.

[0032] (2) The present invention uses a reasonable layered coating technology to oxidize H2 in the exhaust gas and release heat through passive heating of the coating, thereby increasing the temperature of the N2O decomposition coating bed and reaching the decomposition temperature of N2O in advance, which further promotes the decomposition of N2O.

[0033] (3) By adjusting the particle size of the coating slurry, the present invention achieves the applicability matching of multiple coating materials, making the coating and the carrier and the coatings bond firmly, effectively solving the problem of insufficient adhesion of multiple coatings. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of the N2O decomposition catalyst for the hydrogen engine of the present invention;

[0035] Among them: 1-passive heating coating; 2-high water and N2O decomposition resistant coating; 3-direct-flow carrier;

[0036] Figure 2 This is a schematic diagram of the inter-coating interaction mechanism of the N2O decomposition catalyst for hydrogen engines according to the present invention;

[0037] Among them: 1-passive heating coating; 2-high water and N2O decomposition resistant coating; 3-direct carrier; 4-rhodium oxide; 5-alkali metal / alkaline earth metal oxide; 6-water resistant group.

[0038] Table 1 shows the comparison of the catalytic activity of different catalysts for the decomposition of N2O (T 50 (This represents the temperature at which 50% of N2O decomposes).

[0039] Table 2 shows a comparison of the coating peeling rates of different catalysts;

[0040] Table 3 shows the maximum temperature rise capacity of different catalysts (the maximum temperature rise capacity is calculated as the maximum difference between the catalyst outlet temperature and the catalyst inlet temperature).

[0041] Table 4 shows the different reaction atmospheres for the catalyst water resistance test;

[0042] Table 5 shows a comparison of the test results of the catalysts' water resistance. Detailed Implementation

[0043] The present invention will be further described below with reference to embodiments. Example 1

[0044] like Figure 1 As shown, an N2O decomposition catalyst includes a straight-through support 3, a passively heated coating 1 (first layer material coating) coated on the straight-through support, and a highly water-resistant N2O decomposition coating 2 (second layer material coating) coated on the passively heated coating. The straight-through support 3 is a prior art component.

[0045] In the passive heating coating, the mass content of Pt is 0.5%, the mass content of Cu is 1%, and the balance is cobalt oxide and unavoidable impurities. In the high water-resistant N2O decomposition coating, the mass content of Rh is 2%, the mass content of Ba is 5%, and the balance is cobalt oxide and unavoidable impurities. The loading of the passive heating coating is 20% of the total loading of the N2O decomposition catalyst material coating, with the balance being the high water-resistant N2O decomposition coating. Figure 1 As shown, the passive heating coating covers 75% of the length of the through-type carrier, while the high water-resistant N2O decomposition coating covers 100% of the length of the through-type carrier. The high water-resistant N2O decomposition coating is directly applied to a section of the through-type carrier that is not coated with the passive heating coating. The particle size of the passive heating coating... D 90 The material particle size of the highly water-resistant N2O decomposition-resistant coating is 4.0 μm. D 90 It is 7.0 μm.

[0046] The N2O decomposition catalyst of this invention is applied to the aftertreatment of pollutants emitted from hydrogen engines. Its mechanism of action is described in [reference needed]. Figure 2 .

[0047] Hydrogen engine exhaust contains a large amount of water vapor (water content: 20-30%). The N2O decomposition catalyst of this invention employs a rationally layered coating of a passive heating coating and a highly water-resistant N2O decomposition coating, with the latter placed on top. This effectively solves the problem of severely reduced N2O decomposition activity caused by excessive H2O covering active sites during the N2O decomposition reaction, resulting in excellent low-temperature N2O decomposition performance and water resistance. Simultaneously, the H2 emitted from the exhaust gas releases heat through an oxidation reaction (2H2 + O2 → 2H2O) under the action of the passive heating coating, heating the highly water-resistant N2O decomposition coating (located on top of the passive heating coating). This raises the bed temperature of the N2O decomposition coating, reaching the N2O decomposition temperature earlier and further facilitating N2O decomposition.

[0048] The preparation method of N2O decomposition catalyst is as follows:

[0049] (1) Preparation of passively heated coating:

[0050] Diethoxydimethylsilane was added to acetone and dissolved completely to obtain an acetone solution of diethoxydimethylsilane. Cobalt oxide was added to the acetone solution of diethoxydimethylsilane, stirred evenly in a water bath at 50°C, allowed to stand for reaction, washed with deionized water, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain cobalt oxide A.

[0051] Fluoroacetylacetonate platinum and trifluoroacetylacetonate copper were uniformly mixed and fully dissolved in acetone to prepare a platinum-copper mixed solution. Cobalt oxide A was added to the platinum-copper mixed solution, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain a dry mixture. The dry mixture was calcined at 300°C for 1 hour under static air conditions, cooled to below 50°C, and then H2 was introduced and calcined at 400°C for 4 hours to obtain a passively heated coating powder. The powder was further prepared into a slurry, ground to the designed particle size, and coated onto a direct-flow carrier to form the first layer of material coating.

[0052] (2) Preparation of a coating with high resistance to water N2O decomposition:

[0053] Diethoxydimethylsilane was added to acetone and dissolved completely to obtain an acetone solution of diethoxydimethylsilane. Cobalt oxide was added to the acetone solution of diethoxydimethylsilane, stirred evenly in a water bath at 50°C, allowed to stand for reaction, washed with deionized water, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain cobalt oxide A.

[0054] A rhodium-barium dicarbonyl precursor and barium acetylacetone precursor were uniformly mixed and fully dissolved in acetone to prepare a rhodium-barium mixed solution. Cobalt oxide A was added to the rhodium-barium mixed solution, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain a dried mixture. The dried mixture was calcined at 300°C for 1 hour under static air conditions, cooled to below 50°C, and then O2 was introduced and calcined at 400°C for 4 hours to obtain a coating powder.

[0055] Diethoxydimethylsilane was added to acetone and dissolved completely to obtain an acetone solution of diethoxydimethylsilane. The above coating powder was added to the acetone solution of diethoxydimethylsilane, and after ultrasonic stirring, it was centrifuged. The solid part obtained after the treatment was ground to the designed particle size and then prepared into a slurry and coated on the first material coating to form the second material coating of the catalyst, namely the high water resistance to N2O decomposition coating.

[0056] (3) The straight-through carrier after the first and second material coatings are applied is dried at 90°C to prepare the N2O decomposition catalyst. Example 2

[0057] The structure of the N2O decomposition catalyst, the composition of the passive heating coating, the composition of the high water-resistant N2O decomposition coating, and the preparation method of this embodiment are the same as those in Example 1. The only difference is that the loading of the passive heating coating is 15% of the total loading of all coating materials of the N2O decomposition catalyst, and the remainder is the high water-resistant N2O decomposition coating. Example 3

[0058] The structure of the N2O decomposition catalyst, the composition of the passive heating coating, the composition of the high water-resistant N2O decomposition coating, and the preparation method of this embodiment are the same as those in Example 1. The only difference is that the loading of the passive heating coating is 25% of the total loading of all coating materials of the N2O decomposition catalyst, and the remainder is the high water-resistant N2O decomposition coating. Example 4

[0059] The N2O decomposition catalyst structure, passive heating coating composition, high water-resistant N2O decomposition coating composition, and preparation method of this embodiment are the same as those of Example 1. The only difference is that the coating length of the passive heating coating is 50% of the length of the through-type carrier. Example 5

[0060] The N2O decomposition catalyst structure, passive heating coating composition, high water-resistant N2O decomposition coating composition, and preparation method of this embodiment are the same as those of Example 1. The difference is that the coating length is 100% of the length of the through-type carrier, and the passive heating coating completely covers the through-type carrier. Example 6

[0061] A N2O decomposition catalyst has a passively heated coating containing 0.5% Pt and 1% Cu by mass, with the remainder being cobalt oxide and unavoidable impurities. A highly water-resistant N2O decomposition coating contains 2% Rh and 5% Ba by mass, with the remainder being cobalt oxide and unavoidable impurities. The passively heated coating is loaded at 20% of the total N2O decomposition catalyst material coating, with the remainder being the highly water-resistant N2O decomposition coating. The passively heated coating covers 75% of the length of the straight-through support, while the highly water-resistant N2O decomposition coating covers 100% of the length of the straight-through support. The highly water-resistant N2O decomposition coating is directly coated on a section of the straight-through support that is not coated with the passively heated coating. The particle size of the passively heated coating is specified. D 90 The material particle size of the highly water-resistant N2O decomposition-resistant coating is 4.0 μm. D 90 It is 7.0 μm.

[0062] The preparation method of N2O decomposition catalyst is as follows:

[0063] (1) Preparation of passively heated coating:

[0064] 3-Glycidyl etheroxypropyltrimethoxysilane was added to acetone and dissolved completely to obtain an acetone solution of 3-glycidyl etheroxypropyltrimethoxysilane; cobalt oxide was added to the acetone solution of 3-glycidyl etheroxypropyltrimethoxysilane, stirred evenly in a water bath at 70°C, allowed to stand for reaction, washed with deionized water, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain cobalt oxide A.

[0065] Cyclopentadienyltrimethylplatinum and copper acetylacetonate were uniformly mixed and fully dissolved in acetone to prepare a platinum-copper mixed solution. Cobalt oxide A was added to the platinum-copper mixed solution, and the mixture was centrifuged. The solid part obtained by centrifugation was freeze-dried to obtain a dry mixture. The dry mixture was calcined at 350°C for 1 hour under static air conditions, cooled to below 50°C, and then H2 was introduced and calcined at 400°C for 2 hours to obtain a passively heated coating powder. The powder was further prepared into a slurry, ground to the designed particle size, and coated onto a straight-through carrier to form the first layer of material coating.

[0066] (2) Preparation of a coating with high resistance to water N2O decomposition:

[0067] 3-Glycidyl etheroxypropyltrimethoxysilane was added to acetone and dissolved completely to obtain an acetone solution of 3-glycidyl etheroxypropyltrimethoxysilane; cobalt oxide was added to the acetone solution of 3-glycidyl etheroxypropyltrimethoxysilane, stirred evenly in a water bath at 50°C, allowed to stand for reaction, washed with deionized water, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain cobalt oxide A.

[0068] A rhodium-barium mixed solution was prepared by uniformly mixing acetylacetone, triphenylphosphine, rhodium carbonyl, and barium acetylacetone precursor and dissolving them in acetone. Cobalt oxide A was added to the rhodium-barium mixed solution, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain a dried mixture. The dried mixture was calcined at 300°C for 1 hour under static air conditions, cooled to below 50°C, and then calcined at 400°C for 4 hours after introducing O2 to obtain a coating powder.

[0069] 3-Glycidyl etheroxypropyltrimethoxysilane was added to acetone and dissolved completely to obtain an acetone solution of 3-glycidyl etheroxypropyltrimethoxysilane. The above coating powder was added to the acetone solution of 3-glycidyl etheroxypropyltrimethoxysilane, ultrasonically stirred and centrifuged. The solid part obtained after the treatment was ground to the designed particle size and then prepared into a slurry and coated on the first material coating to form the second material coating of the catalyst.

[0070] (3) The straight-through carrier after the first and second material coatings are applied is dried at 70°C to prepare the N2O decomposition catalyst. Example 7

[0071] The structure of the N2O decomposition catalyst, the composition of the passive heating coating, and the composition of the highly water-resistant N2O decomposition coating in this embodiment are the same as in Example 6. The preparation method of the N2O decomposition catalyst is as follows:

[0072] (1) Preparation of passively heated coating:

[0073] 3-Glycidyl etheroxypropyltrimethoxysilane was added to acetone and dissolved completely to obtain an acetone solution of 3-glycidyl etheroxypropyltrimethoxysilane; cobalt oxide was added to the acetone solution of 3-glycidyl etheroxypropyltrimethoxysilane, stirred evenly in a water bath at 50°C, allowed to stand for reaction, washed with deionized water, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain cobalt oxide A.

[0074] Cyclopentadienyltrimethylplatinum and phenylacetylcopper were uniformly mixed and dissolved in acetone to prepare a platinum-copper mixed solution. Cobalt oxide A was added to the platinum-copper mixed solution, and the mixture was centrifuged. The solid part obtained by centrifugation was freeze-dried to obtain a dried mixture. The dried mixture was calcined at 300°C for 2 hours under static air conditions, cooled to below 50°C, and then H2 was introduced. The mixture was calcined at 500°C for 2 hours to obtain a passively heated coating powder. The powder was further prepared into a slurry, ground to the designed particle size, and coated onto a direct-flow carrier to form the first layer of material coating.

[0075] (2) Preparation of a coating with high resistance to water N2O decomposition:

[0076] Polydimethylsiloxane was added to acetone and dissolved completely to obtain an acetone solution of polydimethylsiloxane; cobalt oxide was added to the acetone solution of polydimethylsiloxane, stirred evenly in a water bath at 70°C, allowed to stand for reaction, washed with deionized water, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain cobalt oxide A.

[0077] (1,5-cyclooctadiene) rhodium chloride dimer and barium acetylacetonate precursor were uniformly mixed and fully dissolved in acetone to prepare a rhodium-barium mixed solution. Cobalt oxide A was added to the rhodium-barium mixed solution, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain a dried mixture. The dried mixture was calcined at 300°C for 1 hour under static air, cooled to below 50°C, and then calcined at 400°C for 2 hours after passing O2 through it to obtain a coating powder.

[0078] Polydimethylsiloxane was added to acetone and dissolved completely to obtain an acetone solution of polydimethylsiloxane. The above coating powder was added to the acetone solution of polydimethylsiloxane, ultrasonically stirred and centrifuged. The solid part obtained after the treatment was ground to the designed particle size and then prepared into a slurry and coated on the first material coating to form the second material coating of the catalyst.

[0079] (3) The straight-through carrier after the first and second material coatings are applied is dried at 100°C to prepare the N2O decomposition catalyst. Example 8

[0080] The structure of the N2O decomposition catalyst, the composition of the passive heating coating, and the composition of the highly water-resistant N2O decomposition coating in this embodiment are the same as in Example 6. The preparation method of the N2O decomposition catalyst is as follows:

[0081] (1) Preparation of passively heated coating:

[0082] Trimethylsilylacetylene was added to acetone and dissolved completely to obtain an acetone solution of trimethylsilylacetylene. Cobalt oxide was added to the acetone solution of trimethylsilylacetylene, stirred evenly in a water bath at 50°C, allowed to stand for reaction, washed with deionized water, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain cobalt oxide A.

[0083] Dipentenylplatinum and bis(hexafluoroacetylacetone)copper were uniformly mixed and dissolved in acetone to prepare a platinum-copper mixed solution. Cobalt oxide A was added to the platinum-copper mixed solution, and the mixture was centrifuged. The solid part obtained by centrifugation was freeze-dried to obtain a dry mixture. The dry mixture was calcined at 300°C for 1 hour under static air conditions, cooled to below 50°C, and then H2 was introduced and calcined at 400°C for 4 hours to obtain a passively heated coating powder. The powder was further prepared into a slurry, ground to the designed particle size, and coated onto a direct-flow carrier to form the first layer of material coating.

[0084] (2) Preparation of a coating with high resistance to water N2O decomposition:

[0085] Trimethylsilylacetylene was added to acetone and dissolved completely to obtain an acetone solution of trimethylsilylacetylene. Cobalt oxide was added to the acetone solution of trimethylsilylacetylene, stirred evenly in a water bath at 70°C, allowed to stand for reaction, washed with deionized water, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain cobalt oxide A.

[0086] Rhodium acetylacetone and barium acetylacetone precursors were uniformly mixed and fully dissolved in acetone to prepare a rhodium-barium mixed solution. Cobalt oxide A was added to the rhodium-barium mixed solution, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain a dried mixture. The dried mixture was calcined at 350°C for 2 hours under static air conditions, cooled to below 50°C, and then O2 was introduced and calcined at 500°C for 4 hours to obtain a coating powder.

[0087] Polydimethylsiloxane was added to acetone and dissolved completely to obtain an acetone solution of polydimethylsiloxane. The above coating powder was added to the acetone solution of polydimethylsiloxane, ultrasonically stirred and centrifuged. The solid part obtained after the treatment was ground to the designed particle size and then prepared into a slurry and coated on the first material coating to form the second material coating of the catalyst.

[0088] (3) The straight-through carrier after the first and second material coatings are applied is dried at 100°C to prepare the N2O decomposition catalyst. Example 9

[0089] The structure of the N2O decomposition catalyst, the composition of the passive heating coating, and the composition of the high water-resistant N2O decomposition coating in this embodiment are the same as those in Example 6. The difference lies in the preparation method of the N2O decomposition catalyst. In step (1), the organosilicon compound used is vinyltriethoxysilane, the platinum precursor is dipentenylplatinum, and the copper precursor is bis(hexafluoroacetylacetone)copper; in step (2), the organosilicon compound used is vinyltriethoxysilane, the rhodium precursor is rhodium acetylacetone, and the alkali metal / alkaline earth metal precursor is strontium acetylacetone. Example 10

[0090] A N2O decomposition catalyst has a passively heated coating containing 0.5% Pt and 1% Cu by mass, with the remainder being cobalt oxide and unavoidable impurities. A highly water-resistant N2O decomposition coating contains 2% Rh and 5% Ba by mass, with the remainder being cobalt oxide and unavoidable impurities. The passively heated coating is loaded at 20% of the total N2O decomposition catalyst material coating, with the remainder being the highly water-resistant N2O decomposition coating. The passively heated coating covers 75% of the length of the straight-through support, while the highly water-resistant N2O decomposition coating covers 100% of the length of the straight-through support. The highly water-resistant N2O decomposition coating is directly coated on a section of the straight-through support that is not coated with the passively heated coating. The particle size of the passively heated coating is specified. D 90 The material particle size of the 3.0μm high water-resistant N2O decomposition coating D 90 8.0 μm.

[0091] The preparation method of the N2O decomposition catalyst is the same as in Example 1. The difference is that in the preparation method of the N2O decomposition catalyst, in step (1), the dried mixture is calcined in static air at 350°C for 2 hours, then cooled to below 50°C, and then H2 is introduced and calcined at 500°C for 2 hours to obtain passively heated coating powder; in step (2), the dried mixture is calcined in static air at 350°C for 2 hours, then cooled to below 50°C, and then O2 is introduced and calcined at 500°C for 2 hours to obtain coating powder; in step (3), the drying temperature is 70°C. Example 11

[0092] The structure of the N2O decomposition catalyst, the composition of the passive heating coating, the composition of the high water-resistant N2O decomposition coating, and the preparation method of the N2O decomposition catalyst in this embodiment are all the same as in Example 10. The difference lies in the particle size of the passive heating coating. D 90 The material particle size of the 5.0μm high water-resistant N2O decomposition coating D 90 6.0 μm.

[0093] The preparation method of the N2O decomposition catalyst is the same as in Example 1. The difference is that in the preparation method of the N2O decomposition catalyst, the drying temperature in step (3) is 100℃. Example 12

[0094] A N2O decomposition catalyst has a passively heated coating containing 0.1% Pt and 0.2% Cu by mass, with the remainder being cobalt oxide and unavoidable impurities. A highly water-resistant N2O decomposition coating contains 4% Rh and 10% Ba by mass, with the remainder being cobalt oxide and unavoidable impurities. The passively heated coating is loaded at 20% of the total N2O decomposition catalyst material coating, with the remainder being the highly water-resistant N2O decomposition coating. The passively heated coating covers 50% of the length of the through-type support, while the highly water-resistant N2O decomposition coating covers 100% of the length of the through-type support. The highly water-resistant N2O decomposition coating is directly coated on a section of the through-type support that is not coated with the passively heated coating. The particle size of the passively heated coating is specified. D 90 The material particle size of the highly water-resistant N2O decomposition-resistant coating is 4.0 μm. D 90 7.0 μm.

[0095] The preparation method of the N2O decomposition catalyst is the same as in Example 1. Example 13

[0096] A N₂O decomposition catalyst has a passively heated coating comprising 1% Pt and 2% Cu by mass, with the balance being cobalt oxide and unavoidable impurities. A highly water-resistant N₂O decomposition coating comprises 0.5% Rh and 1% Ba by mass, with the balance being cobalt oxide and unavoidable impurities. The passively heated coating is loaded at 20% of the total N₂O decomposition catalyst material coating, with the balance being the highly water-resistant N₂O decomposition coating. The length of both the passively heated and highly water-resistant N₂O decomposition coatings covers 100% of the length of the through-type support. The particle size of the passively heated coating is specified. D 90The material particle size of the highly water-resistant N2O decomposition-resistant coating is 4.0 μm. D 90 7.0 μm.

[0097] The preparation method of the N2O decomposition catalyst is the same as in Example 1. Example 14

[0098] A N₂O decomposition catalyst has a passively heated coating containing 1% Pt and 2% Cu by mass, with the balance being cobalt oxide and unavoidable impurities. A highly water-resistant N₂O decomposition coating contains 4% Rh and 10% Ba by mass, with the balance being cobalt oxide and unavoidable impurities. The passively heated coating is loaded at 20% of the total N₂O decomposition catalyst material coating, with the balance being the highly water-resistant N₂O decomposition coating. The length of both the passively heated and highly water-resistant N₂O decomposition coatings covers 100% of the length of the through-type support. The particle size of the passively heated coating is specified. D 90 The material particle size of the highly water-resistant N2O decomposition-resistant coating is 4.0 μm. D 90 7.0 μm.

[0099] The preparation method of the N2O decomposition catalyst is the same as in Example 1. Comparative Example 1

[0100] The method for preparing N2O decomposition catalyst is as follows:

[0101] (1) Preparation of passively heated powder:

[0102] Diethoxydimethylsilane was added to acetone and dissolved completely to obtain an acetone solution of diethoxydimethylsilane; cobalt oxide was added to the acetone solution of diethoxydimethylsilane, stirred evenly in a water bath at 50°C, allowed to stand for reaction, washed with deionized water, centrifuged to obtain the solid component, and freeze-dried to obtain cobalt oxide A.

[0103] Platinum fluoroacetylacetonate and copper trifluoroacetylacetonate were uniformly mixed and dissolved in acetone to prepare a platinum-copper mixed solution. Cobalt oxide A was added to the platinum-copper mixed solution, centrifuged, and freeze-dried to obtain a dried mixture. The dried mixture was calcined at 300°C for 1 hour under static air conditions, cooled to below 50°C, and then calcined at 400°C for 4 hours after H2 was introduced to obtain a passively heated powder. The powder contained 0.5% Pt and 1% Cu by mass, with the remainder being cobalt oxide and unavoidable impurities.

[0104] (2) Preparation of N2O decomposition powder:

[0105] Diethoxydimethylsilane was added to acetone and dissolved completely to obtain an acetone solution of diethoxydimethylsilane; cobalt oxide was added to the acetone solution of diethoxydimethylsilane, stirred evenly in a water bath at 50°C, allowed to stand for reaction, washed with deionized water, centrifuged to obtain the solid component, and freeze-dried to obtain cobalt oxide A.

[0106] A rhodium-barium dicarbonyl precursor and barium acetylacetone precursor were uniformly mixed and dissolved in acetone to prepare a rhodium-barium mixed solution. Cobalt oxide A was added to the rhodium-barium mixed solution, and the solid component was obtained by centrifugation and freeze-drying to obtain a dry mixture. The dry mixture was calcined at 300°C for 1 hour under static air, cooled to below 50°C, and then calcined at 400°C for 2-4 hours after passing O2 through it to obtain N2O decomposition powder. The powder contained 2% Rh and 5% Ba by mass, with the remainder being cobalt oxide.

[0107] Diethoxydimethylsilane was added to acetone and dissolved completely to obtain an organosilicon compound solution. The passively heated powder obtained in step (1) and the N2O decomposition powder obtained in step (2) were added to the organosilicon compound solution. The amount of passively heated powder added was 20% of the loading of the N2O decomposition catalyst material coating, and the remainder was N2O decomposition powder. Then, the mixture was ultrasonically stirred, filtered to obtain the solid component, prepared into a slurry, and ground to a suitable particle size of 7.0 μm. The slurry was then coated onto a straight-through support and dried at 90°C to obtain the N2O decomposition catalyst. Comparative Example 2

[0108] The method for preparing N2O decomposition catalyst is as follows:

[0109] Diethoxydimethylsilane was added to acetone and dissolved completely to obtain an acetone solution of diethoxydimethylsilane. Cobalt oxide was added to the acetone solution of diethoxydimethylsilane, stirred evenly in a water bath at 50°C, allowed to stand for reaction, washed with deionized water, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain cobalt oxide A.

[0110] A rhodium-barium dicarbonyl precursor and barium acetylacetone precursor were uniformly mixed and fully dissolved in acetone to prepare a rhodium-barium mixed solution. Cobalt oxide A was added to the rhodium-barium mixed solution and centrifuged. The solid part obtained by centrifugation was freeze-dried to obtain a dried mixture. The dried mixture was calcined at 300°C for 1 hour under static air conditions, cooled to below 50°C, and then calcined at 400°C for 4 hours after passing O2 through it to obtain a coating powder.

[0111] Diethoxydimethylsilane was added to acetone and fully dissolved to obtain an acetone solution of diethoxydimethylsilane. The coating powder was then added to the diethoxydimethylsilane acetone solution, ultrasonically stirred, and centrifuged. The resulting solid fraction was prepared into a slurry and ground to the designed particle size to obtain the N2O decomposition coating material. In this coating material, the mass content of Rh is 2%, the mass content of Ba is 5%, and the balance is cobalt oxide and unavoidable impurities. The particle size of the N2O decomposition coating material is... D 90 It is 7.0 μm.

[0112] The N2O decomposition coating material was applied to a straight-through support and dried at 90°C to prepare the N2O decomposition catalyst. Comparative Example 3

[0113] The passive heating coating accounts for 30% of the total coating load of the N2O decomposition catalyst, with the remainder being a highly water-resistant N2O decomposition coating. The particle size of the passive heating coating... D 90 The material particle size of the highly water-resistant N2O decomposition-resistant coating is 4.0 μm. D 90 The thickness is 7.0 μm. The passive heating coating has a coating length of 75% of the length of the through-type carrier, while the high water-resistant N2O decomposition coating has a coating length of 100% of the length of the through-type carrier.

[0114] The method for preparing N2O decomposition catalyst is as follows:

[0115] (1) Preparation of passively heated coating:

[0116] Diethoxydimethylsilane was added to acetone and dissolved completely to obtain an acetone solution of diethoxydimethylsilane. Cobalt oxide was added to the acetone solution of diethoxydimethylsilane, stirred evenly in a water bath at 50°C, allowed to stand for reaction, washed with deionized water, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain cobalt oxide A.

[0117] Platinum fluoroacetylacetonate and copper trifluoroacetylacetonate were uniformly mixed and thoroughly dissolved in acetone to prepare a platinum-copper mixed solution. Cobalt oxide A was added to the platinum-copper mixed solution, and the mixture was centrifuged. The solid fraction obtained by centrifugation was freeze-dried to obtain a dried mixture. The dried mixture was calcined at 300°C for 1 hour under static air, cooled to below 50°C, and then calcined at 400°C for 4 hours after H2 was introduced to obtain a passive heating coating powder. The powder was further prepared into a slurry, ground to the designed particle size, and coated onto a through-type carrier to form the first material coating. In the passive heating coating, the mass content of Pt was 0.5%, the mass content of Cu was 1%, and the balance was cobalt oxide and unavoidable impurities.

[0118] (2) Preparation of a coating with high resistance to water N2O decomposition:

[0119] Diethoxydimethylsilane was added to acetone and dissolved completely to obtain an acetone solution of diethoxydimethylsilane. Cobalt oxide was added to the acetone solution of diethoxydimethylsilane, stirred evenly in a water bath at 50°C, allowed to stand for reaction, washed with deionized water, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain cobalt oxide A.

[0120] A rhodium-barium dicarbonyl precursor and barium acetylacetone precursor were uniformly mixed and fully dissolved in acetone to prepare a rhodium-barium mixed solution. Cobalt oxide A was added to the rhodium-barium mixed solution, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain a dried mixture. The dried mixture was calcined at 300°C for 1 hour under static air conditions, cooled to below 50°C, and then O2 was introduced and calcined at 400°C for 4 hours to obtain a coating powder.

[0121] Diethoxydimethylsilane was added to acetone and dissolved completely to obtain an acetone solution of diethoxydimethylsilane. The above coating powder was added to the acetone solution of diethoxydimethylsilane, ultrasonically stirred, and then centrifuged. The solid part obtained after the treatment was ground to the designed particle size and then prepared into a slurry and coated on the first material coating to form the second material coating of the catalyst, namely the high water-resistant N2O decomposition coating. The mass content of Rh in this coating is 2%, the mass content of Ba is 5%, and the balance is cobalt oxide and unavoidable impurities.

[0122] (3) The straight-through carrier after the first and second material coatings are applied is dried at 90°C to prepare the N2O decomposition catalyst. Comparative Example 4

[0123] The N2O decomposition catalyst was prepared using the same method as Comparative Example 3, except that the loading of the passive heating coating was 10% of the total coating loading of the entire N2O decomposition catalyst, with the remainder being a highly water-resistant N2O decomposition coating; the particle size of the passive heating coating was also different. D 90 The material particle size of the highly water-resistant N2O decomposition-resistant coating is 6.0 μm. D 90 It is 9.0 μm. Comparative Example 5

[0124] The N2O decomposition catalyst was prepared using the same method as Comparative Example 3, except that the length of the passive heating coating was 45% of the length of the through-type support; the particle size of the passive heating coating was also different. D 90 The material particle size of the 2.0μm high water-resistant N2O decomposition coating D90 It is 5.0 μm. Comparative Example 6

[0125] The N2O decomposition catalyst was prepared using the same method as Comparative Example 3, except that the passive heating coating was loaded at 20% of the total coating loading of the entire N2O decomposition catalyst, with the remainder being a highly water-resistant N2O decomposition coating. The particle size of the passive heating coating was... D 90 The material particle size of the highly water-resistant N2O decomposition-resistant coating is 6.0 μm. D 90 It is 5.0 μm. Comparative Example 7

[0126] The N2O decomposition catalyst was prepared using the same method as Comparative Example 3, except that the loading of the passively heated coating was 20% of the total coating loading of the entire N2O decomposition catalyst. The particle size of the passively heated coating was... D 90 The material particle size of the 2.0μm high water-resistant N2O decomposition coating D 90 It is 9.0 μm. Comparative Example 8

[0127] The passive heating coating accounts for 20% of the total coating material load of the entire N2O decomposition catalyst, with the remainder being a high-water-resistant N2O decomposition coating. The passive heating coating is applied for 75% of the length of the straight-through support, while the high-water-resistant N2O decomposition coating is applied for 100% of the length of the straight-through support. The particle size of the first layer of coating... D 90 The material particle size of the highly water-resistant N2O decomposition-resistant coating is 4.0 μm. D 90 It is 7.0 μm.

[0128] The method for preparing N2O decomposition catalyst is as follows:

[0129] (1) Preparation of passively heated coating:

[0130] Diethoxydimethylsilane was added to acetone and dissolved completely to obtain an acetone solution of diethoxydimethylsilane; cobalt oxide was added to the acetone solution of diethoxydimethylsilane, stirred evenly in a water bath at 50°C, allowed to stand for reaction, washed with deionized water, centrifuged, and freeze-dried to obtain cobalt oxide A.

[0131] Copper trifluoroacetylacetonate was uniformly dissolved in acetone to obtain a copper solution. Cobalt oxide A was added to the copper solution, and the mixture was centrifuged. The separated solid material was freeze-dried to obtain a dried mixture. The dried mixture was calcined at 300°C for 1 hour under static air, cooled to below 50°C, and then calcined at 400°C for 4 hours after H2 was introduced to obtain a passive heating coating powder. This powder was further prepared into a slurry, ground to a suitable particle size, and coated onto a straight-through support as the first layer of the catalyst coating. In the passive heating coating, the mass content of Cu was 1%, with the balance being cobalt oxide and unavoidable impurities.

[0132] (2) Preparation of a coating with high resistance to water N2O decomposition:

[0133] Diethoxydimethylsilane was added to acetone and dissolved completely to obtain an acetone solution of diethoxydimethylsilane. Cobalt oxide was added to the acetone solution of diethoxydimethylsilane, stirred evenly in a water bath at 50°C, allowed to stand for reaction, washed with deionized water, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain cobalt oxide A.

[0134] A rhodium-barium dicarbonyl precursor and barium acetylacetone precursor were uniformly mixed and fully dissolved in acetone to prepare a rhodium-barium mixed solution. Cobalt oxide A was added to the rhodium-barium mixed solution, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain a dried mixture. The dried mixture was calcined at 300°C for 1 hour under static air conditions, cooled to below 50°C, and then O2 was introduced and calcined at 400°C for 4 hours to obtain a coating powder.

[0135] Diethoxydimethylsilane was added to acetone and fully dissolved to obtain an acetone solution of diethoxydimethylsilane. The coating powder was then added to the acetone solution of diethoxydimethylsilane, ultrasonically stirred, and centrifuged. The resulting solid fraction was ground to the designed particle size and then prepared into a slurry. This slurry was then coated onto the first material coating to form the second material coating of the catalyst, namely the highly water-resistant N2O decomposition coating. In the highly water-resistant N2O decomposition coating, the mass content of Rh was 2%, the mass content of Ba was 5%, and the balance was cobalt oxide and unavoidable impurities.

[0136] (3) The straight-through carrier after the first and second material coatings are applied is dried at 90°C to prepare the N2O decomposition catalyst. Comparative Example 9

[0137] The passive heating coating accounts for 20% of the total coating material load of the entire N2O decomposition catalyst, with the remainder being a highly water-resistant N2O decomposition coating. The passive heating coating covers 75% of the length of the through-type carrier, and the material particle size... D 90The thickness is 4.0 μm. The high water-resistant N2O decomposition-resistant coating covers 100% of the length of the through-type carrier, and the material particle size is... D 90 It is 7.0 μm.

[0138] The method for preparing N2O decomposition catalyst is as follows:

[0139] (1) Preparation of passively heated coating:

[0140] Diethoxydimethylsilane was added to acetone and dissolved completely to obtain an acetone solution of diethoxydimethylsilane. Cobalt oxide was added to the acetone solution of diethoxydimethylsilane, stirred evenly in a water bath at 50°C, allowed to stand for reaction, washed with deionized water, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain cobalt oxide A.

[0141] Platinum fluoroacetylacetonate and copper trifluoroacetylacetonate were uniformly mixed and dissolved in acetone to obtain a platinum-copper mixed solution. Cobalt oxide A was added to the platinum-copper mixed solution, and the mixture was centrifuged. The solid part obtained by centrifugation was freeze-dried to obtain a dried mixture. The dried mixture was calcined at 300°C for 1 hour under static air conditions, cooled to below 50°C, and then calcined at 400°C for 4 hours after H2 was introduced to obtain a passively heated coating powder. The powder was further prepared into a slurry, ground to the designed particle size, and coated onto a straight-through carrier to form the first material coating. The coating contained 0.5% Pt and 1% Cu by mass, with the remainder being cobalt oxide and unavoidable impurities.

[0142] (2) Preparation of a coating with high resistance to water N2O decomposition:

[0143] Diethoxydimethylsilane was added to acetone and dissolved completely to obtain an acetone solution of diethoxydimethylsilane; cobalt oxide was added to the acetone solution of diethoxydimethylsilane, stirred evenly in a water bath at 50°C, allowed to stand for reaction, washed with deionized water, centrifuged, and freeze-dried to obtain cobalt oxide A.

[0144] Barium acetylacetonate precursor was uniformly mixed and fully dissolved in acetone to prepare a barium mixed solution. Cobalt oxide A was added to the barium mixed solution, centrifuged, and freeze-dried to obtain a dry mixture. The dry mixture was calcined at 300°C for 1 hour under static air conditions, cooled to below 50°C, and then calcined at 400°C for 4 hours after passing O2 through it to obtain a coating powder. Diethoxydimethylsilane was added to acetone and fully dissolved to obtain an organosilicon compound solution. The above coating powder was added to the organosilicon compound solution, ultrasonically stirred, filtered, and the solid part after filtration was ground to the designed particle size to prepare a slurry. This slurry was then coated onto the first material coating to form the second material coating of the catalyst. In this coating, the mass content of Ba was 5%, and the balance was cobalt oxide and unavoidable impurities.

[0145] (3) The straight-through carrier after the first and second material coatings are applied is dried at 70°C to prepare the N2O decomposition catalyst. Comparative Example 10

[0146] The N2O decomposition catalyst was prepared using the same method as Comparative Example 3, except that in the passive heating coating, the mass content of Pt was 0.05%, the mass content of Cu was 1%, and the balance was cobalt oxide and unavoidable impurities; in the high water-resistant N2O decomposition coating, the mass content of Rh was 4.5%, the mass content of Ba was 5%, and the balance was cobalt oxide and unavoidable impurities. The loading of the passive heating coating was 20% of the total coating loading of the entire N2O decomposition catalyst, with the balance being the high water-resistant N2O decomposition coating. The particle size of the passive heating coating was... D 90 The material particle size of the highly water-resistant N2O decomposition-resistant coating is 4.0 μm. D 90 It is 7.0 μm. Comparative Example 11

[0147] The N2O decomposition catalyst was prepared using the same method as Comparative Example 10, except that in the passively heated coating, the mass content of Pt was 1.5%, the mass content of Cu was 1%, and the balance was cobalt oxide and unavoidable impurities; in the high water-resistant N2O decomposition coating, the mass content of Rh was 0.4%, the mass content of Ba was 5%, and the balance was cobalt oxide and unavoidable impurities. Comparative Example 12

[0148] The passive heating coating comprises 20% of the total coating material loading of the entire N2O decomposition catalyst, with the remainder being a highly water-resistant N2O decomposition coating. The passive heating coating covers 75% of the length of the through-type carrier, and the material particle size... D 90 The thickness is 4.0 μm. The high water-resistant N2O decomposition-resistant coating covers 100% of the length of the through-type carrier, and the material particle size is... D 90 It is 7.0 μm.

[0149] The preparation method for N2O decomposition catalyst is as follows:

[0150] (1) Preparation of passively heated coating:

[0151] Diethoxydimethylsilane was added to acetone and dissolved completely to obtain an acetone solution of diethoxydimethylsilane; cobalt oxide was added to the acetone solution of diethoxydimethylsilane, stirred evenly in a water bath at 50°C, allowed to stand for reaction, washed with deionized water, centrifuged to obtain a solid substance, and freeze-dried to obtain cobalt oxide A.

[0152] Platinum fluoroacetylacetonate and copper trifluoroacetylacetonate were uniformly mixed and thoroughly dissolved in acetone to prepare a platinum-copper mixed solution. Cobalt oxide A was added to the platinum-copper mixed solution, and the mixture was centrifuged to obtain a solid substance. The solid substance was freeze-dried to obtain a dried mixture. The dried mixture was calcined at 300°C for 1 hour under static air conditions and then cooled to below 50°C to obtain a passively heated coating powder. The powder was further prepared into a slurry, ground to the designed particle size, and coated onto a straight-through support as the first layer of the catalyst material. In the first heated coating, the mass content of Pt was 0.5%, the mass content of Cu was 1%, and the balance was cobalt oxide and unavoidable impurities.

[0153] (2) Preparation of a coating with high resistance to water N2O decomposition:

[0154] Diethoxydimethylsilane was added to acetone and dissolved completely to obtain an acetone solution of diethoxydimethylsilane; cobalt oxide was added to the acetone solution of diethoxydimethylsilane, stirred evenly in a water bath at 50°C, allowed to stand for reaction, washed with deionized water, centrifuged to obtain a solid substance, and freeze-dried to obtain cobalt oxide A.

[0155] A rhodium-barium dicarbonyl precursor and barium acetylacetone were uniformly mixed and dissolved in acetone to prepare a rhodium-barium mixed solution. Cobalt oxide A was added to the rhodium-barium mixed solution to obtain a solid substance. The solid substance was freeze-dried to obtain a dried mixture. The dried mixture was calcined at 300°C for 1 hour under static air, cooled to below 50°C, and then calcined at 400°C for 2-4 hours after introducing O2 to obtain a coating powder. Diethoxydimethylsilane was added to acetone and dissolved completely to prepare an organosilicon compound solution. The above coating powder was added to the organosilicon compound solution, ultrasonically mixed, and centrifuged to obtain a solid substance. The solid substance was freeze-dried, ground to the designed particle size, and prepared into a slurry for coating the first material coating, which is the second material coating of the catalyst. In the second material coating, the mass content of Rh is 2%, the mass content of Ba is 5%, and the balance is cobalt oxide and unavoidable impurities.

[0156] (3) The coated monolithic catalyst was dried at 70°C to prepare the N2O decomposition catalyst. Comparative Example 13

[0157] The passively heated coating load is 20% of the total coating material load of the entire N2O decomposition catalyst, with the remainder being a highly water-resistant N2O decomposition coating. The first layer of coating covers 75% of the length of the through-type carrier, and the material particle size... D 90 The thickness is 4.0 μm. The high water-resistant N2O decomposition-resistant coating covers 100% of the length of the through-type carrier, and the material particle size is... D90 It is 7.0 μm.

[0158] The preparation method for N2O decomposition catalyst is as follows:

[0159] (1) Preparation of passively heated coating:

[0160] Diethoxydimethylsilane was added to acetone and dissolved completely to obtain an acetone solution of diethoxydimethylsilane; cobalt oxide was added to the acetone solution of diethoxydimethylsilane, stirred evenly in a water bath at 50°C, allowed to stand for reaction, washed with deionized water, centrifuged to obtain a solid substance, and freeze-dried to obtain cobalt oxide A.

[0161] Platinum fluoroacetylacetonate and copper trifluoroacetylacetonate were uniformly mixed and thoroughly dissolved in acetone to prepare a platinum-copper mixed solution. Cobalt oxide A was added to the platinum-copper mixed solution, and the mixture was centrifuged to obtain a solid substance. The solid substance was freeze-dried to obtain a dried mixture. The dried mixture was calcined at 300°C for 1 hour under static air, cooled to below 50°C, and then calcined at 400°C for 2-4 hours after H2 was introduced to obtain a passively heated coating powder. The powder was further prepared into a slurry, ground to the designed particle size, and coated onto a straight-through support as the first layer of the catalyst material. In this coating, the mass content of Pt was 0.5%, the mass content of Cu was 1%, and the balance was cobalt oxide and unavoidable impurities.

[0162] (2) Preparation of a coating with high resistance to water N2O decomposition:

[0163] Diethoxydimethylsilane was added to acetone and dissolved completely to obtain an acetone solution of diethoxydimethylsilane; cobalt oxide was added to the acetone solution of diethoxydimethylsilane, stirred evenly in a water bath at 50°C, allowed to stand for reaction, washed with deionized water, centrifuged to obtain a solid substance, and freeze-dried to obtain cobalt oxide A.

[0164] A rhodium-barium dicarbonyl precursor and barium acetylacetone were uniformly mixed and fully dissolved in acetone to prepare a rhodium-barium mixed solution. Cobalt oxide A was added to the rhodium-barium mixed solution, centrifuged, and freeze-dried to obtain a dried mixture. The dried mixture was calcined at 300°C for 1 hour under static air conditions and then cooled to below 50°C to obtain a coating powder. Diethoxydimethylsilane was added to acetone and fully dissolved to prepare an organosilicon compound solution. The above coating powder was added to the organosilicon compound solution, ultrasonically stirred, and then centrifuged to obtain a solid material. The solid material was ground to the designed particle size and prepared into a slurry, which was then coated onto the first material coating to form the second material coating of the catalyst. In this coating, the mass content of Rh was 2%, the mass content of Ba was 5%, and the balance was cobalt oxide and unavoidable impurities.

[0165] (3) The coated monolithic catalyst was dried at 70°C to prepare the N2O decomposition catalyst. Comparative Example 14

[0166] The passive heating coating accounts for 20% of the total coating material load of the entire N2O decomposition catalyst, with the remainder being a highly water-resistant N2O decomposition coating. The passive heating coating covers 75% of the length of the through-type carrier, and the material particle size... D 90 The thickness is 4.0 μm. The high water-resistant N2O decomposition-resistant coating covers 100% of the length of the through-type carrier, and the material particle size is... D 90 It is 7.0 μm.

[0167] The preparation method for N2O decomposition catalyst is as follows:

[0168] (1) Preparation of passively heated coating:

[0169] Diethoxydimethylsilane was added to acetone and dissolved completely to obtain an acetone solution of diethoxydimethylsilane; cobalt oxide was added to the acetone solution of diethoxydimethylsilane, stirred evenly in a water bath at 50°C, allowed to stand for reaction, washed with deionized water, centrifuged to obtain a solid substance, and freeze-dried to obtain cobalt oxide A.

[0170] Platinum fluoroacetylacetonate and copper trifluoroacetylacetonate were uniformly mixed and thoroughly dissolved in acetone to prepare a platinum-copper mixed solution. Cobalt oxide A was added to the platinum-copper mixed solution, and the mixture was centrifuged to obtain a solid substance. The solid substance was freeze-dried to obtain a dried mixture. The dried mixture was calcined at 300°C for 1 hour under static air, cooled to below 50°C, and then calcined at 400°C for 4 hours after H2 was introduced to obtain a heated coating powder. The powder was further prepared into a slurry, ground to the designed particle size, and coated onto a straight-through support as the first layer of the catalyst material. In this coating, the mass content of Pt was 0.5%, the mass content of Cu was 1%, and the balance was cobalt oxide and unavoidable impurities.

[0171] (2) Preparation of a coating with high resistance to water N2O decomposition:

[0172] Diethoxydimethylsilane was added to acetone and dissolved completely to obtain an acetone solution of diethoxydimethylsilane; cobalt oxide was added to the acetone solution of diethoxydimethylsilane, stirred evenly in a water bath at 50°C, allowed to stand for reaction, washed with deionized water, centrifuged to obtain a solid substance, and freeze-dried to obtain cobalt oxide A.

[0173] A rhodium-barium dicarbonyl precursor and barium acetylacetone were uniformly mixed and dissolved in acetone to prepare a rhodium-barium mixed solution. Cobalt oxide A was added to the rhodium-barium mixed solution, and the mixture was centrifuged to obtain a solid substance. The solid substance was freeze-dried to obtain a dry mixture. The dry mixture was calcined at 300°C for 1 hour under static air, cooled to below 50°C, and then calcined at 400°C for 4 hours after introducing O2 to obtain a coating powder. The coating powder was prepared into a slurry, ground to the designed particle size, and coated onto the first material coating to form the second material coating of the catalyst. In this coating, the mass content of Rh was 2%, the mass content of Ba was 5%, and the balance was cobalt oxide and unavoidable impurities.

[0174] (3) The coated monolithic catalyst was dried at 70°C to prepare the N2O decomposition catalyst. Comparative Example 15

[0175] The passive heating coating accounts for 20% of the total coating material load of the entire N2O decomposition catalyst, with the remainder being a highly water-resistant N2O decomposition coating. The passive heating coating covers 75% of the length of the through-type carrier, and the material particle size... D 90 The thickness is 4.0 μm. The high water-resistant N2O decomposition-resistant coating covers 100% of the length of the through-type carrier, and the material particle size is... D 90 It is 7.0 μm.

[0176] The preparation method for N2O decomposition catalyst is as follows:

[0177] (1) Preparation of passively heated coating:

[0178] Diethoxydimethylsilane was added to acetone and dissolved completely to obtain an acetone solution of diethoxydimethylsilane; cobalt oxide was added to the acetone solution of diethoxydimethylsilane, stirred evenly in a water bath at 50°C, allowed to stand for reaction, washed with deionized water, centrifuged to obtain a solid substance, and freeze-dried to obtain cobalt oxide A.

[0179] Platinum fluoroacetylacetonate and copper trifluoroacetylacetonate were uniformly mixed and thoroughly dissolved in acetone to prepare a platinum-copper mixed solution. Cobalt oxide A was added to the platinum-copper mixed solution, and the mixture was centrifuged to obtain a solid substance. The solid substance was freeze-dried to obtain a dried mixture. The dried mixture was calcined at 300°C for 1 hour under static air, cooled to below 50°C, and then calcined at 300°C for 4 hours after H2 was introduced to obtain a passively heated coating powder. The powder was further prepared into a slurry, ground to a suitable particle size, and coated onto a straight-through support as the first layer of the catalyst material coating. In this material coating, the mass content of Pt was 0.5%, the mass content of Cu was 1%, and the balance was cobalt oxide and unavoidable impurities.

[0180] (2) Preparation of a coating with high resistance to water N2O decomposition:

[0181] Diethoxydimethylsilane was added to acetone and dissolved completely to obtain an acetone solution of diethoxydimethylsilane; cobalt oxide was added to the acetone solution of diethoxydimethylsilane, stirred evenly in a water bath at 50°C, allowed to stand for reaction, washed with deionized water, centrifuged to obtain a solid substance, and freeze-dried to obtain cobalt oxide A.

[0182] A rhodium-barium dicarbonyl precursor and barium acetylacetone were uniformly mixed and fully dissolved in acetone to prepare a rhodium-barium mixed solution. Cobalt oxide A was added to the rhodium-barium mixed solution, and the mixture was centrifuged to obtain a solid substance. The solid substance was freeze-dried to obtain a dry mixture. The dry mixture was calcined at 300°C for 1 hour under static air, cooled to below 50°C, and then calcined at 300°C for 4 hours after introducing O2 to obtain a coating powder. Diethoxydimethylsilane was added to acetone and fully dissolved to prepare an organosilicon compound solution. The above coating powder was added to the organosilicon compound solution, ultrasonically stirred, and centrifuged to obtain a solid substance. The solid substance was ground to the designed particle size and then prepared into a slurry for coating the first material coating, which is the second material coating of the catalyst. In this material coating, the mass content of Rh is 2%, the mass content of Ba is 5%, and the balance is cobalt oxide and unavoidable impurities.

[0183] (3) The coated monolithic catalyst was dried at 70°C to prepare the N2O decomposition catalyst.

[0184] Table 1 lists the catalytic decomposition activities (T) of the catalysts in Examples 1-13 and Comparative Examples 1-15 for N2O. 50 (This indicates the temperature at which 50% of N2O decomposes) and its corresponding N2 selectivity.

[0185] Table 1 Comparison of the catalytic activities of different catalysts for the decomposition of N2O

[0186]

[0187] Test methods and conditions for catalyst N2O decomposition activity: The catalyst N2O decomposition activity was evaluated in a stationary reactor. Reaction atmosphere: 200ppm N2O + 1000ppm H2 + 10% O2 + 25% H2O + N2 balance gas, total flow rate 3000 ml / min, volume hourly space velocity (VHSV) 100000 h⁻¹ -1 .

[0188] As can be seen from Table 1:

[0189] (1) A comparison of the N2O catalytic decomposition activities of Examples 1, 2, 3, Comparative Example 3, and Comparative Example 4 reveals that the passively heated coating accounts for 15% to 25% of the coating loading of the N2O decomposition catalyst material, with the remainder being a highly water-resistant N2O decomposition coating. The N2O catalytic decomposition activity T 50 Within the temperature range of 220℃ to 240℃, when the passive heating coating has a coating loading of 10%, the N2O catalytic decomposition activity T 50 At 275℃, when the passive heating coating loading accounts for 30%, the N2O catalytic decomposition activity T 50 The temperature was 280℃, indicating that the passive heating coating accounted for a certain range of the N2O decomposition catalyst material coating loading, and the N2O catalytic decomposition activity decreased.

[0190] (2) A comparison of the N2O catalytic decomposition activities of Examples 1, 4, 5 and Comparative Example 5 reveals that when the length of the passively heated coating is ≥50% of the length of the through-type support, the N2O catalytic decomposition activity T 50 It has obvious advantages.

[0191] (3) The comparison of the N2O catalytic decomposition activities of Examples 1, 12, 13, Comparative Example 8, and Comparative Example 12 shows that platinum is the key active species for oxidation and temperature rise in the passive heating coating. The passive heating coating effectively reduces T by raising the temperature of the N2O decomposition coating through heat transfer. 50 The addition of hydrogen during the roasting process can effectively improve the oxidation and heat release capacity of the passively heated coating, thereby enhancing the catalytic decomposition activity of N2O.

[0192] (4) The comparison of N2O catalytic decomposition activities in Examples 1, 12, 13, Comparative Example 9 and Comparative Example 13 shows that rhodium is the key active species for N2O decomposition in the N2O decomposition coating, and the addition of oxygen during the calcination process can effectively improve the N2O catalytic decomposition activity.

[0193] (5) The comparison of N2O catalytic decomposition activities in Examples 1, 12, 13, Comparative Example 10 and Comparative Example 11 shows that the mass content of Pt is 0.1-1% and the mass content of Rh is 0.5-4%, which effectively improves the N2O catalytic decomposition activity.

[0194] (6) The comparison of N2O catalytic decomposition activities in Examples 1, 2, 3, 4, 5, 6, 7, 8, 9 and Comparative Example 14 shows that water-resistant treatment of the material effectively prevents the water atmosphere from covering the active sites and significantly improves the N2O catalytic decomposition activity.

[0195] (7) The comparison of N2O catalytic decomposition activities in Examples 1, 2, 3, 4, 5, 6, 7, 8, 9 and Comparative Example 15 shows that calcining the material at a higher temperature is beneficial to the distribution state of active species and the reconstruction of surface chemical state, which significantly improves the N2O catalytic decomposition activity.

[0196] (8) The comparison of N2O catalytic decomposition activities in Examples 1, 2, 3, 4, 5, 6, 7, 8, 9 and Comparative Example 1 shows that mixing the dynamic heating coating and the high water-resistant N2O catalytic decomposition coating reduces the N2O catalytic decomposition activity and severely reduces the N2 selectivity.

[0197] (9) The comparison of N2O catalytic decomposition activities of Examples 1, 2, 3, 4, 5, 6, 7, 8, 9 and Comparative Example 2 shows that the N2O catalytic decomposition activity will decrease significantly with only the high water-resistant N2O catalytic decomposition coating.

[0198] Table 2 shows a comparison of the coating peeling rates of different catalysts.

[0199] Table 2 Comparison of coating peeling rates for different catalysts

[0200]

[0201] As can be seen from Table 2, the coating peeling rate comparison of Examples 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, Comparative Example 4, Comparative Example 5, Comparative Example 6, and Comparative Example 7 shows that the coating peeling rate of Examples 1-13 is less than 1%, indicating good adhesion, while the coating peeling rate of Comparative Examples 4-7 is much greater than 1%, indicating poor adhesion and visible dust.

[0202] Catalyst heating capacity test: The catalyst heating capacity was evaluated in a stationary reactor. The catalyst inlet temperature was continuously stabilized at 180℃, with one pulse (reaction atmosphere: 1000ppm H2+ 10% O2+ N2 balance gas, total flow rate 3000ml / min, volumetric hourly space velocity 100000h). -1 Thermocouples are used to detect the temperature at the catalyst inlet.

[0203] Table 3 shows the maximum temperature rise capacity of the catalyst (the maximum temperature rise capacity is calculated as the maximum difference between the catalyst outlet temperature and the catalyst inlet temperature).

[0204] Table 3 Maximum temperature rise capacity of different catalysts

[0205]

[0206] As can be seen from Table 3:

[0207] (1) By comparing the maximum heating capacity of Examples 1, 2, 3, 3, and 4, it can be found that the passive heating coating accounts for 15% to 25% of the N2O decomposition catalyst material coating load, with the remainder being the N2O decomposition coating. The maximum heating capacity of the catalyst is 113 to 116°C. When the passive heating coating load accounts for 10%, the maximum heating capacity of the catalyst is 55°C, indicating that the proportion of the passive heating coating in the N2O decomposition catalyst material coating load is lower than a certain range, and the maximum heating capacity of the catalyst is significantly reduced. Combined with Table 1, it is found that the N2O catalytic decomposition activity decreases. When the passive heating coating load accounts for 30%, the maximum heating capacity of the catalyst is 116°C, indicating that the proportion of the passive heating coating in the N2O decomposition catalyst material coating load is higher than a certain range, and the maximum heating capacity of the catalyst remains unchanged. It has reached the limit of the catalyst's heating capacity under this condition. Combined with Table 1, the excessively high passive heating coating load is not only not conducive to heating, but also leads to a decrease in N2O catalytic decomposition activity due to the relative reduction of the high water-resistant N2O catalytic decomposition coating.

[0208] (2) By comparing the maximum heating capacity of Examples 1, 4, 5 and Comparative Example 5, it can be found that the maximum heating capacity of the catalyst is significantly increased when the length of the passive heating coating is ≥50% of the length of the straight-through carrier.

[0209] (3) The comparison of the maximum heating capacity of Examples 1, 12, 13, Comparative Example 8, and Comparative Example 12 reveals that platinum is the key active species for oxidation heating in the passive heating coating, which can effectively improve the heating capacity of the catalyst. At the same time, the addition of hydrogen during the calcination process can effectively improve the oxidation exothermic capacity of the passive heating coating. Combined with Table 1, it can be shown that the passive heating coating effectively reduces T through heat transfer to raise the temperature of the N2O decomposition coating. 50 .

[0210] (4) By comparing the maximum heating capacity of Examples 1, 12, 13, Comparative Example 10 and Comparative Example 11, it can be found that the mass content of Pt is 0.1-1%, which effectively improves the maximum heating capacity. When the mass content of Pt is 0.05%, the maximum heating capacity of the catalyst is 40°C, which is obviously insufficient. When the mass content of Pt is 1.5%, the maximum heating capacity of the catalyst is 114°C, which shows that further increasing the platinum content cannot effectively improve the heating capacity of the catalyst.

[0211] (5) The comparison of the maximum heating capacity of Examples 1, 2, 3, 4, 5 and Comparative Example 15 shows that calcining the material at a higher temperature is beneficial to the distribution state of active species and the reconstruction of surface chemical state, and significantly improves the heating capacity of the catalyst.

[0212] (6) By comparing the maximum heating capacity of Examples 1, 2, 3, 4, 5 and Comparative Example 1, it can be found that the maximum heating capacity decreases when the dynamic heating coating and the high water-resistant N2O catalytic decomposition coating are mixed.

[0213] (7) From the maximum heating capacity of Examples 1, 2, 3, 4, 5 and Comparative Example 2, it can be found that only the highly water-resistant N2O catalytic decomposition coating has almost no heating capacity.

[0214] Catalyst water resistance test: H2O of different percentages was introduced into a stationary reactor to evaluate the catalyst's N2O decomposition activity. The total flow rate was 3000 ml / min, and the volumetric space velocity was 100000 h⁻¹. -1 The reaction atmosphere is shown in Table 4:

[0215] Table 4. Catalyst water resistance test reaction atmosphere

[0216]

[0217] Table 5 shows the test results of the catalyst's water resistance.

[0218] Table 5. Test results of the catalyst's water resistance.

[0219]

[0220] As can be seen from Table 5:

[0221] (1) The comparison of the catalyst water resistance tests of Examples 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 and Comparative Example 12 shows that the addition of hydrogen during the calcination process can effectively improve the catalyst’s tolerance to high water content.

[0222] (2) The comparison of the catalyst water resistance tests of Examples 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 and Comparative Example 13 shows that the addition of oxygen during the calcination process can effectively improve the catalyst’s tolerance to high water content.

[0223] (3) The comparison of the water resistance tests of the catalysts in Examples 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 and Comparative Example 14 shows that water resistance treatment of the material effectively prevents the water atmosphere from covering the active sites and significantly improves the catalyst's tolerance to high water content.

[0224] (4) The comparison of the water resistance tests of the catalysts in Examples 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 and Comparative Example 15 shows that calcining the material at a higher temperature is beneficial to the distribution state of active species and the reconstruction of surface chemical state, and significantly improves the catalyst's tolerance to high water content.

[0225] (5) The comparison of the catalyst water resistance test of Examples 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 and Comparative Example 1 shows that when the dynamic heating coating and the high water-resistant N2O catalytic decomposition coating are mixed, the catalyst’s tolerance to high water content decreases.

[0226] The above embodiments are only some embodiments of the present invention and are not intended to limit the scope of protection of the present invention. All modifications and equivalent substitutions made based on the scope defined by the claims of the present invention shall fall within the scope of protection of the present invention. Accordingly, in the first layer of the material coating of the present invention, the mass content of Pt is 0.1-1%, and the mass content of Cu is 0.2-2%. In the second layer of the material coating, the mass content of Rh is 0.5-4%, and the mass content of alkali metal / alkaline earth metal is 1-10%. The alkali metal or alkaline earth metal precursors include, but are not limited to, potassium acetylacetonate, sodium acetylacetonate, magnesium acetylacetonate, calcium acetylacetonate, barium acetylacetonate, and strontium acetylacetonate. The organosilicon compounds include, but are not limited to, polydimethylsiloxane, trimethylsilylacetylene, hexamethyldisilaneamine, vinyltriethoxysilane, diethoxydimethylsilane, tetraethyl orthosilicate, vinyltriethoxysilane, and 3-glycidyl etheroxypropyltrimethoxysilane. The platinum precursors include, but are not limited to, platinum acetylacetonate, fluoroacetylacetonate, dipentenylplatinum, and cyclopentadienyltrimethylplatinum. The copper precursors include, but are not limited to, copper acetylacetonate, phenylacetylated copper, bis(hexafluoroacetylacetonate)copper, and trifluoroacetylacetonate copper. The rhodium precursors include, but are not limited to, rhodium acetylacetonate, rhodium dicarbonyl acetylacetonate, rhodium carbonyl acetylacetonate, and (1,5-cyclooctadiene) rhodium chloride dimer.

Claims

1. A N2O decomposition catalyst for a hydrogen engine, characterized in that, It includes a through-type carrier, a first material coating applied to the through-type carrier, and a second material coating applied on the first material coating; The first layer of material coating is a passive heating coating, containing Pt, Cu and cobalt oxide. The mass content of Pt is 0.1-1%, the mass content of Cu is 0.2-2%, and the balance is cobalt oxide and unavoidable impurities. The passive heating coating releases heat from H2 in the oxidizing waste gas to heat the second layer of material coating located on the passive heating coating, thereby increasing the bed temperature of the second layer of material coating and accelerating the attainment of the decomposition temperature of N2O. The second layer of material coating is a highly water-resistant N2O decomposition coating, containing Rh, alkali metal / alkaline earth metal and cobalt oxide. The mass content of Rh is 0.5-4%, the mass content of alkali metal / alkaline earth metal is 1-10%, and the balance is cobalt oxide and unavoidable impurities. The water-resistant N2O decomposition coating is used to reduce the adsorption selectivity of H2O on the catalyst surface, prevent H2O from covering the active sites, facilitate the adsorption of N2O on the active sites, decompose N2O and have high water resistance.

2. The N2O decomposition catalyst for a hydrogen engine according to claim 1, characterized in that, The loading of the first layer of material coating accounts for 15% to 25% of the total coating loading on the N2O decomposition catalyst, with the remainder being the second layer of material coating.

3. The N2O decomposition catalyst for a hydrogen engine according to claim 1, characterized in that, The length of the first layer of material coating covers 50% to 100% of the length of the through-type carrier, and the length of the second layer of material coating covers 100% of the length of the through-type carrier.

4. The N2O decomposition catalyst for a hydrogen engine according to claim 1, characterized in that, The particle size of the first layer of material coating D 90 The particle size of the second layer of material coating is 3.0–5.0 μm. D 90 The thickness is 6.0–8.0 μm.

5. The N2O decomposition catalyst for a hydrogen engine according to claim 1, characterized in that, The alkali metal / alkaline earth metal precursor is one or more of potassium acetylacetonate, sodium acetylacetonate, magnesium acetylacetonate, calcium acetylacetonate, barium acetylacetonate, and strontium acetylacetonate.

6. The method for preparing the N2O decomposition catalyst for a hydrogen engine according to any one of claims 1 to 5, characterized in that, The preparation method is as follows: (1) Preparation of the first material coating: The organosilicon compound was added to acetone and dissolved completely to obtain an organosilicon compound solution. Cobalt oxide was added to the organosilicon compound solution, stirred evenly in a water bath at 50℃~70℃, allowed to stand for reaction, washed with deionized water, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain cobalt oxide A. After uniformly mixing platinum and copper precursors, the mixture is fully dissolved in acetone to obtain a platinum-copper mixed solution. Cobalt oxide A is added to the platinum-copper mixed solution, and the mixture is centrifuged. The solid fraction obtained by centrifugation is freeze-dried to obtain a dry mixture. The dry mixture is calcined at 300℃~350℃ for 1~2 hours under static air conditions, cooled to below 50℃, and then H2 is introduced. The mixture is calcined at 400℃~500℃ for 2~4 hours to obtain a passively heated coating powder. The powder is further prepared into a slurry, ground to the required particle size, and then coated onto a direct-flow carrier to form the first layer of material coating. (2) Preparation of the second material coating: The organosilicon compound was added to acetone and dissolved completely to obtain an organosilicon compound solution. Cobalt oxide was added to the organosilicon compound solution, stirred evenly in a water bath at 50℃~70℃, allowed to stand for reaction, washed with deionized water, centrifuged, and the solid part obtained by centrifugation was freeze-dried to obtain cobalt oxide A. After uniformly mixing the rhodium precursor and the alkali metal / alkaline earth metal precursor, the mixture is fully dissolved in acetone to obtain a rhodium-alkali metal / alkaline earth metal mixed solution. Cobalt oxide A is added to the rhodium-alkali metal / alkaline earth metal mixed solution, and the mixture is centrifuged. The solid part obtained by centrifugation is freeze-dried to obtain a dried mixture. The dried mixture is calcined at 300℃~350℃ for 1~2 hours under static air conditions, cooled to below 50℃, and then O2 is introduced. The mixture is then calcined at 400℃~500℃ for 2~4 hours to obtain a coating powder. The organosilicon compound is added to acetone and fully dissolved to obtain an organosilicon compound solution. The above coating powder is added to the organosilicon compound solution, ultrasonically stirred and centrifuged. The solid part obtained is prepared into a slurry, ground to the required particle size, and then coated on the first material coating to form the second material coating. (3) The straight-through carrier after the first and second material coatings are applied is dried at 70~100℃ to prepare the N2O decomposition catalyst; In the above steps, the organosilicon compound is one of polydimethylsiloxane, trimethylsilylacetylene, hexamethyldisilaneamine, vinyltriethoxysilane, diethoxydimethylsilane, tetraethyl orthosilicate, vinyltriethoxysilane, and 3-glycidoxypropyltrimethoxysilane.

7. The method for preparing the N2O decomposition catalyst according to claim 6, characterized in that, The platinum precursor is one or more of platinum acetylacetonate, fluoroplatinum acetylacetonate, dipentenylplatinum, and cyclopentadienyltrimethylplatinum.

8. The method for preparing the N2O decomposition catalyst according to claim 6, characterized in that, The copper precursor is one of copper acetylacetonate, phenylacetyl copper, bis(hexafluoroacetylacetonate)copper, and copper trifluoroacetylacetonate.

9. The method for preparing the N2O decomposition catalyst according to claim 6, characterized in that, The rhodium precursor is one of rhodium acetylacetonate, rhodium acetylacetonate dicarbonyl, rhodium acetylacetonate triphenylphosphine carbonyl, or (1,5-cyclooctadiene) rhodium chloride dimer.

10. The N2O decomposition catalyst according to any one of claims 1 to 5 is used for the aftertreatment of pollutants emitted by hydrogen engines.

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