High-temperature-resistant ammonia decomposition catalyst as well as preparation method and application thereof

Abstract

The invention relates to the field of automobile exhaust purification and particularly provides a high-temperature-resistant ammonia decomposition catalyst as well as a preparation method and application thereof. The high-temperature-resistant ammonia decomposition catalyst is prepared from an active component Ru, a carrier and an auxiliary agent, the carrier comprises a carrier A and a carrier B, the carrier A comprises a CeO2-ZrO2 solid solution, and the carrier B comprises at least one of Fe2O3, CaCO3, Pr6O11 or La2O3; the auxiliary agent comprises at least one of Li, Na, K, Rb or Cs. The catalyst has excellent ammonia gas decomposition catalytic performance and high-temperature stability (the catalyst is not inactivated at the temperature of 800 DEG C or above), volatilization loss of Ru at the high temperature can be effectively inhibited, and the catalyst is prevented from being rapidly inactivated at the high temperature. The catalyst and a three-way catalyst are applied to automobile exhaust purification together, NH3 generated on the three-way catalyst can be decomposed into H2 and N2, and the problem of ammonia emission is solved.

Description

Technical Field

[0001] The present invention relates to the field of automobile exhaust purification, and in particular to a high-temperature resistant ammonia decomposition catalyst and a preparation method and application thereof. Background Art

[0002] The exhaust of vehicles that use equivalent ratio combustion (such as gasoline vehicles, natural gas vehicles, and methanol vehicles) contains pollutants such as HC (hydrocarbons), NOx (nitrogen oxides), and CO. By installing a three-way catalyst on the exhaust pipe, these pollutants can be converted into CO2, H2O, and N2 that are harmless to the human body. However, during the exhaust gas purification process, side reactions will occur, producing a large amount of NH3 by-products, resulting in excessive NH3 emissions. Adding ammonia decomposition catalytic materials to traditional three-way catalysts and decomposing the NH3 by-products produced on the three-way catalyst into N2 and H2 is one of the effective ways to solve the ammonia emission problem. Ru-based catalysts are currently the catalysts with the best ammonia decomposition catalytic performance and are widely used in the field of ammonia decomposition and hydrogen production, but they are less used in the field of automobile exhaust purification. The field of ammonia decomposition and hydrogen production focuses on the low-temperature activity of ammonia decomposition catalysts. The operating temperature of the catalyst usually does not exceed 500°C, and Ru-based catalysts can operate stably at this temperature. However, in the field of automobile exhaust purification, the exhaust temperature of automobiles can be as high as 800°C or even 1000°C. At such high temperatures, Ru is easily volatilized and lost, resulting in rapid deactivation of the ammonia decomposition catalyst.

[0003] In view of this, the present invention is proposed. Summary of the invention

[0004] The object of the present invention is to provide a high temperature resistant ammonia decomposition catalyst and a preparation method and application thereof, so as to solve the problem in the prior art that Ru is easily volatilized and lost at a high temperature above 800°C, resulting in catalyst deactivation.

[0005] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted: In a first aspect, the present invention provides a high temperature resistant ammonia decomposition catalyst, wherein the catalyst is made of an active component Ru, a carrier and an additive; The carrier includes a carrier A and a carrier B, wherein the carrier A includes a CeO2-ZrO2 solid solution, and the carrier B includes Fe2O3, CaCO3, Pr6O 11 Or at least one of La2O3; the auxiliary agent includes at least one of Li, Na, K, Rb or Cs.

[0006] As a further preferred technical solution, the mass ratio of the carrier A to the carrier B is 1:9~9:1.

[0007] As a further preferred technical solution, the active component content accounts for 0.5wt%~5wt% of the catalyst, the carrier content accounts for 85wt%~99wt% of the catalyst, and the additive content accounts for 0.5wt%~10wt% of the catalyst.

[0008] As a further preferred technical solution, the auxiliary agent includes at least one of K, Rb or Cs.

[0009] As a further preferred technical solution, the carrier B includes Fe2O3, or Fe2O3 and compound C, wherein compound C includes CaCO3, Pr6O 11 Or at least one of La2O3.

[0010] In a second aspect, the present invention provides a method for preparing the above-mentioned high temperature resistant ammonia decomposition catalyst, comprising the following steps: The active component Ru precursor aqueous solution and the auxiliary agent precursor aqueous solution are uniformly mixed to obtain a precursor mixed solution; The carrier A and the carrier B are mixed evenly by ball milling to obtain a mixed carrier; The mixed carrier and the precursor mixed solution are mixed and allowed to stand for more than 2 hours, and then dried and calcined to obtain the high temperature resistant ammonia decomposition catalyst.

[0011] As a further preferred technical solution, the auxiliary agent precursor includes at least one of auxiliary agent nitrate, auxiliary agent carbonate or auxiliary agent hydroxide.

[0012] As a further preferred technical solution, the active component Ru precursor includes ruthenium nitrate and / or ruthenium chloride.

[0013] As a further preferred technical solution, the drying conditions are 100-120° C. for 3-5 hours, and the calcination conditions are 500-600° C. for 2-5 hours.

[0014] In a third aspect, the present invention provides an application of the above-mentioned high-temperature resistant ammonia decomposition catalyst or the high-temperature resistant ammonia decomposition catalyst obtained by the above-mentioned preparation method in automobile exhaust purification.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The high temperature resistant ammonia decomposition catalyst provided by the present invention is made of active component Ru, a carrier of specific composition and an auxiliary agent of specific composition. The catalyst has excellent ammonia decomposition catalytic performance and high temperature stability (no deactivation above 800°C), can effectively inhibit the volatilization loss of Ru at high temperature, and prevent the catalyst from deactivating rapidly at high temperature. The catalyst is used together with a three-way catalyst for automobile exhaust purification, and can decompose NH3 generated on the three-way catalyst into H2 and N2, solving the ammonia emission problem. DETAILED DESCRIPTION

[0016] The embodiments of the present invention will be described in detail below in conjunction with examples, but those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. If no specific conditions are specified in the examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer.

[0017] In one aspect, the present invention provides a high temperature resistant ammonia decomposition catalyst, wherein the catalyst is made of an active component Ru, a carrier and an additive; The carrier includes a carrier A and a carrier B, wherein the carrier A includes a CeO2-ZrO2 solid solution, and the carrier B includes Fe2O3, CaCO3, Pr6O 11 Or at least one of La2O3; the auxiliary agent includes at least one of Li, Na, K, Rb or Cs.

[0018] The mass ratio of Ce to Zr in the CeO2-ZrO2 solid solution is 1:2~2:1. Carrier B includes but is not limited to Fe2O3, CaCO3, Pr6O 11 , La2O3, Fe2O3 and CaCO3, CaCO3 and Pr6O 11 Combination of Pr6O 11 Combination of La2O3, Fe2O3, CaCO3 and Pr6O 11 Combination of CaCO3, Pr6O 11 and La2O3, or Fe2O3, CaCO3, Pr6O 11 and La2O3, etc. The additives include, but are not limited to, Li, Na, K, Rb, Cs, a combination of Li and Na, a combination of Na and K, a combination of K and Rb, a combination of K and Cs, a combination of Rb and Cs, a combination of Li, Na and K, a combination of Na, K and Rb, a combination of K, Rb and Cs, a combination of Li, Na, K and Rb, a combination of Na, K, Rb and Cs, or a combination of Li, Na, K, Rb and Cs, etc.

[0019] Carrier A, i.e. CeO2-ZrO2 solid solution, has abundant oxygen vacancies, and additives, i.e. Li, Na, K, Rb, and Cs, can provide high-density alkaline sites. The two can promote the transfer of electrons from the carrier or additive to Ru, increase the electron density of Ru, and thus improve the catalytic activity of Ru-based catalysts for ammonia decomposition. Carrier B, i.e. Fe2O3, CaCO3, Pr6O 11 There is a strong interaction between La2O3 and Ru, or it can form a solid solution with Ru, thereby stabilizing Ru and inhibiting the volatilization loss of Ru at high temperature.

[0020] In an optional embodiment, the mass ratio of the carrier A to the carrier B is 1:9 to 9:1. Carrier A has abundant oxygen vacancies, which can promote the transfer of electrons from the carrier to Ru, increase the electron density of Ru, and thus improve the catalytic activity of Ru-based catalysts for ammonia decomposition; there is a strong interaction between carrier B and Ru, or it can form a solid solution with Ru, thereby stabilizing Ru and inhibiting the volatilization loss of Ru at high temperatures. When the mass ratio of carrier A to carrier B is lower than 1:9, the catalytic activity of ammonia decomposition of the catalyst is poor; when it is higher than 9:1, Ru is more susceptible to volatilization loss. The ratio includes but is not limited to 1:9, 1:8, 1:7, 1:6, 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1 or 9:1.

[0021] In an optional embodiment, the active component content accounts for 0.5wt%~5wt% of the catalyst, the carrier content accounts for 85wt%~99wt% of the catalyst, and the auxiliary agent content accounts for 0.5wt%~10wt% of the catalyst. If the content of the active component is lower than 0.5wt%, the catalyst has poor ammonia decomposition catalytic activity; if it is higher than 5wt%, the cost of the catalyst is higher. If the content of the auxiliary agent is lower than 0.5wt%, the catalyst has poor ammonia decomposition activity; if it is higher than 10wt%, Ru is more likely to be volatilized and lost. Among them, the content of active ingredients includes but is not limited to 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt% or 5wt%; the content of carrier includes but is not limited to 85wt%, 86wt%, 87wt%, 88wt%, 89wt%, 90wt%, 91wt%, 92wt%, 93wt%, 94wt%, 95wt%, 96wt%, 97wt%, 98wt% or 99wt%; the content of auxiliary agent includes but is not limited to 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt% or 10wt%.

[0022] In an optional embodiment, the auxiliary agent includes at least one of K, Rb or Cs. When the auxiliary agent is at least one of K, Rb or Cs, the catalyst has better ammonia decomposition performance. The auxiliary agent K, Rb or Cs can provide a high-density alkaline site, promote the transfer of electrons from the auxiliary agent to Ru, increase the electron density of Ru, and thus improve the ammonia decomposition catalytic activity of the Ru-based catalyst.

[0023] In an optional embodiment, the carrier B comprises Fe2O3, or Fe2O3 and compound C, wherein compound C comprises CaCO3, Pr6O 11or La2O3. When carrier B is the above components, the Ru aging loss rate is lower, and when carrier B is Fe2O3, the Ru aging loss rate is the lowest. There is a strong interaction between carrier B and Ru, or it can form a solid solution with Ru, thereby stabilizing Ru and inhibiting the volatilization loss of Ru at high temperature.

[0024] The above catalyst has excellent ammonia decomposition catalytic performance and high temperature stability (no deactivation above 800°C), can effectively inhibit the volatilization loss of Ru at high temperature, and prevent the catalyst from rapid deactivation at high temperature. The catalyst is used together with the three-way catalyst for automobile exhaust purification, which can decompose the NH3 generated on the three-way catalyst into H2 and N2, solving the ammonia emission problem.

[0025] On the other hand, the present invention provides a method for preparing the above-mentioned high temperature resistant ammonia decomposition catalyst, comprising the following steps: The active component Ru precursor aqueous solution and the auxiliary agent precursor aqueous solution are uniformly mixed to obtain a precursor mixed solution; The carrier A and the carrier B are mixed evenly by ball milling to obtain a mixed carrier; The mixed carrier and the precursor mixed solution are mixed and allowed to stand for more than 2 hours, and then dried and calcined to obtain the high temperature resistant ammonia decomposition catalyst.

[0026] The method has scientific technology, strong controllability in the preparation process, and is easy to mass produce. The obtained catalyst has good ammonia catalytic effect, can effectively inhibit the high-temperature volatilization loss of Ru above 800°C, and prevent the rapid deactivation of the catalyst at high temperature.

[0027] In an optional embodiment, the auxiliary agent precursor includes at least one of auxiliary agent nitrate, auxiliary agent carbonate or auxiliary agent hydroxide. The above auxiliary agent precursor includes but is not limited to auxiliary agent nitrate, auxiliary agent carbonate, auxiliary agent hydroxide, a combination of auxiliary agent nitrate and auxiliary agent carbonate, a combination of auxiliary agent carbonate and auxiliary agent hydroxide, a combination of auxiliary agent nitrate and auxiliary agent hydroxide, or a combination of auxiliary agent nitrate, auxiliary agent carbonate and auxiliary agent hydroxide, etc.

[0028] It can be understood that when the auxiliary agent precursor is auxiliary agent nitrate and the auxiliary agent is K, the auxiliary agent precursor is potassium nitrate.

[0029] In an optional embodiment, the active component Ru precursor includes ruthenium nitrate and / or ruthenium chloride.

[0030] In an optional embodiment, the drying condition is 100-120°C for 3-5 hours, and the roasting condition is 500-600°C for 2-5 hours. The drying temperature includes but is not limited to 100°C, 105°C, 110°C, 115°C or 120°C, and the drying time includes but is not limited to 3h, 3.5h, 4h, 4.5h or 5h. The roasting temperature includes but is not limited to 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C or 600°C, and the roasting time includes but is not limited to 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h.

[0031] In another aspect, the present invention provides an application of the above-mentioned high temperature resistant ammonia decomposition catalyst or the high temperature resistant ammonia decomposition catalyst obtained by the above-mentioned preparation method in automobile exhaust purification. The above-mentioned catalyst is applied to automobile exhaust purification to effectively remove ammonia at high temperature and improve the purification effect.

[0032] It should be noted that the present invention mainly applies the above catalyst to automobile exhaust purification. As for the specific application method, the present invention does not make any special limitation, and any achievable method in the art can be adopted.

[0033] The present invention is further described in detail below with reference to Examples and Comparative Examples.

[0034] Example 1 (Ru+K) / (9CeO2-ZrO2+1Fe2O3) S1. Dissolve potassium nitrate with a K content of 0.3 g in deionized water to obtain a potassium nitrate solution.

[0035] S2. Stir and mix the ruthenium nitrate solution with a Ru content of 0.1 g and the potassium nitrate solution in S1 to obtain a precursor mixed solution.

[0036] S3. 8.64 g of CeO2-ZrO2 solid solution powder and 0.96 g of Fe2O3 powder are ball-milled to obtain a mixed carrier powder.

[0037] S4. Add the mixed carrier powder in S3 to the precursor mixed solution in S2, stir quickly and evenly, let it stand for 2 hours, then dry it at 120°C for 4 hours, and calcine it at 550°C for 3 hours to obtain the final catalyst, in which the content of active component Ru is 1wt%, the content of the carrier is 96wt%, and the content of the auxiliary agent is 3wt%.

[0038] Example 2 (Ru+K) / (9CeO2-ZrO2+1CaCO3) S1. A precursor mixed solution is obtained by the same method as S1-S2 in Example 1.

[0039] S2. 8.64 g of CeO2-ZrO2 solid solution powder and 0.96 g of CaCO3 powder are ball-milled to obtain a mixed carrier powder.

[0040] S3. Add the mixed carrier powder in S2 to the precursor mixed solution in S1, stir quickly and evenly, let it stand for 2 hours, then dry it at 120°C for 4 hours, and calcine it at 550°C for 3 hours to obtain the final catalyst, in which the content of active component Ru is 1wt%, the content of the carrier is 96wt%, and the content of the auxiliary agent is 3wt%.

[0041] Example 3 (Ru+K) / (9CeO2-ZrO2+1La2O3) S1. A precursor mixed solution is obtained by the same method as S1-S2 in Example 1.

[0042] S2. 8.64 g of CeO2-ZrO2 solid solution powder and 0.96 g of La2O3 powder were mixed by ball milling to obtain a mixed carrier powder.

[0043] S3. Add the mixed carrier powder in S2 to the precursor mixed solution in S1, stir quickly and evenly, let it stand for 2 hours, then dry it at 120°C for 4 hours, and calcine it at 550°C for 3 hours to obtain the final catalyst, in which the content of active component Ru is 1wt%, the content of the carrier is 96wt%, and the content of the auxiliary agent is 3wt%.

[0044] Example 4 (Ru+K) / (9CeO2-ZrO2+1Pr6O 11 ) S1. A precursor mixed solution is obtained by the same method as S1-S2 in Example 1.

[0045] S2, 8.64g CeO2-ZrO2 solid solution powder and 0.96g Pr6O 11 The powders are ball-milled to obtain mixed carrier powder.

[0046] S3. Add the mixed carrier powder in S2 to the precursor mixed solution in S1, stir quickly and evenly, let it stand for 2 hours, then dry it at 120°C for 4 hours, and calcine it at 550°C for 3 hours to obtain the final catalyst, in which the content of active component Ru is 1wt%, the content of the carrier is 96wt%, and the content of the auxiliary agent is 3wt%.

[0047] Example 5 (Ru+K) / (1CeO2-ZrO2+9Fe2O3) S1. A precursor mixed solution is obtained by the same method as S1-S2 in Example 1.

[0048] S2. 0.96 g of CeO2-ZrO2 solid solution powder and 8.64 g of Fe2O3 powder are ball-milled to obtain a mixed carrier powder.

[0049] S3. Add the mixed carrier powder in S2 to the precursor mixed solution in S1, stir quickly and evenly, let it stand for 2 hours, then dry it at 120°C for 4 hours, and calcine it at 550°C for 3 hours to obtain the final catalyst, in which the content of active component Ru is 1wt%, the content of the carrier is 96wt%, and the content of the auxiliary agent is 3wt%.

[0050] Example 6 (Ru+K+Rb) / (1CeO2-ZrO2+9Fe2O3) S1. Dissolve potassium nitrate with a K content of 0.15 g and rubidium nitrate with a Rb content of 0.15 g in deionized water to obtain an additive mixed solution.

[0051] S2. Stir and mix the ruthenium nitrate solution with a Ru content of 0.1 g and the auxiliary agent mixed solution in S1 to obtain a precursor mixed solution.

[0052] S3. 0.96 g of CeO2-ZrO2 solid solution powder and 8.64 g of Fe2O3 powder are ball-milled to obtain a mixed carrier powder.

[0053] S4. Add the mixed carrier powder in S3 to the precursor mixed solution in S2, stir quickly and evenly, let it stand for 2 hours, then dry it at 120°C for 4 hours, and calcine it at 550°C for 3 hours to obtain the final catalyst, in which the content of active component Ru is 1wt%, the content of the carrier is 96wt%, and the content of the auxiliary agent is 3wt%.

[0054] Example 7 (Ru+Cs) / (1CeO2-ZrO2+9Fe2O3) S1. Dissolve cesium nitrate having a Cs content of 0.3 g in deionized water to obtain a cesium nitrate solution.

[0055] S2. Stir and mix a ruthenium nitrate solution having a Ru content of 0.1 g with the cesium nitrate solution in S1 to obtain a precursor mixed solution.

[0056] S3. 0.96 g of CeO2-ZrO2 solid solution powder and 8.64 g of Fe2O3 powder are ball-milled to obtain a mixed carrier powder.

[0057] S4. Add the mixed carrier powder in S3 to the precursor mixed solution in S2, stir quickly and evenly, let it stand for 2 hours, then dry it at 120°C for 4 hours, and calcine it at 550°C for 3 hours to obtain the final catalyst, in which the content of active component Ru is 1wt%, the content of the carrier is 96wt%, and the content of the auxiliary agent is 3wt%.

[0058] Example 8 (Ru+K) / (1CeO2-ZrO2+1Fe2O3) S1. A precursor mixed solution is obtained by the same method as S1-S2 in Example 1.

[0059] S2. 4.8 g of CeO2-ZrO2 solid solution powder and 4.8 g of Fe2O3 powder are ball-milled to obtain a mixed carrier powder.

[0060] S3. Add the mixed carrier powder in S2 to the precursor mixed solution in S1, stir quickly and evenly, let it stand for 2 hours, then dry it at 120°C for 4 hours, and calcine it at 550°C for 3 hours to obtain the final catalyst, in which the content of active component Ru is 1wt%, the content of the carrier is 96wt%, and the content of the auxiliary agent is 3wt%.

[0061] Example 9 (Ru+K) / (9CeO2-ZrO2+1Fe2O3) S1. Dissolve potassium nitrate with a K content of 0.03 g in deionized water to obtain a potassium nitrate solution.

[0062] S2. Stir and mix the ruthenium nitrate solution with a Ru content of 0.03 g with the potassium nitrate solution in S1 to obtain a precursor mixed solution.

[0063] S3. 8.946 g of CeO2-ZrO2 solid solution powder and 0.994 g of Fe2O3 powder are ball-milled to obtain a mixed carrier powder.

[0064] S4. Add the mixed carrier powder in S3 to the precursor mixed solution in S2, stir quickly and evenly, let it stand for 2 hours, then dry it at 120°C for 4 hours, and calcine it at 550°C for 3 hours to obtain the final catalyst, in which the content of active component Ru is 0.3wt%, the content of the carrier is 0.3wt%, and the content of the auxiliary agent is 99.4wt%.

[0065] Comparative Example 1 (Ru+K) / CeO2-ZrO2 S1, obtaining a precursor mixed solution by the same method as S1-S2 in Example 1; S2. Add 9.6 g CeO2-ZrO2 solid solution powder to the precursor mixed solution in S1, stir quickly and evenly, let stand for 2 h, then dry at 120 °C for 4 h, and calcine at 550 °C for 3 h to obtain the final catalyst.

[0066] Comparative Example 2 (Ru+K) / Fe2O3 S1, obtaining a precursor mixed solution by the same method as S1-S2 in Example 1; S2. Add 9.6 g Fe2O3 solid solution powder into the precursor mixed solution in S1, stir quickly and evenly, let stand for 2 h, then dry at 120 °C for 4 h, and calcine at 550 °C for 3 h to obtain the final catalyst.

[0067] Comparative Example 3 Ru / (9CeO2-ZrO2+1Fe2O3) S1. 8.91 g of CeO2-ZrO2 solid solution powder and 0.99 g of Fe2O3 powder are mixed by ball milling to obtain a mixed carrier powder.

[0068] S2. Add the mixed carrier powder in S1 into a ruthenium nitrate solution with a Ru content of 0.1 g, stir quickly and evenly, let stand for 2 hours, then dry at 120°C for 4 hours, and calcine at 550°C for 3 hours to obtain the final catalyst.

[0069] Comparative Example 4 (Ru+Ca) / CeO2-ZrO2 S1. Dissolve calcium nitrate with a Ca content of 0.3 g in deionized water to obtain a calcium nitrate solution.

[0070] S2. Stir and mix a ruthenium nitrate solution having a Ru content of 0.1 g with the calcium nitrate solution in S1 to obtain a precursor mixed solution.

[0071] S3. Add 9.6 g CeO2-ZrO2 solid solution powder to the precursor mixed solution in S2, stir quickly and evenly, let it stand for 2 hours, then dry it at 120°C for 4 hours, and calcine it at 550°C for 3 hours to obtain the final catalyst, in which the content of active component Ru is 1wt%, the content of the carrier is 96wt%, and the content of Ca is 3wt%.

[0072] Comparative Example 5 (Ru+K) / (9CeO2-ZrO2+1Al2O3) S1. A precursor mixed solution is obtained by the same method as S1-S2 in Example 1.

[0073] S2. 8.64 g of CeO2-ZrO2 solid solution powder and 0.96 g of Al2O3 powder were ball-milled to obtain a mixed carrier powder.

[0074] S3. Add the mixed carrier powder in S3 to the precursor mixed solution in S1, stir quickly and evenly, let it stand for 2 hours, then dry it at 120°C for 4 hours, and calcine it at 550°C for 3 hours to obtain the final catalyst, in which the content of active component Ru is 1wt%, the content of the carrier is 96wt%, and the content of the auxiliary agent is 3wt%.

[0075] Comparative Example 6 (Ni+K) / (9CeO2-ZrO2+1Fe2O3) S1. Dissolve potassium nitrate with a K content of 0.3 g in deionized water to obtain a potassium nitrate solution.

[0076] S2. Stir and mix a nickel nitrate solution with a Ni content of 0.1 g and the potassium nitrate solution in S1 to obtain a precursor mixed solution.

[0077] S3. 8.64 g of CeO2-ZrO2 solid solution powder and 0.96 g of Fe2O3 powder are ball-milled to obtain a mixed carrier powder.

[0078] S4. Add the mixed carrier powder in S3 to the precursor mixed solution in S2, stir quickly and evenly, let it stand for 2 hours, then dry it at 120°C for 4 hours, and calcine it at 550°C for 3 hours to obtain the final catalyst, in which the content of active component Ni is 1wt%, the content of carrier is 96wt%, and the content of auxiliary agent is 3wt%.

[0079] Performance Verification The catalysts prepared in Examples 1 to 9 and Comparative Examples 1 to 5 were subjected to hydrothermal aging treatment at 800° C. for 12 h in an air atmosphere containing 10 vol.% H2O to obtain aged catalysts. The Ru or Ni content in the catalysts before and after aging was tested by inductively coupled plasma mass spectrometry, and the Ru or Ni loss rate of the catalysts after hydrothermal aging was obtained by calculation, and the results are listed in Table 1.

[0080] The catalytic performance of aged catalysts for ammonia decomposition was evaluated in an atmosphere containing 800 ppm NH3 and N2 as carrier gas. The reaction temperature (T 50 ) is used to indicate the ammonia decomposition performance of the catalyst, T 50 The smaller the T, the better the ammonia decomposition performance of the catalyst. 50 The results are listed in Table 2.

[0081] The comparison between Examples 1 to 4 and Comparative Example 5 in Table 1 shows that compared with Al2O3, the Fe2O 3、 CaCO3, La2O3, Pr6O 11 At least one of them is used as carrier B, which can significantly inhibit the volatilization loss of Ru at high temperature. The comparison between Examples 1 to 4 shows that carrier B is preferably Fe2O3, and the aging loss rate of Ru is the lowest. The comparison between Example 1, Example 5, Example 8, and Comparative Example 2 shows that the higher the proportion of Fe2O3, the lower the aging loss rate of Ru. The comparison between Example 1 and Comparative Example 1 shows that when the catalyst does not contain carrier B, the aging loss rate of Ru is the highest. The comparison between Example 1 and Comparative Example 6 shows that Ni is more easily volatilized than Ru.

[0082] The comparison between Examples 1 to 4 and Comparative Example 5 in Table 2 shows that compared with Al2O3, the Fe2O 3、 CaCO3, La2O3, Pr6O 11 At least one of the carriers B can significantly inhibit the volatilization loss of Ru at high temperature, and the catalytic performance of ammonia decomposition of the aged catalyst is better. The comparison between Examples 1 to 4 shows that the carrier B is preferably Fe2O3, the Ru volatilization loss of the aged catalyst is small, and the ammonia decomposition performance of the catalyst is better. The comparison between Example 4, Example 5, and Example 8 shows that the higher the ratio of carrier A: carrier B, the more oxygen vacancies of the catalyst, the more conducive to ammonia decomposition, and the lower the ratio of carrier A: carrier B, the less likely Ru is to volatilize and lose. When the ratio of the two is controlled at 1:9~9:1, the ammonia decomposition performance of the aged catalyst is equivalent. The comparison between Example 5, Example 6, and Example 7 shows that the auxiliary agent is one or more of K, Rb, and Cs, and the ammonia decomposition catalytic performance of the aged catalyst is equivalent. The comparison between Example 1 and Example 9 shows that the higher the Ru content and the auxiliary agent content in the catalyst, the better the ammonia decomposition catalytic performance of the aged catalyst. The comparison between Example 1 and Comparative Example 1 shows that when the catalyst does not contain carrier B, Ru is lost in large quantities during the aging process, and the performance of the aged catalyst is the worst. Comparison between Example 1 and Comparative Example 2 shows that when the catalyst contains carrier A, there are more oxygen vacancies in the catalyst, and the ammonia decomposition performance of the aged catalyst is better. Comparison between Example 1 and Comparative Example 3 shows that after adding the additive, the basic sites increase, and the ammonia decomposition performance of the aged catalyst is better. Comparison between Comparative Example 1 and Comparative Example 4 shows that compared with Ca, the present invention adds K as an additive, and the ammonia decomposition performance of the aged catalyst is better. Comparison between Example 1 and Comparative Example 6 shows that compared with Ni, the present invention uses Ru as an active component, and the ammonia decomposition catalytic performance of the aged catalyst is significantly better.

[0083] Table 1 Ru or Ni loss rate in catalysts after hydrothermal aging

[0084] Table 2 Catalytic performance of aged catalysts for ammonia decomposition

[0085] Although the present invention has been illustrated and described with specific embodiments, it will be appreciated that many other changes and modifications may be made without departing from the spirit and scope of the present invention. Therefore, it is intended to include all such changes and modifications within the scope of the present invention in the appended claims.

Claims

1. A high temperature resistant ammonia decomposition catalyst, characterized in that: The catalyst is made of active component Ru, a carrier and an additive; The carrier includes a carrier A and a carrier B, wherein the carrier A includes a CeO2-ZrO2 solid solution, and the carrier B includes Fe2O3, CaCO3, Pr6O 11 Or at least one of La2O3; the auxiliary agent includes at least one of Li, Na, K, Rb or Cs.

2. The high temperature resistant ammonia decomposition catalyst according to claim 1, characterized in that: The mass ratio of the carrier A to the carrier B is 1:9~9:

1.

3. The high temperature resistant ammonia decomposition catalyst according to claim 1, characterized in that: The active component content accounts for 0.5wt%~5wt% of the catalyst, the carrier content accounts for 85wt%~99wt% of the catalyst, and the auxiliary agent content accounts for 0.5wt%~10wt% of the catalyst.

4. The high temperature resistant ammonia decomposition catalyst according to claim 1, characterized in that: The auxiliary agent includes at least one of K, Rb or Cs.

5. The high temperature resistant ammonia decomposition catalyst according to claim 1, characterized in that: The carrier B includes Fe2O3, or Fe2O3 and compound C, wherein compound C includes CaCO3, Pr6O 11 Or at least one of La2O3.

6. The method for preparing the high temperature resistant ammonia decomposition catalyst according to any one of claims 1 to 5, characterized in that: The following steps are involved: The active component Ru precursor aqueous solution and the auxiliary agent precursor aqueous solution are uniformly mixed to obtain a precursor mixed solution; The carrier A and the carrier B are ball-milled and mixed evenly to obtain a mixed carrier; The mixed carrier and the precursor mixed solution are mixed and allowed to stand for more than 2 hours, and then dried and calcined to obtain the high temperature resistant ammonia decomposition catalyst.

7. The method for preparing a high temperature resistant ammonia decomposition catalyst according to claim 6, characterized in that: The auxiliary agent precursor includes at least one of auxiliary agent nitrate, auxiliary agent carbonate or auxiliary agent hydroxide.

8. The method for preparing a high temperature resistant ammonia decomposition catalyst according to claim 6, characterized in that: The active component Ru precursor includes ruthenium nitrate and / or ruthenium chloride.

9. The method for preparing a high temperature resistant ammonia decomposition catalyst according to claim 6, characterized in that: The drying conditions are 100~120℃ for 3~5h, and the calcination conditions are 500~600℃ for 2~5h.

10. Use of the high temperature resistant ammonia decomposition catalyst according to any one of claims 1 to 5 or the high temperature resistant ammonia decomposition catalyst obtained by the preparation method according to any one of claims 6 to 9 in automobile exhaust purification.

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