An alkaline earth metal modified Ru / CeO2 passive nitrogen oxide adsorbent and a preparation method and application thereof

Abstract

The application relates to an alkaline earth metal modified Ru / CeO2 passive nitrogen oxide adsorbent (PNA) and a preparation method and application thereof, which comprises a main active component Ru, a carrier CeO2 and an alkaline earth metal additive. The molar ratio of the alkaline earth metal and Ru is controlled to be 0.5-3.0, and the mass ratio of Ru is 0.1%-3.0%. A co-impregnation method is used to prepare a Ru-M / CeO2 (M=Mg, Ca, Ba) adsorbent, and the adsorbent is used for treating NOx-containing tail gas. Compared with the Ru / CeO2 adsorbent, the Ru-M / CeO2 adsorbent disclosed by the application significantly improves the adsorption capacity, and the Ru-Ba / CeO2 adsorbent also effectively improves the thermal aging stability. The application effectively solves the problem of poor water thermal aging resistance of traditional metal oxides, simultaneously improves the PNA performance and the water thermal aging stability of the adsorbent, and is favorable for industrial application.

Description

Technical Field

[0001] This invention belongs to the field of nitrogen oxide treatment, and relates to an alkaline earth metal modified Ru / CeO2 passive nitrogen oxide adsorbent, its preparation method and application. Background Technology

[0002] Diesel engines are widely used in transportation and heavy machinery due to their high thermal efficiency, high torque, and good fuel economy. However, their exhaust gases contain nitrogen oxides (NOx). x Photochemical smog is one of the major air pollutants that contributes to photochemical smog, acid rain, and fine particulate matter (PM2.5). 2.5 The formation of NOx poses a serious threat to the environment and human health. With increasingly stringent global emission regulations, the development of efficient NOx emission control technologies is crucial. x After-treatment technologies are crucial. SCR is an essential part of diesel vehicle NOx emission control. x The mainstream emission control technology requires injecting a reducing agent (such as urea) into the exhaust gas to reduce NO under the action of a catalyst. x It is converted into harmless N2. However, during the cold start phase of a diesel engine, the exhaust temperature is often lower than the effective operating window of the SCR catalyst (typically >200°C), resulting in a large amount of NO being released. x Direct discharge without treatment.

[0003] To address NO during the cold start phase x Emissions issues, passive nitrogen oxide adsorbents (Passive NO) x Adsorber (PNA) technology emerged to address this need. PNA is designed to adsorb and store NO during low-temperature engine operation. x After the exhaust temperature rises to a range where the SCR catalyst can operate effectively, the stored NO will be... x Released for conversion. Therefore, an ideal PNA material should have the following characteristics: (1) high NO content at low temperatures (<200 °C, especially 60~150 °C). x (2) It can efficiently release NO within the target desorption temperature window (usually matched with the ignition temperature of the downstream SCR catalyst, such as 200~400 °C). x (3) Good hydrothermal stability and resistance to sulfur poisoning.

[0004] CeO2 is widely used as a key component of passive nitrogen oxide adsorbents (PNAs) due to its excellent oxygen storage and release capacity and strong interaction with noble metals. CN120502305A discloses a Ru / CeO2 passive nitrogen oxide adsorbent, its preparation method, and its applications. It compares the PNA activities of Ru loaded on different metal oxides and different noble metals on CeO2, finding that the Ru / CeO2 adsorbent exhibits the highest NO... xIt possesses good adsorption capacity and a suitable desorption temperature, along with good resistance to water and CO, and cycling stability. However, studies have found that the Ru / CeO2 adsorbent exhibits poor hydrothermal stability; after 10 hours of hydrothermal aging at 650 °C with 10 vol.% H2O, 20 vol.% O2, and Ar as the equilibrium gas, NO... x The adsorption / desorption capacity decreased by nearly 30%.

[0005] Introducing appropriate modifying components to modulate the chemical environment of active sites and the surface properties of materials is an effective strategy for improving PNA performance. Alkaline earth metal oxides are key NO in NSR technology. x Storage components that can effectively store NO in nitrate / nitrite form over a wide temperature range x Introducing alkaline earth metals into the Ru / CeO2 system holds promise for constructing multifunctional composite adsorbents: Ru sites are responsible for low-temperature NO activation, CeO2 provides rapid oxygen migration, and highly dispersed alkaline earth metal species act as the primary NO adsorbent. x Storage sites. This synergistic design theoretically enables efficient low-temperature capture and controlled mid-temperature release, and may enhance the structural stability of the material through the stabilizing effect of alkaline earth metals.

[0006] Therefore, it is necessary to develop a novel, high-performance, highly stable, and relatively cost-effective alkaline earth metal-modified Ru / CeO2 passive nitrogen oxide adsorbent, provide a reproducible preparation method, and clarify its performance in cold-start NO from diesel vehicle exhaust. x Its application in purification is of great practical significance and application value in making up for the shortcomings of existing technologies and meeting increasingly stringent emission regulations. Summary of the Invention

[0007] The purpose of this invention is to overcome the defects of the prior art by providing an alkaline earth metal modified Ru / CeO2 passive nitrogen oxide adsorbent, its preparation and application, which has higher adsorption capacity and higher desorption efficiency, and significantly improves the hydrothermal stability of the adsorbent.

[0008] The objective of this invention can be achieved through the following technical solutions: One of the objectives of this invention is to provide a Ru-M / CeO2 (M = Mg, Ca, Ba) passive nitrogen oxide adsorbent to further improve the adsorption capacity and desorption efficiency of the adsorbent. After hydrothermal aging for 10 hours at 650 °C with 10 vol.% H2O, 20 vol.% O2, and Ar as the equilibrium gas, the adsorbent's adsorption capacity and desorption efficiency do not decrease significantly, demonstrating excellent adsorption activity and stability.

[0009] This invention provides a Ru-M / CeO2 (M = Mg, Ca, Ba) passive nitrogen oxide adsorbent, comprising the following components and contents: Ru: 0.1%~3.0% (mass fraction) M:M / Ru = 0.5~3.0 (molar ratio) CeO2: The remaining carrier portion.

[0010] Furthermore, the CeO2 support was prepared by calcining cerium nitrate hexahydrate (Ce(NO3)3·6H2O) at 500~700 °C in air atmosphere for 2~6 hours, and then grinding it to obtain a light yellow powder.

[0011] A second objective of this invention is to provide a method for preparing a Ru-M / CeO2 (M = Mg, Ca, Ba) passive nitrogen oxide adsorbent using a co-impregnation method. Specifically, a CeO2 support is added to a mixed solution containing ruthenium nitrate and alkaline earth metal nitrates, and diluted with deionized water. The mixture is stirred at room temperature for 8-12 hours, then the mixture is rotary evaporated at 60-80°C, dried in an oven at 60-100°C for 8-14 hours, and finally calcined in air at 400-600°C for 2-6 hours.

[0012] A third objective of this invention is to provide an application of a Ru-M / CeO2 (M = Mg, Ca, Ba) passive nitrogen oxide adsorbent, specifically for treating NO-containing... x exhaust.

[0013] Furthermore, the Ru-M / CeO2 (M = Mg, Ca, Ba) adsorbent is pretreated before adsorption, specifically by pretreating the Ru-M / CeO2 adsorbent at 450~550 °C, preferably 500 °C, under conditions of O2 concentration of 5%~25% and Ar used to balance the gas pressure for 30~120 min.

[0014] Furthermore, the Ru-M / CeO2 (M = Mg, Ca, Ba) adsorbent is reacted at 60–150 °C with a space velocity of 30,000–120,000 mL·g. -1 ·h -1 NO adsorption under the conditions x exhaust.

[0015] Furthermore, the NO-containing substances to be processed x NO in exhaust gas x The concentration is 100~500 ppm, and the O2 concentration is 5%~25%.

[0016] Furthermore, the Ru-M / CeO2 (M = Mg, Ca, Ba) adsorbent, after adsorption, completes the NO removal process at 200~500 °C. x The exhaust gas is desorbed under the following conditions: with an O2 concentration of 5% to 25% and Ar used to balance the gas pressure, the temperature is increased to 450 to 550 °C at a certain rate and treated for 30 to 120 min.

[0017] Furthermore, the Ru-M / CeO2 (M = Mg, Ca, Ba) adsorbent was subjected to hydrothermal aging treatment for 10 h at 650 °C with 10 vol.% H2O, 20 vol.% O2, and Ar as the equilibrium gas, and was further used for PNA performance testing to test the hydrothermal stability of the adsorbent.

[0018] Compared with the prior art, the present invention has the following beneficial effects: One of the significant advantages of this invention is that, compared to Ru / CeO2 adsorbents, the addition of alkaline earth metals provides additional NO. x The adsorption sites further enhance the adsorption and desorption capacity of the adsorbent.

[0019] A second significant advantage of this invention is that, compared to Ru / CeO2 adsorbents, the addition of Ba effectively stabilizes the CeO2 structure, inhibits the migration of atoms and grain growth on the CeO2 surface, and enhances the metal-support interaction between Ru and CeO2 by altering the electronic state of the CeO2 surface. This prevents Ru agglomeration and sintering, significantly improving the adsorbent's resistance to hydrothermal aging, with almost no decrease in PNA activity. This provides an innovative solution for the widespread application of noble metal-supported metal oxides in the PNA field. Attached Figure Description

[0020] Figure 1 NO before and after hydrothermal aging at 650 ℃ using 1Ru-M1 / CeO2 (M = Mg, Ca, Ba) adsorbent x Adsorption-desorption curves; Figure 2 NO before and after hydrothermal aging at 650 ℃ using 1Ru-M1 / CeO2 (M = Mg, Ca, Ba) adsorbent x Desorption volume bar chart; Figure 3 NO2 content of M1 / CeO2 (M = Mg, Ca, Ba) adsorbent before and after hydrothermal aging at 650 °C x Adsorption-desorption curves; Figure 4 NO2 content of M1 / CeO2 (M = Mg, Ca, Ba) adsorbent before and after hydrothermal aging at 650 °Cx Bar chart of desorption volume. Detailed Implementation

[0021] The present invention will now be described in detail with reference to specific embodiments, but this is by no means a limitation on the scope of protection of the present invention. Example

[0022] Preparation of 1Ru-Mg1 / CeO2 adsorbent: 0.025 g of solid Mg(NO3)2·6H2O and 0.98 g of aqueous solution of Ru(NO)NO3 (Ru content 1.02 wt.%) were weighed into a round-bottom flask, controlling the molar ratio Mg / Ru = 1.0. 30 mL of deionized water was added for dilution, and the mixture was stirred evenly. Then, 0.988 g of CeO2 from Comparative Example 1 was added, and the mixture was stirred at room temperature for 10 h. After thorough mixing, the mixture was rotary evaporated at 60 ℃ and dried in an oven at 80 ℃ for 12 h. The powder was then ground in a mortar and finally calcined in a muffle furnace at 550 ℃ for 4 h to obtain the 1Ru-Mg1 / CeO2 adsorbent. Example

[0023] Preparation of 1Ru-Ca1 / CeO2 adsorbent: 0.023 g of solid Ca(NO3)2·4H2O and 0.98 g of aqueous solution of Ru(NO)NO3 (Ru content 1.02 wt.%) were weighed into a round-bottom flask, controlling the molar ratio Ca / Ru = 1.0. 30 mL of deionized water was added for dilution, and the mixture was stirred evenly. Then, 0.986 g of CeO2 from Comparative Example 1 was added, and the mixture was stirred at room temperature for 10 h. After thorough mixing, the mixture was rotary evaporated at 60 ℃ and dried in an oven at 80 ℃ for 12 h. The powder was then ground in a mortar and finally calcined in a muffle furnace at 550 ℃ for 4 h to obtain the 1Ru-Ca1 / CeO2 adsorbent. Example

[0024] Preparation of 1Ru-Ba1 / CeO2 adsorbent: 0.026 g of solid Ba(NO3)2 and 0.98 g of aqueous solution Ru(NO)NO3 (Ru content 1.02 wt.%) were weighed into a round-bottom flask, controlling the molar ratio Ba / Ru = 1.0. 30 mL of deionized water was added for dilution, and the mixture was stirred thoroughly. Then, 0.976 g of CeO2 from Comparative Example 1 was added, and the mixture was stirred at room temperature for 10 h. After thorough mixing, the mixture was rotary evaporated at 60 ℃ and dried in an oven at 80 ℃ for 12 h. The powder was then ground in a mortar and finally calcined in a muffle furnace at 550 ℃ for 4 h to obtain the 1Ru-Ba1 / CeO2 adsorbent.

[0025] Comparative Example 1: Preparation of CeO2 adsorbent: Ce(NO3)3·6H2O was calcined in a muffle furnace at 600 ℃ for 4 h and then ground into powder in a mortar to obtain CeO2 adsorbent.

[0026] Comparative Example 2: Preparation of CeO2-HTA adsorbent: The CeO2 adsorbent in Comparative Example 1 was subjected to hydrothermal aging treatment at 650 °C for 10 h under the conditions of 10 vol.% H2O, 20 vol.% O2, and Ar as the equilibrium gas to obtain CeO2-HTA adsorbent.

[0027] Comparative Example 3: Preparation of 1Ru / CeO2 adsorbent: Weigh 0.98 g of Ru(NO)NO3 aqueous solution (Ru content 1.02 wt.%) into a round-bottom flask, dilute with 30 mL of deionized water, then add 0.990 g of CeO2 from Comparative Example 1, and stir at room temperature for 10 h. After thorough mixing, rotary evaporate at 60 ℃, dry in an oven at 80 ℃ for 12 h, grind into powder in a mortar, and finally calcine in a muffle furnace at 550 ℃ for 4 h to obtain 1Ru / CeO2 adsorbent.

[0028] Comparative Example 4: Preparation of 1Ru / CeO2-HTA adsorbent: The 1Ru / CeO2 adsorbent in Comparative Example 3 was subjected to hydrothermal aging treatment at 650 °C for 10 h under the conditions of 10 vol.% H2O, 20 vol.% O2, and Ar as the equilibrium gas to obtain the 1Ru / CeO2-HTA adsorbent.

[0029] Comparative Example 5: Preparation of Mg1 / CeO2 adsorbent: Weigh 0.025 g of Mg(NO3)2·6H2O solid into a round-bottom flask, add 30 mL of deionized water to dilute, stir evenly, then add 0.998 g of CeO2 from Comparative Example 1, and stir at room temperature for 10 h. After thorough mixing, rotary evaporate at 60 ℃, dry in an oven at 80 ℃ for 12 h, grind into powder in a mortar, and finally calcine in a muffle furnace at 550 ℃ for 4 h to obtain the Mg1 / CeO2 adsorbent.

[0030] Comparative Example 6: Preparation of Mg1 / CeO2-HTA adsorbent: The Mg1 / CeO2 adsorbent in Comparative Example 5 was subjected to hydrothermal aging treatment at 650 °C for 10 h under the conditions of 10 vol.% H2O, 20 vol.% O2, and Ar as the equilibrium gas to obtain the Mg1 / CeO2-HTA adsorbent.

[0031] Comparative Example 7: Preparation of Ca1 / CeO2 adsorbent: Weigh 0.023 g of Ca(NO3)2·4H2O solid into a round-bottom flask, add 30 mL of deionized water to dilute, stir evenly, then add 0.996 g of CeO2 from Comparative Example 1, and stir at room temperature for 10 h. After thorough mixing, rotary evaporate at 60 ℃, dry in an oven at 80 ℃ for 12 h, grind into powder in a mortar, and finally calcine in a muffle furnace at 550 ℃ for 4 h to obtain Ca1 / CeO2 adsorbent.

[0032] Comparative Example 8: Preparation of Ca1 / CeO2-HTA adsorbent: The Ca1 / CeO2 adsorbent in Comparative Example 7 was subjected to hydrothermal aging treatment at 650 °C for 10 h under the conditions of 10 vol.% H2O, 20 vol.% O2, and Ar as the equilibrium gas to obtain the Ca1 / CeO2-HTA adsorbent.

[0033] Comparative Example 9: Preparation of Ba1 / CeO2 adsorbent: Weigh 0.026 g of Ba(NO3)2 solid into a round-bottom flask, add 30 mL of deionized water to dilute, stir evenly, then add 0.986 g of CeO2 from Comparative Example 1, and stir at room temperature for 10 h. After thorough mixing, rotary evaporate at 60 °C, dry in an oven at 80 °C for 12 h, grind into powder in a mortar, and finally calcine in a muffle furnace at 550 °C for 4 h to obtain Ba1 / CeO2 adsorbent.

[0034] Comparative Example 10: Preparation of Ba1 / CeO2-HTA adsorbent: The Ba1 / CeO2 adsorbent in Comparative Example 9 was subjected to hydrothermal aging treatment at 650 °C for 10 h under the conditions of 10 vol.% H2O, 20 vol.% O2, and Ar as the equilibrium gas to obtain the Ba1 / CeO2-HTA adsorbent.

[0035] Comparative Example 11: Preparation of 1Ru-Mg1 / CeO2-HTA adsorbent: The 1Ru-Mg1 / CeO2 adsorbent in Example 1 was subjected to hydrothermal aging treatment at 650 °C for 10 h under the conditions of 10 vol.% H2O, 20 vol.% O2, and Ar as the equilibrium gas to obtain the 1Ru-Mg1 / CeO2-HTA adsorbent.

[0036] Comparative Example 12: Preparation of 1Ru-Ca1 / CeO2-HTA adsorbent: The 1Ru-Ca1 / CeO2 adsorbent in Example 2 was subjected to hydrothermal aging treatment at 650 °C for 10 h under the conditions of 10 vol.% H2O, 20 vol.% O2, and Ar as the equilibrium gas to obtain the 1Ru-Ca1 / CeO2-HTA adsorbent.

[0037] Comparative Example 13: Preparation of 1Ru-Ba1 / CeO2-HTA adsorbent: The 1Ru-Ba1 / CeO2 adsorbent in Example 3 was subjected to hydrothermal aging treatment at 650 °C for 10 h under the conditions of 10 vol.% H2O, 20 vol.% O2, and Ar as the equilibrium gas to obtain the 1Ru-Ba1 / CeO2-HTA adsorbent.

[0038] The performance evaluation of PNA adsorbents mainly includes pretreatment, NO adsorption, and NO... x Desorption involves three steps.

[0039] Pretreatment: Weigh 0.100 g of the above adsorbent (40-60 mesh) into a fixed-bed quartz reactor, introduce 8 vol.% O2 / Ar, and pretreat at 500 °C for 30 min with a total gas flow rate of 100 mL / min.

[0040] Adsorption: After pretreatment, the temperature was lowered to 80 °C, and the gas was passed through an empty tube. 500 ppm NO and 8 vol.% O2 were introduced, with Ar used as the equilibrium gas. The total gas flow rate was 100 mL / min, and the mass hourly space velocity (MHV) was 60000 mL·g. -1 ·h -1 After the NO concentration stabilizes, the gas is introduced into the reactor and adsorbed at 80 °C for 3 h until the adsorbent is saturated.

[0041] Desorption: Close the NO gas path, purge with 8 vol.% O2 / Ar at 80 °C for 45 min, then raise the temperature to 500 °C at a rate of 20 °C / min and stabilize for 30 min.

[0042] NO is used in the reaction tail gas x Concentration analysis was used for detection. The performance evaluation of this adsorbent is mainly determined by the desorption rate at 100~500 °C.

[0043] The adsorbents in Examples 1-3 and Comparative Examples 3-4 and 11-13 were evaluated for NO using the methods described above. x Adsorption-desorption performance test results are as follows: Figure 1 and Figure 2As shown in the figure, the desorption capacity of the 1Ru / CeO2 adsorbent without the addition of alkaline earth metals was only 220.0 μmol / g. After introducing Mg, Ca, or Ba, the desorption capacity increased to 283.4 μmol / g, 318.1 μmol / g, and 272.9 μmol / g, respectively, showing a significant improvement. After hydrothermal aging at 650 ℃, the desorption capacity of the 1Ru / CeO2 adsorbent decreased to 157.5 μmol / g, a decrease of 28.4%. The adsorbents with the addition of Mg or Ca showed a decrease in desorption capacity to 192.9 μmol / g and 259.9 μmol / g, respectively, after hydrothermal aging, with decreases of 31.9% and 18.3%, respectively, and no significant improvement in hydrothermal stability was observed. In contrast, the introduction of Ba significantly enhanced the hydrothermal aging resistance of the 1Ru / CeO2 adsorbent, with the desorption capacity remaining at 252.7 μmol / g after hydrothermal aging, a decrease of only 7.4%.

[0044] Furthermore, the same evaluation method was used to test the NO content of the adsorbents in proportions 1-2 and 5-10. x Adsorption-desorption performance evaluation results are as follows: Figure 3 and Figure 4 As shown, for the Ru-free adsorbent system, doping with Mg, Ca, or Ba did not significantly improve the desorption capacity of CeO2, nor did it effectively inhibit the decrease in PNA activity caused by hydrothermal aging of CeO2. This indicates that doping alkaline earth metals into the Ru / CeO2 adsorbent does not introduce additional adsorption sites, but may instead optimize the distribution of Ru on CeO2, or create new interactions between Ru and alkaline earth metals, thereby promoting the adsorption of NO on Ru / CeO2.

[0045] Table 1 shows the adsorption and desorption amounts of passive nitrogen oxide adsorbents in different embodiments and comparative examples.

[0046] Table 1. Adsorbent effect on NO x Adsorption and desorption statistics Adsorbent Adsorption capacity (pmol / g) Desorption capacity (pmol / g) Example 1 1 Ru-Mg1 / CeO2 331.4 283.4 Example 2 1 Ru-Ca1 / CeO2 405.1 318.1 Example 3 1 Ru-Ba1 / CeO2 296.7 272.9 Comparative Example 1 CeO2 183.8 163.6 Comparative Example 2 CeO2-HTA 131.4 66.8 Comparative Example 3 1 Ru / CeO2 275.5 220.0 Comparative Example 4 1 Ru / CeO2-HTA 209.3 157.5 Comparative Example 5 [Mg1 / CeO2] 262.6 179.6 Comparative Example 6 Mg1 / CeO2-HTA 149.2 80.2 Comparative Example 7 Ca1 / CeO2 263.4 169.7 Comparative Example 8 Ca1 / CeO2-HTA 149.0 71.7 Comparative Example 9 [Ba1 / CeO2] 190.1 182.4 Comparative Example 10 [Ba1 / CeO2-HTA] 152.4 105.9 Comparative Example 11 1 Ru-Mg1 / CeO2-HTA 248.1 192.9 Comparative Example 12 1 Ru-Ca1 / CeO2-HTA 292.7 259.9 Comparative Example 13 1 Ru-Ba1 / CeO2-HTA 274.7 252.7 In summary, this invention provides an alkaline earth metal-modified Ru / CeO2 passive nitrogen oxide adsorbent, its preparation method, and its application. After incorporating small amounts of Mg, Ca, and Ba, respectively, the desorption capacity of the Ru / CeO2 adsorbent was significantly improved, increasing by 28.8%, 44.6%, and 24.0%, respectively. In particular, the introduction of Ba further enhances the adsorbent's resistance to hydrothermal aging; after hydrothermal aging at 650 °C for 10 h, the desorption capacity decreased by only 7.4%. Furthermore, the preparation method is simple and easy to implement, making it suitable for large-scale application.

[0047] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A Ru-M / CeO2 (M = Mg, Ca, Ba) passive nitrogen oxide adsorbent, characterized in that, It includes the following components and contents: Ru: 0.1%~3.0% (mass fraction) M:M / Ru = 0.5~3.0 (molar ratio) CeO2: The remaining carrier portion.

2. The Ru-M / CeO2 (M = Mg, Ca, Ba) passive nitrogen oxide adsorbent according to claim 1, characterized in that, The CeO2 carrier is prepared by calcining cerium nitrate hexahydrate at 500-700 °C in air for 2-6 hours, and then grinding it to obtain a light yellow powder.

3. A method for preparing the Ru-M / CeO2 (M = Mg, Ca, Ba) passive nitrogen oxide adsorbent as described in claim 1, characterized in that, The Ru-M / CeO2 adsorbent was prepared by co-impregnation method as follows: CeO2 support was added to a mixed solution containing ruthenium nitrate and alkaline earth metal nitrate, and deionized water was added for dilution. The mixture was stirred at room temperature for 8-12 hours, then the mixture was rotary evaporated at 60-80 °C and dried in an oven at 60-100 °C for 8-14 hours. Finally, it was calcined in air at 400-600 °C for 2-6 hours.

4. The application of the Ru-M / CeO2 (M = Mg, Ca, Ba) passive nitrogen oxide adsorbent as described in claim 3, characterized in that, The adsorbent is used to treat NO-containing x exhaust.

5. The application of the Ru-M / CeO2 (M = Mg, Ca, Ba) passive nitrogen oxide adsorbent according to claim 4, characterized in that, The Ru-M / CeO2 adsorbent is pretreated before adsorption, specifically by pretreating the Ru-M / CeO2 adsorbent at 450~550 °C for 30~120 min under conditions of O2 concentration of 5%~25% and Ar used to balance the gas pressure.

6. The application of the Ru-M / CeO2 (M = Mg, Ca, Ba) passive nitrogen oxide adsorbent according to claim 4, characterized in that, The Ru-M / CeO2 adsorbent was reacted at 60–150 °C with a space velocity of 30,000–120,000 mL·g. -1 ·h -1 NO adsorption under the conditions x exhaust.

7. The application of a Ru-M / CeO2 (M = Mg, Ca, Ba) passive nitrogen oxide adsorbent according to claim 4 or 6, characterized in that, NO to be processed x NO in exhaust gas x The concentration is 100~500 ppm, and the O2 concentration is 5%~25%.

8. The application of the Ru-M / CeO2 (M = Mg, Ca, Ba) passive nitrogen oxide adsorbent according to claim 4, characterized in that, The Ru-M / CeO2 adsorbent, after adsorption, completes the NO removal process at 200~500℃. x The exhaust gas is desorbed under the following conditions: with an O2 concentration of 5% to 25% and Ar used to balance the gas pressure, the temperature is increased to 450 to 550 ℃ at a certain rate (2 to 20 ℃ / min) and treated for 30 to 120 min.

9. The application of the Ru-M / CeO2 (M = Mg, Ca, Ba) passive nitrogen oxide adsorbent according to claim 4, characterized in that, The Ru-M / CeO2 adsorbent was subjected to hydrothermal aging treatment at 650 °C for 10 h under the conditions of 10 vol.% H2O, 20 vol.% O2, and Ar as the equilibrium gas, and was further used in the treatment described in claims 5 to 8 to test the hydrothermal stability of the adsorbent.

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