A catalyst, a nitrogen oxide gas treatment system, and a vehicle

Abstract

This application discloses a catalyst, a nitrogen oxide gas treatment system, and a vehicle, relating to the field of catalysis technology, and aims to solve the problem of low catalytic activity of catalysts. The catalyst includes copper element; the copper element includes isolated copper ions and copper ions present in copper oxide, wherein the number of atoms of the isolated copper ions is greater than the number of atoms of the copper ions in the copper oxide.

Description

Technical Field

[0001] This application relates to the field of catalysis technology, and more particularly to a catalyst, a nitrogen oxide gas treatment system, and a vehicle. Background Technology

[0002] Nitrogen oxides (NOx) are one of the main pollutants in vehicle exhaust, contributing to atmospheric pollution. Selective catalytic reduction (SCR) systems, through the action of a catalyst, can selectively reduce NOx gases into nitrogen and water, effectively reducing NOx emissions from vehicle exhaust. However, current SCR catalysts exhibit low catalytic activity within the temperature window of 550℃ to 650℃, affecting the conversion rate of the NOx reduction reaction. Summary of the Invention

[0003] The purpose of this application is to provide a catalyst, a nitrogen oxide gas treatment system, and a vehicle, which aims to solve the problem of low catalytic activity of the catalyst in the temperature window range of 550°C to 650°C.

[0004] To achieve the above objectives, this application adopts the following technical solution:

[0005] In a first aspect, this application provides a catalyst for catalyzing the reduction reaction of nitrogen oxide gas. The catalyst comprises copper. The copper element includes isolated copper ions and copper ions present in copper oxide, wherein the number of isolated copper ions is greater than the number of copper ions present in copper oxide.

[0006] The catalyst provided in this application uses copper as an active component that catalyzes the reduction reaction of nitrogen oxides. The active sites in copper promote the reaction between nitrogen oxides and the reducing agent. Copper exists primarily in the form of isolated copper ions and copper ions present in copper oxide, including isolated Cu. 2+ CuO and Cu + Among them, isolated Cu 2+ As the active site for the reduction reaction of nitrogen oxides, it can more easily come into contact with and interact with nitrogen oxides. The isolated copper ions react with nitrogen oxides through two reduction steps to finally reduce to Cu(Cu). 2+ →Cu + Cu + →Cu): At temperatures below 800℃, Cu 2+ Reduced to Cu + At temperatures above 800℃, Cu +The copper ions are reduced to Cu, thus promoting the catalytic reaction. Furthermore, isolated copper ions tend to directly participate in the reduction of nitrogen oxides, promoting their decomposition and reduction through processes such as electron transfer. By setting the number of isolated copper ions to be greater than that of copper ions in copper oxide, even at higher temperatures of 550℃ to 650℃ where a small number of isolated copper ions aggregate, there are still sufficient isolated copper ions present, preventing the formation of large amounts of copper oxide particles. This weakens the effect on ammonia oxidation, reducing the consumption of reducing agent and allowing more reducing agent to be used for the reduction of nitrogen oxides, thereby increasing the conversion rate of nitrogen oxides.

[0007] Therefore, the more isolated copper ions there are in copper, the more active sites there are, and the better the catalyst performance. Increasing the number of atoms will help improve the overall catalytic activity of the catalyst, promote the reduction reaction of nitrogen oxides, and improve the conversion rate of nitrogen oxide gas reduction reaction of the catalyst in the temperature window range of 550℃~650℃.

[0008] In some embodiments, the catalyst further includes a molecular sieve.

[0009] The ratio of the mass of copper to the sum of the mass of the molecular sieve and the mass of copper ranges from 0.01 to 0.04.

[0010] In some embodiments, the catalyst includes a first catalyst and a second catalyst, wherein the second catalyst is different from the first catalyst.

[0011] In some embodiments, within a temperature range of 550°C to 650°C, the conversion rate of the first catalyst for the reduction reaction of nitrogen oxides is greater than that of the second catalyst for the reduction reaction of nitrogen oxides.

[0012] In some embodiments, the first catalyst includes at least one of AEI-type molecular sieve and CHA-type molecular sieve.

[0013] In some embodiments, the first catalyst comprises Cu-SSZ-39.

[0014] In some embodiments, the ratio of the mass of copper in Cu-SSZ-39 to the mass of Cu-SSZ-39 ranges from 0.01 to 0.04.

[0015] In some embodiments, the ratio of the mass of copper in Cu-SSZ-39 to the mass of Cu-SSZ-39 ranges from 0.01 to 0.03.

[0016] In some embodiments, the second catalyst includes at least one of BEA-type molecular sieve, MFI-type molecular sieve, and CHA-type molecular sieve.

[0017] In some embodiments, the second catalyst comprises Cu-SSZ-13.

[0018] In some embodiments, the ratio of the mass of copper in Cu-SSZ-13 to the mass of Cu-SSZ-13 ranges from 0.01 to 0.04.

[0019] In some embodiments, the ratio of the mass of copper in Cu-SSZ-13 to the mass of Cu-SSZ-13 ranges from 0.01 to 0.03.

[0020] In some embodiments, the catalyst further includes a support. The catalyst is disposed on the support.

[0021] In some embodiments, the carrier comprises a porous ceramic material.

[0022] In some embodiments, the support includes a first support and a second support. A first catalyst is disposed on the first support. A second catalyst is disposed on the second support.

[0023] In some embodiments, the first support has a porous structure. The first catalyst is at least partially disposed on the pore walls of the first support. The thickness of the first catalyst on the pore walls of the first support ranges from 50 μm to 100 μm.

[0024] In some embodiments, the second support has a porous structure. The second catalyst is at least partially disposed on the pore walls of the second support. The thickness of the second catalyst on the pore walls of the second support ranges from 50 μm to 100 μm.

[0025] In some embodiments, the thickness of the first catalyst on the pore wall of the first support ranges from 70 μm to 80 μm.

[0026] In some embodiments, the thickness of the second catalyst on the pore wall of the second support ranges from 70 μm to 80 μm.

[0027] In some embodiments, the catalyst includes a first catalytic region and a second catalytic region arranged along a first direction. The first direction is the flow direction of the nitrogen oxide gas. The first catalytic region comprises a first support and a first catalyst. The second catalytic region comprises a second support and a second catalyst.

[0028] In some embodiments, the ratio between the length of the first catalytic region and the length of the second catalytic region ranges from 0.2 to 5. The length direction is the flow direction of the nitrogen oxide gas.

[0029] In some embodiments, the ratio of the mass of the first catalyst to the mass of the second catalyst ranges from 0.2 to 5.

[0030] Secondly, this application provides a nitrogen oxide gas treatment system. The treatment system includes: an inlet end disposed along a first direction, a catalyst as described in any of the above embodiments, and an outlet end.

[0031] In some embodiments, when the catalyst includes a first catalytic region and a second catalytic region arranged along a first direction, the first catalytic region is closer to the intake end than the second catalytic region.

[0032] It is understood that the beneficial effects of the nitrogen oxide gas treatment system provided in the above embodiments of this application can be referred to the beneficial effects of the catalyst mentioned above, and will not be repeated here.

[0033] Thirdly, this application provides a vehicle. The vehicle includes a nitrogen oxide gas treatment system as described in the above embodiments.

[0034] It is understood that the beneficial effects that the vehicle provided in the above embodiments of this application can achieve can be referred to the beneficial effects of the catalyst mentioned above, and will not be repeated here. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 A schematic diagram of a nitrogen oxide gas treatment system provided for some embodiments of this application;

[0037] Figure 2 A cross-sectional schematic diagram of a catalyst provided for some embodiments of this application;

[0038] Figure 3 A cross-sectional schematic diagram of yet another catalyst provided in some embodiments of this application;

[0039] Figure 4 This is a graph showing the conversion rate of nitrogen oxides in a fresh sample of the catalyst according to an embodiment of this application.

[0040] Figure 5 This is a graph showing the conversion rate of nitrogen oxides in the catalyst aging sample of this application embodiment;

[0041] Figure 6 The H2- temperature-programmed reduction spectrum of Cu-SSZ-13 provided in Example 3 of this application;

[0042] Figure 7The H2- temperature-programmed reduction spectrum of Cu-SSZ-39 provided in Example 2 of this application.

[0043] Reference numerals: C1 - first catalytic region, C2 - second catalytic region, 10 - catalyst, 11 - first support, 12 - first catalyst, 13 - second support, 14 - second catalyst. Detailed Implementation

[0044] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0045] In the description of this application, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or relative positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and for simplification, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Unless otherwise specified, the above-mentioned orientational descriptions can be flexibly set in practical applications, provided that the relative positional relationships shown in the accompanying drawings are satisfied.

[0046] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0047] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "communication" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. They can refer to a direct connection or an indirect connection through an intermediate medium, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0048] In embodiments of this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, article, or apparatus that includes that element.

[0049] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0050] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0051] Vehicles are an indispensable means of transportation; however, nitrogen oxides in vehicle exhaust are one of the major air pollutants, which have a serious impact on the atmospheric environment and human health.

[0052] An embodiment of this application provides a vehicle. The vehicle includes a nitrogen oxide gas treatment system.

[0053] Nitrogen oxide gas treatment systems, as a type of exhaust gas purification technology, use a catalyst to chemically react nitrogen oxide gases in the exhaust gas with a reducing agent (such as ammonia) to ultimately produce harmless nitrogen and water, thus effectively purifying nitrogen oxide gases in automobile exhaust and are widely used in the automotive field.

[0054] like Figure 1 As shown, this application provides a schematic diagram of a nitrogen oxide gas treatment system. The treatment system includes an inlet end I, a catalyst 10, and an outlet end E arranged along a first direction X.

[0055] Understandably, intake end I is the starting point of the nitrogen oxide gas treatment system, responsible for receiving exhaust gases from the vehicle's nitrogen oxide emission sources. Exit end E is the end point of the nitrogen oxide gas treatment system, which releases the treated exhaust gases into the atmosphere.

[0056] Catalyst 10 is the core component of the treatment system, located between the inlet end I and the outlet end E. It can promote the chemical reaction between nitrogen oxide gas and reducing agent, accelerate the reaction between reducing agent and nitrogen oxide gas, and generate harmless nitrogen and water.

[0057] In some implementations, the catalyst 10 exhibits low reactivity over a wide reaction temperature range (e.g., 200–700 °C), particularly within a temperature window of 550 °C–650 °C, resulting in a low conversion rate for the reduction reaction of nitrogen oxides gas and affecting the efficiency of the nitrogen oxide gas treatment system.

[0058] Based on this, this application provides a catalyst 10 for catalyzing the reduction reaction of nitrogen oxide gas. The catalyst 10 comprises copper element. The copper element includes isolated copper ions and copper ions present in copper oxide. The number of isolated copper ions is greater than the number of copper ions present in copper oxide.

[0059] Copper is an active component that catalyzes the reduction reaction of nitrogen oxides. The active sites in copper can promote the reaction between nitrogen oxides and reducing agents, thereby increasing the conversion rate of nitrogen oxides.

[0060] The copper element in catalyst 10 exists mainly in the forms of isolated copper ions and copper ions present in copper oxide, including isolated Cu. 2+ CuO and Cu + In copper oxide, copper ions form polar covalent bonds with oxygen, while isolated copper ions are bonded to other elements through ionic bonds or other non-covalent bonds. Among these, isolated Cu... 2+ As an active site for the reduction reaction of nitrogen oxides, it can more easily come into contact with and interact with nitrogen oxides. The isolated copper ions react with nitrogen oxides through two reduction steps to finally reduce to Cu. 0 (Cu 2+ →Cu + Cu + →Cu 0 ): At temperatures below 800℃, Cu 2+ Reduced to Cu + At temperatures above 800℃, Cu + Reduced to Cu 0 This promotes the catalytic reaction; moreover, isolated copper ions tend to directly participate in the reduction reaction of nitrogen oxides, promoting the decomposition and reduction of nitrogen oxides through processes such as electron transfer.

[0061] However, at temperatures between 550℃ and 650℃, a small number of metal atoms coordinated with isolated copper ions will be removed, causing the isolated copper ions to aggregate and form copper oxide particles. These copper oxide particles promote the oxidation reaction of ammonia and consume the reducing agent in the reduction reaction of nitrogen oxides. Therefore, by setting the number of isolated copper ions to be greater than the number of copper ions in copper oxide, even if a small number of isolated copper ions aggregate at the higher temperatures of 550℃ to 650℃, there will still be enough isolated copper ions to form a large number of copper oxide particles. This will have a weaker impact on the oxidation of ammonia, thereby reducing the consumption of reducing agent and allowing more reducing agent to be used in the reduction reaction of nitrogen oxides, thus improving the conversion rate of nitrogen oxides.

[0062] Therefore, the more isolated copper ions there are in copper, the more active sites there are, and the better the performance of catalyst 10. Increasing the number of atoms will help improve the overall catalytic activity of catalyst 10 and promote the reduction reaction of nitrogen oxides. It can also improve the conversion rate of nitrogen oxide gas reduction reaction of catalyst 10 in the temperature window range of 550℃~650℃.

[0063] In this application, each copper element in catalyst 10 can be characterized by H2-temperature programmed reduction (H2-TPR) spectrum. Isolated copper ions located near the eight-membered ring window are more easily reduced by the reducing agent (H2), thus corresponding to the reduction peak at a lower temperature (200℃~300℃) of H2-TPR. Isolated copper ions located at the center of the hexagonal prism are coordinated with two tetragonal Al crystals, making the isolated copper ions more stable. Therefore, a higher temperature is required for reduction, corresponding to the reduction peak at a higher temperature (400℃~700℃) of H2-TPR. Furthermore, copper ions in copper oxide are reduced at moderate temperatures (300℃~400℃), corresponding to the reduction peak of H2-TPR in the temperature range of 300℃~400℃; at the same time, the number of copper atoms can be obtained from the integrated area of ​​the reduction peak, that is, the number of isolated copper ions can be obtained by summing the integrated area of ​​the reduction peak at 200℃~300℃ and the integrated area of ​​the reduction peak at 400℃~700℃; the number of copper ions in copper oxide can be obtained by the integrated area of ​​the reduction peak at 300℃~400℃.

[0064] In some embodiments, catalyst 10 further includes a molecular sieve.

[0065] The ratio of the mass of copper to the sum of the mass of the molecular sieve and the mass of copper ranges from 0.01 to 0.04.

[0066] For example, the ratio of the mass of copper to the sum of the mass of the molecular sieve and the mass of copper can be 0.01, 0.02, 0.027, 0.03, or 0.04, etc., and there is no limitation here.

[0067] Understandably, molecular sieves are inorganic crystalline materials with regular pore structures formed by connecting tetrahedrons with common vertices. They have abundant acidic sites and ion exchange sites, exhibiting excellent catalytic activity against nitrogen oxides, nitrogen selectivity, hydrothermal stability, and a wide temperature window. Furthermore, they can efficiently remove nitrogen oxides under high space velocity conditions.

[0068] By setting the ratio of the mass of copper to the sum of the mass of the molecular sieve and the mass of copper within the range of 0.01 to 0.04, the distribution of active sites in catalyst 10 can be optimized, allowing copper to achieve the best dispersion state on the surface of catalyst 10, thereby improving the catalytic effect of catalyst 10 on nitrogen oxides. It can also prevent the problem of insufficient catalyst activity due to too low copper content, and the problem of copper agglomeration or migration due to too high copper content, effectively preventing the deactivation or performance degradation of catalyst 10, so that copper can exist stably in the channels of copper-based molecular sieve, and is not prone to migration or agglomeration, thereby maintaining the stability of catalyst 10.

[0069] In some embodiments, such as Figure 2 and Figure 3 As shown, catalyst 10 includes a first catalyst 12 and a second catalyst 14, and the second catalyst 14 is different from the first catalyst 12.

[0070] Understandably, different catalysts 10 (first catalyst 12 and second catalyst 14) have different catalytic activities, providing more active sites and increasing the reduction rate of nitrogen oxides. Furthermore, different catalysts 10 have different reaction temperature ranges, allowing them to maintain high activity over a wider temperature range. Therefore, first catalyst 12 and second catalyst 14 can optimize the diffusion process of nitrogen oxides on the surface of catalyst 10, improving reaction efficiency. Moreover, the second catalyst 14 differs from the first catalyst 12; that is, the structural difference between the second catalyst 14 and the first catalyst 12 allows them to exhibit different catalytic activities in the catalytic reaction. This makes catalyst 10 suitable for catalytic activity within the overall temperature window (200℃~700℃), thereby further improving the catalytic conversion of catalyst 10 within the overall temperature window.

[0071] In some embodiments, within a temperature range of 550°C to 650°C, the conversion rate of the first catalyst 12 for the reduction reaction of nitrogen oxides is greater than that of the second catalyst 14 for the reduction reaction of nitrogen oxides.

[0072] Understandably, within the temperature range of 550℃ to 650℃, the first catalyst 12 can effectively promote the chemical reaction between nitrogen oxide gas and the reducing agent, generating harmless nitrogen gas and water vapor. The first catalyst 12 is more effective at temperatures between 550℃ and 650℃, which solves the problem of the second catalyst 14 having a low conversion rate at higher temperatures. Thus, the first catalyst 12 and the second catalyst 14 can work synergistically, enabling the catalyst 10 to achieve a good conversion rate within the overall temperature window (200℃ to 700℃) of the nitrogen oxide gas treatment system, thereby providing a higher overall catalytic efficiency.

[0073] In some embodiments, the first catalyst 12 comprises at least one of AEI-type molecular sieve and CHA-type molecular sieve.

[0074] AEI-type molecular sieves are composed of tetrahedral units of silicon, aluminum, and phosphorus interconnected through shared oxygen atoms, forming a stable framework structure. The framework contains nanocages, which facilitate effective contact and reaction between nitrogen oxide gases and reducing agents, resulting in excellent thermal stability and catalytic activity. CHA-type molecular sieves are silicon-aluminum molecular sieves with an eight-membered ring crystal structure. Their small pore size allows them to form unique nanocages; and their cation exchangeability makes them highly efficient catalyst supports for the reduction of nitrogen oxide gases, exhibiting excellent thermal stability and catalytic performance.

[0075] In catalyst 10, isolated copper ions act as active centers for the reduction reaction of nitrogen oxides, promoting the catalytic reduction of nitrogen oxides. The nanocages in the AEI-type and CHA-type molecular sieve structures confine the isolated copper ions, separating them and preventing their aggregation.

[0076] Therefore, the nanocages in the structures of AEI-type and CHA-type molecular sieves confine isolated copper ions, resulting in better dispersion of isolated copper ions and a larger contact area between nitrogen oxides and isolated copper ions, which is more conducive to the reduction reaction of nitrogen oxides.

[0077] When the number of isolated copper ions is the same, and the isolated copper ions are dispersed in nanocages at the atomic level, the isolated copper ions can fully contact nitrogen oxides. Compared to the case where isolated copper ions are directly contacted with nitrogen oxides, i.e., the isolated copper ions may aggregate to form spheres, and the contact area between nitrogen oxides and isolated copper ions is only the outer surface of the spheres, the contact area between isolated copper ions and nitrogen oxides in the AEI-type molecular sieve and CHA-type molecular sieve structures is larger, which is conducive to the reduction reaction of nitrogen oxide gas and the conversion of nitrogen oxides.

[0078] In some embodiments, the first catalyst 12 comprises Cu-SSZ-39.

[0079] Cu-SSZ-39 belongs to the AEI type molecular sieve structure. Its aluminum-rich characteristics and relatively tortuous pore structure enable it to inhibit the migration and accumulation of copper species and the extraction of skeletal aluminum during hydrothermal aging. This makes it less prone to the migration, accumulation, or transformation of copper species in Cu-SSZ-39, thus maintaining excellent catalytic performance even after severe hydrothermal aging at relatively high temperatures (550℃~600℃). Therefore, using Cu-SSZ-39 as the first catalyst 12 can improve the conversion rate of catalyst 10. Moreover, Cu-SSZ-39 is relatively inexpensive, effectively reducing the cost of catalyst 10 while ensuring its catalytic effect. Further details regarding the excellent catalytic performance of Cu-SSZ-39 after hydrothermal aging will be provided later.

[0080] like Figure 7 The image shows the H2-TPR spectrum of Cu-SSZ-39 in Preparation Example 2. Based on the temperature ranges corresponding to isolated copper ions and copper ions in copper oxide in the H2-TPR spectrum, the reduction peaks at 200℃~300℃ and 400℃~700℃ are attributed to isolated Cu. 2+ The reduction peak at 300℃~400℃ belongs to CuO. Figure 7 It can be seen that the sum of the integrated area of ​​the reduction peak at 200℃~300℃ and the integrated area of ​​the reduction peak at 400℃~700℃ is much larger than the integrated area of ​​the reduction peak at 300℃~400℃. This means that the number of isolated copper ions is much greater than the number of copper ions in copper oxide. Copper ions in copper oxide only account for a small portion of all copper; most copper exists as isolated copper ions. 2+ The more active sites there are, the better the catalytic activity of Cu-SSZ-39.

[0081] In some embodiments, the ratio of the mass of copper in Cu-SSZ-39 to the mass of Cu-SSZ-39 ranges from 0.01 to 0.04.

[0082] For example, the ratio of the mass of copper in Cu-SSZ-39 to the mass of Cu-SSZ-39 can be 0.01, 0.02, 0.03 or 0.04, etc., and there is no limitation here.

[0083] In some embodiments, the ratio of the mass of copper in Cu-SSZ-39 to the mass of Cu-SSZ-39 ranges from 0.01 to 0.03.

[0084] For example, the ratio of the mass of copper in Cu-SSZ-39 to the mass of Cu-SSZ-39 can be 0.01, 0.015, 0.02, 0.025 or 0.03, etc., and there is no limitation here.

[0085] By further setting the ratio of the mass of copper to the mass of Cu-SSZ-39 within the range of 0.01 to 0.03, the catalytic effect of the first catalyst 12 on nitrogen oxide gas and the stability of the first catalyst 12 can be further improved.

[0086] In some embodiments, the second catalyst 14 includes at least one of BEA-type molecular sieve, MFI-type molecular sieve, and CHA-type molecular sieve.

[0087] The structure of CHA-type molecular sieves has been described above and will not be repeated here. BEA-type molecular sieves possess a three-dimensional twelve-membered ring pore structure. These intersecting channels form a complex network, giving them a large specific surface area and adsorption capacity. This allows them to adsorb and enrich reactant molecules, promoting catalytic reactions and resulting in high activity and selectivity in catalytic reactions. MFI-type molecular sieves are composed of silicon-oxygen tetrahedra and aluminum-oxygen tetrahedra connected by shared oxygen atoms, forming a three-dimensional intersecting pore system. The alternation of straight and sinusoidal channels provides excellent diffusion channels for reactant molecules, enabling MFI-type molecular sieves to exhibit high activity and selectivity in catalytic reactions. Both BEA-type and MFI-type molecular sieves have abundant pore and cavity structures. These cavities function similarly to nanocages, increasing the contact area between isolated copper ions and nitrogen oxides, which is beneficial for the reduction and conversion of nitrogen oxides.

[0088] At least one of the above-mentioned BEA-type molecular sieves, MFI-type molecular sieves, and CHA-type molecular sieves can be used as the second catalyst 14 to improve the conversion rate of the reduction reaction of nitrogen oxide gas by the second catalyst 14, while maintaining good stability and selectivity.

[0089] In some embodiments, the second catalyst 14 comprises Cu-SSZ-13.

[0090] Cu-SSZ-13 belongs to the CHA-type molecular sieve structure. At higher temperatures (e.g., above 550℃), it may experience stability issues such as copper species aggregation and dealumination of the molecular sieve framework. However, at lower temperatures (e.g., below 550℃), it exhibits good structural stability and is not prone to collapse or deformation. This results in Cu-SSZ-13 displaying good catalytic activity and high-temperature hydrothermal stability between 200℃ and 550℃, thus ensuring the continuous progress of the catalytic reaction. Moreover, Cu-SSZ-13 is relatively inexpensive, effectively reducing the cost of catalyst 10 while maintaining its catalytic effect.

[0091] like Figure 6 To prepare the H2-TPR spectrum of Cu-SSZ-13 in Example 3, and considering the corresponding temperature ranges of isolated copper ions and copper ions in copper oxide in the H2-TPR, the reduction peaks at 200℃~300℃ and 400℃~700℃ were attributed to isolated Cu. 2+ The reduction peak at 300℃~400℃ is attributed to copper ions in CuO. Figure 6 From the integrated areas of the corresponding reduction peaks of isolated copper ions and copper ions in copper oxide, it can be seen that the sum of the integrated areas of the reduction peaks at 200℃–300℃ and 400℃–700℃ is much larger than the integrated area of ​​the reduction peak at 300℃–400℃. This means that the number of isolated copper ions is much greater than the number of copper ions in copper oxide. Copper ions in copper oxide only account for a small portion of all copper; most copper exists as isolated copper ions. In the Cu element, isolated Cu… 2+ The more active sites a catalyst has, the better its performance. Therefore, Cu-SSZ-13 exhibits good catalytic activity.

[0092] In some embodiments, the ratio of the mass of copper in Cu-SSZ-13 to the mass of Cu-SSZ-13 ranges from 0.01 to 0.04.

[0093] For example, the ratio of the mass of copper in Cu-SSZ-13 to the mass of Cu-SSZ-13 can be 0.01, 0.02, 0.03 or 0.04, etc., and there is no limitation here.

[0094] In some embodiments, the ratio of the mass of copper in Cu-SSZ-13 to the mass of Cu-SSZ-13 ranges from 0.01 to 0.03.

[0095] For example, the ratio of the mass of copper in Cu-SSZ-13 to the mass of Cu-SSZ-13 can be 0.01, 0.015, 0.02, 0.025 or 0.03, etc., and there is no limitation here.

[0096] By further setting the ratio of the mass of copper in Cu-SSZ-13 to the mass of Cu-SSZ-13 within the range of 0.01 to 0.03, the catalytic effect of the second catalyst 14 on nitrogen oxide gas and the stability of the second catalyst 14 can be further improved.

[0097] In some embodiments, the catalyst further includes a support. The catalyst 10 is disposed on the support.

[0098] Understandably, the support is the material that supports the catalyst.

[0099] Here, the catalyst 10 disposed on the support means not only directly on the support, but also above or on the support having intermediate features or layers therein, and not only above or on the support, but also above or on the support without intermediate features or layers therein (i.e., directly on the support).

[0100] In some embodiments, the carrier comprises a porous ceramic material.

[0101] For example, the porous ceramic material can be cyanite.

[0102] In some embodiments, such as Figure 2 As shown, the support includes a first support 11 and a second support 13. A first catalyst 12 is disposed on the first support 11. A second catalyst 14 is disposed on the second support 13.

[0103] Understandably, the first support 11 is the supporting material for the first catalyst 12. The second support 13 is the supporting material for the second catalyst 14.

[0104] Porous ceramic materials have a very high specific surface area, which can provide more surface area for loading catalyst 10 and adsorption of reactants, thereby enhancing the efficiency of catalytic reaction. The porous structure is conducive to the diffusion and transport of nitrogen oxide gas reactants inside the support, reducing mass transfer resistance and allowing reactants to reach the surface of catalyst 10 for reaction more quickly, thereby increasing the rate of catalytic reaction. In addition, porous ceramic materials have high thermal stability and mechanical strength, which can maintain stable performance under harsh conditions such as high temperature and high pressure, and extend the service life of catalyst 10.

[0105] In some embodiments, such as Figure 2 As shown, the first support 11 has a porous structure. The first catalyst 12 is at least partially disposed on the pore walls of the first support 11. Here, the first support 11 and the second support 13 may be the same or different, and there is no limitation here.

[0106] The thickness D of the first catalyst 12 on the pore wall of the first support 11 ranges from 50 μm to 100 μm.

[0107] For example, the thickness D of the first catalyst 12 on the pore wall of the first support 11 can be 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm, etc., and there is no limitation here.

[0108] In some embodiments, such as Figure 3 As shown, the second support 13 has a porous structure. The second catalyst 14 is at least partially disposed on the pore wall of the second support 13. The thickness H of the second catalyst 14 on the pore wall of the second support 13 ranges from 50 μm to 100 μm.

[0109] For example, the thickness H of the second catalyst 14 on the pore wall of the second support 13 can be 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm, etc., and there is no limitation here.

[0110] By setting the thickness D of the first catalyst 12 on the pore wall of the first support 11 to be in the range of 50 μm to 100 μm, and the thickness H of the second catalyst 14 on the pore wall of the second support 13 to be in the range of 50 μm to 100 μm, the first catalyst 12 and the second catalyst 14 can provide a large surface area, which helps nitrogen oxides diffuse to the surface of the first catalyst 12 and the second catalyst 14 more quickly, forming effective contact with the active sites, thereby improving the catalytic effect of the catalytic reaction; it can also reduce mass transfer resistance, allowing reactants to reach the surface of the catalyst 10 more quickly, and reducing the decrease in reaction rate caused by mass transfer limitation; and it effectively prevents the first catalyst 12 from clogging the pores of the first support 11 and the second catalyst 14 from clogging the pores of the second support 13, thus affecting the contact between nitrogen oxide gas and the active sites.

[0111] In some embodiments, the thickness D of the first catalyst 12 on the pore wall of the first support 11 ranges from 70 μm to 80 μm.

[0112] For example, the thickness of the first catalyst 12 on the pore wall of the first support 11 can be 70μm, 72μm, 74μm, 76μm, 78μm or 80μm, etc., and there is no limitation here.

[0113] In some embodiments, the thickness H of the second catalyst 14 on the pore wall of the second support 13 ranges from 70 μm to 80 μm.

[0114] For example, the thickness H of the second catalyst 14 on the pore wall of the second support 13 can be 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm, etc., and there is no limitation here.

[0115] In some embodiments, such as Figure 1As shown, catalyst 10 includes a first catalytic region C1 and a second catalytic region C2 arranged along a first direction X. The first direction X is the flow direction of nitrogen oxide gas.

[0116] The first catalytic region C1 is configured with a first support 11 and a first catalyst 12.

[0117] The second catalytic region C2 is configured with: a second support 13 and a second catalyst 14.

[0118] The setup of the first catalytic region C1 and the second catalytic region C2 allows the catalyst 10 to perform multiple catalytic functions simultaneously in the reaction system. In other words, the two catalytic regions can be optimized for different stages of the reaction or different reactants, thereby improving the overall reaction efficiency of the catalyst 10. Moreover, the setup of the first catalytic region C1 and the second catalytic region C2 also allows for more precise control of the reaction conditions to adapt to the complex or variable reaction environment in the nitrogen oxide gas treatment system.

[0119] In some embodiments, the ratio between the length of the first catalytic region and the length of the second catalytic region ranges from 0.2 to 5. The length direction is the flow direction of the nitrogen oxide gas.

[0120] For example, the ratio between the length of the first catalytic region C1 and the length of the second catalytic region C2 can be 0.2, 1, 2, 3, 4 or 5, etc., and there is no limitation here.

[0121] In some embodiments, the ratio of the mass of the first catalyst 12 to the mass of the second catalyst 14 ranges from 0.2 to 5.

[0122] For example, the ratio of the mass of the first catalyst 12 to the mass of the second catalyst 14 can be 0.2, 1, 2, 3, 4 or 5, etc., and there is no limitation here.

[0123] In some examples, such as Figure 1 As shown, the length of the first catalytic region C1 and the length of the second catalytic region C2 are equal.

[0124] By setting the above parameters, the lengths of the two catalytic regions can be adjusted to optimize the overall catalytic performance, enabling the catalyst to maintain high activity under different reaction conditions; it also allows catalyst 10 to maintain good catalytic effect under different operating conditions.

[0125] In some embodiments, when the catalyst 10 in the above embodiments is applied to a nitrogen oxide gas treatment system, the temperature of the inlet end I is relatively high, the first catalytic region C1 of the catalyst 10 is closer to the inlet end I than the second catalytic region C2 of the catalyst 10, and the first catalyst 12 in the first catalytic region C1 has better catalytic performance at higher temperatures. This allows the catalyst 10 to have excellent catalytic activity and stability throughout the entire temperature range (200°C to 700°C).

[0126] Based on the catalyst 10 described above, the following preparation examples and embodiments are provided.

[0127] Preparation Example 1

[0128] Preparation Example 1 provides a copper-based molecular sieve Cu-SSZ-39, in which the mass ratio of copper to Cu-SSZ-39 is 0.013. Cu-SSZ-39 is obtained by the following preparation method:

[0129] A copper nitrate precursor solution was mixed with CHA molecular sieves and stirred until fully dispersed. The mixture was then heated to 80°C and stirred to allow for ion exchange for 12 hours. The mixture was then filtered, washed, dried, and calcined at 600°C for 4 hours to obtain Cu-SSZ-39.

[0130] Preparation Example 2

[0131] Preparation Example 2 provides a copper-based molecular sieve Cu-SSZ-39, in which the mass ratio of copper to Cu-SSZ-39 is 0.027. Cu-SSZ-39 is obtained by the following preparation method:

[0132] A copper nitrate precursor solution was mixed with CHA molecular sieves and stirred until fully dispersed. The mixture was then heated to 80°C and stirred to induce ion exchange for 8 hours. The solution was then filtered, washed, dried, and calcined at 600°C for 4 hours to obtain Cu-SSZ-39.

[0133] like Figure 7 As shown, the reduction peaks at 200℃~300℃ and 400℃~700℃ belong to isolated Cu. 2+ The reduction peak at 300℃~400℃ belongs to CuO. It can be seen that the sum of the integrated area of ​​the reduction peak at 200℃~300℃ and the integrated area of ​​the reduction peak at 400℃~700℃ is much larger than the integrated area of ​​the reduction peak at 300℃~400℃. This means that the number of isolated copper ions is much greater than the number of copper ions in copper oxide. Copper ions in copper oxide only account for a small portion of all copper elements; most copper exists in the form of isolated copper ions.

[0134] Preparation Example 3

[0135] Preparation Example 3 provides a copper-based molecular sieve Cu-SSZ-13, in which the mass ratio of copper to Cu-SSZ-13 is 0.027. Cu-SSZ-13 is obtained by the following preparation method:

[0136] A copper nitrate precursor solution was mixed with AEI molecular sieves and stirred until fully dispersed. The mixture was then heated to 80°C and stirred to induce ion exchange for 6 hours. The solution was then filtered, washed, dried, and calcined at 600°C for 4 hours to obtain Cu-SSZ-13.

[0137] The results are as follows Figure 6 As shown, the reduction peaks at 200℃~300℃ and 400℃~700℃ belong to isolated Cu. 2+ The reduction peak at 300℃~400℃ is attributed to copper ions in CuO. Figure 6 From the integrated areas of the corresponding reduction peaks of isolated copper ions and copper ions in copper oxide, it can be seen that the sum of the integrated areas of the reduction peaks at 200℃–300℃ and 400℃–700℃ is much larger than the integrated area of ​​the reduction peak at 300℃–400℃. This means that the number of isolated copper ions is much greater than the number of copper ions in copper oxide. Copper ions in copper oxide only account for a small portion of all copper; most copper exists in the form of isolated copper ions.

[0138] Example 1

[0139] Example 1 provides a catalyst 10, which is obtained by the following preparation method:

[0140] S1 forms the first catalytic region C1: The first catalyst 12, binder (silica sol) and thickener (carboxymethyl cellulose) and defoamer are made into a mixed slurry. One end of the carrier (cyanite honeycomb ceramic) is immersed in the slurry, and then taken out and dried at 100°C for 15 hours.

[0141] S2 forms the second catalytic region C2: The second catalyst 14, binder and defoamer are made into a mixed slurry, the other end of the carrier is immersed in the slurry, and then taken out and dried.

[0142] S3: The carrier impregnated with the slurry was calcined at 550°C for 4 hours to obtain catalyst 10. The thickness of the first catalyst 12 on the carrier is 70 μm, and the thickness of the second catalyst 14 on the carrier is 70 μm. The ratio between the area of ​​the first catalytic region C1 and the area of ​​the second catalytic region C2 is 1.

[0143] The first catalyst 12 is Cu-SSZ-39 prepared in Preparation Example 1. The second catalyst 14 is Cu-SSZ-13 prepared in Preparation Example 3.

[0144] Example 2

[0145] Example 2 provides a catalyst 10, which is prepared in the same way as in Example 1, except that the first catalyst 12 is Cu-SSZ-39 prepared in Preparation Example 2, and the second catalyst 14 is Cu-SSZ-13 prepared in Preparation Example 3.

[0146] Performance testing

[0147] The conversion rate of nitrogen oxides was tested using a catalyst testing platform for fresh and aged samples of catalyst 10 from the example.

[0148] Among them, (1) the test conditions were: NO content was 500 PPM, and space velocity was 60000 h⁻¹. -1 The result is as follows Figure 4 and Figure 5 As shown.

[0149] (2) The fresh sample was aged to obtain the aged sample. The aging method was to treat the sample at 800℃, 10% water vapor, and normal pressure for 16h.

[0150] (3) The formula for calculating the conversion rate of nitrogen oxides (NOx) is:

[0151]

[0152] (4) H2-Programmed Temperature Reduction (TPR) Analysis: The AutoChemII 2920 chemisorption analyzer from Micromeritics, USA, was used. TPR is a technique that involves continuously introducing reducing gas H2 under programmed temperature conditions to cause the active components to undergo a reduction reaction, and then measuring the change in the concentration of the reducing gas in the outflowing gas to determine its reduction rate.

[0153] from Figure 4 It can be seen that the catalysts 10 of Examples 1 and 2 have a nitrogen oxide conversion rate in the range of 65% to 99% at lower temperatures (200℃ to 400℃), a nitrogen oxide conversion rate in the range of 85% to 99% at medium temperatures (400℃ to 550℃), and a nitrogen oxide conversion rate in the range of 70% to 90% at higher temperatures (550℃ to 700℃). Therefore, the fresh samples of catalysts 10 provided in Examples 1 and 2 have good nitrogen oxide conversion rates in the range of 200℃ to 700℃.

[0154] like Figure 5 As shown, the catalysts 10 of Examples 1 and 2 exhibit nitrogen oxide conversion rates ranging from 55% to 99% at lower temperatures (200°C to 400°C), from 90% to 99% at medium temperatures (400°C to 550°C), and from 65% to 90% at higher temperatures (550°C to 700°C). Therefore, the aged samples of catalysts 10 provided in Examples 1 and 2 all demonstrate good nitrogen oxide conversion rates within the temperature range of 200°C to 700°C.

[0155] Therefore, by Figure 4 and Figure 5 It can be seen that, within the temperature range of 200℃ to 700℃, the catalyst 10 provided in the embodiments of this application has a good conversion rate for the reduction reaction of nitrogen oxide gas.

[0156] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A catalyst for catalyzing the reduction reaction of nitrogen oxide gas, characterized in that, include: Copper element; The copper element includes: isolated copper ions and copper ions present in copper oxide; The number of atoms of the isolated copper ion is greater than the number of atoms of the copper ion in the copper oxide.

2. The catalyst according to claim 1, characterized in that, Also includes: Molecular sieves; The ratio of the mass of copper to the sum of the mass of the molecular sieve and the mass of copper is in the range of 0.01 to 0.

04.

3. The catalyst according to claim 1 or 2, characterized in that, The catalyst includes a first catalyst and a second catalyst; and the second catalyst is different from the first catalyst.

4. The catalyst according to claim 3, characterized in that, Within a temperature range of 550℃ to 600℃, the conversion rate of the first catalyst for the reduction reaction of nitrogen oxides is greater than that of the second catalyst.

5. The catalyst according to claim 3 or 4, characterized in that, The first catalyst includes at least one of AEI-type molecular sieve and CHA-type molecular sieve.

6. The catalyst according to any one of claims 3 to 5, characterized in that, The first catalyst comprises: Cu-SSZ-39.

7. The catalyst according to claim 6, characterized in that, The ratio of the mass of copper in Cu-SSZ-39 to the mass of Cu-SSZ-39 ranges from 0.01 to 0.

04.

8. The catalyst according to claim 7, characterized in that, The ratio of the mass of copper in Cu-SSZ-39 to the mass of Cu-SSZ-39 ranges from 0.01 to 0.

03.

9. The catalyst according to any one of claims 3 to 8, characterized in that, The second catalyst includes at least one of BEA-type molecular sieves, MFI-type molecular sieves, and CHA-type molecular sieves.

10. The catalyst according to claim 9, characterized in that, The second catalyst includes Cu-SSZ-13.

11. The catalyst according to claim 10, characterized in that, The ratio of the mass of copper in Cu-SSZ-13 to the mass of Cu-SSZ-13 ranges from 0.01 to 0.

04.

12. The catalyst according to claim 11, characterized in that, The ratio of the mass of copper in Cu-SSZ-13 to the mass of Cu-SSZ-13 ranges from 0.01 to 0.

03.

13. The catalyst according to any one of claims 1 to 12, characterized in that, The catalyst further includes a support, wherein the catalyst is disposed on the support.

14. The catalyst according to claim 13, characterized in that, The carrier includes: porous ceramic material.

15. The catalyst according to claim 13 or 14, characterized in that, The carrier includes a first carrier and a second carrier, wherein the first catalyst is disposed on the first carrier and the second catalyst is disposed on the second carrier.

16. The catalyst according to claim 15, characterized in that, The first support has a porous structure, and the first catalyst is at least partially disposed on the pore wall of the first support, the thickness of the first catalyst on the pore wall of the first support ranging from 50 μm to 100 μm; and / or, The second support has a porous structure, and the second catalyst is at least partially disposed on the pore wall of the second support, with the thickness of the second catalyst on the pore wall of the second support ranging from 50 μm to 100 μm.

17. The catalyst according to claim 16, characterized in that, The thickness of the first catalyst on the pore walls of the first support ranges from 70 μm to 80 μm; and / or The thickness of the second catalyst on the pore wall of the second support ranges from 70 μm to 80 μm.

18. The catalyst according to claim 13, characterized in that, The catalyst includes a first catalytic region and a second catalytic region arranged along a first direction; the first direction is the flow direction of the nitrogen oxide gas. The first catalytic region comprises the first support and the first catalyst; The second catalytic region has the second support and the second catalyst.

19. The catalyst according to claim 18, characterized in that, The ratio of the length of the first catalytic region to the length of the second catalytic region is in the range of 0.2 to 5; the length direction is the flow direction of the nitrogen oxide gas. Alternatively, the ratio of the mass of the first catalyst to the mass of the second catalyst is in the range of 0.2 to 5.

20. A nitrogen oxide gas treatment system, characterized in that, include: The catalyst as described in any one of claims 1 to 19.

21. The nitrogen oxide gas treatment system according to claim 20, characterized in that, The catalyst includes a first catalytic region and a second catalytic region. The first catalytic region includes a first catalyst, and the second catalytic region includes a second catalyst. The first catalytic region is closer to the intake end than the second catalytic region.

22. A vehicle, characterized in that, include: The nitrogen oxide gas treatment system as described in claim 20 or 21.

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