A rare earth ion modified Pd-based SSZ-13 molecular sieve composite material, a preparation method and application thereof

Abstract

The present application relates to a kind of rare earth element ion modified Pd base SSZ-13 molecular sieve composite material and its preparation method and application.The preparation method includes the following steps: after ammonium chloride and H-SSZ-13 molecular sieve are mixed, reaction is carried out, product is collected to obtain NH4 + -SSZ-13 molecular sieve;After NH4 + -SSZ-13 molecular sieve is mixed with palladium salt, rare earth element ion precursor salt, co-ion exchange reaction is carried out;Product is collected, grinds after calcination, and rare earth element ion-Pd / SSZ-13 composite material is obtained;Rare earth element ion-Pd / SSZ-13 composite material is hydrothermally aged, and the final rare earth element ion modified Pd base SSZ-13 molecular sieve composite material is obtained.Compared with prior art, the Pd base SSZ-13 molecular sieve composite material of the present application has excellent low-temperature NO x storage performance, high stability, small secondary pollution, and can be widely applied to the low-temperature efficient adsorption of NO x of motor vehicle exhaust cold start stage, and adapt to downstream SCR unit to realize NO x Deep removal.

Description

Technical Field

[0001] This invention relates to the field of exhaust gas adsorption materials technology, and in particular to a rare earth element ion modified Pd-based SSZ-13 molecular sieve composite material, its preparation method and application. Background Technology

[0002] Nitrogen oxides (NO) x Nitrogen oxides (NOx), as one of the major air pollutants, not only cause environmental problems such as acid rain and photochemical smog, but also seriously endanger human health, becoming a core bottleneck restricting the improvement of ecological environment quality and the protection of public health. x Sources of nitrogen oxides are diverse, including industrial boilers, coking plants, power heating, non-road mobile sources, and road mobile sources. Among these, diesel engines are widely used due to their advantages such as high power, high fuel efficiency, and low hydrocarbon (HCs) and CO content; however, their high air-fuel ratio leads to high NO content in exhaust gases. x Emissions. Currently, my country's mobile source NOx emissions... x Emissions from this source now account for over 50% of total emissions, with NOx emissions during the cold start phase of motor vehicles (exhaust temperature ≤150 ℃) being particularly high. x Emissions account for over 80%, becoming the NOx emission standard in vehicle exhaust. x The main source of emissions. Therefore, effectively promoting cold-start NO x Deep emission reduction has become the top priority for controlling gaseous pollutants from mobile sources. Currently, NO... x Storage reduction (NSR), ammonia selective catalytic reduction of NO x Technologies such as NH3-SCR have been widely used in motor vehicle exhaust aftertreatment systems. However, existing catalytic technologies have limitations in addressing NO3 emissions from motor vehicle exhaust. x Effective removal is not possible at low temperatures; low-temperature high-efficiency NO removal is required. x The research and application of catalyst removal technology has become a key area for NO removal in motor vehicle exhaust. x The key bottleneck to control.

[0003] Passive NO x Purified adsorption (PNA) technology, with its "low-temperature adsorption-high-temperature release" characteristics, can rapidly adsorb NO during the cold start phase of vehicle exhaust aftertreatment systems. x Once the exhaust gas temperature rises to the activation temperature of the aftertreatment system, the stored NO will be gradually released as the temperature increases. x And (nitrite) species, which are then effectively removed by the downstream tightly coupled selective catalytic reduction (SCR) unit, forming an "adsorption-reduction" synergistic system, has become a key technical path to solve the cold start emission problem. Currently, Pd-based SSZ-13 molecular sieves are highly regarded for their excellent NO removal properties. xAdsorption performance, thermal stability, and hydrothermal aging resistance have become research hotspots for Pd / SSZ-13 materials. However, in practical applications, Pd / SSZ-13 materials alone still face several technical challenges, such as NO adsorption at low temperatures (<150 °C). x Limited adsorption capacity, NO under high temperature conditions x A series of problems, such as difficulty in desorption and the migration and aggregation of Pd active sites during adsorption and desorption leading to decreased cycle stability, make it impossible to achieve continuous NO emission during the cold start phase. x Effective storage and efficient removal of pollutants are insufficient to meet stringent emission regulations.

[0004] CN111957342A discloses a microporous molecular sieve-supported bimetallic material for low-temperature removal of nitrogen oxides from diesel vehicle exhaust. A PdCe-SSZ-13 catalyst was successfully prepared by adding Ce to a Pd-based molecular sieve, which can solve the NO removal problem during the cold start stage. x To address the issue of low removal efficiency and achieve efficient low-temperature NO removal. x The removal of ions and improved material stability make it suitable for diesel vehicle exhaust treatment. However, this Ce-ion-modified molecular sieve catalyst requires multiple ion exchange / impregnation and calcination steps, making the preparation process cumbersome and some process parameters energy-intensive.

[0005] Therefore, regarding the existing Pd-based SSZ-13 molecular sieve composites in the NO emissions from motor vehicle exhaust... x The problems existing in adsorption and desorption still require the development of a method to achieve NO x A novel Pd-based SSZ-13 molecular sieve material for low-temperature and high-efficiency storage. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects of the prior art and provide a rare earth element ion modified Pd-based SSZ-13 molecular sieve composite material, its preparation method and application.

[0007] The objective of this invention can be achieved through the following technical solutions: This invention provides a method for preparing a rare earth element ion modified Pd-based SSZ-13 molecular sieve composite material, the preparation method comprising the following steps: S1: Ammonium chloride and H-SSZ-13 molecular sieve are mixed and reacted, and the product is collected to obtain NH4. + -SSZ-13 molecular sieve; S2: NH4 obtained from S1 + -SSZ-13 molecular sieve was mixed with palladium salt and rare earth element ion precursor salt and then subjected to co-ion exchange reaction; the product was collected, ground and calcined to obtain rare earth element ion-Pd / SSZ-13 composite material. S3: The rare earth element ion-Pd / SSZ-13 composite material prepared in S2 is subjected to hydrothermal aging to obtain the final rare earth element ion modified Pd-based SSZ-13 molecular sieve composite material.

[0008] Further, in step S1, the mass ratio of ammonium chloride to H-SSZ-13 molecular sieve is (2-3):1.

[0009] Furthermore, in step S1, the reaction temperature is 80-90 °C.

[0010] Furthermore, in step S1, the reaction time is 2-4 hours.

[0011] Further, in step S2, the NH4 + The mass ratio of SSZ-13 molecular sieve to palladium salt is 1:(0.6-1.4).

[0012] Further, in step S2, the rare earth element ion in the rare earth element ion precursor salt is Ce. 3+ 、Sm 3+ 、Nd 3+ Pr 3+ La 3+ ,Sc 3+ Gd 3+ Y 3+ At least one of them.

[0013] Further, in step S2, the molar concentration of the rare earth element ion precursor salt is 0.01~0.2 mol / L. Excessively high rare earth metal ion concentrations are detrimental to the high dispersion of the active component Pd, further weakening NO. x The adsorption and complexation capacity is important, but a low concentration of rare earth metal ions is detrimental to the effective distribution and site occupancy regulation of the active component Pd, both of which will affect the subsequent NO adsorption and complexation. x The adsorption process.

[0014] Further, in step S2, the palladium salt is any one or more of palladium nitrate, palladium chloride, and palladium sulfate.

[0015] Furthermore, in step S2, the reaction temperature is 60-80 °C.

[0016] Furthermore, in step S2, the reaction time is 18-24 h.

[0017] Furthermore, in step S2, the calcination temperature is 450-550 ℃.

[0018] Furthermore, in step S2, the secondary calcination time is 3-5 hours.

[0019] Furthermore, in step S3, the hydrothermal aging is carried out in an air atmosphere containing 5-15 vol.% water vapor.

[0020] Furthermore, in step S3, the temperature of the hydrothermal aging is 700-750 ℃.

[0021] Furthermore, in step S3, the hydrothermal aging time is 12-16 hours.

[0022] The present invention also provides a rare earth element ion modified Pd-based SSZ-13 molecular sieve composite material, which is prepared by any of the above preparation methods.

[0023] Furthermore, the composite material uses SSZ-13 molecular sieve as a carrier and is loaded with Pd active components and modifying agents.

[0024] Furthermore, the silica-alumina ratio of the SSZ-13 molecular sieve is 13 to 31, which is adjustable within this range.

[0025] Furthermore, the loading of the Pd active component is 1 to 3% of the mass of the SSZ-13 molecular sieve.

[0026] Furthermore, the modifying agent is a rare earth element ion, specifically Ce. 3+ 、Sm 3+ 、Nd 3+ Pr 3+ La 3+ ,Sc 3 + Gd 3+ Y 3+ One or more of them.

[0027] This invention also provides a rare earth element ion-modified Pd-based SSZ-13 molecular sieve composite material for low-temperature and high-efficiency NO storage. x Applications in [the field].

[0028] Furthermore, the rare earth element ion modified Pd-based SSZ-13 molecular sieve composite material can be widely adapted to NO emissions from various motor vehicle exhaust gases. x The low-temperature adsorption module, in conjunction with the downstream SCR unit, efficiently solves NO emission during cold starts (<150 ℃) in motor vehicles. x Emissions issues.

[0029] Rare earth element ions (such as Ce) 3+ La 3+ Gd 3+ Due to their unique electronic structure (including unfilled 4f orbitals) and redox properties, etc., in traditional NO xSignificant advantages are observed during adsorption and activation. The synergistic effect of rare earth element ions and molecular sieves can often be better utilized through effective combination. Rare earth element ions can effectively regulate the chemical coordination environment of the Pd active component through a special charge compensation effect, enhancing its affinity for NO. x This enhances the adsorption affinity of the coupling material and improves the dispersibility and stability of the active components, thereby improving the NO content of the coupling material. x Low-temperature adsorption performance.

[0030] However, in existing traditional methods, the electronic state of the core active component Pd is difficult to control precisely. This makes it easy for the Pd component in the material to agglomerate under the high humidity and multi-component interference conditions of the vehicle exhaust aftertreatment system, leading to NO... x The adsorption capacity and adsorption rate decrease, making it difficult to meet the requirements of stringent exhaust gas purification standards.

[0031] Based on this, the present invention introduces rare earth element ions into the Pd-based SSZ-13 material system through a co-ion exchange method. By forming efficient electron transfer interactions with the Pd active component, the electron cloud distribution of the Pd active sites is precisely controlled, resulting in a stable electron-deficient state, thereby significantly improving NO content. x Adsorption capacity and low-temperature adsorption efficiency. Furthermore, rare earth element ions can effectively promote the dispersion of Pd active components, increase the exposure of active sites, and maintain the excellent hydrothermal stability of the composite material, ultimately achieving NO adsorption capacity and low-temperature adsorption efficiency. x Synergistic improvement of adsorption capacity, adsorption rate and hydrothermal stability.

[0032] Compared with the prior art, the present invention has the following technical advantages: (1) This invention innovatively introduces different rare earth element ions and Pd active components simultaneously into SSZ-13 molecular sieves via a co-ion exchange method, which can leverage the highly efficient synergistic effect of rare earth element ions, Pd active species, and molecular sieve support. Rare earth ions induce the formation of electron-deficient Pd through electron transfer interactions with the Pd active components. 2+ Active sites significantly improve the NO content of the modified material. x It achieves high adsorption capacity and low-temperature adsorption efficiency while maintaining excellent hydrothermal aging stability of the material.

[0033] (2) This invention achieves precise targeted regulation of the electronic state of Pd active sites by modifying Pd-based SSZ-13 composite materials with rare earth element ions, and constructs stable electron-deficient Pd through rare earth element-Pd electron transfer interactions. 2+ Sites that significantly promote NO x The low-temperature adsorption capacity is improved; at the same time, it effectively promotes the dispersion of Pd active components, increases the exposure of active sites, maintains the excellent hydrothermal stability of the composite material, and significantly improves the low-temperature NO adsorption capacity of the composite material.x Adsorption performance and adsorption efficiency.

[0034] (3) This invention introduces rare earth element ions and Pd active species into SSZ-13 molecular sieves simultaneously via a one-step ion exchange method, achieving efficient synergistic regulation of Pd active components and rare earth element modified components. Compared to the stepwise introduction of Pd and Ce species disclosed in CN111957342A, this Ce ion-modified molecular sieve catalytic material requires multiple ion exchange / impregnation and calcination processes, making the preparation steps cumbersome. Furthermore, after hydrothermal aging and activation treatment, the simultaneously introduced rare earth element ions and Pd active components can achieve high dispersion and stable coordination of the active Pd components through reasonable site redistribution, which is beneficial for subsequent NO production. x Stable adsorption complexation.

[0035] (4) NO of the present invention x The low-temperature, high-efficiency storage material has a simple synthesis process, good repeatability, and strong stability in cyclic testing, making it suitable for the thermal aging and regeneration conditions of vehicle exhaust aftertreatment. This material is widely applicable to various types of vehicle exhaust NO₂. x The low-temperature adsorption module, in conjunction with the downstream SCR unit, efficiently solves the NO emission problem during cold starts of motor vehicles. x Emissions issues. Attached Figure Description

[0036] Figure 1 Ce-Pd / SSZ-13 NO prepared in Example 1 of this invention x XRD pattern of low-temperature high-efficiency storage materials.

[0037] Figure 2 Ce-Pd / SSZ-13 NO prepared in Example 1 of this invention x SEM image of low-temperature high-efficiency storage materials.

[0038] Figure 3 Pd / SSZ-13 NO prepared for Comparative Example 1 of this invention x Adsorption-desorption performance test curves of composite materials.

[0039] Figure 4 Pd / SSZ-13 NO prepared for Comparative Example 1 of this invention x NO in composite materials x Adsorption / desorption volume bar chart.

[0040] Figure 5 Ce-Pd / SSZ-13 NO prepared in Example 1 of this invention x Adsorption-desorption performance test curves of low-temperature high-efficiency storage materials.

[0041] Figure 6Ce-Pd / SSZ-13 NO prepared in Example 1 of this invention x NO in low-temperature high-efficiency storage materials x Adsorption / desorption volume bar chart. Detailed Implementation

[0042] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0043] For simplicity, this application only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form a range not explicitly stated; and any lower limit can be combined with other lower limits to form a range not explicitly stated, just as any upper limit can be combined with any other upper limit to form a range not explicitly stated. Furthermore, although not explicitly stated, each point or individual value between the endpoints of a range is included within that range. Therefore, each point or individual value can be used as its own lower or upper limit and combined with any other point or individual value, or combined with other lower or upper limits, to form a range not explicitly stated. In the description of this application, it should be noted that, unless otherwise stated, "above" includes the stated number, and "multiple" in "one or more" means two or more.

[0044] The foregoing description of this application is not intended to describe every disclosed implementation or method. The following description provides more specific examples of exemplary implementations. In each instance, the examples are provided as representative groups only and should not be construed as exhaustive.

[0045] Unless otherwise specified, the reagents, methods, instruments, and equipment used in this invention are conventional in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0046] Example 1: This embodiment provides a rare earth element ion modified Pd-based SSZ-13 molecular sieve type NO x The low-temperature high-efficiency storage material, specifically Ce-Pd / SSZ-13, is prepared using the following method: (1) Take 50 mL of deionized water into a flask, weigh 2.6745 g of ammonium chloride solid and dissolve it in the water. Add a magnetic stir bar and stir until the solid dissolves. Weigh 1 g of H-SSZ-13 molecular sieve (silicon-to-aluminum ratio of 20) and add it to the solution while stirring. Place the flask in an 80 ℃ constant temperature oil bath, reflux and stir for 2 h. After the oil bath, centrifuge and wash until the supernatant is neutral. Place it in an 80 ℃ oven to dry, grind and obtain NH4. + -SSZ-13.

[0047] (2) Take 5 mL of deionized water into a round-bottomed flask, and add NH4+. + -SSZ-13 material was dissolved in water, and stirred with a magnetic stirrer until the solid dissolved. 0.0554 g of a 18.09 wt.% Pd(NO3)2 solution and 0.0434 g of Ce(NO3)4·6H2O solid were weighed and added to the solution while stirring. The mixed solution was then transferred to a 65 ℃ constant temperature oil bath and refluxed with stirring for 24 h. After the reaction was complete, the mixture was centrifuged and washed until the supernatant was neutral. It was then dried in an 80 ℃ oven, ground, and calcined in a muffle furnace at 550 ℃ for 4 h. The resulting product was Ce-Pd / SSZ-13 NO. x Low-temperature, high-efficiency storage materials.

[0048] (3) The obtained material was placed in a tube furnace and hydrothermally treated at 700 °C for 16 h in an air atmosphere containing 10 vol.% water vapor to obtain the hydrothermally aged composite material.

[0049] Ce-Pd / SSZ-13 NO prepared in this embodiment x In the low-temperature high-efficiency storage material, the Pd loading is 2% of the mass of SSZ-13 molecular sieve.

[0050] like Figure 1 As shown, in the XRD results of this embodiment, all samples exhibited characteristic diffraction peaks of CHA-type zeolite (SSZ-13), indicating hydrothermal aging and Ce... 3+ The modified molecular sieve framework structure remained intact. No obvious PdO characteristic peaks were detected, indicating that the Pd species were highly dispersed.

[0051] like Figure 2 As shown in the scanning electron microscope, the Ce-Pd / SSZ-13 materials in this embodiment all exhibit a regular cubic morphology, indicating that the SSZ-13 molecular sieve structure remains intact during hydrothermal aging and Ce ion exchange preparation. Furthermore, the Pd species in the material are uniformly dispersed on the support surface, and hydrothermal aging has minimal impact on their distribution; and the Ce ions from ion exchange are highly uniformly dispersed within the molecular sieve pore structure. In addition, the uniform distribution of Si, Al, and O elements in the SSZ-13 framework further demonstrates that the Ce-Pd-SSZ-13 material possesses good hydrothermal aging stability.

[0052] Example 2: This embodiment provides a rare earth element ion modified Pd-based SSZ-13 molecular sieve type NO x The low-temperature high-efficiency storage material, specifically Sm-Pd / SSZ-13, is prepared using the following method: (1) Take 50 mL of deionized water into a flask, weigh 2.6745 g of ammonium chloride solid and dissolve it in the water. Add a magnetic stir bar and stir until the solid dissolves. Weigh 1 g of H-SSZ-13 molecular sieve and add it to the solution while stirring. Place the flask in an 80 ℃ constant temperature oil bath, reflux and stir for 2 h. After the oil bath, centrifuge and wash until the supernatant is neutral. Place it in an 80 ℃ oven to dry, grind and obtain NH4. + -SSZ-13.

[0053] (2) Take 5 mL of deionized water into a round-bottomed flask, and add NH4+. + -SSZ-13 material was dissolved in water, and stirred with a magnetic stirrer until the solid dissolved. 0.0554 g of a 18.09 wt.% Pd(NO3)2 solution and 0.0445 g of Sm(NO3)4·6H2O solid were weighed and added to the solution while stirring. The mixed solution was then transferred to a 65 ℃ constant temperature oil bath and refluxed with stirring for 24 h. After the reaction was complete, the mixture was centrifuged and washed until the supernatant was neutral. It was then dried in an 80 ℃ oven, ground, and calcined in a muffle furnace at 550 ℃ for 4 h. The resulting product was Sm-Pd / SSZ-13 NO x Low-temperature, high-efficiency storage materials.

[0054] (3) The obtained material was placed in a tube furnace and hydrothermally treated at 750 °C for 14 h in an air atmosphere containing 10 vol.% water vapor to obtain the hydrothermally aged material.

[0055] Example 3: This embodiment provides a rare earth element ion modified Pd-based SSZ-13 molecular sieve type NO x The low-temperature high-efficiency storage material, specifically Pr-Pd / SSZ-13, is prepared using the following method: (1) Take 50 mL of deionized water into a flask, weigh 2.6745 g of ammonium chloride solid and dissolve it in the water. Add a magnetic stir bar and stir until the solid dissolves. Weigh 1 g of H-SSZ-13 molecular sieve and add it to the solution while stirring. Place the flask in an 80 ℃ constant temperature oil bath, reflux and stir for 2 h. After the oil bath, centrifuge and wash until the supernatant is neutral. Place it in an 80 ℃ oven to dry, grind and obtain NH4. + -SSZ-13.

[0056] (2) Take 5 mL of deionized water into a round-bottomed flask, and add NH4+. +-SSZ-13 material was dissolved in water, and stirred with a magnetic stirrer until the solid dissolved. 0.0554 g of a 18.09 wt.% Pd(NO3)2 solution and 0.0435 g of Pr(NO3)4·6H2O solid were weighed and added to the solution while stirring. The mixed solution was then transferred to a 65 ℃ constant temperature oil bath and refluxed with stirring for 24 h. After the reaction was complete, the mixture was centrifuged and washed until the supernatant was neutral. It was then dried in an 80 ℃ oven, ground, and calcined in a muffle furnace at 550 ℃ for 4 h. The resulting product was Pr-Pd / SSZ-13 NO. x Low-temperature, high-efficiency storage materials.

[0057] (3) The obtained material was placed in a tube furnace and hydrothermally treated at 700 °C for 12 h in an air atmosphere containing 10 vol.% water vapor to obtain the hydrothermally aged material.

[0058] Example 4: This embodiment provides a rare earth element ion modified Pd-based SSZ-13 molecular sieve type NO x The low-temperature high-efficiency storage material, specifically La-Pd / SSZ-13, is prepared using the following method: (1) Take 50 mL of deionized water into a flask, weigh 2.6745 g of ammonium chloride solid and dissolve it in the water. Add a magnetic stir bar and stir until the solid dissolves. Weigh 1 g of H-SSZ-13 molecular sieve and add it to the solution while stirring. Place the flask in a constant temperature oil bath at 90 ℃, reflux and stir for 4 h. After the oil bath, centrifuge and wash until the supernatant is neutral. Place it in an oven at 80 ℃ to dry, grind and obtain NH4. + -SSZ-13.

[0059] (2) Take 5 mL of deionized water into a round-bottomed flask, and add NH4+. + -SSZ-13 material was dissolved in water, and stirred with a magnetic stirrer until the solid dissolved. 0.0554 g of a 18.09 wt.% Pd(NO3)2 solution and 0.0433 g of La(NO3)4·6H2O solid were weighed and added to the solution while stirring. The mixed solution was then transferred to a 65 ℃ constant-temperature oil bath and refluxed with stirring for 24 h. After the reaction was complete, the mixture was centrifuged and washed until the supernatant was neutral. It was then dried in an 80 ℃ oven, ground, and calcined in a muffle furnace at 550 ℃ for 4 h. The resulting product was La-Pd / SSZ-13 NO x Low-temperature, high-efficiency storage materials.

[0060] (3) The obtained material was placed in a tube furnace and hydrothermally treated at 750 °C for 12 h in an air atmosphere containing 10 vol.% water vapor to obtain the hydrothermally aged material.

[0061] Example 5: This embodiment provides a rare earth element ion modified Pd-based SSZ-13 molecular sieve type NO x The low-temperature high-efficiency storage material, specifically Gd-Pd / SSZ-13, is prepared using the following method: (1) Take 50 mL of deionized water into a flask, weigh 2.6745 g of ammonium chloride solid and dissolve it in the water. Add a magnetic stir bar and stir until the solid dissolves. Weigh 1 g of H-SSZ-13 molecular sieve and add it to the solution while stirring. Place the flask in a constant temperature oil bath at 90 ℃, reflux and stir for 4 h. After the oil bath, centrifuge and wash until the supernatant is neutral. Place it in an oven at 80 ℃ to dry, grind and obtain NH4. + -SSZ-13.

[0062] (2) Take 5 mL of deionized water into a round-bottomed flask, and add NH4+. + -SSZ-13 material was dissolved in water, and stirred with a magnetic stirrer until the solid dissolved. 0.0554 g of a 18.09 wt.% Pd(NO3)2 solution and 0.0451 g of solid Gd(NO3)4·6H2O were weighed and added to the solution while stirring. The mixed solution was then transferred to a 65 ℃ constant-temperature oil bath and refluxed with stirring for 24 h. After the reaction was complete, the mixture was centrifuged and washed until the supernatant was neutral. It was then dried in an 80 ℃ oven, ground, and calcined in a muffle furnace at 550 ℃ for 4 h. The resulting product was Gd-Pd / SSZ-13 NO. x Low-temperature, high-efficiency storage materials.

[0063] (3) The obtained material was placed in a tube furnace and hydrothermally treated at 750 °C for 12 h in an air atmosphere containing 10 vol.% water vapor to obtain the hydrothermally aged material.

[0064] Comparative Example 1: This comparative example is a Pd-based SSZ-13 molecular sieve supported only on Pd, without any metal oxide additives. The specific preparation method is as follows: (1) Take 50 mL of deionized water into a flask, weigh 2.6745 g of ammonium chloride solid and dissolve it in the water. Add a magnetic stir bar and stir until the solid dissolves. Weigh 1 g of H-SSZ-13 molecular sieve and add it to the solution while stirring. Place the flask in an 80 ℃ constant temperature oil bath, reflux and stir for 2 h. After the oil bath, centrifuge and wash until the supernatant is neutral. Place it in an 80 ℃ oven to dry, grind and obtain NH4. + -SSZ-13.

[0065] (2) Take 5 mL of deionized water into a round-bottomed flask, and add NH4+. +-SSZ-13 material was dissolved in water, and stirred with a magnetic stirrer until the solid dissolved. 0.0554 g of a 18.09 wt.% Pd(NO3)2 solution was weighed and added to the solution while stirring. The mixture was then transferred to a 65 ℃ constant-temperature oil bath and refluxed with stirring for 24 h. After the reaction, the mixture was centrifuged and washed until the supernatant was neutral. It was then dried in an 80 ℃ oven, ground, and calcined in a muffle furnace at 550 ℃ for 4 h. The resulting product was Ce-Pd / SSZ-13 NO. x Low-temperature, high-efficiency storage materials.

[0066] (3) The obtained composite material was placed in a tube furnace and hydrothermally treated at 700 °C for 16 h in an air atmosphere containing 10 vol.% water vapor to obtain the hydrothermally aged composite material.

[0067] Comparative Example 2: This comparative example provides a rare earth element ion modified Pd-based SSZ-13 molecular sieve type NO. x The low-temperature high-efficiency storage material is specifically Ce-Pd / SSZ-13. The difference from Example 1 is that this comparative example uses a two-step method to introduce Pd and Ce separately. The specific preparation method is as follows: (1) Take 50 mL of deionized water into a flask, weigh 2.6745 g of ammonium chloride solid and dissolve it in the water. Add a magnetic stir bar and stir until the solid dissolves. Weigh 1 g of H-SSZ-13 molecular sieve (silicon-to-aluminum ratio of 20) and add it to the solution while stirring. Place the flask in an 80 ℃ constant temperature oil bath, reflux and stir for 2 h. After the oil bath, centrifuge and wash until the supernatant is neutral. Place it in an 80 ℃ oven to dry, grind and obtain NH4. + -SSZ-13.

[0068] (2) Take 5 mL of deionized water into a round-bottomed flask, and add NH4+. + -SSZ-13 material was dissolved in water, and a magnetic stirrer was added until the solid dissolved. 0.0434 g of Ce(NO3)4·6H2O solid was weighed and added to the solution while stirring. The mixed solution was then transferred to a constant temperature oil bath at 65 ℃, refluxed and stirred for 5 h. After the reaction was completed, the supernatant was centrifuged and washed until it was neutral. It was then dried in an oven at 80 ℃, ground, and calcined in a muffle furnace at 550 ℃ for 4 h. The resulting product was Ce / SSZ-13 material.

[0069] (3) Take 5 mL of deionized water in a round-bottom flask, dissolve the above Ce / SSZ-13 material in the water, add a magnetic stir bar and stir until the solid dissolves. Weigh 0.0554 g of Pd(NO3)2 solution with a mass fraction of 18.09 wt.% and add it to the solution while stirring. Then transfer the mixed solution to a constant temperature oil bath at 65 ℃, reflux and stir for 24 h. After the reaction is complete, centrifuge and wash until the supernatant is neutral, dry it in an oven at 80 ℃, grind it and calcine it in a muffle furnace at 550 ℃ for 4 h. The product obtained is Ce-Pd / SSZ-13 NO x Low-temperature, high-efficiency storage materials.

[0070] (4) The obtained material was placed in a tube furnace and hydrothermally treated at 700 °C for 16 h in an air atmosphere containing 10 vol.% water vapor to obtain the hydrothermally aged composite material.

[0071] Comparative Example 3: This comparative example provides a rare earth element ion modified Pd-based SSZ-13 molecular sieve type NO. x The low-temperature high-efficiency storage material, specifically Nd-Pd / SSZ-13, is prepared using the following method: (1) Take 50 mL of deionized water into a flask, weigh 2.6745 g of ammonium chloride solid and dissolve it in the water. Add a magnetic stir bar and stir until the solid dissolves. Weigh 1 g of H-SSZ-13 molecular sieve (silicon-to-aluminum ratio of 20) and add it to the solution while stirring. Place the flask in an 80 ℃ constant temperature oil bath, reflux and stir for 2 h. After the oil bath, centrifuge and wash until the supernatant is neutral. Place it in an 80 ℃ oven to dry, grind and obtain NH4. + -SSZ-13.

[0072] (2) Take 5 mL of deionized water into a round-bottomed flask, and add NH4+. + -SSZ-13 material was dissolved in water, and stirred with a magnetic stirrer until the solid dissolved. 0.0554 g of a 18.09 wt.% Pd(NO3)2 solution and 0.0438 g of Nd(NO3)4·6H2O solid were weighed and added to the solution while stirring. The mixed solution was then transferred to a 65 ℃ constant temperature oil bath and refluxed with stirring for 24 h. After the reaction was complete, the mixture was centrifuged and washed until the supernatant was neutral. It was then dried in an 80 ℃ oven, ground, and calcined in a muffle furnace at 550 ℃ for 4 h. The resulting product was Nd-Pd / SSZ-13 NO. x Low-temperature, high-efficiency storage materials.

[0073] (3) The obtained material was placed in a tube furnace and hydrothermally treated at 700 °C for 16 h in an air atmosphere containing 10 vol.% water vapor to obtain the hydrothermally aged composite material.

[0074] Comparative Example 4: This comparative example provides a rare earth element ion modified Pd-based SSZ-13 molecular sieve type NO. x The low-temperature high-efficiency storage material, specifically Sc-Pd / SSZ-13, is prepared using the following method: (1) Take 50 mL of deionized water into a flask, weigh 2.6745 g of ammonium chloride solid and dissolve it in the water. Add a magnetic stir bar and stir until the solid dissolves. Weigh 1 g of H-SSZ-13 molecular sieve (silicon-to-aluminum ratio of 20) and add it to the solution while stirring. Place the flask in an 80 ℃ constant temperature oil bath, reflux and stir for 2 h. After the oil bath, centrifuge and wash until the supernatant is neutral. Place it in an 80 ℃ oven to dry, grind and obtain NH4. + -SSZ-13.

[0075] (2) Take 5 mL of deionized water into a round-bottomed flask, and add NH4+. + -SSZ-13 material was dissolved in water, and stirred with a magnetic stirrer until the solid dissolved. 0.0554 g of a 18.09 wt.% Pd(NO3)2 solution and 0.0339 g of Sc(NO3)4·6H2O solid were weighed and added to the solution while stirring. The mixed solution was then transferred to a 65 ℃ constant temperature oil bath and refluxed with stirring for 24 h. After the reaction was complete, the mixture was centrifuged and washed until the supernatant was neutral. It was then dried in an 80 ℃ oven, ground, and calcined in a muffle furnace at 550 ℃ for 4 h. The resulting product was Sc-Pd / SSZ-13 NO. x Low-temperature, high-efficiency storage materials.

[0076] (3) The obtained material was placed in a tube furnace and hydrothermally treated at 700 °C for 16 h in an air atmosphere containing 10 vol.% water vapor to obtain the hydrothermally aged composite material.

[0077] Comparative Example 5: This embodiment provides a rare earth element ion modified Pd-based SSZ-13 molecular sieve type NO x The low-temperature high-efficiency storage material, specifically Y-Pd / SSZ-13, is prepared using the following method: (1) Take 50 mL of deionized water into a flask, weigh 2.6745 g of ammonium chloride solid and dissolve it in the water. Add a magnetic stir bar and stir until the solid dissolves. Weigh 1 g of H-SSZ-13 molecular sieve (silicon-to-aluminum ratio of 20) and add it to the solution while stirring. Place the flask in an 80 ℃ constant temperature oil bath, reflux and stir for 2 h. After the oil bath, centrifuge and wash until the supernatant is neutral. Place it in an 80 ℃ oven to dry, grind and obtain NH4. + -SSZ-13.

[0078] (2) Take 5 mL of deionized water into a round-bottomed flask, and add NH4+. + -SSZ-13 material was dissolved in water, and stirred with a magnetic stirrer until the solid dissolved. 0.0554 g of a 18.09 wt.% Pd(NO3)2 solution and 0.0383 g of Y(NO3)4·6H2O solid were weighed and added to the solution while stirring. The mixed solution was then transferred to a 65 ℃ constant temperature oil bath and refluxed with stirring for 24 h. After the reaction was complete, the mixture was centrifuged and washed until the supernatant was neutral. It was then dried in an 80 ℃ oven, ground, and calcined in a muffle furnace at 550 ℃ for 4 h. The resulting product was Y-Pd / SSZ-13 NO x Low-temperature, high-efficiency storage materials.

[0079] (3) The obtained material was placed in a tube furnace and hydrothermally treated at 700 °C for 16 h in an air atmosphere containing 10 vol.% water vapor to obtain the hydrothermally aged composite material.

[0080] Based on the successful preparation of the above embodiments, this invention further explores the application of the above material in low-temperature and high-efficiency NO storage. x Applications in [the field].

[0081] NO x The specific procedure for the adsorption / desorption test in NO is as follows: The prepared catalyst is granulated to 40-60 mesh and placed in a reactor for constant temperature NO testing. x Adsorption and temperature-programmed desorption tests were conducted. (Regarding the adsorption of NO...) x Pretreatment was performed first: 120 mg of sample was pretreated for 1 h in a 20% O2 flowing gas balanced with nitrogen at 500 °C, then the temperature was lowered to 100 °C and 200 ppm NO was introduced. x A gas feed of 10% O2, 5% H2O and 5% CO2 at a total flow rate of 400 mL / min is used for NO treatment. x Adsorption process. Desorption process: NO feed is shut off, and the temperature is increased to 500 °C at a rate of 10 °C / min.

[0082] The product information obtained from Examples 1-5 and Comparative Example 1 is summarized in Table 1.

[0083] Table 1 Summary of product composition from Examples 1-5 like Figure 2-3 As shown, NO in Pd / SSZ-13 in Comparative Example 1 x The adsorption capacity is 96.1 μmol·g. -1 The desorption capacity reached 62.9 μmol·g -1In contrast, the Ce-Pd / SSZ-13 material prepared in Example 1 using a co-ion exchange method to simultaneously introduce rare earth element ions and Pd active species showed NO content significantly higher. x The adsorption-desorption performance is significantly improved. For example... Figure 4-5 As shown, its NO after hydrothermal aging x The adsorption capacity and desorption capacity reached 127.3 μmol·g. -1 and 81.2 μmol·g -1 .

[0084] As can be seen from the above results, Ce in Example 1 3+ The introduction of Ce not only enables precise targeted regulation of the electronic state of Pd active sites, but also allows for the control of the electronic state of Pd active sites through Ce 3+ / Ce 4+ The cyclic electronic interaction effectively regulates Pd 2+ The active site is in an electronic defect state, promoting Pd 2+ Active site and NO x Coordination complexation of N atoms in NO significantly promotes NO x The low-temperature adsorption capacity was observed. A bimetallic supported molecular sieve PNA material was synthesized and constructed via a co-ion exchange method, allowing Ce ions to interact with Pd ions. 2+ Active sites form tight interaction pairs through the overlap of interfacial electron clouds, and further through Ce... 3+ / Ce 4+ The cyclic electronic interaction effectively regulates Pd 2+ The active site is in an electronic defect state, promoting Pd 2+ Active site and NO x Coordination complexation of N atoms in the middle.

[0085] On the other hand, by optimizing NO x The adsorption configuration allows it to exist in a stable monodentate or bidentate nitrate adsorption state, thereby significantly improving the NO content of the material. x Storage capacity completely solves the problem of difficult electronic structure regulation of Pd active sites and NO in traditional materials. x The problem of insufficient adsorption activity was solved, and the low-temperature NO adsorption capacity of the composite material was significantly enhanced. x Adsorption capacity and hydrothermal stability.

[0086] In addition, Sm introduced in Examples 2-5 3+ Pr 3+ La 3+ Gd 3+ Rare earth element ions can significantly improve the low-temperature NO x Adsorption capacity and adsorption efficiency.

[0087] Sm introduced in Example 2 3+By coordinating with the cation sites of SSZ-13 molecular sieve to form a Sm-O-Al / Sm-O-Si structure, the desilication phenomenon during hydrothermal aging is effectively suppressed, maintaining the integrity of the SSZ-13 framework structure, and thus significantly improving the material's low-temperature NO content. x Adsorption capacity and adsorption efficiency.

[0088] In Example 3, Pr 3+ The introduction of Z-[Pd] can effectively regulate the spatial coordination environment of Pd active sites through charge synergy, promoting the preferential complexation of Pd active components in the eight-membered ring channels of the molecular sieve, thereby forming highly active Z-[Pd] 2+ (OH)] - Species, improve NO x Adsorption selectivity and storage stability.

[0089] In Example 4, La 3+ The introduction of this technology not only effectively inhibits the damage to the molecular sieve framework structure caused by hydrothermal aging, but also promotes NO oxidation, significantly improving the material's low-temperature NO reduction performance. x Adsorption capacity and adsorption efficiency.

[0090] Gd introduced in Example 5 3+ By uniformly distributing Pd within the molecular sieve channel structure and creating a steric hindrance effect, the charge repulsion between ions inhibits the migration and aggregation of the active Pd component, thereby improving Pd dispersion stability and enhancing the NO content of the material. x Adsorption capacity.

[0091] In summary, the effective introduction of rare earth element ions not only modulates the electronic state of the Pd active component through charge compensation effect, but also significantly improves the low-temperature NO2 content. x Adsorption capacity and efficiency; simultaneously, it can effectively inhibit the damage to the molecular sieve framework structure caused by hydrothermal aging, and effectively promote NO adsorption. x Low-temperature adsorption storage.

[0092] In contrast, Comparative Example 2 introduced Pd and Ce species stepwise, Ce 3+ Preferentially occupying sites in the molecular sieve framework, thus leading to Pd 2+ The active components cannot be saturated and exchanged to the molecular sieve framework sites, which is detrimental to the material's NO content. x Improved adsorption performance.

[0093] In comparison, Nd in Comparative Example 3 3+ The introduction of [a substance] cannot effectively inhibit the damage to the molecular sieve framework structure caused by hydrothermal aging; therefore, NO [is present] after hydrothermal aging. x There was no significant improvement in adsorption performance.

[0094] The Sc introduced in Comparative Example 4 3+ Its electron transfer ability is weak and it cannot be compared with Pd.2+ The formation of effective charge interactions cannot effectively control the electronic state of Pd, nor can it optimize the coordination environment of Pd, making it difficult to improve the low-temperature NO production. x Adsorption capacity and efficiency.

[0095] Y introduced in Comparative Example 5 3+ The binding force with the molecular sieve framework is weak, making it difficult to inhibit framework structure damage during hydrothermal aging, and thus unable to improve the material's low-temperature NO adsorption through stable adsorption. x Adsorption capacity and efficiency.

[0096] In summary, this invention innovatively develops a method with good NO content. x NO2-low temperature storage capacity and water-heat aging stability x Storage catalytic materials. This invention innovatively synthesizes and constructs bimetallic supported molecular sieve PNA materials via a co-ion exchange method, achieving a highly efficient synergistic effect between rare earth element ions, Pd active species, and the molecular sieve support, significantly improving the NO storage capacity of the composite material. x The invention achieves high adsorption capacity and low-temperature adsorption efficiency while maintaining excellent hydrothermal aging stability of the composite material. The rare-earth element ion-modified Pd-based SSZ-13 molecular sieve composite material prepared in this invention exhibits low-temperature NO adsorption capacity and low-temperature adsorption efficiency. x With its superior storage performance, high stability, and simple manufacturing process, it can be coupled with NO x Catalytic reduction raw materials are widely applicable to NO emissions from various motor vehicle exhaust gases. x The low-temperature adsorption module, in conjunction with a downstream SCR unit, is suitable for automotive exhaust aftertreatment systems and can efficiently solve NO2 emissions during cold starts of motor vehicles. x Emissions issues.

[0097] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a rare earth element ion modified Pd-based SSZ-13 molecular sieve composite material, characterized in that, The preparation method includes the following steps: S1: Ammonium chloride and H-SSZ-13 molecular sieve are mixed and reacted, and the product is collected to obtain NH4. + -SSZ-13 molecular sieve; S2: NH4 obtained from S1 + -SSZ-13 molecular sieve was mixed with palladium salt and rare earth element ion precursor salt and then subjected to co-ion exchange reaction; the product was collected, ground and calcined to obtain rare earth element ion-Pd / SSZ-13 composite material. S3: The rare earth element ion-Pd / SSZ-13 composite material prepared in S2 is subjected to hydrothermal aging to obtain the final rare earth element ion modified Pd-based SSZ-13 molecular sieve composite material.

2. The preparation method of the rare earth element ion modified Pd-based SSZ-13 molecular sieve composite material according to claim 1, characterized in that, In step S1, the mass ratio of ammonium chloride to H-SSZ-13 molecular sieve is (2-3):1; The reaction temperature is 80-90 ℃, and the reaction time is 2-4 h.

3. The preparation method of a rare earth element ion modified Pd-based SSZ-13 molecular sieve composite material according to claim 1, characterized in that, In step S2, the NH4 + The mass ratio of SSZ-13 molecular sieve to palladium salt is 1:(0.6-1.4).

4. The preparation method of a rare earth element ion modified Pd-based SSZ-13 molecular sieve composite material according to claim 1, characterized in that, In step S2, the rare earth element ion in the rare earth element ion precursor salt is Ce. 3+ 、Sm 3+ 、Nd 3 + Pr 3+ La 3+ ,Sc 3+ Gd 3+ Y 3+ At least one of them; The molar concentration of the rare earth element ion precursor salt is 0.01~0.2 mol / L.

5. The preparation method of a rare earth element ion modified Pd-based SSZ-13 molecular sieve composite material according to claim 1, characterized in that, In step S2, the palladium salt is any one or more of palladium nitrate, palladium chloride, and palladium sulfate.

6. The method for preparing a rare earth element ion modified Pd-based SSZ-13 molecular sieve composite material according to claim 1, characterized in that, In step S2, the reaction temperature is 60-80 °C, and the reaction time is 18-24 h; The calcination temperature is 450-550 ℃, and the second calcination time is 3-5 h.

7. The preparation method of a rare earth element ion modified Pd-based SSZ-13 molecular sieve composite material according to claim 1, characterized in that, In step S3, the hydrothermal aging is carried out in an air atmosphere containing 5-15 vol.% water vapor; The hydrothermal aging temperature is 700-750 ℃, and the hydrothermal aging time is 12-16 h.

8. A rare earth element ion-modified Pd-based SSZ-13 molecular sieve composite material, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.

9. The rare earth element ion-modified Pd-based SSZ-13 molecular sieve composite material according to claim 8, characterized in that, The composite material uses SSZ-13 molecular sieve as a carrier and is loaded with Pd active components and modifying agents; The loading of the Pd active component is 1-3% of the mass of SSZ-13 molecular sieve; The modifying agent is a rare earth element ion, specifically Ce. 3+ 、Sm 3+ 、Nd 3+ Pr 3+ La 3+ ,Sc 3+ Gd 3+ Y 3+ One or more of them.

10. A rare earth element ion-modified Pd-based SSZ-13 molecular sieve composite material as described in claim 8 for low-temperature and high-efficiency storage of NO. x Applications in [the field].

Images