Tail gas NOx adsorption catalyst for rubber-tyred diesel vehicle and application of preparation method of tail gas NOx adsorption catalyst
By using sepiolite-based CuOx catalysts in the exhaust gas of rubber-tired diesel vehicles, the problems of insufficient low-temperature activity and sulfur resistance have been solved, achieving a highly efficient NOx purification effect, which is suitable for the purification of exhaust gas from rubber-tired diesel vehicles.
Patent Information
- Application Number
- CN202510970771.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-15
- Publication Date
- 2025-11-07
AI Technical Summary
Existing catalysts for nitrogen oxides (NOx) in the exhaust of rubber-tired diesel vehicles have insufficient activity at low temperatures, poor hydrothermal stability, and are easily affected by sulfur pollution, making it difficult to effectively purify exhaust gases.
Using sepiolite as a carrier, a catalyst was prepared by strong acid modification and copper salt impregnation to form CuOx active components, thereby improving the low-temperature activity and sulfur resistance of the catalyst. By utilizing the natural fibrous structure of sepiolite and the specific adsorption capacity of CuOx, rapid adsorption and reduction of NOx can be achieved.
It significantly improves the low-temperature activity and sulfur resistance of the catalyst, has good NOx reduction performance and rapid adsorption capacity, and has a simple process and low cost, making it suitable for exhaust gas purification of rubber-tired diesel vehicles.
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Figure CN120900577A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of motor vehicle exhaust purification, and particularly relates to a rubber-tired diesel vehicle exhaust NOx adsorption catalyst and application of a preparation method thereof. BACKGROUND
[0002] With increasingly stringent environmental protection regulations in China, the emission control of nitrogen oxides (NOx) in diesel vehicle exhaust is facing a major challenge. Rubber-tired diesel vehicles (including port machinery, mine vehicles and other non-road mobile sources) have a low exhaust pollution control level due to their special working conditions, which causes air quality deterioration and seriously affects the life and health of residents. Vehicle exhaust has become one of the main air pollution sources, and the treatment of vehicle exhaust has become a very urgent task.
[0003] Rubber-tired diesel vehicles frequently start and stop, and the exhaust temperature is often lower than 200℃. The conversion efficiency of traditional SCR catalysts in this temperature window is less than 40%. The existing NH3-SCR (ammonia selective catalytic reduction method) denitration technology removes NOx by using NH3 or urea as a reducing agent to reduce NOx to N2 under the action of a catalyst. However, the catalyst prepared by NH3-SCR (ammonia selective catalytic reduction method) is easily deactivated in a sulfur-containing environment, and the activity decreases by more than 50%.
[0004] Nitrogen oxides in vehicle exhaust have great harm to the environment, but the commonly used catalysts have poor water solubility and reaction activity, and the treatment is difficult. In order to control and prevent vehicle exhaust pollution, scientists and researchers around the world have done a lot of research work, and this research has very important practical significance. SUMMARY
[0005] The purpose of the present application is to solve the above problems, and to provide a preparation method of a rubber-tired diesel vehicle exhaust NOx adsorption catalyst, which solves the problems of insufficient hydrothermal stability and poor low-temperature activity of existing NOx adsorption catalysts. The preparation method significantly improves the low-temperature activity and sulfur resistance of the catalyst, and has the advantages of simple process, low cost, good NOx reduction performance and fast adsorption capacity.
[0006] To this end, the first aspect of the present application provides a preparation method of a rubber-tired diesel vehicle exhaust NOx adsorption catalyst, which comprises: immersing the purified sepiolite in a strong acid solution, then drying and calcining the sepiolite carrier to obtain a sepiolite carrier; immersing the sepiolite carrier in a copper salt solution, then drying and calcining the sepiolite carrier to obtain the rubber-tired diesel vehicle exhaust NOx adsorption catalyst.
[0007] Compared with traditional catalytic materials, the natural fibrous structure of sepiolite provides a super large specific surface area, and the unique pore structure is conducive to the dispersion of active components, and the cost is only 1 / 5 of the molecular sieve carrier, and the CuOx active component has strong specific adsorption capacity for NO molecules, and the sulfur resistance is better than that of traditional noble metals.
[0008] The active component Cu is loaded on the sepiolite modified by strong acid, which can make NOx desorb and reduce to N2 at low temperature, complete the regeneration of the catalyst and the catalytic reduction of NOx.
[0009] As a preferred solution, before the first drying, it further includes a process of washing with deionized water.
[0010] As a preferred solution, after the reduction, it further includes a shaping treatment: grinding and mixing the catalyst uniformly, and then tabletting and shaping.
[0011] As a preferred solution, the step of purifying sepiolite includes: Mixing sepiolite raw ore with water, pouring off the upper suspension, retaining the middle suspension, and treating the lower precipitate according to the above method several times, filtering all the obtained suspensions, and drying the obtained solid to obtain purified sepiolite.
[0012] As a preferred solution, the preparation method of the above-mentioned NOx adsorption catalyst for diesel vehicle exhaust of rubber-tyred vehicles at least meets one of the following characteristics: The strong acid includes at least one of nitric acid and / or hydrochloric acid, and optionally meets: the concentration of the strong acid is 1-2 mol / L; modifying sepiolite with the above-mentioned strong acid can increase its specific surface area, improve the dispersion degree of active components, and significantly improve the low-temperature activity and sulfur resistance of the catalyst; The temperature at which the purified sepiolite is fully soaked in the strong acid solution is 60-80°C; The time for which the purified sepiolite is fully soaked in the strong acid solution is 4-8h.
[0013] As a preferred solution, the preparation method of the above-mentioned NOx adsorption catalyst for diesel vehicle exhaust of rubber-tyred vehicles at least meets one of the following characteristics: The copper salt is copper nitrate; The loading amount of copper is 5-20wt%.
[0014] As a preferred solution, the preparation method of the above-mentioned NOx adsorption catalyst for diesel vehicle exhaust of rubber-tyred vehicles at least meets one of the following characteristics: The temperature of the first drying is 100-300°C; The temperature of the first calcination is 200-300°C; The time of the first calcination is 2-6h; The temperature of the second drying is 50-70°C; The temperature of the second calcination is 300-500℃; The time of the second calcination is 3-5h.
[0015] As a preferred solution, the second calcination preferably adopts a programmed temperature rising mode, and the temperature rising rate is preferably 2-10℃ / min.
[0016] As a preferred solution, the preparation method of the above-mentioned NOx adsorption catalyst for rubber-tired diesel vehicle exhaust adopts ultrasonic-assisted impregnation, and simultaneously optionally meets: The time of the ultrasonic-assisted impregnation is 1-2h; The power of the ultrasonic-assisted impregnation is 180-220W, such as 200W, so as to achieve uniform loading.
[0017] As a preferred solution, the preparation method of the above-mentioned NOx adsorption catalyst for rubber-tired diesel vehicle exhaust is reduced in a hydrogen atmosphere, and at least meets one of the following characteristics: The concentration of hydrogen is 4-6vol%; The temperature of the reduction is 350-450℃; The time of the reduction is 2-3h.
[0018] The second aspect of the present application provides the NOx adsorption catalyst for rubber-tired diesel vehicle exhaust obtained by the above-mentioned preparation method. After loading Cu element, various Cu phases are formed in the catalyst carrier, in addition to CuO species, there are also a small amount of Cu2O and Cu species.
[0019] The third aspect of the present application provides the application of the above-mentioned NOx adsorption catalyst for rubber-tired diesel vehicle exhaust in adsorbing NOx of rubber-tired diesel vehicle exhaust.
[0020] According to the present application, the temperature for adsorbing NOx of rubber-tired diesel vehicle exhaust is 150-400℃.
[0021] Compared with the prior art, the present application at least includes the following beneficial effects: (1) The catalyst prepared by the above-mentioned method has good low-temperature activity, excellent sulfur resistance, good NOx reduction performance and rapid adsorption capacity.
[0022] (2) The preparation method of the present application and the required equipment are simple, the process is simple, the cost is low, the operation is easy, the process parameters are easy to control, the raw materials and instrument equipment have low use cost, etc.
[0023] The above description is only a summary of the technical solutions of the present application, in order to more clearly understand the technical means of the present application, the specific embodiments of the present application can be implemented according to the content of the specification, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS
[0024] Figure 1 SEM image of CuOx / sea-sand catalyst; Figure 2 XRD spectrum of sea-sand raw ore and modified sea-sand catalyst; Figure 3 NOx removal rate curve of different catalysts. DETAILED DESCRIPTION
[0025] In the following description, numerous specific details are set forth to provide a more thorough understanding of the disclosed technology. However, it will be apparent to one of skill in the art that the technology provided herein can be practiced without one or more of these specific details.
[0026] Several specific examples are given below to further understand the present application.
[0027] In the examples and comparative examples of the present application, the sea-sand is sea-sand raw ore powder (Henan Leibao sea-sand company, 280 mesh, industrial grade), and the weight percentage of the three elements in the raw ore is: Si 42.01%, Al 3.28%, Mg 6.78%.
[0028] In the examples and comparative examples of the present application, the purification steps of sea-sand include: stirring the sea-sand raw ore with an appropriate amount of distilled water for 10 min, standing for a while, pouring off the upper suspended matter, taking the middle suspended solution, and treating the lower precipitate several times according to the above method. All the obtained suspensions are filtered, and the obtained solid is dried at 200℃.
[0029] In the examples of the present application, the power of ultrasonic-assisted impregnation is 200W.
[0030] In the examples of the present application, the copper nitrate used is a blue crystalline solid purchased, which is prepared into a 1 mol / L copper nitrate solution.
[0031] Example 1 Take 100g sea-sand and purify it with distilled water, fully immerse the purified sea-sand in a 1.5 mol / L hydrochloric acid solution for 6h at a temperature of 70℃, and fully stir, then dry at 200℃, calcine the obtained acid-washed and dried solid at 220℃ for 4h, to prepare the carrier; prepare a copper nitrate solution and add the above obtained carrier, ultrasonic-assisted impregnation for 1h, dry at 60℃, calcine the dried solid at 400℃ for 5h, then reduce in a hydrogen atmosphere (hydrogen concentration 5 vol%) at 350℃ for 2h, to obtain a catalyst for NOx adsorption of rubber diesel vehicle exhaust. Treat the catalyst sample in a water vapor atmosphere (water vapor concentration 10 vol%) at 350℃ for 24h, then test its specific surface area and dispersion of active components. Denoted as 1#.
[0032] Example 2 Take 100 g of sea sponges with distilled water to purify, after purification of sea sponges are fully immersed in 1.0 mol / L hydrochloric acid solution for 6 h, the temperature is 70 ℃, and fully stirred, and then dried at 200 ℃, the obtained acid washing dried solid is calcined at 220 ℃ for 4 h, to prepare the carrier; preparation of copper nitrate solution, and add the obtained carrier, ultrasonic assisted immersion for 1 hour, dry at 60 ℃, the dried solid is calcined at 400 ℃ for 5 h, and then reduced in hydrogen atmosphere (hydrogen concentration 5 vol%) at 350 ℃ for 2 h, to obtain the catalyst for rubber diesel vehicle exhaust NOx adsorption, marked as 2#.
[0033] Example 3 Take 100 g of sea sponges with distilled water to purify, after purification of sea sponges are fully immersed in 2 mol / L hydrochloric acid solution for 6 h, the temperature is 70 ℃, and fully stirred, and then dried at 200 ℃, the obtained acid washing dried solid is calcined at 220 ℃ for 4 h, to prepare the carrier; preparation of copper nitrate solution, and add the obtained carrier, ultrasonic assisted immersion for 1 hour, dry at 60 ℃, the dried solid is calcined at 400 ℃ for 5 h, and then reduced in hydrogen atmosphere (hydrogen concentration 5 vol%) at 350 ℃ for 2 h, to obtain the catalyst for rubber diesel vehicle exhaust NOx adsorption, marked as 3#.
[0034] Example 4 Take 100 g of sea sponges with distilled water to purify, after purification of sea sponges are fully immersed in 1.0 mol / L nitric acid solution for 6 h, the temperature is 70 ℃, and fully stirred, and then dried at 200 ℃, the obtained acid washing dried solid is calcined at 220 ℃ for 4 h, to prepare the carrier; preparation of copper nitrate solution, and add the obtained carrier, ultrasonic assisted immersion for 1 hour, dry at 60 ℃, the dried solid is calcined at 400 ℃ for 5 h, and then reduced in hydrogen atmosphere (hydrogen concentration 5 vol%) at 350 ℃ for 2 h, to obtain the catalyst for rubber diesel vehicle exhaust NOx adsorption, marked as 4#.
[0035] Example 5 Take 100 g of sea sponges with distilled water to purify, after purification of sea sponges are fully immersed in 1.5 mol / L nitric acid solution for 6 h, the temperature is 70 ℃, and fully stirred, and then dried at 200 ℃, the obtained acid washing dried solid is calcined at 220 ℃ for 4 h, to prepare the carrier; preparation of copper nitrate solution, and add the obtained carrier, ultrasonic assisted immersion for 1 hour, dry at 60 ℃, the dried solid is calcined at 400 ℃ for 5 h, and then reduced in hydrogen atmosphere (hydrogen concentration 5 vol%) at 350 ℃ for 2 h, to obtain the catalyst for rubber diesel vehicle exhaust NOx adsorption, marked as 5#.
[0036] Example 6 Take 100 g of sepiolite and purify it with distilled water, soak the purified sepiolite in a 2.0 mol / L nitric acid solution for 6 h at 70°C with sufficient stirring, then dry at 200°C, and the obtained acid-washed and dried solid is calcined at 220°C for 4 h to prepare the carrier; prepare a copper nitrate solution and add the above obtained carrier, ultrasonic-assisted impregnation for 1 h, dry at 60°C, and the dried solid is calcined at 400°C for 5 h, then reduced at 350°C for 2 h in a hydrogen atmosphere (hydrogen concentration 5 vol%) to obtain a catalyst for adsorbing NOx in the exhaust gas of a rubber-tyred diesel vehicle, denoted as 6#.
[0037] Comparative Example 1 The difference from Example 1 is that acetic acid is used instead of hydrochloric acid, and the other steps are exactly the same as Example 1. The comparison results show that the effect of acetic acid acidification modification of sepiolite is not as good as that of hydrochloric acid and nitric acid, because acetic acid is a weak acid, which not only cannot remove the impurities on the surface of sepiolite as efficiently as hydrochloric acid, but also the modification effect on sepiolite is not as good as that of hydrochloric acid, resulting in lower specific surface area and lower dispersion of active components of the catalyst.
[0038] Comparative Example 2 The difference from Example 5 is that sodium carbonate is used for modification, and the other steps are exactly the same as Example 5. The comparison results show that the specific surface area of the catalyst modified by sodium carbonate and treated in a water vapor atmosphere is 90 m 2 / g, and the dispersion of copper decreases significantly. Acid modification removes impurities and increases the pore structure, making the surface of sepiolite more conducive to the uniform dispersion of copper, and because the acid treatment improves the surface chemical properties of sepiolite, it reduces the risk of sulfur poisoning, thereby improving the activity, stability and sulfur resistance of the catalyst at low temperature.
[0039] Comparative Example 3 The difference from Example 2 is that the same concentration of iron salt Fe(NO3)3 solution is used instead of Cu(NO3)2 solution for loading, and the other steps are exactly the same as Example 2.
[0040] The comparison results show that there is a significant difference in catalytic performance between iron oxide (FeOx) and copper oxide (CuOx), and the sulfur resistance and low-temperature activity of iron oxide are not as good as those of copper oxide at low temperature.
[0041] Comparative Example 4 Take 100 g of sepiolite and wash it with distilled water to purify. Dry the purified sepiolite at 200°C. After acid washing and drying, the solid is calcined at 220°C for 4 hours to prepare the carrier. Prepare a copper nitrate solution and add the carrier obtained above. Ultrasonic-assisted impregnation for 1 hour, drying at 60°C, calcining the dried solid at 400°C for 5 hours, and then reducing at 350°C for 2 hours in a hydrogen atmosphere (hydrogen concentration 5 vol%) to obtain a catalyst for adsorbing NOx from the exhaust gas of a rubber-tired diesel vehicle, denoted as 7#.
[0042] Test Example The performance of the catalysts obtained in the examples and comparative examples was tested, and the results are as follows: Table 1
[0043] Table 2
[0044] Table 3
[0045] Table Explanation: Loading: represents the content of copper and iron in the catalyst, in weight percentage (wt%). Higher loading generally means more active sites, thus improving catalytic performance.
[0046] Hydrothermal stability: evaluated by specific surface area and copper dispersion. Higher specific surface area and good dispersion indicate that the catalyst can maintain good structural stability under hydrothermal conditions.
[0047] Sulfur resistance: evaluated by the activity retention rate of the catalyst in a sulfur-containing environment. Higher activity retention rate indicates that the catalyst has better stability in a sulfur-containing environment.
[0048] The catalysts of the examples are superior to the comparative examples in various performance, especially in loading, hydrothermal stability, low-temperature activity, sulfur resistance, and NOx adsorption efficiency. This shows that the preparation method of the present application can significantly improve the performance of the catalyst, making it more suitable for adsorbing and purifying NOx from the exhaust gas of a rubber-tired diesel vehicle.
[0049] Figure 1 The scanning electron microscope (SEM) image of the CuOx / sepiolite catalyst shows that the active component Cu is evenly distributed on the surface and in the pores of the catalyst. When the loading is moderate, no large agglomerates are observed, achieving a certain degree of dispersion.
[0050] Figure 2 The XRD spectrum of the sepiolite raw ore and the modified sepiolite catalyst, Figure 2In the table, a. raw sepiolite; b. raw sepiolite without acid washing was directly immersed in copper nitrate solution for 1d and calcined at 400℃; c. sepiolite was immersed in 1.0mol / L hydrochloric acid for 1d, then immersed in copper nitrate solution for 1d and calcined at 400℃; d. sepiolite was immersed in 1.5mol / L hydrochloric acid for 2d, then immersed in copper nitrate solution for 1d and calcined at 400℃; e. sepiolite was immersed in 2.0mol / L hydrochloric acid for 3d, then immersed in copper nitrate solution for 1d and calcined at 400℃. It can be seen that the strong acid modification can effectively improve the porosity of sepiolite and promote the uniform loading of CuO.
[0051] Figure 3 The figure is a curve of NOx removal rate of different catalysts, which shows the relationship between NOx removal rate of different modified sepiolite catalysts and reaction temperature. 1# is 1.5mol / L HCl copper-impregnated sepiolite; 2# is 1.0mol / L HCl copper-impregnated sepiolite; 3# is 2.0mol / L HCl copper-impregnated sepiolite; 4# is 1.0mol / L HNO3 copper-impregnated sepiolite; 5# is 1.5mol / L HNO3 copper-impregnated sepiolite; 6# is 2.0mol / L HNO3 copper-impregnated sepiolite; 7# is copper-impregnated sepiolite without acid washing. It can be seen that the NOx removal rate of the catalysts of the embodiments of the present application is significantly better than that of the copper-impregnated sepiolite catalyst without acid washing at 150-400℃. Figure 3 It can be seen that the NOx removal rate of the catalysts of the embodiments of the present application is significantly better than that of the copper-impregnated sepiolite catalyst without acid washing at 150-400℃.
[0052] The above only describes the preferred embodiments of the present application and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A method for preparing a rubber-tired diesel vehicle exhaust NOx adsorbing catalyst, characterized by, The preparation method comprises: immersing the purified sepiolite in a strong acid solution, and then obtaining the sepiolite carrier through first drying and first calcination; immersing the sepiolite carrier in a copper salt solution, and then obtaining the rubber-tired diesel vehicle exhaust NOx adsorption catalyst through second drying, second calcination and reduction; The loading amount of copper is 8-10 wt%.
2. The preparation method of the NOx adsorption catalyst for rubber-tired diesel vehicle exhaust according to claim 1, characterized in that, The step of purifying the sepiolite comprises: mixing the sepiolite ore with water, pouring off the upper suspension, retaining the middle suspension, re-treating the lower precipitate according to the above method for several times, extracting all the suspensions, drying the obtained solid, and obtaining the purified sepiolite.
3. The preparation method of the NOx adsorption catalyst for rubber-tired diesel vehicle exhaust according to claim 1, characterized in that, At least one of the following characteristics is satisfied: The strong acid comprises at least one of nitric acid and / or hydrochloric acid, and optionally, the concentration of the strong acid is 1-2 mol / L; The temperature for immersing the purified sepiolite in the strong acid solution is 60-80℃; The time for immersing the purified sepiolite in the strong acid solution is 4-8 h.
4. The preparation method of the NOx adsorption catalyst for rubber-tired diesel vehicle exhaust according to claim 1, characterized in that: The copper salt is copper nitrate.
5. The preparation method of the NOx adsorption catalyst for rubber-tired diesel vehicle exhaust according to claim 1, characterized in that, At least one of the following characteristics is satisfied: The temperature for the first drying is 100-300℃; The temperature for the first calcination is 200-300℃; The time for the first calcination is 2-6 h; The temperature for the second drying is 50-70℃; The temperature for the second calcination is 300-500℃; The time for the second calcination is 3-5 h.
6. The method for preparing the NOx adsorption catalyst for rubber-tired diesel vehicle exhaust according to claim 1, characterized in that, Ultrasonic-assisted immersion is adopted, and optionally, the following characteristics are satisfied: The time for the ultrasonic-assisted immersion is 1-2 h; The power for the ultrasonic-assisted immersion is 180-220 W.
7. The preparation method of the NOx adsorption catalyst for rubber-tired diesel vehicle exhaust according to claim 1, characterized in that, The reduction is performed in a hydrogen atmosphere, and at least one of the following characteristics is satisfied: The concentration of hydrogen is 4-6 vol%; The temperature for the reduction is 350-450℃; The time for the reduction is 2-3 h.
8. The rubber-tired diesel vehicle exhaust NOx adsorption catalyst obtained by the preparation method in any one of claims 1-7.
9. The rubber-tired diesel vehicle exhaust NOx adsorption catalyst in claim 8 is used for adsorbing rubber-tired diesel vehicle exhaust NOx.
10. Use according to claim 9, characterized in that, The temperature for the rubber-tired diesel vehicle exhaust NOx adsorption is 150-400℃.