Catalyst for treating exhaust gas of natural gas vehicle and preparation method thereof

Abstract

The application discloses a kind of catalysts for treating natural gas automobile exhaust and preparation method thereof, the catalyst is that noble metal Pd is loaded on two composite material mixed carrier, the composite material is composed of material 1 and material 2, the material 1 is cerium zirconium aluminum composite material, wherein the cerium zirconium aluminum content ratio is Ce 0~20%, Zr 0~10%, Al 68~98%, other rare earth metal content 2%;The material 2 is cerium zirconium composite material, wherein the cerium zirconium ratio is Ce 10~45%, Zr 35~45%, for other rare earth metal 0~20%.The application preparation method is simple, and the preparation process is easy to operate, and the catalyst has excellent CH4 conversion performance, low energy consumption, and excellent anti-aging performance. The method for preparing catalyst by reduction one-step pulp preparation improves the catalytic performance of natural gas catalyst, while reducing the energy consumption in the process of preparing catalyst by traditional impregnation method, and is more energy-saving.

Description

Technical Field

[0001] This invention relates to the field of automotive exhaust catalytic technology, specifically to a catalyst for treating natural gas vehicle exhaust and its preparation method. Background Technology

[0002] With the development of the times, energy and environmental issues have gradually become a focus of attention. The gradual depletion of oil resources and the series of environmental problems caused by oil combustion have led people to focus on developing alternatives to oil. Currently, natural gas has gradually become one of the best alternative energy sources. As a clean energy source, natural gas has advantages such as abundant reserves, high combustion efficiency, and low emissions. Compared with traditional gasoline vehicles, natural gas vehicles produce less CO, HC, and NO in their exhaust. x Natural gas vehicles emit lower levels of pollutants and are more environmentally friendly. Therefore, developing efficient and stable catalysts for natural gas vehicles to reduce methane emissions has become an important direction for the development of natural gas vehicles.

[0003] Traditional natural gas three-way catalysts are generally composed of Pt, Pd, and Rh active components mixed with transition metals or alkali metals as additives, and oxygen storage materials or alumina materials as catalyst supports. The active components and additives are loaded onto the catalyst support by high-temperature drying and calcination using an impregnation method, and then coated onto a honeycomb ceramic support through multiple layers. More and more engine manufacturers are demanding continuous cost reduction, so reducing the catalyst preparation process has become one of the means to reduce the production cost of catalysts.

[0004] Chinese patent CN114870860 A discloses a perovskite-type catalyst. This catalyst uses different reducing agents as dispersants to adjust the solution pH, and forms a sol with different transition metal salts and alumina. After drying and calcination, different catalyst powders are obtained. A layered coating method is used to allow different coatings to perform different functions, and their combined use reduces pollutant emissions. A composite La... x A y Mn z B 1-z As the first coating, modified alumina is used as the second coating, and Pt, Rh or Pd, Rh noble metals are loaded onto cerium-zirconium solid solution as the third coating. Each layer is coated and dried separately, and then calcined after all coatings are dried. The multiple coating and drying processes increase the production cost of the catalyst.

[0005] Chinese patent CN115970687A discloses a method for preparing a Pt-based catalyst. The method involves loading noble metals onto cerium-zirconium oxide in a hydrophobic aqueous solution to improve the dispersion of the noble metal active components and thus enhance catalytic activity. In the preparation of the inner layer powder of the catalyst, a reducing agent is added, which reduces the valence state of the noble metals Pt and Pd to form atomic-level bonds, inhibiting the migration and agglomeration of the noble metals and improving the anti-aging performance of the catalyst.

[0006] The above-mentioned technical solutions all require multi-layer coating and drying calcination, and the preparation process parameters are relatively complex. Therefore, it is necessary to develop catalysts with simpler preparation processes, lower precious metal content, and higher catalytic efficiency. Summary of the Invention

[0007] The purpose of this invention is to provide a catalyst for treating natural gas vehicle exhaust and its preparation method, so as to solve the technical problems of the existing technology that requires multi-layer coating, drying and calcination, and has a complicated preparation process.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] This invention provides a catalyst for treating natural gas vehicle exhaust. The catalyst is composed of a precious metal Pd loaded on a composite material carrier consisting of material 1 and material 2. Material 1 is a cerium-zirconium-aluminum composite material, wherein the cerium-zirconium-aluminum content is Ce 0-20%, Zr 0-10%, Al 68-98%, and other rare earth metal La 2%. Material 2 is a cerium-zirconium composite material, wherein the cerium-zirconium content is Ce 10-45%, Zr 35-45%, and other rare earth metal La 0-20%.

[0010] Furthermore, the mass ratio of Pd in ​​material 1 and material 2 is 1:1.

[0011] Furthermore, the mass ratio of material 1 to material 2 is 1:10 to 10:1.

[0012] This invention also provides a method for preparing a catalyst for treating natural gas vehicle exhaust, comprising the following steps:

[0013] Step 1: Preparation of the slurry

[0014] (1) Take palladium nitrate solution, material 1, material 2, reducing agent and deionized water according to the proportions and mix them. Stir in a water bath at 60°C.

[0015] (2) Add the slurry prepared in step (1) into the ball mill jar and add acetic acid to adjust the pH of the slurry to 2-7. Add binder to keep the slurry viscous and put it into the ball mill and stir quickly.

[0016] Step 2: Applying starch and drying

[0017] The slurry prepared in (2) was coated onto a cordierite ceramic carrier, dried for 2-4 hours, and then calcined at 500°C for 2 hours to obtain the catalyst.

[0018] Furthermore, the reducing agent is one of ascorbic acid, glucose, or ethylene glycol.

[0019] Furthermore, the content of the reducing agent is 5 times the molar content of the precious metal Pd.

[0020] Furthermore, this invention uses cordierite honeycomb ceramic as a carrier, cerium-zirconium-aluminum material as a coating, and precious metal Pd as a catalyst active component, with a coating amount of 120 g / L.

[0021] In the preparation of the catalyst, the honeycomb ceramic support used is a cube with a honeycomb-like structure. The cube has a large number of mesh-like channels. The thin walls of the channels can greatly increase the surface area of ​​the support. The catalyst slurry is coated in these channels. The amount of catalyst coated can be determined by the volume of the cube and the mass of the slurry coated on the cube. Therefore, it can be expressed in g / L.

[0022] Furthermore, step one: preparation of the slurry.

[0023] (1) Take palladium nitrate solution, one part of material 1, two parts of material 2, reducing agent and 80 ml of deionized water according to the proportions, mix them, and stir in a 60°C immersion water bath.

[0024] (2) Add the slurry prepared in step (1) into the ball mill jar and add acetic acid to adjust the pH of the slurry to 2-7. Add binder to keep the slurry viscous and put it into the ball mill and stir quickly.

[0025] Step 2: Applying starch and drying

[0026] The slurry prepared in (2) was coated onto a cordierite ceramic carrier, dried for 2-4 hours, and then calcined at 500°C for 2 hours to obtain the catalyst.

[0027] Furthermore, step one: preparation of the slurry.

[0028] (1) Take palladium nitrate solution, two portions of material 1, one portion of material 2, reducing agent and 80 ml of deionized water according to the proportions, mix them, and stir in a 60°C immersion water bath.

[0029] (2) Add the slurry prepared in step (1) into the ball mill jar and add acetic acid to adjust the pH of the slurry to 2-7. Add binder to keep the slurry viscous and put it into the ball mill and stir quickly.

[0030] Step 2: Applying starch and drying

[0031] The slurry prepared in (2) was coated onto a cordierite ceramic carrier, dried for 2-4 hours, and then calcined at 500°C for 2 hours to obtain the catalyst.

[0032] Based on the above technical solution, the embodiments of the present invention can produce at least the following technical effects:

[0033] (1) The present invention uses a reduction one-step slurry preparation method to prepare catalysts, which improves the catalytic performance of natural gas catalysts and reduces the energy consumption in the traditional impregnation method for preparing catalysts, making it more energy-efficient.

[0034] (2) The present invention provides a catalyst for treating natural gas vehicle exhaust gas and its preparation method. The preparation method is simple and easy to operate. The catalyst has excellent CH4 conversion performance, low energy consumption and excellent anti-aging performance.

[0035] (3) The catalyst prepared by the reducing agent in this invention has significantly improved catalytic performance of methane. Among them, the catalyst prepared by one-step slurry preparation with the reducing agent ascorbic acid, glucose, and ethylene glycol has improved catalytic performance in the fresh state. 50 All were around 320℃, with a significant decrease in ignition temperature, while the T of the aged catalyst... 50 It also maintains a temperature of around 350℃, exhibiting superior catalytic performance compared to traditional catalysts. Furthermore, the direct preparation and roasting of the reduced slurry during the pulping process reduces the steps involved in traditional catalyst preparation, such as drying and roasting the powder before preparing the slurry, thus lowering energy consumption. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0037] Figure 1 These are the results of the fresh catalyst activity evaluation tests of Comparative Examples 1-3 of this invention;

[0038] Figure 2 These are the results of the aging catalyst activity evaluation tests of Comparative Examples 1-3 of this invention;

[0039] Figure 3 These are the results of the fresh catalyst activity evaluation tests in Examples 1-3 of this invention;

[0040] Figure 4 These are the results of the aging catalyst activity evaluation tests in Examples 1-3 of this invention;

[0041] Figure 5 These are the results of the fresh catalyst activity evaluation tests in Examples 4-6 of this invention;

[0042] Figure 6 These are the results of the aging catalyst activity evaluation tests in Examples 4-6 of this invention. Detailed Implementation

[0043] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0044] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0045] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0046] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0047] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0048] This invention is configured with material 1 and material 2:

[0049] Optimizing the formation of active sites: The ratio of cerium, zirconium, and aluminum in the catalyst can be adjusted by changing the ratio of the two materials. A reasonable cerium-zirconium-aluminum ratio is conducive to the formation of active sites in the catalyst. Under different ratios, the materials will undergo different degrees of structural changes and interactions during pretreatment such as high temperature or actual reaction, which will promote the formation of specific active site structures on the support. The geometry and electronic environment of these structures are more favorable for the adsorption and activation of reactant molecules and the transformation of reaction intermediates.

[0050] Controlling raw material costs: Under the premise of meeting the catalytic performance requirements of natural gas, the preparation cost of the support and even the entire catalyst can be effectively reduced by adjusting the ratio of cerium, zirconium and aluminum and reasonably controlling the amount of cerium, zirconium and aluminum in the support.

[0051] During pulping, the pulp contains various components such as precious metal active components, carriers, binders, and reducing agents. A pH of 2-7 helps maintain the colloidal stability of the pulp system. Within this pH range, the interactions between the components are relatively balanced, making it less likely for particle aggregation and precipitation to occur due to factors such as excessive or insufficient electrostatic repulsion or changes in solubility.

[0052] Good slurry stability ensures that the slurry remains uniform during subsequent stirring and coating operations. After coating, the slurry is not easily detached from the honeycomb ceramic carrier, allowing the active components and the carrier to maintain a good dispersion and binding relationship.

[0053] In composite materials with a fixed cerium-zirconium ratio, cerium (Ce) has oxygen storage capacity. During redox reactions, cerium can... 3+ and Ce 4+ The oxygen can be stored and released through conversion between these processes. Cerium's oxygen storage capacity allows for timely replenishment of oxygen when oxygen content fluctuates in natural gas catalytic reactions, promoting efficient reaction processes. However, the oxygen storage capacity of cerium alone has limitations and may not fully meet requirements in some complex reaction conditions with significant variations in oxygen demand. The addition of zirconium (Zr) allows for interaction with cerium. Zirconium can alter the crystal structure and surface properties of cerium, thereby optimizing its oxygen storage performance.

[0054] Different cerium-zirconium ratios result in different cerium-zirconium solid solution structures and varying oxygen storage performance. Within a certain range, as the zirconium content increases, the oxygen vacancy concentration in the solid solution initially increases and then tends to stabilize. For example, at lower zirconium contents, zirconium atoms gradually enter the cerium lattice, forming more oxygen vacancies, making oxygen easier to adsorb, store, and release, thus enhancing oxygen storage performance. However, when the zirconium content is too high, excessive lattice distortion or the formation of other phase structures may cause oxygen vacancies to no longer increase significantly or even decrease, weakening the effect on improving oxygen storage performance.

[0055] Example 1

[0056] Step 1: Preparation of the slurry:

[0057] (1) Take 3.3882g of palladium nitrate solution, 12.152g of Material 1, 24.552g of Material 2, 4.1043g of ascorbic acid, and 80mL of deionized water and add them to a beaker. Immerse the mixture in a 60℃ water bath and stir until the weight reaches 87.23g.

[0058] (2) Add the powder prepared in step (1) into the ball mill jar, add 4g of acetic acid to adjust the pH of the slurry to 2-7, add 4g of binder to keep the slurry viscous, and put it into the ball mill and stir quickly.

[0059] Step 2: Sizing and Drying

[0060] The slurry prepared in (2) was coated onto a cordierite ceramic carrier with a loading of 120 g / L. After drying for 4-6 h, it was calcined at 500 °C for 2 h to obtain the catalyst.

[0061] Example 2

[0062] Step 1, Preparation of slurry: (1) Take 3.3882g palladium nitrate solution, 12.152g material 1, 24.552g material 2, 4.1984g glucose, and 80mL deionized water and add them to a beaker. Soak in a 60℃ water bath and stir until the weight reaches 87.23g.

[0063] (2) Add the powder prepared in step (1) into the ball mill jar, add 4g of acetic acid to adjust the pH of the slurry to 2-7, add 4g of binder to keep the slurry viscous, and put it into the ball mill and stir quickly.

[0064] Step 2, slurry coating and drying: The slurry prepared in (2) is coated on a cordierite ceramic carrier with a loading of 120 g / L. After drying for 4-6 h, it is calcined at 500 °C for 2 h to obtain the catalyst.

[0065] Example 3

[0066] Step 1, Preparation of slurry: (1) Take 3.3882g palladium nitrate solution, 12.152g material 1, 24.552g material 2, 1.4464g ethylene glycol, and 80mL deionized water and add them to a beaker. Immerse in a 60℃ water bath and stir until the weight reaches 87.23g.

[0067] (2) Add the powder prepared in step (1) into the ball mill jar, add 4g of acetic acid to adjust the pH of the slurry to 2-7, add 4g of binder to keep the slurry viscous, and put it into the ball mill and stir quickly.

[0068] Step 2, slurry coating and drying: The slurry prepared in (2) is coated on a cordierite ceramic carrier with a loading of 120 g / L. After drying for 4-6 h, it is calcined at 500 °C for 2 h to obtain the catalyst.

[0069] Example 4

[0070] Step 1, Preparation of slurry: (1) Take 3.3882g palladium nitrate solution, 24.552g material 1, 12.152g material 2, 4.1043g ascorbic acid, and 80mL deionized water and add them to a beaker. Soak in a 60℃ water bath and stir until the weight reaches 87.23g.

[0071] (2) Add the powder prepared in step (1) into the ball mill jar, add 4g of acetic acid to adjust the pH of the slurry to 2-7, add 4g of binder to keep the slurry viscous, and put it into the ball mill and stir quickly.

[0072] Step 2, slurry coating and drying: The slurry prepared in (2) is coated on a cordierite ceramic carrier with a loading of 120 g / L. After drying for 4-6 h, it is calcined at 500 °C for 2 h to obtain the catalyst.

[0073] Example 5

[0074] Step 1, Preparation of slurry: (1) Take 3.3882g palladium nitrate solution, 24.552g material 1, 12.152g material 2, 4.1984g glucose, and 80mL deionized water and add them to a beaker. Soak in a 60℃ water bath and stir until the weight reaches 87.23g.

[0075] (2) Add the powder prepared in step (1) into the ball mill jar, add 4g of acetic acid to adjust the pH of the slurry to 2-7, add 4g of binder to keep the slurry viscous, and put it into the ball mill and stir quickly.

[0076] Step 2, slurry coating and drying: The slurry prepared in (2) is coated on a cordierite ceramic carrier with a loading of 120 g / L. After drying for 4-6 h, it is calcined at 500 °C for 2 h to obtain the catalyst.

[0077] Example 6

[0078] Step 1, Preparation of slurry: (1) Take 3.3882g palladium nitrate solution, 24.552g material 1, 12.152g material 2, 1.4464g ethylene glycol, and 80mL deionized water and add them to a beaker. Immerse in a 60℃ water bath and stir until the weight reaches 87.23g.

[0079] (2) Add the powder prepared in step (1) into the ball mill jar, add 4g of acetic acid to adjust the pH of the slurry to 2-7, add 4g of binder to keep the slurry viscous, and put it into the ball mill and stir quickly.

[0080] Step 2, slurry coating and drying: The slurry prepared in (2) is coated on a cordierite ceramic carrier with a loading of 120 g / L. After drying for 4-6 h, it is calcined at 500 °C for 2 h to obtain the catalyst.

[0081] Comparative Example 1

[0082] (1) Take 1.6941g of palladium nitrate solution, 12.152g of material 1, and 11.423g of deionized water and add them to a beaker. After soaking and stirring for 2 hours, evaporate and dry the mixture in a water bath at 90℃. Then, calcine the resulting powder at 500℃ for 2 hours.

[0083] (2) Take 1.6941g of palladium nitrate solution, 24.552g of material 2, and 13.5036g of deionized water to prepare the powder according to step (1).

[0084] (3) Add the powder prepared in steps (1) and (2) into the ball mill jar, add 47.14g of deionized water and 4g of acetic acid to adjust the pH of the slurry to 2-7, add 4g of binder to keep the slurry viscous, and put it into the ball mill and stir quickly.

[0085] Slurry loading and drying: (4) The slurry prepared in (3) is coated onto a cordierite ceramic carrier with a loading of 120 g / L. After drying for 4-6 h, it is calcined at 500 °C for 2 h to obtain the catalyst.

[0086] Comparative Example 2

[0087] Preparation of slurry: (1) Take 3.3882g palladium nitrate solution, 12.152g material 1, 24.552g material 2, and 24.9266g deionized water and add them to a beaker for soaking and stirring for 2 hours. Then, evaporate and dry the slurry in a water bath at 90℃. Finally, calcine the resulting powder at 500℃ for 2 hours.

[0088] (2) Add the powder prepared in step (1) into the ball mill jar, add 47.14g of deionized water and 4g of acetic acid to adjust the pH of the slurry to 2-7, add 4g of binder to keep the slurry viscous, and put it into the ball mill and stir quickly.

[0089] Slurry loading and drying: (3) The slurry prepared in (2) is coated onto a cordierite ceramic carrier with a loading of 120 g / L. After drying for 4-6 h, it is calcined at 500 °C for 2 h to obtain the catalyst.

[0090] Comparative Example 3

[0091] (1) Take 3.3882g of palladium nitrate solution, 12.152g of material 1, 24.552g of material 2, 0.88g of NaBH4, and 80mL of deionized water and add them to a beaker. Immerse the mixture in a 60℃ water bath and stir until the weight reaches 87.23g.

[0092] (2) Add the powder prepared in step (1) into the ball mill jar, add 4g of acetic acid to adjust the pH of the slurry to 2-7, add 4g of binder to keep the slurry viscous, and put it into the ball mill and stir quickly.

[0093] Slurry drying: (3) The slurry prepared in (2) is coated on a cordierite ceramic carrier with a loading of 120 g / L. After drying for 4-6 h, it is calcined at 500 °C for 2 h to obtain the catalyst.

[0094] The activity evaluation results of the catalysts in Comparative Examples 1-3 are as follows: Figure 1 , 2 The figures show the activity evaluation data for comparative examples 1 and 2, respectively.

[0095] Table 1 CH4 activity data of different comparative catalysts

[0096]

[0097] The activity evaluation results of the catalysts in Examples 1-3 above are as follows: Figure 3 , 4 The figures represent the activity evaluation data for Examples 1, 2, and 3, respectively.

[0098] Table 2. CH4 activity data of catalysts in different embodiments

[0099]

[0100] Tables 1 and 2 show that, based on the data from Comparative Examples 1 and 2 and the Examples, the reduction impregnation method exhibits superior catalyst performance compared to the conventional catalyst impregnation method when using the same amount of precious metal. Example 3, using ethylene glycol reduction, demonstrates the superior catalyst performance of fresh catalyst T under the same evaluation conditions. 50 =310℃ and Comparative Example 3: Fresh Catalyst T Reduced with Strong Reducing Agent NaBH4 50 The temperature dropped by 119℃ compared to 429℃, indicating that the catalytic performance is better when using a reducing agent with milder reducing properties.

[0101] The activity evaluation results of the catalysts in Examples 4-6 above are as follows: Figure 5 , 6 The figures represent the activity evaluation data for Examples 4, 5, and 6, respectively.

[0102] Table 3. CH4 activity data of catalysts in different embodiments

[0103]

[0104]

[0105] Table 3 shows that, comparing Examples 4, 5, and 6 with Examples 1, 2, and 3, the catalyst using a higher mass ratio of material 1 exhibits superior catalytic performance after aging. Example 6, using ethylene glycol to reduce material 1 in a ratio of 2:1, shows better catalytic performance after aging than Example 3, which uses material 1 in a ratio of 1:2. Example 6 after aging... 90 It can still maintain high catalytic activity at 356℃, and the higher proportion of material 1 may make the catalyst more resistant to aging.

[0106] The catalysts prepared in Examples 1-6 under fresh conditions (T) 50 All were around 320℃, with a significant decrease in ignition temperature, while the T of the aged catalyst... 50 It also maintains a temperature of around 350℃, and its catalytic effect is superior to that of traditional catalysts.

[0107] The catalytic effect of the catalyst on methane was measured using the catalytic temperature T for the conversion of 50% and 90% of methane. 50 T 90 Measured by high and low, T 50 T 90 A lower value indicates that methane can achieve a higher conversion rate at a lower temperature, indicating higher catalyst activity. In this invention, the catalysts used in Examples 1-6 (reduction method) compared to those in Comparative Examples 1-2 (freshly aged) prepared by conventional methods have different T values. 50 T 90 Lower values ​​indicate improved catalytic performance of methane.

[0108] Finally, it should be noted that:

[0109] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a catalyst for treating natural gas vehicle exhaust, characterized in that, The catalyst is a composite material in which the noble metal Pd is supported on a mixed support of two composite materials. The composite material consists of material 1 and material 2. Material 1 is a cerium-zirconium-aluminum composite material, wherein the content of cerium, zirconium, and aluminum is Ce 0-20%, Zr 0-10%, Al 68-98%, and other rare earth metal La 2%. Material 2 is a cerium-zirconium composite material, wherein the content of cerium and zirconium is Ce 10-45%, Zr 35-45%, and other rare earth metal La 0-20%. The preparation method includes the following steps: Step 1: Preparation of slurry (1) Take palladium nitrate solution, material 1, material 2, reducing agent and deionized water according to the proportion and mix them. Stir in a water bath at 60°C. (2) Add the slurry prepared in step (1) into the ball mill jar and add acetic acid to adjust the pH of the slurry to 2-7. Add binder to keep the slurry viscous and put it into the ball mill and stir quickly. Step 2: Slurry coating and drying. The slurry prepared in (2) is coated onto a cordierite ceramic carrier, dried for 2-4 hours, and then calcined at 500℃ for 2 hours to obtain the catalyst.

2. The method for preparing a catalyst for treating natural gas vehicle exhaust according to claim 1, characterized in that, The mass ratio of Pd in ​​material 1 and material 2 is 1:

1.

3. The method for preparing a catalyst for treating natural gas vehicle exhaust according to claim 1, characterized in that, The mass ratio of material 1 to material 2 is 1:10 to 10:

1.

4. The method for preparing a catalyst for treating natural gas vehicle exhaust according to claim 1, characterized in that, The reducing agent is one of ascorbic acid, glucose, or ethylene glycol.

5. The method for preparing a catalyst for treating natural gas vehicle exhaust according to claim 1, characterized in that, The reducing agent content is 5 times the molar content of the precious metal Pd.

6. The method for preparing a catalyst for treating natural gas vehicle exhaust according to claim 1, characterized in that, In step two, the amount of slurry coated on the cordierite ceramic carrier is 120 g / L.

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