Ordered honeycomb rare earth-based catalyst exhaust filter and method for manufacturing the same, method for manufacturing pyramid-shaped catalyst exhaust filter

Abstract

The present application relates to the motor vehicle exhaust purification technical field, specifically to order honeycomb rare earth base catalyst exhaust filter and its preparation method, the preparation method of pyramid type catalyst exhaust filter.Order honeycomb rare earth base catalyst exhaust filter preparation method includes: (1) the exhaust filter to be handled is treated with acid, and the exhaust filter I is obtained; (2) the exhaust filter I is treated with first impregnation in modified aluminum sol, and the obtained exhaust filter II is treated with first calcination, and the exhaust filter III coated with modified coating is obtained; (3) the exhaust filter III is treated with second impregnation in the mixed solution containing PMMA microsphere emulsion and solution I, and the order honeycomb rare earth base catalyst exhaust filter is obtained.The order honeycomb rare earth base catalyst exhaust filter prepared by the method has simple preparation process, high catalytic activity and stable catalyst structure.

Description

Technical Field

[0001] This invention belongs to the field of motor vehicle exhaust purification technology, specifically relating to ordered honeycomb rare earth-based catalyst exhaust filters and their preparation methods, and methods for preparing pyramid-shaped catalyst exhaust filters. Background Technology

[0002] Internal combustion engines (fuel engines, gas engines, and dual-fuel engines) are the main way to utilize oil and gas resources. The particulate matter (PM) emitted by these engines consists of soot (particle size >25nm) cores and volatile organic compounds, heavy metals, and inorganic salts adsorbed on their surfaces. PM is a major source of primary PM2.5 particles in the atmosphere and an important component in the formation of secondary particles, seriously endangering the atmospheric environment and human health.

[0003] Particulate matter, as a major pollutant controlled under the "China VI Emission Standard for Motor Vehicles," has always been a challenging yet priority area in air pollution control and industrial catalysis research. Compared to the limitations of improving fuel quality and optimizing in-engine combustion technology to reduce pollutant emissions, catalytic aftertreatment technology is a core step in addressing PM pollution control. Especially with increasingly stringent emission regulations, continuous filtration and regeneration technology combining particulate matter traps and catalysts is the most effective and essential technology to meet the China VI emission standards.

[0004] Because the oxidation and elimination of soot is a complex, deep oxidation process involving a gas-solid (smoke)-solid (catalyst) three-phase system, the improvement of catalyst activity is closely related not only to the intrinsic redox properties of oxide catalysts but also to the effective contact efficiency between soot particles and the solid catalyst. For catalysts with the same active component, the higher the contact efficiency with soot particles, the higher the catalytic elimination efficiency.

[0005] However, due to the large particle size of soot particles (the diameter of a single soot particle is greater than 25 nm), it is difficult to utilize the abundant active sites within the catalyst or support. Even with ultra-large mesoporous molecular sieves (maximum pore size of about 20 nm), soot particles can only contact their outer surface, thus significantly reducing the utilization rate of the active surface area. In contrast, ordered honeycomb catalysts typically have pore sizes of 200-500 nm, and their ordered, interconnected pore structure allows for effective mass transfer and diffusion of soot particles within them, greatly improving the effective contact efficiency between soot particles and solid catalysts. Therefore, the preparation of ordered honeycomb catalysts is of great significance for the oxidation and elimination of soot particles from motor vehicle emissions.

[0006] The core component of a vehicle exhaust purifier is primarily the catalyst, which is an integral catalyst composed of a carrier, a coating, and catalytically active components. Cordierite (2MgO·2Al2O3·5SiO2) honeycomb ceramic bodies possess characteristics such as high mechanical strength, low pressure drop, low coefficient of thermal expansion, high thermal stability, and large geometric surface area, and are commonly used as carriers for vehicle exhaust purification catalysts.

[0007] However, due to the very small specific surface area of ​​cordierite honeycomb ceramic carriers (<1m²), 2 ·g -1 Therefore, it is necessary to coat the surface of the cordierite honeycomb ceramic carrier with an active coating with a high specific surface area, thereby expanding the effective catalytic area of ​​the catalytic active components.

[0008] In monolithic catalysts, the ceramic honeycomb support serves only as an indirect support, while the active coating is the actual carrier of the catalytically active components, and can be referred to as the "second carrier" of the ceramic honeycomb catalyst. It can provide a large and stable surface for coating the catalytically active components onto.

[0009] Currently, activated alumina (γ-Al₂O₃) is one of the most widely used coating materials in modern motor vehicles. This is mainly due to the porosity and high specific surface area (150-300 μm²) of γ-Al₂O₃. 2 It exhibits good adhesion and adsorption properties, readily supports metal oxides and noble metals, and is relatively resistant to reaction with noble metal components. The preparation of coatings with strong adhesion to the support, good thermal stability, and high specific surface area is crucial for ensuring the catalytic performance of the active components and guaranteeing better catalyst stability and longer service life.

[0010] Over the years, researchers at home and abroad have conducted extensive research on PM catalytic combustion catalysts, and have made great progress in the design and preparation of ordered honeycomb catalysts and the understanding of their catalytic effects.

[0011] Zhang Guizhen et al. invented a thermally stable three-dimensional ordered honeycomb carbon soot combustion catalyst, in which noble metals are incorporated as ion dopants into the cerium-based or cerium-zirconium solid solution lattice, which helps to improve catalytic activity (Publication No.: CN102794175A).

[0012] Zhao Zhen et al. (publiced ​​as CN101992089A, CN101982234A, CN101940925A, CN101733110A and other existing technologies) invented a series of three-dimensional ordered honeycomb composite oxide catalysts supporting precious metals using their independently developed gas film assisted reduction method. The obtained catalysts have high activity in catalyzing the combustion of carbon soot particles.

[0013] However, current research is only at the stage of laboratory micro-reactions. How to coat nanoparticles and ordered honeycomb-based catalysts onto the filters (DPF) of motor vehicle exhaust aftertreatment devices, and how to ensure the structural stability of ordered honeycomb-based catalysts while ensuring high activity are all problems that need to be solved in this field. Summary of the Invention

[0014] The purpose of this invention is to overcome the problems of disordered structure and poor activity of catalysts coated on motor vehicle exhaust filters in the prior art.

[0015] To achieve the above objectives, a first aspect of the present invention provides a method for preparing an ordered honeycomb rare earth-based catalyst tail gas filter, the method comprising:

[0016] (1) The exhaust gas filter to be treated is acid-treated to obtain exhaust gas filter I;

[0017] (2) The exhaust filter I is first impregnated in modified alumina sol, and the resulting exhaust filter II is first calcined to obtain exhaust filter III coated with modified coating; the modified alumina sol is a product obtained by mixing and reacting pseudoboehmite and nitrate in a mass ratio of 1:0.2-0.3.

[0018] (3) The exhaust gas filter III is subjected to a second impregnation treatment in a mixed solution containing PMMA microsphere emulsion and solution I to obtain an ordered honeycomb rare earth-based catalyst exhaust gas filter; the volume ratio of PMMA microsphere emulsion to solution I is 1:4-8.

[0019] The solute in solution I is a metal nitrate, and the solvent is a mixture of ethylene glycol, methanol, ethanol, and cyclohexane; the amount of solvent used is such that the metal nitrate is supersaturated in solution I.

[0020] A second aspect of the present invention provides an ordered honeycomb rare earth-based catalyst exhaust filter prepared by the method described in the first aspect above.

[0021] A third aspect of the present invention provides a method for preparing a pyramid-shaped catalyst exhaust filter, the method comprising:

[0022] (S1) An ordered honeycomb rare earth-based catalyst tail gas filter is prepared by the method described in the first aspect above;

[0023] (S2) The ordered honeycomb rare earth-based catalyst tail gas filter is subjected to a third impregnation treatment in a noble metal solution, and then an ammonia solution is added for stirring and reaction. The resulting tail gas filter IV is then subjected to a third calcination to obtain the pyramid-shaped catalyst tail gas filter.

[0024] In step (S2), the concentration of the noble metal solution is 10-30 mmol / L; the metal element in the noble metal solution is selected from at least one of platinum, palladium, and ruthenium.

[0025] The solution provided by the present invention, through the above technical solution, has at least the following advantages:

[0026] (1) It improves the removal efficiency of carbon particulate matter in motor vehicle exhaust and the filter works stably.

[0027] (2) The filter provided by this solution can improve the mass transfer and diffusion of soot particles, and achieve the dual effect of filtration and elimination.

[0028] (3) It reduces the combustion temperature of soot particles and improves the continuous regeneration capability of the filter.

[0029] (4) The preparation method provided by the present invention is simple and of great significance for reducing motor vehicle exhaust pollution and protecting the environment.

[0030] (5) The filter provided by this solution has a three-dimensional ordered and interconnected honeycomb mesh structure, and has the advantages of high catalytic activity, strong pressure resistance, strong shock resistance and strong stability. Attached Figure Description

[0031] Figure 1 These are scanning electron microscope (SEM) images of the LaFeO3 ordered honeycomb rare earth-based catalyst tail gas filter (G1) at different scales. Figure 1 The left side of the image shows a scanning electron microscope image of G1 at 20 μm. Figure 1 The image on the right in the image shows a scanning electron microscope image of G1 at 5 μm.

[0032] Figure 2 It is La 1.8 K 0.2 Scanning electron microscope (SEM) images of NiCoO6 ordered honeycomb rare earth-based catalyst exhaust gas filter (G2-6) at different scales. Figure 2 The left side of the image shows a scanning electron microscope image of G2-6 at 20 μm. Figure 2 The right side of the image shows a scanning electron microscope image of G2-6 at 5 μm;

[0033] Figure 3 It is Pt2 / Ce 0.8 Co 0.2 Scanning electron microscope (SEM) images and transmission electron microscope (TEM) images at different scales of the O2 pyramidal catalyst (G3-2) exhaust filter, among which Figure 3 In the image, A is a scanning electron microscope image of G3-2 at 5.0 μm. Figure 3 In the image, B is a transmission electron microscope (TEM) image of G3-2 at 0.2 μm. Figure 3 C in the image is a transmission electron microscope image of G3-2 at 50 nm.

[0034] Figure 4 It is Pt2 / Ce 0.8 Co 0.2 A pyramid-shaped schematic diagram of the O2 pyramid-shaped catalyst (G3-2) exhaust filter;

[0035] Figure 5 It is La after 10 cycles of reaction 1.8 K 0.2 Scanning electron microscope image of NiCoO6 ordered honeycomb rare earth-based catalyst exhaust filter (G2-6).

[0036] Explanation of reference numerals in the attached figures

[0037] 1. Exhaust gas filter ceramic; 2. Modified alumina sol substrate.

[0038] 3. Ordered honeycomb rare earth oxides 4. Precious metal particles Detailed Implementation

[0039] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0040] As previously stated, a first aspect of the present invention provides a method for preparing an ordered honeycomb rare earth-based catalyst tail gas filter, the method comprising:

[0041] (1) The exhaust gas filter to be treated is acid-treated to obtain exhaust gas filter I;

[0042] (2) The exhaust filter I is first impregnated in modified alumina sol, and the resulting exhaust filter II is first calcined to obtain exhaust filter III coated with modified coating; the modified alumina sol is a product obtained by mixing and reacting pseudoboehmite and nitrate in a mass ratio of 1:0.2-0.3.

[0043] (3) The exhaust gas filter III is subjected to a second impregnation treatment in a mixed solution containing PMMA microsphere emulsion and solution I to obtain an ordered honeycomb rare earth-based catalyst exhaust gas filter; the volume ratio of PMMA microsphere emulsion to solution I is 1:4-8.

[0044] The solute in solution I is a metal nitrate, and the solvent is a mixture of ethylene glycol, methanol, ethanol, and cyclohexane; the amount of solvent used is such that the metal nitrate is supersaturated in solution I.

[0045] Preferably, in step (1), the exhaust gas filter to be treated has a size of (3-5)cm×(3-5)cm, a porosity of 50-70%, and square channels of (0.8-1.2)×(0.8-1.2)mm.

[0046] Preferably, in step (1), the acid treatment is carried out in an acid solution, and the conditions for the acid treatment include: a time of 25-30 hours and a hydrogen ion concentration of 0.5-1 mol / L in the acid solution. The inventors of this invention have found that under these preferred conditions, the ordered honeycomb rare earth-based catalyst tail gas filter obtained by this method has stronger pressure resistance and shock resistance.

[0047] Preferably, the acid used in the acid treatment is nitric acid.

[0048] In step (1), the acid treatment may further include ultrasonic assistance. The ultrasonic assistance described in this invention can be performed using ultrasonic conditions known in the art, which will not be detailed here, and should not be construed as a limitation of the invention by those skilled in the art.

[0049] The method of the present invention may further include: in step (1), the intermediate obtained after the acid treatment is sequentially washed and subjected to a first drying to obtain the exhaust gas filter I. The present invention does not have special requirements for the operating conditions of the washing and the first drying; methods known in the art can be used, such as washing with distilled water, provided that the distilled water after washing is neutral. The operating conditions for the first drying may include: a time of 10-14 hours and a temperature of 100-140°C.

[0050] According to a preferred embodiment, in step (2), the step of mixing the boehmite and the nitrate further includes:

[0051] (a1) In the presence of water, the pseudoboehmite and the nitrate are first mixed to obtain mixture I;

[0052] (a2) Adjust the pH of the mixture I to 3.5-5.5 to obtain the modified aluminum sol.

[0053] Preferably, in step (a1), the nitrate is selected from at least one of cerium nitrate, zirconium nitrate, and lanthanum nitrate.

[0054] In a preferred embodiment, in step (a1), the temperature of the first mixture is 70-90°C.

[0055] The present invention does not have any special requirements for the time and stirring speed of the first mixing in step (a1). For example, the boehmite and the nitrate can be dissolved in the water until there are no solid particles.

[0056] For example, in step (a2), the pH value of the mixture I can be adjusted using ammonia water with a mass concentration of 4-8%.

[0057] Preferably, in step (a1), the total amount of the pseudoboehmite and the nitrate is used in a weight ratio of 1:5-10 to the amount of water.

[0058] Preferably, in step (2), the conditions for the first impregnation treatment include a time of 10-12 hours.

[0059] In a preferred embodiment, in step (2), the conditions for the first impregnation treatment include a temperature of 10-35°C.

[0060] Preferably, in step (2), the method of the present invention further includes: before performing the first calcination, performing a second drying treatment on the exhaust gas filter II, and then performing the first calcination on the intermediate obtained after the second drying to obtain the exhaust gas filter III.

[0061] In a preferred embodiment, the first calcination conditions include a temperature of 650-750°C and a time of 4-5 hours. The inventors of this invention have discovered that under these preferred conditions, the obtained exhaust filter III has a solid content of 15-20 wt%. The solid content is the percentage of the mass of the modified coating to the total mass of the exhaust filter III.

[0062] In a preferred embodiment, the conditions for the second drying include a temperature of 40-60°C and a time of 5-8 hours.

[0063] According to a preferred embodiment, in step (3), the method further includes preparing the PMMA microsphere emulsion using a method comprising the following steps: at 78-82°C,

[0064] (b1) Acetone and methyl methacrylate are reacted in a first reaction to obtain reactant I;

[0065] (b2) The reactant I is reacted with potassium persulfate solution to obtain the PMMA microsphere emulsion.

[0066] In a preferred embodiment, the volume ratio of the methyl methacrylate, the potassium persulfate solution, and the acetone is 1:0.45-0.55:3-4.

[0067] In a preferred embodiment, in step (b2), the solvent for the potassium persulfate solution is acetone.

[0068] Preferably, in step (b2), the concentration of the potassium persulfate solution is 100-150 mg / mL.

[0069] To obtain PMMA microsphere emulsions with more uniform particle size and narrower particle size distribution, the PMMA microsphere emulsion prepared in step (b2) can be screened using gravity flotation. This gives the microspheres of the present invention the advantage of uniform particle size and flexible selection of average particle size.

[0070] In a preferred embodiment, in step (3), the average particle size of the microspheres in the PMMA microsphere emulsion is 400 nm-450 nm. The inventors of this invention have found that, under this preferred embodiment, the ordered honeycomb rare earth-based catalyst tail gas filter provided by this invention exhibits higher soot combustion activity.

[0071] Preferably, the first reaction and / or the second reaction are carried out under a protective atmosphere selected from at least one of nitrogen, argon, and helium.

[0072] Preferably, in step (b1), the conditions for the first reaction include: a stirring time of 20-40 min and a stirring rate of 200-300 rpm.

[0073] According to a preferred embodiment, the potassium persulfate solution is preheated to 78-82°C before reacting with reactant I in the second reaction, and then reacted with reactant I in the second reaction.

[0074] Preferably, the conditions for the second reaction include: a stirring time of 1.5-2 hours and a stirring speed of 350-400 rpm.

[0075] Preferably, in step (3), the volume ratio of the content of ethylene glycol, methanol, ethanol and cyclohexane in the solvent is 1:2-3:1-1.5:1-1.2.

[0076] Preferably, in step (3), the metal nitrate is selected from at least two of lanthanum, sodium, potassium, cesium, manganese, iron, cobalt, nickel, copper, cerium and praseodymium, and includes at least one rare earth metal.

[0077] According to a preferred embodiment, in step (3), the metal nitrate is composed of lanthanum and iron, and the molar ratio of lanthanum to iron is 1:1.

[0078] According to another preferred embodiment, in step (3), the metal nitrate is lanthanum, potassium, nickel and cobalt, and the molar ratio of lanthanum, potassium, nickel and cobalt is 0.9:0.1:1:1.

[0079] According to a preferred embodiment, in step (3), the second impregnation treatment is carried out in at least two stages of impregnation, each stage containing an immersion process and a separation and extraction process in sequence, and the number of stages of impregnation is controlled so that the catalyst layer thickness of the ordered honeycomb rare earth-based catalyst tail gas filter is 10-15 μm.

[0080] Preferably, in step (3), in each stage, the immersion process is independently 40-60 min; the separation and extraction process is independently 10-20 min.

[0081] Preferably, the temperature of the immersion process is 10-35°C.

[0082] In step (3), the method of the present invention may further include: in order to make the obtained ordered honeycomb rare earth-based catalyst tail gas filter pores more regular and ordered, the pores may be cleared by blowing air at a uniform speed into the pores of the intermediate ordered honeycomb rare earth-based catalyst tail gas filter during the separation and extraction process in each stage.

[0083] Preferably, in step (3), the method further includes: after the second impregnation treatment, the intermediate ordered honeycomb rare earth-based catalyst tail gas filter that has undergone pore clearing treatment is subjected to vacuum drying and second calcination in sequence to obtain the ordered honeycomb rare earth-based catalyst tail gas filter.

[0084] For example, in step (3), the method may further include: rapidly transferring the intermediate ordered honeycomb rare earth-based catalyst tail gas filter that has been treated to clear the channels to a vacuum drying oven and evacuating it to a vacuum degree of -0.08 MPa or below. The vacuum drying conditions also include: a temperature of 40-60°C and a time of 10-14 h.

[0085] Preferably, the conditions for the second calcination include: heating to 650-750°C at a rate of 2-3°C and holding for 5-7 hours.

[0086] As previously stated, a second aspect of the present invention provides an ordered honeycomb rare earth-based catalyst exhaust filter prepared by the method described in the first aspect.

[0087] As previously described, a third aspect of the present invention provides a method for preparing a pyramid-shaped catalyst exhaust filter, the method comprising:

[0088] (S1) An ordered honeycomb rare earth-based catalyst tail gas filter is prepared by the method described in the first aspect above;

[0089] (S2) The ordered honeycomb rare earth-based catalyst tail gas filter is subjected to a third impregnation treatment in a noble metal solution, and then an ammonia solution is added for stirring and reaction. The resulting tail gas filter IV is then subjected to a third calcination to obtain the pyramid-shaped catalyst tail gas filter.

[0090] In step (S2), the concentration of the noble metal solution is 10-30 mmol / L; the metal element in the noble metal solution is selected from at least one of platinum, palladium, and ruthenium.

[0091] For example, in step (S2), the mass fraction of the ammonia solution is 4-8%.

[0092] In a preferred embodiment, the volume ratio of the noble metal solution to the ammonia solution is 1:1.5-2.

[0093] Preferably, the conditions for the third impregnation and the stirring reaction are independent of each other, including a temperature of 10-35°C and a time of 5-7 hours.

[0094] It should be noted that in step (S2), before the third calcination, the exhaust gas filter IV can be washed with deionized water until the washing water is neutral before the third calcination is performed.

[0095] Preferably, the conditions for the third calcination include: heating to 500-800°C at a rate of 1-3°C / min and holding for 3-7 hours.

[0096] The present invention will be described in detail below through examples. In the following examples, unless otherwise specified, all raw materials and instruments used are commercially available products, and the specific sources of the raw materials are shown in Table 1.

[0097] Table 1

[0098]

[0099] The A-series preparation examples of the present invention are used to prepare modified aluminum sol.

[0100] Preparation Example A1

[0101] (a1) In the presence of 200g of water, 20g of boehmite and 4g of cerium nitrate hexahydrate were mixed until all the solids were dissolved to obtain mixture I;

[0102] (a2) The pH of the above mixture I was adjusted to 3.6 with 6% ammonia water to obtain modified aluminum sol L1.

[0103] The temperature of the first mixture is 75°C.

[0104] Preparation Example A2

[0105] (a1) In the presence of 200g of water, 20g of pseudoboehmite and 6g of zirconium nitrate pentahydrate were mixed until all the solids were dissolved to obtain mixture I;

[0106] (a2) The pH of the above mixture I was adjusted to 5.5 with 4% ammonia water to obtain modified aluminum sol L2.

[0107] The temperature of the first mixture is 85°C.

[0108] Comparative preparation example D-A1

[0109] This comparative preparation example was prepared using the same method as preparation example A1, except that no nitrate was added in this comparative preparation example, resulting in unmodified aluminum sol D-L1.

[0110] The B series preparation examples of the present invention are used to prepare PMMA microsphere emulsions.

[0111] Preparation Example B1

[0112] (b1) Under a nitrogen atmosphere, at 80°C, 200 mL of acetone and 60 mL of methyl methacrylate were subjected to a first reaction to obtain reactant I;

[0113] (b2) 28 mL of potassium persulfate solution with a concentration of 120 mg / L (acetone as solvent) was heated to 80 °C and then added to reactant I above to carry out the second reaction, so as to obtain PMMA microsphere emulsion W1.

[0114] The conditions for the first reaction are: stirring time of 30 min and stirring speed of 300 rpm.

[0115] The conditions for the second reaction were: stirring time of 1.8 h and stirring speed of 380 rpm.

[0116] Microsphere emulsions with average particle sizes of 400 nm, 420 nm, and 450 nm were screened by gravity flotation.

[0117] Preparation Example B2

[0118] (b1) Under a nitrogen atmosphere, at 80°C, 220 mL of acetone and 60 mL of methyl methacrylate were subjected to a first reaction to obtain reactant I;

[0119] (b2) 30 mL of potassium persulfate solution with a concentration of 120 mg / L (solvent is acetone) was heated to 82 °C and then added to reactant I above to carry out the second reaction, so as to obtain PMMA microsphere emulsion W2.

[0120] The conditions for the first reaction are: stirring time of 25 min and stirring speed of 300 rpm.

[0121] The conditions for the second reaction are: stirring time of 2 hours and stirring speed of 350 rpm.

[0122] Microsphere emulsions with an average particle size of 420 nm were screened by gravity flotation.

[0123] Example 1: Preparation of a LaFeO3 ordered honeycomb rare earth-based catalyst tail gas filter

[0124] (1) The tail gas filter to be treated is treated with nitric acid solution and then washed. After washing until the distilled water after washing is neutral, the first drying is carried out to obtain tail gas filter I.

[0125] (2) The exhaust gas filter I is first impregnated in modified aluminum sol, and the resulting exhaust gas filter II is then subjected to second drying and first calcination to obtain exhaust gas filter III coated with modified coating.

[0126] (3) The tail gas filter III was subjected to a second impregnation treatment, vacuum drying and second calcination in a mixed solution containing PMMA microsphere emulsion and solution I to obtain an ordered honeycomb rare earth-based catalyst tail gas filter, named G1.

[0127] The solute metal nitrate in solution I is 0.1 mol lanthanum nitrate hexahydrate and 0.1 mol ferric nitrate nonahydrate, and the solvent is a mixture of 40 mL ethylene glycol, 80 mL methanol, 50 mL ethanol and 40 mL cyclohexane.

[0128] Other process parameters involved in this embodiment are listed in Table 2.

[0129] Example 2: La x K 1-x Preparation of NiCoO6 ordered honeycomb rare earth-based catalyst tail gas filter

[0130] This embodiment prepared a series of La x K 1-x NiCoO6 ordered honeycomb rare earth-based catalyst tail gas filter. In this embodiment, except for the different types of solute metal nitrates in solution I, all other parameters in this series of embodiments are consistent.

[0131] This embodiment uses the same method as Embodiment 1, except that the process parameters, raw materials and raw material usage are different. Unless otherwise specified, the specific parameters are shown in Table 2.

[0132] Solution I is a mixture of 50 mL ethylene glycol, 120 mL methanol, 60 mL ethanol and 60 mL cyclohexane.

[0133] LaNiO3 ordered honeycomb rare earth-based catalyst tail gas filter (G2-1): The solute metal nitrates in solution I are 0.1 mol lanthanum nitrate hexahydrate and 0.1 mol nickel nitrate hexahydrate.

[0134] The LaCoO3 ordered honeycomb rare earth-based catalyst tail gas filter (G2-2) contains 0.1 mol of lanthanum nitrate hexahydrate and 0.1 mol of cobalt nitrate hexahydrate as solute metal nitrates in solution I.

[0135] The La2NiCoO6 ordered honeycomb rare earth-based catalyst tail gas filter (G2-3) contains the following solute metal nitrates in solution I: 0.1 mol lanthanum nitrate hexahydrate, 0.05 mol cobalt nitrate hexahydrate, and 0.05 mol nickel nitrate hexahydrate.

[0136] La 1.95 K 0.05 The NiCoO6 ordered honeycomb rare earth-based catalyst tail gas filter (G2-4) contains the following solute metal nitrates in solution I: 0.0975 mol lanthanum nitrate hexahydrate, 0.0025 mol potassium nitrate, 0.05 mol nickel nitrate hexahydrate, and 0.05 mol cobalt nitrate hexahydrate.

[0137] La 1.90 K 0.10 The NiCoO6 ordered honeycomb rare earth-based catalyst tail gas filter (G2-5) contains the following solute metal nitrates in solution I: 0.095 mol lanthanum nitrate hexahydrate, 0.005 mol potassium nitrate, 0.05 mol nickel nitrate hexahydrate, and 0.05 mol cobalt nitrate hexahydrate.

[0138] La 1.80 K 0.20 The NiCoO6 ordered honeycomb rare earth-based catalyst tail gas filter (G2-6) contains the following solute metal nitrates in solution I: 0.09 mol lanthanum nitrate hexahydrate, 0.01 mol potassium nitrate, 0.05 mol nickel nitrate hexahydrate, and 0.05 mol cobalt nitrate hexahydrate.

[0139] La 1.70 K 0.30 The NiCoO6 ordered honeycomb rare earth-based catalyst tail gas filter (G2-7) contains the following solute metal nitrates in solution I: 0.085 mol lanthanum nitrate hexahydrate, 0.015 mol potassium nitrate, 0.05 mol nickel nitrate hexahydrate, and 0.05 mol cobalt nitrate hexahydrate.

[0140] La 1.60 K 0.40The NiCoO6 ordered honeycomb rare earth-based catalyst tail gas filter (G2-8) contains the following solute metal nitrates in solution I: 0.08 mol lanthanum nitrate hexahydrate, 0.02 mol potassium nitrate, 0.05 mol nickel nitrate hexahydrate, and 0.05 mol cobalt nitrate hexahydrate.

[0141] Example 3: Pt2 / Ce 0.8 Co 0.2 Preparation of O2 pyramid-shaped catalyst exhaust filter

[0142] This embodiment exemplarily provides the preparation of a pyramid-shaped catalyst exhaust filter:

[0143] (1) Preparation of Ce 0.8 Co 0.2 The O2 ordered honeycomb rare earth-based catalyst tail gas filter (G3-1) is prepared using the same method as in Example 1. The difference is that the process parameters, raw materials, and raw material dosages are different. Unless otherwise specified, the specific parameters are shown in Table 2.

[0144] Solution I contains 0.8 mol of cerium nitrate and 0.2 mol of cobalt nitrate hexahydrate as solutes and 30 mL of ethylene glycol, 90 mL of methanol, 40 mL of ethanol and 36 mL of cyclohexane as solvents.

[0145] (2) Preparation of Pt2 / Ce 0.8 Co 0.2 O2 pyramid-shaped catalyst exhaust filter

[0146] The above Ce 0.8 Co 0.2 An O2-ordered honeycomb rare-earth-based catalyst tail gas filter (G3-1) underwent a third impregnation treatment in a 30 mL solution of HPtCl4·6H2O with a platinum concentration of 10 mmol / L. Following this, 45 mL of ammonia solution was added and the mixture was stirred. The resulting tail gas filter IV was then washed with deionized water until neutral and subjected to a third calcination to obtain Pt2 / Ce. 0.8 Co 0.2 O2 pyramid-shaped catalyst exhaust filter (G3-2).

[0147] The conditions for the stirred reaction included a temperature of 25°C and a time of 6 hours.

[0148] The conditions for the third impregnation treatment are: a temperature of 25°C and a time of 7 hours.

[0149] The conditions for the third roasting include: heating to 550°C at a rate of 2°C / min and roasting for 6 hours.

[0150] Example 4: LaMn 0.7 Cu0.3 Preparation of O3 ordered honeycomb rare earth-based catalyst exhaust filter (G4)

[0151] This embodiment uses the same method as Embodiment 1, except that the process parameters, raw materials and raw material usage are different. Unless otherwise specified, the specific parameters are shown in Table 2.

[0152] The solute metal nitrate in solution I is 0.1 mol lanthanum nitrate hexahydrate, 0.07 mol manganese nitrate (commercially available 50 wt% manganese nitrate solution), and 0.03 mol copper nitrate. The solvent is a mixture of 40 mL ethylene glycol, 90 mL methanol, 60 mL ethanol, and 40 mL cyclohexane.

[0153] Table 2

[0154]

[0155]

[0156] Example 5

[0157] This embodiment uses the same method as in Example 1. The difference is that in step (3), the average particle size of the microspheres in the PMMA microsphere emulsion is 500 nm, and the LaFeO3 ordered honeycomb rare earth-based catalyst tail gas filter G5 is prepared.

[0158] Example 6

[0159] This embodiment uses the same method as Example 1. The difference is that in step (3), while keeping the solute, the amount of solute and the total amount of solution I unchanged, the amount of each substance in the solvent is changed. Specifically, the amounts are 30 mL of ethylene glycol, 30 mL of methanol, 90 mL of ethanol and 60 mL of cyclohexane, to prepare the LaFeO3 ordered honeycomb rare earth-based catalyst tail gas filter G6.

[0160] Example 7

[0161] This embodiment uses the same method as in Example 1, except that in step (2), the first calcination temperature is adjusted to 620°C to obtain the LaFeO3 ordered honeycomb rare earth-based catalyst tail gas filter G7.

[0162] Comparative Example 1

[0163] This comparative example was carried out using the same method as Example 1. The difference is that in step (3), while keeping the solute, the amount of solute and the total amount of solution I unchanged, the solvent of solution I was a mixture of 120 mL methanol, 70 mL ethanol and 20 mL cyclohexane, to prepare granular LaFeO3 rare earth-based catalyst tail gas filter D-G1.

[0164] Comparative Example 2

[0165] This comparative example was carried out using the same method as Example 1. The difference is that in step (2), unmodified aluminum sol D-L1 was used in this comparative example to prepare LaFeO3 ordered honeycomb rare earth-based catalyst tail gas filter D-G2.

[0166] Comparative Example 3

[0167] Steps (1) and (2) are the same as in Example 1.

[0168] Step (3): The tail gas filter III is subjected to a second impregnation treatment, vacuum drying and second calcination in solution I to obtain an ordered honeycomb rare earth-based catalyst tail gas filter, named D-G3.

[0169] Solution I and its dosage are the same as in Example 1.

[0170] The process conditions for the second impregnation treatment, vacuum drying, and second calcination are the same as in Example 1.

[0171] Test case

[0172] This invention provides, exemplarily, scanning electron microscope (SEM) images of the LaFeO3 ordered honeycomb rare earth-based catalyst tail gas filter (G1) of Example 1 at different scales, and LaFeO3 ordered honeycomb rare earth-based catalyst tail gas filter (G1) of Example 2. 1.8 K 0.2 Scanning electron microscope images of NiCoO6 ordered honeycomb rare earth-based catalyst exhaust filter (G2-6) at different scales, and Pt2 / Ce in Example 3. 0.8 Co 0.2 Scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the O2 pyramid-shaped catalyst exhaust filter (G3-2) at different scales, a schematic diagram of the pyramid-shaped structure of G3-2, and La after 10 cycles of reaction. 1.8 K 0.2 Scanning electron microscope (SEM) images of the NiCoO6 ordered honeycomb rare earth-based catalyst tail gas filter (G2-6) are shown below. Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 .

[0173] Figure 1 The left side of the image shows a scanning electron microscope image of G1 at 20 μm, which shows that the honeycomb macroporous structure was successfully coated on the ceramic surface of the exhaust filter. Figure 1 The image on the right shows a scanning electron microscope image of G1 at 5 μm. It can be seen that the G1 catalyst has a three-dimensional ordered and interconnected honeycomb network structure with an average pore size of 360 nm and a uniform pore wall thickness of 30 nm.

[0174] Figure 2 The left side of the image shows a scanning electron microscope image of G2-6 at 20 μm, which shows that the honeycomb macroporous structure was successfully coated on the ceramic surface of the exhaust filter. Figure 2 The image on the right shows a scanning electron microscope (SEM) image of G2-6 at 5 μm. It reveals a three-dimensional, ordered, interconnected honeycomb network structure within the G2-6 catalyst. Statistical analysis of the ordered honeycomb dimensions in the SEM image shows pore sizes between 350 and 390 nm. A clear small window with a diameter of 80 nm can be observed beneath each large pore. This three-dimensional, ordered, interconnected pore structure significantly promotes mass transfer and diffusion of reactant soot and oxygen molecules within the catalyst.

[0175] Figure 3 In the image, A is a scanning electron microscope image of G3-2 at 5.0 μm, which shows that the honeycomb macroporous structure is uniformly coated on the ceramic surface of the exhaust filter, with a coating thickness of 14.6 μm. Figure 3 B in the image is a transmission electron microscope image of G3-2 at 0.2 μm. It can be seen that after impregnation with noble metal, the three-dimensional ordered and interconnected honeycomb network structure inside the catalyst is still well maintained. Figure 3 C in the image is a transmission electron microscope (TEM) image of G3-2 at 50 nm. It can be seen that under high magnification TEM, small black dots with a particle size of 4-6 nm were observed, which are noble metal Pt nanoparticles.

[0176] Figure 4 The diagram shows the pyramid-shaped G3-2 catalyst exhaust filter, which is composed of exhaust filter ceramic, modified alumina sol substrate, ordered honeycomb rare earth oxides and precious metals.

[0177] Figure 5 These are scanning electron microscope images of G2-6 at 5 μm after 10 reactions. Figure 5 The left side of the image shows that the honeycomb macroporous structure is well maintained after the reaction. Figure 5 As can be seen on the right side, after 10 reactions, the honeycomb macroporous structure is still tightly coated on the surface of the exhaust filter, and the thickness of the catalyst layer is 13.4 nm. This indicates that the ordered honeycomb rare earth-based catalyst exhaust filter provided by the present invention has strong pressure resistance, strong shock resistance and high stability.

[0178] The catalyst layer thickness of the ordered honeycomb rare earth-based catalyst tail gas filter and the pyramid-shaped catalyst tail gas filter in the example was measured using a statistical method with a 100-point average. The specific results are shown in Table 3.

[0179] The fixed-bed simulated soot oxidation method was used to test the catalytic soot combustion activity of the ordered honeycomb rare earth-based catalyst tail gas filter in the example. The specific results are shown in Table 3.

[0180] Table 3

[0181]

[0182]

[0183] The ordered honeycomb rare-earth-based catalyst prepared by this invention provides a low gas resistance in the tail gas filter, which is beneficial for the mass transfer and diffusion of gas molecules and soot particles. As shown in Table 3, the three-dimensional ordered pore structure of the ordered honeycomb rare-earth-based catalyst provided by this invention significantly enhances the mass transfer and diffusion of soot particles and gaseous reactant molecules within the catalyst, thereby improving the oxidation and removal efficiency of soot particles. Among the G2 series catalysts, G2-6 exhibits the best catalytic activity for soot combustion, with a T0... 10 (Low-temperature ignition activity), T 50 T 90 The values ​​were 294℃, 346℃, and 388℃, respectively, and the catalytic combustion activity range overlapped with the temperature range of vehicle exhaust gases. The activity results show that loading platinum onto the G3-1 catalyst further enhanced the catalytic soot combustion activity of the exhaust filter. 10 and T 50 The temperatures were lowered to 275 and 330°C respectively, demonstrating the advantages of its unique pyramidal structure and resulting in better catalytic activity.

[0184] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing an ordered honeycomb rare earth-based catalyst tail gas filter, characterized in that, The method includes: (1) The exhaust gas filter to be treated is acid-treated to obtain exhaust gas filter I; (2) The tail gas filter I is subjected to a first impregnation treatment in modified alumina sol, and the resulting tail gas filter II is subjected to a first calcination to obtain a tail gas filter III coated with a modified coating; the modified alumina sol is a product obtained by mixing and reacting pseudoboehmite and nitrate in a mass ratio of 1:0.2-0.

3. (3) The tail gas filter III is subjected to a second impregnation treatment in a mixed solution containing PMMA microsphere emulsion and solution I to obtain an ordered honeycomb rare earth-based catalyst tail gas filter; the volume ratio of PMMA microsphere emulsion to solution I is 1:4-8. The solute in solution I is a metal nitrate, and the solvent is a mixture of ethylene glycol, methanol, ethanol, and cyclohexane; the amount of solvent used is such that the metal nitrate is supersaturated in solution I.

2. The method according to claim 1, wherein, In step (1), the acid treatment is carried out in an acid solution, and the conditions for the acid treatment include: a time of 25-30 h and a hydrogen ion concentration of 0.5-1 mol / L in the acid solution; And / or, in step (3), the average particle size of the microspheres in the PMMA microsphere emulsion is 400nm-450nm.

3. The method according to claim 1, wherein, In step (2), the step of mixing the boehmite and the nitrate further includes: (a1) In the presence of water, the pseudoboehmite and the nitrate are first mixed to obtain mixture I; (a2) Adjust the pH of the mixture I to 3.5-5.5 to obtain the modified aluminum sol.

4. The method according to claim 3, wherein, In step (a1), the nitrate is selected from at least one of cerium nitrate, zirconium nitrate and lanthanum nitrate.

5. The method according to any one of claims 1-4, wherein, In step (2), the conditions for the first impregnation treatment include: a time of 10-12 hours; And / or, the conditions for the first calcination include: a temperature of 650-750°C and a time of 4-5 hours.

6. The method according to any one of claims 1-4, wherein, In step (3), the method further includes preparing the PMMA microsphere emulsion using a method comprising the following steps: at 78-82°C, (b1) Acetone and methyl methacrylate are reacted in a first reaction to give reactant I; (b2) The reactant I is reacted with potassium persulfate solution to obtain the PMMA microsphere emulsion.

7. The method according to any one of claims 1-4, wherein, In step (3), the volume ratio of the content of the ethylene glycol, the methanol, the ethanol and the cyclohexane in the solvent is 1:2-3:1-1.5:1-1.

2.

8. The method according to any one of claims 1-4, wherein, In step (3), the second impregnation treatment is carried out in at least two stages of impregnation, each stage containing an immersion process and a separation and extraction process in sequence. The number of impregnation stages is controlled so that the catalyst layer thickness of the ordered honeycomb rare earth-based catalyst tail gas filter is 10-15 μm. And / or, in step (3), in each stage, the immersion process is independently 40-60 min; the separation and extraction process is independently 10-20 min.

9. An ordered honeycomb rare earth-based catalyst tail gas filter prepared by the method according to any one of claims 1-8.

10. A method for preparing a pyramid-shaped catalyst tail gas filter, characterized in that, The method includes: (S1) An ordered honeycomb rare earth-based catalyst tail gas filter is prepared by the method described in any one of claims 1-8; (S2) The ordered honeycomb rare earth-based catalyst tail gas filter is subjected to a third impregnation treatment in a precious metal solution, and then an ammonia solution is added for stirring and reaction. The resulting tail gas filter IV is then subjected to a third calcination to obtain the pyramid-shaped catalyst tail gas filter. In step (S2), the concentration of the noble metal solution is 10-30 mmol / L; the metal element in the noble metal solution is selected from at least one of platinum, palladium, and ruthenium.

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