A three-way catalyst, preparation method and application

Abstract

The present application relates to a three-way catalyst, a preparation method and an application, which includes a coated carrier and a composite coating. The surface of the coated carrier is provided with the composite coating. The composite coating includes an inner coating and an outer coating. The inner coating is disposed on the surface of the coated carrier, and the outer coating is disposed on the inner coating. Among them, the inner coating includes a solid solution formed by alumina and a doped element-modified CeO2-ZrO2 composite oxide; the outer coating includes noble metals. CeO2 and ZrO2 carry out heterogeneous in-situ nucleation, and wrapping or interpenetration occurs between different grain structures, thereby constructing a heterogeneous phase interface. By regulating the nucleation and growth of grains and the heterogeneous interface, the sintering energy barrier is increased, so that the thermal stability of the three-way catalyst is significantly improved. By incorporating doped elements, lattice distortion and defects are induced, the defect sites of the lattice are increased, the generation of oxygen vacancies in the lattice is increased, the oxygen mobility of the lattice and the storage and release of oxygen are improved, thereby improving the catalytic efficiency of the three-way catalyst and further improving the thermal stability of the three-way catalyst.

Description

Technical Field

[0001] The present application relates to the technical field of gasoline vehicle catalysts, and particularly relates to a three-way catalyst, a preparation method and an application thereof. Background Art

[0002] With the rapid development of the automotive industry, vehicle exhaust emissions have become adverse factors endangering human health and environmental safety. Research and development of purification technologies to reduce the emissions of harmful gases such as CO, HC, NOx, etc. in vehicle exhaust have received extensive attention. Currently, the active components of the catalysts for catalyzing the conversion of these harmful gases are mainly noble metals such as ruthenium, rhodium, palladium, platinum, etc. However, the price of noble metals such as palladium has been continuously rising, and the cost of the catalyst is also getting higher and higher. Therefore, research has been carried out on replacing palladium with lower-cost metal platinum. However, platinum is prone to sintering and volatilization at high temperatures, and its high-temperature resistance performance is low, which limits its extensive substitution use in the catalyst. In addition, the current catalyst has a relatively high catalytic activation temperature, and its catalytic activity and catalytic efficiency are still relatively low.

[0003] In some related technologies, by preparing a solid solution of Ce-Zr-Al, the thermal stability of Pt is improved, and the migration and diffusion of Pt are inhibited. However, the operation process of this technology is complex, and the catalytic efficiency of the catalyst still needs to be improved. In some other related technologies, palladium is added to the catalyst by the method of fractional infiltration to improve the dispersion degree and catalytic conversion effect. However, the dosage of palladium is high, the problem of low catalyst cost has not been solved yet, and the structural stability of the catalyst is still not high.

[0004] Therefore, it is necessary to provide a three-way catalyst with low cost, high thermal stability, high catalytic conversion efficiency and low catalytic temperature to meet the actual application needs. Summary of the Invention

[0005] The embodiments of the present application provide a three-way catalyst, a preparation method and an application thereof to solve the problem that the structural stability of the catalyst in the related technologies is still not high.

[0006] In a first aspect, a three-way catalyst is provided, which includes a coated carrier and a composite coating. The composite coating is provided on the surface of the coated carrier. The composite coating includes an inner coating and an outer coating. The inner coating is provided on the surface of the coated carrier, and the outer coating is provided on the inner coating.

[0007] Among them, the inner coating includes a solid solution formed by alumina and a doped element-modified CeO2-ZrO2 composite oxide.

[0008] The outer coating includes noble metals.

[0009] In some embodiments, the noble metals include one or more of ruthenium, rhodium, palladium, platinum, gold, and silver.

[0010] In some embodiments, the noble metal is platinum and palladium.

[0011] In some embodiments, the mass ratio of platinum and palladium in the composite coating is (0.5 - 3):1;

[0012] And / or, the precursor of platinum includes one or more of Pt(NO3)2, Pt(NH3NO2)2, Pt(NO2)2(NH2OH)2;

[0013] And / or, the precursor of palladium includes one or more of Pd(NO3)2, Pd(NO3)2, Pd(NO2)2(NH3)2.

[0014] In some embodiments, the doping elements include one or more of rare earth metal elements, alkaline earth metal elements, and Group III - VI main group elements.

[0015] In some embodiments, the Group III - VI main group elements include one or more of B, N, P, S, and Si;

[0016] And / or, the rare earth metal elements include one or more of lanthanum, neodymium, europium, erbium, and yttrium;

[0017] And / or, the alkaline earth metal elements are selected from one or more of magnesium, calcium, and barium.

[0018] In some embodiments, the method for preparing the doping element - modified CeO2 - ZrO2 composite oxide includes the following steps:

[0019] Dissolve the cerium ion source, zirconium ion source, and doping element ion source in water, adjust the pH of the solution to 8 - 12 using a precipitant, add an auxiliary agent to the solution and stir, carry out aging and recrystallization, and then filter and calcine.

[0020] In some embodiments, the calcination temperature during filtration and calcination is 480°C - 650°C, and the time is 2 - 3 h;

[0021] And / or, the cerium ion source includes one or more of cerium nitrate, cerium sulfate, cerium acetate, and cerium hydroxide;

[0022] And / or, the zirconium ion source includes one or more of zirconium nitrate, zirconium sulfate, and zirconyl nitrate;

[0023] And / or, the precipitant includes one or more of sodium hydroxide, ammonium bicarbonate, ammonia water, ethanolamine, tetraethylammonium hydroxide, triethylamine, triethylenediamine, N - methylmorpholine, and vinyl alcohol butylamine;

[0024] And / or, the auxiliary agent includes one or more of chloride ions, nitrate ions, and ammonium ions;

[0025] And / or, the addition amount of the auxiliary agent is 30-50 wt% of the total addition amount of cerium ions and zirconium ions;

[0026] And / or, the molar ratio of the cerium ions, zirconium ions and doped element ions is: (1-3):1:(0.05-2).

[0027] In some embodiments, the doped element ions are yttrium ions, and the molar ratio of cerium ions, zirconium ions and yttrium ions is (1-2.2):1:(0.05-1).

[0028] In some embodiments, the coated carrier includes one or more of cordierite ceramic carrier, metal carrier, silicon carbide carrier, and molecular sieve;

[0029] And / or, the thermal expansion coefficient of the coated carrier is less than or equal to 0.3×10 -6 / °C;

[0030] And / or, the average particle diameter of the alumina is 5-60 μm.

[0031] In some embodiments, the outer coating further includes a dispersant;

[0032] The composite coating further includes an intermediate coating located between the inner coating and the outer coating, and the intermediate coating includes an electronic auxiliary agent.

[0033] In some embodiments, for 1 L of the coated carrier, in the composite coating, the usage amount of alumina is 20-50 g, the usage amount of the doped element-modified CeO2-ZrO2 composite oxide is 180-210 g, the usage amount of the electronic auxiliary agent is 15-50 g, the usage amount of the noble metal is 20-70 g, and the usage amount of the dispersant is 30-70 g.

[0034] In some embodiments, the outer coating further includes a dispersant.

[0035] In some embodiments, the dispersant includes one or more of polyethylene glycol PEG, cyclodextrin, cellulose, and pentaerythritol.

[0036] In some embodiments, the composite coating further includes an intermediate coating located between the inner coating and the outer coating, and the intermediate coating includes an electronic auxiliary agent.

[0037] In some embodiments, the electronic auxiliary agent includes one or more of alkaline earth metal oxides, alkaline earth metal sulfides, transition metal oxides, transition metal sulfides, and rare earth metal oxides.

[0038] In some embodiments, the electronic auxiliary agent includes magnesium oxide and yttrium oxide.

[0039] In some embodiments, the ratio of the total mass concentration of magnesium oxide and yttrium oxide to the mass concentration of the noble metal is (1.5 to 5):(5 to 7);

[0040] and / or, the mass ratio of magnesium oxide to yttrium oxide is (1 to 5):1.

[0041] In a second aspect, there is provided a method for preparing a ternary catalyst as described in any one of the above, which includes:

[0042] Disperse alumina and a doped element-modified CeO2-ZrO2 composite oxide in water to obtain a pre-impregnation solution A;

[0043] Immerse the coated carrier in the pre-impregnation solution A, and then take it out and dry it;

[0044] Continue to immerse it in the pre-impregnation solution B, dry it and then calcine it at a second temperature to obtain a ternary catalyst, and the pre-impregnation solution B includes a precursor of the noble metal.

[0045] In some embodiments, the pre-impregnation solution B further includes a dispersant;

[0046] Alternatively, after taking it out and drying it, and before continuing to immerse it in the pre-impregnation solution B, the preparation method further includes:

[0047] Disperse the electronic promoter in water, adjust the pH to 9 to 11, stir and react for a period of time, then immerse the coated carrier with the pre-impregnation solution A therein, dry it and then calcine it at a first temperature;

[0048] In a third aspect, there is provided a method for preparing a ternary catalyst as described above, which includes:

[0049] Disperse alumina and a doped element-modified CeO2-ZrO2 composite oxide in water to obtain a pre-impregnation solution A;

[0050] Immerse the coated carrier in the pre-impregnation solution A, and then take it out and dry it;

[0051] Disperse the electronic promoter in water, adjust the pH to 9 to 11, stir and react for a period of time, then immerse the coated carrier with the pre-impregnation solution A therein, dry it and then calcine it at a first temperature;

[0052] Continue to immerse it in the pre-impregnation solution B, dry it and then calcine it at a second temperature to obtain a ternary catalyst, and the pre-impregnation solution B includes a precursor of the noble metal and a dispersant.

[0053] In some embodiments, and / or, the time for the coated carrier to be immersed in the pre-impregnation solution A is 20 to 50 s;

[0054] and / or, stir and react for 1 to 3 h;

[0055] And / or, the dipping time of the coated carrier with the impregnating solution A is 10 to 20 s;

[0056] And / or, the first temperature is 500 to 900 °C, and calcination is carried out for 4 to 6 h;

[0057] And / or, the dipping time in the impregnating solution B is 20 to 30 s;

[0058] And / or, the second temperature is 500 to 600 °C, and roasting is carried out for 4 to 6 h.

[0059] In the fourth aspect, an application of the ternary catalyst as described in any one of the above in a vehicle exhaust aftertreatment material is provided.

[0060] The beneficial effects brought by the technical solution provided by this application include:

[0061] The embodiments of this application provide a ternary catalyst, a preparation method and an application. In the ternary catalyst provided by this application, the coated carrier of precious metal is modified, and an Al2O3-CeO2-ZrO2 solid solution is formed on the coated carrier by using alumina and CeO2-ZrO2 composite oxides. CeO2 and ZrO2 carry out heterogeneous in-situ nucleation, and the different grain structures are wrapped or interpenetrated with each other, so as to construct a heterogeneous interface. By regulating the nucleation and growth of grains and the heterogeneous interface, the sintering energy barrier is increased, so that the thermal stability of the ternary catalyst is significantly improved. At the same time, by doping with doping elements, lattice distortion and defects are induced, the defect sites in the lattice are increased, the generation of oxygen vacancies in the lattice is increased, the oxygen mobility in the lattice and the storage and release of oxygen are improved, thereby improving the catalytic efficiency of the ternary catalyst and further improving the thermal stability of the ternary catalyst, and making the ternary catalyst have excellent anti-aging performance, which can effectively anchor precious metals, inhibit the migration and diffusion of precious metals, inhibit their sintering inactivation, and effectively extend the service life of the ternary catalyst.

[0062] By adding a dispersant to the outer coating, the coordination of the crown ether-like cavity formed by the dispersant with precious metal ions such as platinum ions can be utilized to improve its dispersion performance, effectively reduce the activation temperature of the ternary catalyst, and improve the catalytic effect.

[0063] By adding an intermediate coating, the structural stability of the heterogeneous phase and the electronic stability of the electronic additives in the intermediate coating are utilized to effectively improve the anchoring ability and dispersion of the ternary catalyst for precious metals, and then more dispersion sites are generated, effectively improving the high-temperature durability of the ternary catalyst and reducing the usage amount of precious metals.

[0064] After a large amount of research, the applicant unexpectedly found that when the doped element-modified CeO2-ZrO2 composite oxide is limited to yttrium-doped CeO2-ZrO2 composite oxide, and the molar ratio of cerium ions, zirconium ions and yttrium ions is (1-2.2):1:(0.05-1), the ternary catalyst prepared has more excellent stability, lower catalytic temperature and higher efficiency; the applicant speculates that the reason is: the preparation method of the doped element-modified CeO2-ZrO2 composite oxide provided in this application is the heterogeneous in-situ nucleation of CeO2 and ZrO2, with wrapping or interpenetration between different grain structures, thus generating heterogeneous interfaces. By regulating the nucleation and growth of grains and heterogeneous interfaces to increase the sintering energy barrier, the thermal stability of the material will be significantly improved. Furthermore, through the addition of doped element ions, lattice distortion and defects are induced, the generation of oxygen vacancies in the lattice is increased, the oxygen mobility in the lattice and the storage and release of oxygen are improved, and thus the catalytic efficiency of the catalyst is improved. And when the doped element is rare earth yttrium, the catalytic temperature is effectively reduced, but the doping amount needs to be controlled. Since the radius of cerium ions is relatively large, when the content of cerium ions is too high, there are too many large grains, and there are few heterogeneous interfaces and uneven dispersion in the crystal phase; when the content of rare earth yttrium as the doped element is too high, it may cause the collapse of the crystal structure, and the grain structure is uneven and the roughness is large, thus affecting the performance of the coating-bearing matrix.

[0065] After a large amount of research, the applicant unexpectedly found that when the ratio of the total mass concentration of magnesium oxide and yttrium oxide to the mass concentration of noble metal in the conforming coating is (1.5-5):(5-7), the dispersion of noble metal in the ternary catalyst is significantly improved, the amount of noble metal platinum can be increased, and the amount of palladium used can be reduced at the same time; the applicant speculates that the reason is: DFT theoretical calculation shows that the binding energy of metal oxides such as titanium dioxide, zinc oxide, magnesium oxide, yttrium oxide, etc. with noble metals is relatively low. Based on the principle of metal-support interaction, these oxides can be combined with noble metals through electronic effects, thus playing a stabilizing and anchoring effect on noble metals, improving the chemical stability of noble metals, and also helping the dispersion of noble metals on their surfaces, increasing catalytic sites, realizing the substitution of a high proportion of platinum for palladium, and saving costs. However, the ratio of the total mass concentration of magnesium oxide and yttrium oxide to the mass concentration of noble metal needs to be controlled to avoid the masking and failure of the fixed sites and oxygen storage and release sites of the doped element-modified CeO2-ZrO2 composite oxide and Al2O3 when there are too many oxides. Brief Description of the Drawings

[0066] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0067] Figure 1 Flow chart of the preparation method of the three-way catalyst provided by the embodiment of the present application. Detailed implementation manners

[0068] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0069] The embodiment of the present application provides a three-way catalyst, which can solve the problem that the structural stability of the catalyst in the related art is still not high.

[0070] The present application provides a three-way catalyst, which includes a coated carrier and a composite coating. The composite coating is provided on the surface of the coated carrier. The composite coating includes an inner coating and an outer coating. The inner coating is provided on the surface of the coated carrier, and the outer coating is provided on the inner coating. Among them, the inner coating includes a solid solution formed by alumina and a doped element-modified CeO2-ZrO2 composite oxide; the outer coating includes noble metals.

[0071] In the three-way catalyst provided by the present application, the coated carrier of noble metals is modified, and an Al2O3-CeO2-ZrO2 solid solution is formed on the coated carrier by using alumina and CeO2-ZrO2 composite oxide. Heterogeneous in-situ nucleation occurs between CeO2 and ZrO2, and wrapping or interpenetration occurs between different grain structures, thereby constructing a heterogeneous phase interface. By regulating the nucleation and growth of grains and the heterogeneous interface, the sintering energy barrier is increased, so that the thermal stability of the three-way catalyst is significantly improved. At the same time, by doping with doped elements, lattice distortion and defects are induced, the defect sites in the lattice are increased, the generation of oxygen vacancies in the lattice is increased, the oxygen mobility in the lattice and the storage and release of oxygen are improved, thereby improving the catalytic efficiency of the three-way catalyst and further improving the thermal stability of the three-way catalyst, and making the three-way catalyst have excellent anti-aging performance, which can effectively anchor noble metals, inhibit the migration and diffusion of noble metals, inhibit their sintering inactivation, and effectively extend the service life of the three-way catalyst.

[0072] There are many optional types of the above-mentioned coated carriers. For example, as an example, the coated carrier includes one or more of cordierite ceramic carriers, metal carriers, silicon carbide carriers, and molecular sieves.

[0073] Further, the coated carrier is a cordierite ceramic carrier with a pore density of 300-500 meshes per square inch.

[0074] The coefficient of thermal expansion of the above-mentioned coated carrier can be selected according to actual preparation requirements. For example, by way of illustration, the coefficient of thermal expansion of the coated carrier is less than or equal to 0.3×10 -6 / °C.

[0075] The particle size of the above-mentioned alumina can be selected according to actual preparation requirements. For example, by way of illustration, the average particle diameter of the alumina is 5 - 60 μm, preferably 5 - 30 μm.

[0076] There are many optional types of the above-mentioned noble metals. For example, by way of illustration, the noble metals include one or more of ruthenium, rhodium, palladium, platinum, gold, and silver.

[0077] Preferably, the noble metals are platinum and palladium. The mass ratio of platinum and palladium in the composite coating is (0.5 - 3):1.

[0078] There are various types of precursors of the above-mentioned noble metal platinum, which can be selected according to actual needs. For example, by way of illustration, the precursors of platinum include one or more of Pt(NO3)2, Pt(NH3NO2)2, and Pt(NO2)2(NH2OH)2.

[0079] There are various types of precursors of the above-mentioned noble metal palladium, which can be selected according to actual needs. For example, by way of illustration, the precursors of palladium include one or more of Pd(NO3)2, Pd(NO3)2, and Pd(NO2)2(NH3)2.

[0080] There are many types of the above-mentioned doping elements, which can be selected according to actual needs. For example, by way of illustration, the doping elements include one or more of rare earth metal elements, alkaline earth metal elements, Group III main group elements, Group IV main group elements, Group V main group elements, and Group VI main group elements.

[0081] That is to say, the doped element-modified CeO2-ZrO2 composite oxide is modified by one or more doping elements among rare earth metal elements, alkaline earth metal elements, Group III main group elements, Group IV main group elements, Group V main group elements, and Group VI main group elements.

[0082] By way of illustration, the Group III - VI main group elements include one or more of B, N, P, S, and Si.

[0083] By way of illustration, the rare earth metal elements include one or more of lanthanum, neodymium, europium, erbium, and yttrium;

[0084] By way of illustration, the alkaline earth metal elements are selected from one or more of magnesium, calcium, and barium elements.

[0085] Further, in order to obtain the doped element-modified CeO2-ZrO2 composite oxide, the present application also provides a corresponding preparation method. Specifically, the preparation method of the doped element-modified CeO2-ZrO2 composite oxide comprises the following steps: dissolving a cerium ion source, a zirconium ion source, and a doped element ion source in water, adjusting the pH of the solution to 8-12 using a precipitant, adding an auxiliary agent to the solution and stirring, aging and recrystallizing, and then filtering and calcining.

[0086] Among them, the calcination temperature and time during filtration and calcination can be selected according to actual needs. For example, as an example, the calcination temperature is 480°C to 650°C, and the time is 2 to 3 hours.

[0087] There are various types of the above-mentioned cerium ion sources, which can be selected according to actual needs. For example, as an example, the cerium ion source includes one or more of cerium nitrate, cerium sulfate, cerium acetate, and cerium hydroxide.

[0088] There are various types of the above-mentioned zirconium ion sources, which can be selected according to actual needs. For example, as an example, the zirconium ion source includes one or more of zirconium nitrate, zirconium sulfate, and zirconyl nitrate.

[0089] There are various types of the above-mentioned precipitants, which can be selected according to actual needs. For example, as an example, the precipitant includes one or more of sodium hydroxide, ammonium bicarbonate, ammonia water, ethanolamine, tetraethylammonium hydroxide, triethylamine, triethylenediamine, N-methylmorpholine, and vinyl alcohol butylamine.

[0090] In a preferred embodiment, the precipitant is selected from any one of sodium hydroxide, ammonia water, ethanolamine, and tetraethylammonium hydroxide.

[0091] There are various types of the above-mentioned auxiliary agents, which can be selected according to actual needs. For example, as an example, the auxiliary agent includes one or more of chloride ions, nitrate ions, and ammonium ions.

[0092] In a preferred embodiment, the auxiliary agent includes nitrate ions and / or ammonium ions.

[0093] The addition amount of the above-mentioned auxiliary agent can be selected according to actual needs. For example, as an example, the addition amount of the auxiliary agent is 30 to 50 wt% of the total addition amount of cerium ions and zirconium ions.

[0094] In a preferred embodiment, the auxiliary agent is added to the solution and stirred in three times. Preferably, the amount of the auxiliary agent added for the first time accounts for 20 to 40% (volume percentage) of the total amount of the auxiliary agent, the amount of the auxiliary agent added for the second time accounts for 20 to 30% (volume percentage) of the total amount of the auxiliary agent, and the remaining is added for the third time; the auxiliary agent selectively adsorbs on the crystal grains and masks the crystal planes, affecting the nucleation and growth of the crystal grains.

[0095] The addition amounts of the above-mentioned cerium ions, zirconium ions and doped element ions can be selected according to actual needs. For example, by way of example, the molar ratio of the cerium ions, zirconium ions and doped element ions is: (1-3):1:(0.05-2).

[0096] In a preferred embodiment, the doped element ion is a yttrium ion, and the molar ratio of the cerium ions, zirconium ions and yttrium ions is (1-2.2):1:(0.05-1).

[0097] After a large amount of research, the applicant unexpectedly found that: when the doped element-modified CeO2-ZrO2 composite oxide is further defined as a yttrium-doped CeO2-ZrO2 composite oxide, and the molar ratio of the cerium ions, zirconium ions and yttrium ions is (1-2.2):1:(0.05-1), the prepared ternary catalyst has more excellent stability, lower catalytic temperature and higher efficiency; the applicant speculates that the reason is: the preparation method of the doped element-modified CeO2-ZrO2 composite oxide provided in this application is the heterogeneous in-situ nucleation of CeO2 and ZrO2, with wrapping or interpenetration between different grain structures, thereby generating a heterogeneous interface. By regulating the nucleation and growth of grains and the heterogeneous interface to increase the sintering energy barrier, the thermal stability of the material will be significantly improved. Furthermore, by adding doped element ions, lattice distortion and defects are induced, the generation of oxygen vacancies in the lattice is increased, the oxygen mobility in the lattice and the storage and release of oxygen are improved, thereby improving the catalytic efficiency of the catalyst. And when the doped element is rare earth yttrium, the catalytic temperature is effectively reduced, but the doping amount needs to be controlled. Since the radius of the cerium ion is relatively large, when the content of the cerium ion is too much, there are too many large grains, and there are few heterogeneous interfaces and uneven dispersion in the crystal phase; when the content of the rare earth yttrium as the doped element is too much, it may cause the collapse of the crystal structure, and the grain structure is uneven and the roughness is relatively large, thereby affecting the various properties of the coating-bearing matrix.

[0098] In a preferred embodiment, the outer coating further includes a dispersant; at the same time, the composite coating further includes an intermediate coating located between the inner coating and the outer coating, and the intermediate coating includes an electronic promoter. Adding a dispersant to the outer coating can form a crown ether-like cavity with the dispersant to coordinate with noble metal ions such as platinum ions, improve its dispersion performance, effectively reduce the activation temperature of the ternary catalyst, and improve the catalytic effect. At the same time, adding an intermediate coating, using the structural stability of the heterogeneous phase and the electronic stability of the electronic promoter in the intermediate coating, effectively improves the anchoring ability and dispersion of the ternary catalyst to the noble metal, thereby generating more dispersion sites, effectively improving the high-temperature durability of the ternary catalyst, and reducing the usage amount of the noble metal.

[0099] Among them, for a 1L coating carrier, in the composite coating, the usage amount of alumina is 20 - 50 g, the usage amount of the doped element-modified CeO2-ZrO2 composite oxide is 180 - 210 g, the usage amount of the electronic promoter is 15 - 50 g, the usage amount of the noble metal is 20 - 70 g, and the usage amount of the dispersant is 30 - 70 g.

[0100] In a preferred embodiment, the outer coating further includes a dispersant. Adding a dispersant to the outer coating can utilize the crown ether-like cavities formed by the dispersant to coordinate with noble metal ions such as platinum ions, improve its dispersion performance, effectively reduce the activation temperature of the three-way catalyst, and improve the catalytic effect.

[0101] There are various types of the above-mentioned dispersants, which can be selected according to actual needs. For example, as an example, the dispersant includes one or more of polyethylene glycol PEG, cyclodextrin, cellulose, and pentaerythritol.

[0102] Preferably, the dispersant is polyethylene glycol PEG, and the polyethylene glycol PEG is selected from one or more of PEG-400, PEG-600, PEG-800, PEG-1000, PEG-1200, PEG-1500, and PEG-2000.

[0103] Preferably, the polyethylene glycol PEG is selected from one or more of PEG-400, PEG-600, PEG-800, PEG-1000, and PEG-1200.

[0104] In a preferred embodiment, the composite coating further includes an intermediate coating located between the inner coating and the outer coating, and the intermediate coating includes an electronic promoter. Adding an intermediate coating layer effectively improves the anchoring ability and dispersion of the noble metal of the three-way catalyst by utilizing the structural stability of the heterophase and the electronic stability of the electronic promoter in the intermediate coating, thereby generating more dispersion sites, effectively improving the high-temperature durability of the three-way catalyst, and reducing the usage amount of the noble metal.

[0105] There are various types of the above-mentioned electronic promoters, which can be selected according to actual needs. For example, as an example, the electronic promoter includes one or more of alkaline earth metal oxides, alkaline earth metal sulfides, transition metal oxides, transition metal sulfides, and rare earth metal oxides.

[0106] Preferably, the electronic promoter is selected from at least one of titanium dioxide, zinc oxide, magnesium oxide, yttrium oxide, molybdenum sulfide, titanium sulfide, zirconium oxide, and cerium oxide.

[0107] In a preferred embodiment, the electronic promoter is magnesium oxide and / or yttrium oxide. In a preferred embodiment, the electronic promoter includes magnesium oxide and yttrium oxide.

[0108] In a preferred embodiment, the mass ratio of magnesium oxide to yttrium oxide is (1-5):1.

[0109] In a preferred embodiment, the ratio of the total mass concentration of magnesium oxide and yttrium oxide to the mass concentration of the noble metal is (1.5-5):(5-7).

[0110] After a large number of studies, the applicant unexpectedly found that when the ratio of the total mass concentration of magnesium oxide and yttrium oxide to the mass concentration of the noble metal in the coating is limited to (1.5-5):(5-7), the dispersion of the noble metal in the three-way catalyst is significantly improved, the amount of the noble metal platinum can be increased, and the amount of palladium used can be reduced at the same time. The applicant speculates that the reason is that the DFT theoretical calculation shows that the binding energies of metal oxides such as titanium dioxide, zinc oxide, magnesium oxide, and yttrium oxide with the noble metal are all relatively low. Based on the principle of metal-support interaction, these oxides can be combined with the noble metal through an electronic effect, thereby playing a stabilizing and anchoring effect on the noble metal, improving the chemical stability of the noble metal, and also helping the noble metal to disperse on its surface, increasing the catalytic sites, realizing the substitution of a high proportion of platinum for palladium, saving costs, but it is necessary to control the ratio of the total mass concentration of magnesium oxide and yttrium oxide to the mass concentration of the noble metal to avoid the masking and failure of the fixed sites and oxygen storage and release sites of the doped element-modified CeO2-ZrO2 composite oxide and Al2O3 when there are too many oxides.

[0111] See Figure 1 As shown, the present application also provides a method for preparing a three-way catalyst, which includes the following steps:

[0112] 101: Disperse alumina and the doped element-modified CeO2-ZrO2 composite oxide in water to obtain a pre-impregnation solution A.

[0113] 102: Immerse the coated carrier in the pre-impregnation solution A, and then take it out and dry it.

[0114] Among them, in step 102, the time for the coated carrier to be immersed in the pre-impregnation solution A can be determined according to actual preparation needs. For example, as an example, the time for the coated carrier to be immersed in the pre-impregnation solution A is 20-50 s. The drying temperature can be determined according to actual preparation needs. For example, as an example, it is dried at 80-100 °C.

[0115] 103: Disperse the electronic promoter in water, adjust the pH to 9-11, stir and react for a period of time, then immerse the coated carrier with the pre-impregnation solution A therein, dry it and calcine it at a first temperature.

[0116] Among them, in step 103, the pH value can be adjusted by ammonia water or the like. The stirring reaction time can be determined according to actual preparation needs. For example, as an example, the stirring reaction is carried out for 1 to 3 h. The immersion time of the coated carrier with the pre-impregnation liquid A can be determined according to actual preparation needs. For example, as an example, the immersion time of the coated carrier with the pre-impregnation liquid A is 10 to 20 s. The first temperature and time for calcination can be determined according to actual preparation needs. For example, as an example, the first temperature is 500 to 900 °C, and the calcination is carried out for 4 to 6 h.

[0117] 104: Continue to immerse in the pre-impregnation liquid B, dry and then calcine at the second temperature to obtain a ternary catalyst. The pre-impregnation liquid B includes a noble metal precursor and a dispersant.

[0118] Among them, in step 104, the immersion time in the pre-impregnation liquid B can be determined according to actual preparation needs. For example, as an example, the immersion time in the pre-impregnation liquid B is 20 to 30 s; the second temperature and time for calcination can be determined according to actual preparation needs. For example, as an example, the second temperature is 500 to 600 °C, and the calcination is carried out for 4 to 6 h.

[0119] The ternary catalyst provided by this application can be applied in the after-treatment material for vehicle exhaust emissions. For example, as an example, it can be applied in the after-treatment material for the exhaust emissions of the C15TDR model or the M57 model.

[0120] Example 1

[0121] A ternary catalyst, the components of the ternary catalyst include a composite coating and a coated carrier. The composite coating is provided on the surface of the coated carrier. The composite coating includes an inner coating, an intermediate coating, and an outer coating. Among them, the inner coating is provided on the surface of the coated carrier, the intermediate coating is provided on the inner coating, and the outer coating is provided on the intermediate coating; the coated carrier uses a cordierite ceramic carrier; the pore density of the cordierite ceramic carrier is 400 mesh per square inch. Corresponding to 1 L of the coated carrier, in the composite coating, the usage amount of alumina is 40 g, the usage amount of the doped element modified CeO2-ZrO2 composite oxide is 190 g, the usage amount of the electronic promoter is 21 g, the usage amount of the noble metal is 50 g, and the usage amount of the dispersant PEG-1000 is 60 g; the electronic promoter is magnesium oxide and yttrium oxide, and the mass ratio is 4.25:1; the noble metal is Pt and Pd, and the mass ratio of Pt and Pd is 2:1.

[0122] The preparation method of the ternary catalyst includes the following steps:

[0123] (1) Disperse 40 g of alumina (average particle diameter of 25 μm) and 190 g of doped element-modified CeO2-ZrO2 composite oxide in water, with the mass of the solid dispersion phase in the solution being 40 wt% of the water, to obtain pre-impregnation solution A;

[0124] (2) Immerse 1 L of the coating carrier completely in pre-impregnation solution A, take it out after 30 s, and dry it at 100 °C;

[0125] (3) Disperse 115.8 g of magnesium sulfate heptahydrate and 15.06 g of yttrium nitrate hexahydrate in 600 mL of water, add ammonia water and keep the pH of the solution at 9.5, stir and react for 2 h, then immerse the coating carrier in (2) therein for 20 s, dry at 100 °C and calcine at 700 °C for 6 h;

[0126] (4) Immerse the coating carrier in (3) in pre-impregnation solution B for 30 s, dry at 100 °C and calcine at 550 °C for 5 h to obtain a ternary catalyst. Pre-impregnation solution B contains 54.64 g of Pt(NO3)2, 36 g of Pd(NO3)2, 60 g of PEG-1000, and a mixed solution of ethanol and water (v / v is 1:1). The total mass of Pt(NO3)2, Pd(NO3)2, and PEG-1000 accounts for 45 wt% of pre-impregnation solution B.

[0127] The preparation method of the doped element-modified CeO2-ZrO2 composite oxide is as follows: Dissolve cerium nitrate, zirconium nitrate, and yttrium chloride in water, with the molar ratio of cerium ions, zirconium ions, and yttrium ions being 1.5:1:0.8. Then adjust the pH of the solution to 10 with tetraethylammonium hydroxide, add ammonium nitrate to the solution in three portions and stir. The addition amount of ammonium nitrate accounts for 30 wt% of the total amount of cerium nitrate and zirconium nitrate. Add 40% of the mass of ammonium nitrate for the first time, stir for 8 h, then add 30% of the mass of ammonium nitrate, stir for 3 h, and then add the remaining ammonium nitrate and stir for 1 h. After that, filter and calcine at 500 °C for 3 h.

[0128] Example 2

[0129] A three-way catalyst, the components of the three-way catalyst include a composite coating and a coating carrier, the composite coating is provided on the surface of the coating carrier, the composite coating includes an inner coating, an intermediate coating and an outer coating, wherein the inner coating is provided on the surface of the coating carrier, the intermediate coating is provided on the inner coating, and the outer coating is provided on the intermediate coating; the coating carrier is a cordierite ceramic carrier; the pore density of the cordierite ceramic carrier is 500 mesh per square inch. For a 1L coating carrier, in the composite coating, the usage amount of alumina is 20g, the usage amount of doped element-modified CeO2-ZrO2 composite oxide is 210g, the usage amount of electronic promoter is 48g, the usage amount of noble metal is 30g, and the usage amount of dispersant PEG-800 is 70g; the electronic promoter is magnesium oxide and yttrium oxide, and the mass ratio is 5:1; the noble metal is Pt and Pd, and the mass ratio of Pt and Pd is 3:1;

[0130] The preparation method of the three-way catalyst includes the following steps:

[0131] (1) Disperse 20g of alumina (average particle diameter is 30μm) and 210g of doped element-modified CeO2-ZrO2 composite oxide in water, and the mass of the solid dispersion phase in the solution is 50% of that of water to obtain a pre-impregnation solution A;

[0132] (2) Immerse a 1L coating carrier completely into the pre-impregnation solution A, take it out after 20s, and dry it at 100°C;

[0133] (3) Disperse 271.8g of magnesium sulfate heptahydrate and 30.15g of yttrium nitrate hexahydrate in 600mL of water, add ammonia water and keep the solution pH at 11, stir and react for 1h, then immerse the coating carrier in (2) in it for 20s, dry it at 110°C and calcine it at 900°C for 4h;

[0134] (4) Place the coating carrier in (3) in the pre-impregnation solution B for 30s, dry it at 100°C and calcine it at 550°C for 6h to obtain a three-way catalyst. The pre-impregnation solution B contains 36.8g of Pt(NO2)2(NH2OH)2, 16.2g of Pd(NO3)2, 70g of PEG-800 and a mixed solution of ethanol and water (v / v is 1:1). The total mass of Pt(NO2)2(NH2OH)2, Pd(NO3)2 and PEG-800 accounts for 50wt% of the pre-impregnation solution B.

[0135] The preparation method of the doped element-modified CeO2-ZrO2 composite oxide is as follows: Dissolve cerium nitrate, zirconium nitrate, and yttrium chloride in water. The molar ratio of cerium ions, zirconium ions, and yttrium ions is 2.2:1:0.1. Then, adjust the pH of the solution to 12 using tetraethylammonium hydroxide. Add ammonium nitrate to the solution in three portions with stirring. The addition amount of ammonium nitrate accounts for 50 wt% of the total amount of cerium nitrate and zirconium nitrate. Add 20% by mass of ammonium nitrate for the first time. After stirring for 6 h, add 30% by mass of ammonium nitrate and stir for 2 h. Then add the remaining ammonium nitrate and stir for 2 h. After that, filter and calcine at 600 °C for 2 h.

[0136] Example 3

[0137] A three-way catalyst, the components of the three-way catalyst include a composite coating and a coating carrier. The composite coating is provided on the surface of the coating carrier. The composite coating includes an inner coating, an intermediate coating, and an outer coating. Among them, the inner coating is provided on the surface of the coating carrier, the intermediate coating is provided on the inner coating, and the outer coating is provided on the intermediate coating; the coating carrier uses a cordierite ceramic carrier; the pore density of the cordierite ceramic carrier is 350 mesh / square inch. For a 1 L coating carrier, in the composite coating, the usage amount of alumina is 50 g, the usage amount of the doped element-modified CeO2-ZrO2 composite oxide is 180 g, the usage amount of the electronic promoter is 20 g, the usage amount of the noble metal is 30 g, and the usage amount of the dispersant PEG-1000 is 30 g; the electronic promoter is magnesium oxide and yttrium oxide, and the mass ratio is 1:1; the noble metal is Pt and Pd, and the mass ratio of Pt and Pd is 1.5:1;

[0138] The preparation method of the three-way catalyst includes the following steps:

[0139] (1) Disperse 50 g of alumina (average particle diameter is 15 μm) and 180 g of the doped element-modified CeO2-ZrO2 composite oxide in water. The mass of the solid dispersion phase in the solution is 40% of the water to obtain a pre-impregnation solution A;

[0140] (2) Immerse a 1 L coating carrier completely into the pre-impregnation solution A, take it out after 50 s, and dry it at 100 °C;

[0141] (3) Disperse 68 g of magnesium sulfate heptahydrate and 37.7 g of yttrium nitrate hexahydrate in water, add ammonia water and keep the pH of the solution at 9. After stirring and reacting for 3 h, immerse the coating carrier in (2) into it for 10 s, dry it at 100 °C and then calcine it at 600 °C for 8 h.

[0142] (4) Place the coated carrier in (3) into the impregnating solution B for 30 s, dry it at 100 °C and then calcine it at 600 °C for 4 h to obtain a ternary catalyst. The impregnating solution B contains 29.5 g of Pt(NO2)2(NH2OH)2, 26 g of Pd(NO3)2, 30 g of PEG-1000, and a mixed solution of ethanol and water (v / v = 1:1). The total mass of Pt(NO2)2(NH2OH)2, Pd(NO3)2, and PEG-1000 accounts for 40 wt% of the impregnating solution B.

[0143] The preparation method of the doped element-modified CeO2-ZrO2 composite oxide is as follows: Dissolve cerium nitrate, zirconium nitrate, and yttrium chloride in water. The molar ratio of cerium ions, zirconium ions, and yttrium ions is 1:1:1. Then adjust the pH of the solution to 9.5 with tetraethylammonium hydroxide. Add ammonium nitrate to the solution in three portions and stir. The addition amount of ammonium nitrate accounts for 40 wt% of the total amount of cerium nitrate and zirconium nitrate. Add 40% of the mass of ammonium nitrate for the first time, stir for 10 h, then add 20% of the mass of ammonium nitrate, stir for 2 h, and then add the remaining ammonium nitrate and stir for 2 h. After that, filter and calcine at 500 °C for 3 h.

[0144] Comparative Example 1

[0145] It is basically the same as Example 1, except that: The preparation method of the doped element-modified CeO2-ZrO2 composite oxide is as follows: Replace the yttrium chloride with cobalt nitrate. The molar ratio of cerium ions, zirconium ions, and cobalt ions is 1.5:1:0.8.

[0146] Comparative Example 2

[0147] It is basically the same as Example 1, except that: The molar ratio of cerium ions, zirconium ions, and yttrium ions is 2.2:1:0.03.

[0148] Comparative Example 3

[0149] It is basically the same as Example 1, except that: In the composite coating, the usage amount of alumina is 40 g, the usage amount of the doped element-modified CeO2-ZrO2 composite oxide is 190 g, the usage amount of the electronic promoter is 21 g, the usage amount of the noble metal is 50 g, and the usage amount of PEG-1000 is 60 g; The electronic promoter is magnesium oxide; The noble metal is Pt and Pd, and the mass ratio of Pt and Pd is 2:1.

[0150] Comparative Example 4

[0151] Basically the same as Example 1, with the differences being that in the composite coating, the usage amount of alumina is 40 g, the usage amount of the doped element modified CeO2-ZrO2 composite oxide is 190 g, the usage amount of the electronic promoter is 21 g, the usage amount of the noble metal is 50 g, and the usage amount of PEG-1000 is 60 g; the electronic promoter is magnesium oxide and yttrium oxide, and the mass ratio is 1:2; the noble metal is Pt and Pd, and the mass ratio of Pt and Pd is 2:1;

[0152] In step (3) of the preparation method of the ternary catalyst, 27 g of magnesium sulfate heptahydrate and 64 g of yttrium nitrate hexahydrate are used.

[0153] Comparative Example 5

[0154] Basically the same as Example 1, with the difference being that in the preparation method of the doped element modified CeO2-ZrO2 composite oxide, tetraethylammonium hydroxide is replaced by sodium hydroxide.

[0155] Performance test method:

[0156] The catalysts before and after aging in the examples and comparative examples are subjected to performance evaluation of the catalyst in a simulated atmosphere, and the high and low of their T50 (°C) are compared; simulated atmosphere: CH4 3000 ppm, NO 1400 ppm, CO 1500 ppm, H2 3000 ppm, CO2 8%, H2O 10%, adjust the O2 concentration to make the λ value (excess air coefficient) 0.99, and use N2 as the balance gas; aging conditions: aging at 850 °C for 50 h under 10% H2O, and the test results are shown in Table 1.

[0157] Table 1

[0158]

[0159]

[0160] Analysis results:

[0161] Comparing Example 1 and Comparative Example 1, it can be seen that in Comparative Example 1, the doped element is cobalt, and the radius of the +3 valence cobalt ion is smaller than that of the yttrium ion, and the lattice defects and oxygen vacancies generated are far less than those of the yttrium ion (yttrium ion doping is the best), resulting in a lower catalytic performance of the ternary catalyst.

[0162] Comparing Example 1 and Comparative Example 2, it can be seen that in Comparative Example 2, the addition amount of cerium ions is relatively large, while the addition amount of yttrium ions is relatively reduced. As a result, the T50 temperatures of the catalyst in Comparative Example 2 for catalyzing CH4 and NO are both higher than those in Example 2. This may be because when the content of cerium ions with a larger radius is excessive, there are too many large grains, the number of heterogeneous interfaces in the crystal phase is small and the dispersion is uneven. At the same time, the reduction in the doping amount of yttrium ions also leads to a decrease in oxygen vacancies and oxygen storage and release capacity. All of the above affect the catalytic effect of the catalyst.

[0163] Comparing Example 1 and Comparative Examples 3-4, it can be seen that the synergistic effect of magnesium oxide and yttrium oxide can better improve the catalytic efficiency of the catalyst and reduce the catalytic temperature. On the one hand, this may be because magnesium oxide and yttrium oxide themselves increase the oxygen storage capacity and catalytic performance. On the other hand, the synergistic effect of magnesium oxide and yttrium oxide increases the anchoring effect on the noble metal, increasing the number and stability of effective catalytic sites. All of the above improve the catalytic efficiency and reduce the T50 temperature of the gas. However, it is necessary to control the ratio of the two within a certain range, as too much or too little will affect the grain distribution and catalytic efficiency of the catalyst.

[0164] Comparing Example 1 and Comparative Example 5, it can be seen that perhaps because tetraethylammonium hydroxide has a certain interaction with cerium nitrate, zirconium nitrate, and yttrium chloride, using its molecular chain length and charged effect to better disperse the latter three and nucleate and grow at a given position, promoting the doped element-modified CeO2-ZrO2 to have a special grain arrangement state, while sodium hydroxide does not have this effect, so the catalytic performance of the catalyst is slightly reduced.

[0165] In summary, the present application provides a ternary catalyst, the components of which include a composite coating and a coating carrier. The composite coating includes a noble metal, alumina, a doped element-modified CeO2-ZrO2 composite oxide, an electronic promoter, and a dispersant. By constructing heterogeneous phase interfaces and element doping in the catalyst, the defect sites of the crystal are increased, the oxygen storage and release capacity and the thermal stability of the catalyst are improved, and through the structural stability and electronic fixation effect, the anchoring and dispersion of the noble metal are effectively improved. By using the combined action of each component, the usage amount of the noble metal palladium is effectively reduced, and the catalyst has high catalytic activity, good thermal stability, and a long service life.

[0166] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "upper" and "lower" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present application. Unless otherwise clearly specified and defined, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0167] It should be noted that in the present application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the said element.

[0168] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A preparation method of a three-way catalyst, characterized in that, The ternary catalyst includes a coated carrier and a composite coating. The composite coating is provided on the surface of the coated carrier. The composite coating includes an inner coating, an intermediate coating, and an outer coating. The inner coating is provided on the surface of the coated carrier, the intermediate coating is provided on the inner coating, and the outer coating is provided on the intermediate coating. The intermediate coating includes an electronic promoter. The outer coating further includes a dispersant, and the dispersant is polyethylene glycol PEG-1000. The coated carrier uses a cordierite ceramic carrier. The pore density of the cordierite ceramic carrier is 400 mesh per square inch. For a 1L coated carrier, in the composite coating, the usage amount of alumina is 40g, the usage amount of doped element-modified CeO2-ZrO2 composite oxide is 190g, the usage amount of the electronic promoter is 21g, the usage amount of the noble metal is 50g, and the usage amount of the dispersant PEG-1000 is 60g. Among them, the inner coating includes a solid solution formed by alumina and doped element-modified CeO2-ZrO2 composite oxide. The outer coating includes a noble metal. The noble metal is platinum and palladium, and the mass ratio of platinum and palladium in the composite coating is 2:

1. The electronic promoter is magnesium oxide and yttrium oxide, and the mass ratio of magnesium oxide and yttrium oxide is 4.25:

1. The preparation method of the doped element-modified CeO2-ZrO2 composite oxide includes the following steps: Dissolve cerium nitrate, zirconium nitrate, and yttrium chloride in water. The molar ratio of cerium ions, zirconium ions, and yttrium ions is 1.5:1:0.

8. Then adjust the pH of the solution to 10 using tetraethylammonium hydroxide. Add ammonium nitrate to the solution in three batches and stir. The addition amount of ammonium nitrate accounts for 30wt% of the total amount of cerium nitrate and zirconium nitrate. Add 40% of the mass of ammonium nitrate for the first time, stir for 8h, then add 30% of the mass of ammonium nitrate, stir for 3h, and then add the remaining ammonium nitrate and stir for 1h. After that, filter and calcine at 500°C for 3h. The preparation method of the ternary catalyst includes the following steps: (1) Disperse 40g of alumina and 190g of doped element-modified CeO2-ZrO2 composite oxide in water. The mass of the solid dispersion phase in the solution is 40wt% of the water to obtain a pre-impregnation solution A. The average particle diameter of the alumina is 25μm. (2) Immerse a 1L coated carrier completely in the pre-impregnation solution A, take it out after 30s, and dry it at 100°C. (3) Disperse 115.8g of magnesium sulfate heptahydrate and 15.06g of yttrium nitrate hexahydrate in 600mL of water, add ammonia water and keep the pH of the solution at 9.

5. After stirring and reacting for 2h, immerse the coated carrier in (2) in it for 20s, dry it at 100°C and then calcine it at 700°C for 6h. (4) The coated support in (3) is placed in the impregnation solution B for 30 s, dried at 100 °C, and then calcined at 550 °C for 5 h to obtain a ternary catalyst. The impregnation solution B contains 54.64 g of Pt(NO3)2, 36 g of Pd(NO3)2, 60 g of PEG-1000, and a mixed solution of ethanol and water with a volume ratio of ethanol to water being 1:1; the total mass of Pt(NO3)2, Pd(NO3)2, and PEG-1000 accounts for 45 wt% of the impregnation solution B.

2. The method for preparing a ternary catalyst according to claim 1, wherein: The coefficient of thermal expansion of the coated carrier is less than or equal to 0.3×10 -6 / °C.

3. Application of a ternary catalyst prepared by the method for preparing a ternary catalyst according to claim 1 or 2 in a vehicle exhaust aftertreatment material.

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