Thermal conductive materials, catalyst composite coatings and three-way catalysts for automobile exhaust purification

Abstract

The present application relates to a thermally conductive material, a catalyst composite coating, and a three-way catalyst for automobile exhaust purification. By weight, the thermally conductive material includes 20-50% of a low-content lanthanum-modified alumina material, 20-30% of a high-content lanthanum-modified alumina material, 10-30% of a rare earth oxygen storage material, 5-30% of a thermal conductive additive, and 0.1-5% of a processing aid. By coating the surface of a carrier with a thermally conductive material to form a thermally conductive layer, and then coating an active reaction layer, the thermally conductive layer promotes the rapid heating of the upper active reaction layer, thereby achieving rapid ignition of the three-way catalyst. The separate design of the thermally conductive layer allows the existing precious metal coating layering and segmentation scheme to still be carried out, without the need to significantly adjust the existing coating production line, and has good compatibility with engines with different original emissions.

Description

Technical Field

[0001] The present application relates to the technical field of automobile exhaust purification and treatment, and in particular to a thermally conductive material, a catalyst composite coating and a three-way catalyst for automobile exhaust purification. Background Art

[0002] Whether it's a traditional fuel vehicle or a new energy hybrid vehicle, exhaust gas purification and emission control are crucial aspects of automotive product development. Currently, the main measures for controlling vehicle exhaust emissions include pre-engine, in-engine, and post-engine. Post-engine measures involve purifying exhaust gases using air injection, oxidation reactors, and three-way catalytic converters. Post-engine catalytic purification technology is the most effective way to reduce environmental pollution from vehicle exhaust, with the three-way catalyst being the core of off-engine exhaust emission control. Existing three-way catalysts typically consist of a honeycomb ceramic substrate and a catalyst coating applied to its surface. The coating primarily includes precious metals such as platinum, palladium, and rhodium, rare earth oxygen storage materials, and high-area alumina.

[0003] Hybrid vehicles are increasingly gaining market share. To achieve optimal fuel economy, hybrid vehicles require frequent engine starts and stops compared to conventional combustion engines. Hybrid vehicles experience frequent starts and stops, and experience more transient operating conditions, which requires highly reactive three-way catalysts. During these frequent starts and stops, especially during cold starts, the temperature of the three-way catalyst must rise from ambient temperature to the ignition temperature required for the catalytic reaction. However, the thermal conductivity of cordierite-based ceramic honeycomb substrates is relatively low (only approximately 15 W / (m·K)). Before the three-way catalyst reaches the ignition temperature, the vast majority of exhaust pollutants are discharged directly from the exhaust pipe, resulting in substandard exhaust emissions.

[0004] There are two main types of solutions to the above problems.

[0005] One is to lower the ignition temperature of the three-way catalyst. For example, patent CN113019363B discloses an exhaust gas treatment catalyst, which is coated with a first catalyst body, a second catalyst body and a third catalyst body in sequence along the airflow direction. The first catalyst body is only provided with a thin coating layer, and the first coating layer uses Ce-modified La-Al2O3 material. The addition ratio of each raw material is adjusted in a targeted manner, so that the catalyst has excellent ignition performance, which is conducive to rapid ignition of the catalyst.

[0006] Another way to improve the thermal conductivity of the three-way catalyst is that patent CN114931962A provides a fast ignition catalyst coating and its preparation method, which uses black silicon carbide with high thermal conductivity, low heat capacity and high thermal stability as a thermal conductive layer to achieve rapid conduction of exhaust heat in the coating, achieving the effect of rapid temperature rise. However, if black silicon carbide is directly added to the coating material, in order to achieve a good thermal conductivity, the amount of black silicon carbide required is very large, which will not only cause the bonding force between the coating material and the ceramic carrier to decrease, but also increase the cost of the coating material. In addition, the addition of silicon carbide will affect the dispersion and catalytic effect of the precious metal active components and reduce the catalytic efficiency. This strategy of directly adding thermal conductive materials to the functional coating also limits the existing technical strategy of layering and segmented coating of three-way catalysts (according to the original engine exhaust data, it is usually necessary to carry out targeted layering or segmented coating design of different precious metal coatings). Summary of the Invention

[0007] The present invention provides a thermally conductive material, a catalyst composite coating, and a three-way catalyst for automobile exhaust purification. By coating a carrier surface with a thermally conductive material to form a thermally conductive layer, and then applying an active reaction layer, the thermally conductive layer promotes rapid temperature rise of the upper active reaction layer, enabling rapid ignition of the three-way catalyst. The separate design of the thermally conductive layer allows existing precious metal coating layering and segmentation schemes to be implemented without requiring significant adjustments to existing coating production lines, ensuring good compatibility with engines with different exhaust gasses.

[0008] In a first aspect, a thermal conductive material for automobile exhaust purification is provided. By weight, the thermal conductive material includes 20-50% of a low-content lanthanum-modified alumina material, 20-30% of a high-content lanthanum-modified alumina material, 10-30% of a rare earth oxygen storage material, 5-30% of a thermal conductive additive, and 0.1-5% of a processing aid.

[0009] In some embodiments, the weight ratio of lanthanum oxide in the low-content lanthanum-modified alumina material is no more than 6%;

[0010] The weight ratio of lanthanum oxide in the high-content lanthanum-modified alumina material is 6% to 10%.

[0011] In some embodiments, the rare earth oxygen storage material includes cerium oxide and zirconium oxide.

[0012] In some embodiments, the rare earth oxygen storage material further comprises one or more of lanthanum oxide, yttrium oxide, niobium oxide, praseodymium oxide, neodymium oxide, magnesium oxide, barium oxide, erbium oxide, rubidium oxide and aluminum oxide.

[0013] In some embodiments, the lanthanum-modified alumina material includes aluminum oxide and lanthanum oxide, and one or more selected from the group consisting of neodymium oxide, magnesium oxide, barium oxide, silicon dioxide, and calcium oxide.

[0014] In some embodiments, the thermal conductive additive includes one or more of boron nitride BN, silicon carbide SiC, and metal powder.

[0015] In some embodiments, the processing aid includes one or more of zirconium acetate, pseudo-boehmite, polyvinyl alcohol, and polyethylene glycol.

[0016] In some embodiments, the specific surface area of ​​the high-content lanthanum-modified alumina material after aging at 1100°C for 4 hours is not less than 110 m 2 / g.

[0017] In some embodiments, the rare earth oxygen storage material has a specific surface area of ​​not less than 60 m2 after aging at 1000°C for 4 hours. 2 / g, and the oxygen storage capacity is not less than 200μmol / g.

[0018] In some embodiments, the thermal conductivity of the thermal conductive agent is not less than 60 W / (m·K).

[0019] In a second aspect, a catalyst composite coating for automobile exhaust purification is provided, which includes: a heat-conducting layer and an active reaction layer arranged on the heat-conducting layer, and the heat-conducting layer adopts any of the above-mentioned heat-conducting materials for automobile exhaust purification.

[0020] In some embodiments, the active reaction layer contains at least one noble metal selected from the group consisting of Pt, Pd, and Rh, as well as a rare earth oxygen storage material and a lanthanum-modified alumina material.

[0021] In some embodiments, the thickness of the heat-conducting layer is 1 / 10 to 1 / 3 of the thickness of the catalyst composite coating.

[0022] In a third aspect, a three-way catalyst for automobile exhaust purification is provided, which includes a carrier and a catalyst composite coating for automobile exhaust purification as described above, wherein the heat conductive layer is provided on the carrier.

[0023] In a fourth aspect, a method for preparing the above-mentioned three-way catalyst for automobile exhaust purification is provided, which comprises the following steps:

[0024] Adding a low-content lanthanum-modified alumina material, a high-content lanthanum-modified alumina material, a rare earth oxygen storage material, a thermal conductive additive, and a processing aid into water, and stirring uniformly to obtain slurry A;

[0025] Slurry A is coated on a carrier, dried, and then subjected to a first calcination process to obtain a carrier loaded with a heat-conducting layer;

[0026] Weighing a precious metal source, loading the precious metal onto the rare earth oxygen storage material and the lanthanum-modified alumina material by an equal pore volume impregnation method, drying, and then performing a second calcination treatment to obtain a precious metal-loaded rare earth oxygen storage material and a lanthanum-modified alumina material;

[0027] Adding a rare earth oxygen storage material loaded with precious metals and a lanthanum-modified alumina material to an aluminum sol or zirconium acetate aqueous solution with a solid content of 1-5%, and then ball milling to obtain slurry B;

[0028] The slurry B is coated on a carrier loaded with a heat-conducting layer to obtain a three-way catalyst for purifying automobile exhaust gas.

[0029] In some embodiments, slurry A is dried at 100-200° C. for 0.5-2 h;

[0030] The first calcination treatment includes: heating to 500-600° C. at a heating rate of 0.5-10° C. / min and calcining for 1-4 hours.

[0031] In some embodiments, after the precious metal is loaded onto the rare earth oxygen storage material and the lanthanum-modified alumina material, the material is dried at a temperature of 100 to 200° C. for 0.2 to 2 hours;

[0032] The second calcination treatment includes: heating to 200-400° C. at a heating rate of 5-30° C. / min, and calcining for 1-3 hours.

[0033] In some embodiments, the noble metal source includes one or more of palladium nitrate, platinum nitrate, and rhodium nitrate.

[0034] In some embodiments, when the noble metal is Pd, the Pd loading is 5 to 300 g / ft 3 Weigh the precious metal source;

[0035] When the precious metal is Pt, the Pt loading is between 0 and 100 g / ft. 3 Weigh the precious metal source;

[0036] When the precious metal is Rh, the Rh loading is 0.1 to 50 g / ft 3 Weigh the precious metal source.

[0037] In some embodiments, when the rare earth oxygen storage material loaded with precious metals and the lanthanum-modified alumina material are added to an aluminum sol or zirconium acetate aqueous solution with a solid content of 1-5%, the amount of the slurry solidified material is 10-30%.

[0038] The beneficial effects of the technical solution provided by this application include:

[0039] The present invention provides a thermally conductive material, a catalyst composite coating, and a three-way catalyst for automobile exhaust purification. This application forms a thermally conductive layer by coating a carrier surface with a thermally conductive material, followed by an active reaction layer. The thermally conductive layer promotes rapid temperature rise of the upper active reaction layer, enabling rapid ignition of the three-way catalyst. The separate design of the thermally conductive layer allows existing precious metal coating layering and segmentation schemes to be implemented without requiring significant adjustments to existing coating production lines, resulting in improved compatibility with engines with different exhaust gasses.

[0040] In the present application, the addition of a certain amount of high-content lanthanum-modified alumina material helps the thermal conductive material to exert its thermal conductivity without affecting the chemical reaction of the active reaction layer. It may be that the high-content lanthanum-modified alumina material can, on the one hand, stabilize the composition of the thermal conductive layer and prevent the phase separation of the components at high temperatures, resulting in performance degradation; on the other hand, the high specific surface area under high temperature conditions can promote the dispersion of thermal conductive additives and rare earth oxygen storage materials, prevent structural collapse and the precious metal coating of the active reaction layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0042] Figure 1 A schematic diagram of a three-way catalyst provided in an embodiment of the present application from one perspective;

[0043] Figure 2 A schematic diagram of a three-way catalyst from another perspective provided in an embodiment of the present application;

[0044] Figure 3 Schematic diagram of the three-way catalyst provided in the embodiment of the present application (layered coating);

[0045] Figure 4 Schematic diagram of the three-way catalyst provided in the examples of this application (layered and segmented coating).

[0046] In the figure: 1, carrier; 2, catalyst composite coating; 3, heat-conducting layer; 4, active reaction layer; 4-1, lower layer; 4-2, upper layer; 4-3, first section; 4-4, second section. DETAILED DESCRIPTION

[0047] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0048] An embodiment of the present application provides a thermally conductive material for automobile exhaust purification. By weight, the thermally conductive material includes 20-50% of a low-content lanthanum-modified alumina material, 20-30% of a high-content lanthanum-modified alumina material, 10-30% of a rare earth oxygen storage material, 5-30% of a thermal conductive additive, and 0.1-5% of a processing aid.

[0049] This application forms a thermally conductive layer by coating the carrier surface with a thermally conductive material, and then applying an active reaction layer. The thermally conductive layer promotes rapid temperature rise of the active reaction layer above it, achieving rapid ignition of the three-way catalyst. The separate design of the thermally conductive layer allows existing precious metal coating layering and segmentation schemes to be implemented without requiring significant adjustments to existing coating production lines, ensuring good compatibility with engines with different original emissions.

[0050] In the present application, the addition of a certain amount of high-content lanthanum-modified alumina material helps the thermal conductive material to exert its thermal conductivity without affecting the chemical reaction of the active reaction layer. It may be that the high-content lanthanum-modified alumina material can, on the one hand, stabilize the composition of the thermal conductive layer and prevent the phase separation of the components at high temperatures, resulting in performance degradation; on the other hand, the high specific surface area under high temperature conditions can promote the dispersion of thermal conductive additives and rare earth oxygen storage materials, prevent structural collapse and the precious metal coating of the active reaction layer.

[0051] Specifically, when designing thermal conductive materials, the weight ratio of lanthanum oxide in the low-content lanthanum-modified alumina material is not higher than 6%; the weight ratio of lanthanum oxide in the high-content lanthanum-modified alumina material is 6% to 10%, and the specific surface area of ​​the high-content lanthanum-modified alumina material after aging at 1100°C for 4 hours is not less than 110m 2 / g.

[0052] The thermal conductivity of the thermal conductive agent is not less than 60W / (m·K). Too low a thermal conductivity is difficult to play a thermal conductive role. Through a large number of experiments, one or more of boron nitride BN, silicon carbide SiC, and metal powder are preferably used.

[0053] The processing aid disperses the components of the thermally conductive layer, preventing them from agglomerating in the slurry. It also acts as a binder to enhance adhesion between the thermally conductive layer and the carrier. There are various materials available for the processing aid. For example, the processing aid includes one or more of zirconium acetate, pseudo-boehmite, polyvinyl alcohol, and polyethylene glycol.

[0054] The rare earth oxygen storage material includes cerium oxide and zirconium oxide. Of course, according to actual needs, the rare earth oxygen storage material also includes one or more of lanthanum oxide, yttrium oxide, niobium oxide, praseodymium oxide, neodymium oxide, magnesium oxide, barium oxide, erbium oxide, rubidium oxide and aluminum oxide.

[0055] The rare earth oxygen storage material has a specific surface area of ​​not less than 60m after aging at 1000°C for 4 hours. 2 / g, and the oxygen storage capacity is not less than 200μmol / g.

[0056] The lanthanum-modified alumina material includes aluminum oxide and lanthanum oxide, and one or more selected from the group consisting of neodymium oxide, magnesium oxide, barium oxide, silicon dioxide, and calcium oxide.

[0057] Compared with the related art, in which both heat conduction and active reaction are achieved by the active reaction layer, the present application separates the active reaction layer from the heat conduction layer, so that the heat conduction layer only needs to improve heat conduction. Therefore, the heat conducting material does not contain Pt, Pd and Rh.

[0058] See also Figure 1 、 Figure 2 、 Figure 3 and Figure 4 As shown in the figure (the light bold arrow indicates the direction of airflow), an embodiment of the present application also provides a catalyst composite coating for automobile exhaust purification. The catalyst composite coating 2 includes a heat-conducting layer 3 and an active reaction layer 4 arranged on the heat-conducting layer 3. The heat-conducting layer 3 adopts the heat-conducting material for automobile exhaust purification mentioned in any of the above embodiments.

[0059] The catalyst composite coating provided herein features a thermally conductive additive in the thermally conductive layer 3 that provides excellent thermal conductivity. The high content of lanthanum-modified alumina material contributes to this function, promoting rapid temperature rise in the active reaction layer above it without affecting the chemical reactions in the active reaction layer, thereby achieving rapid ignition of the three-way catalyst. The separate design of the thermally conductive layer allows existing precious metal coating layering and segmentation schemes to be implemented without requiring significant adjustments to existing coating production lines, resulting in improved compatibility with engines with different original emissions.

[0060] If the thermal conductive layer 3 is too thin, it will not be able to fully perform its heat conduction function. If the thermal conductive layer 3 is too thick, the coating will easily fall off and it will also be detrimental to the orientation of the thermal conductive additive during the coating process. Therefore, after screening, the thickness of the thermal conductive layer 3 is 1 / 10 to 1 / 3 of the thickness of the catalyst composite coating 2.

[0061] It should be noted that the active reaction layer 4 is used to react with the exhaust gas to purify the exhaust gas, so the active reaction layer 4 contains at least one precious metal of Pt, Pd, and Rh, as well as rare earth oxygen storage materials and lanthanum-modified alumina materials.

[0062] The rare earth oxygen storage material includes cerium oxide and zirconium oxide. Of course, according to actual needs, the rare earth oxygen storage material also includes one or more of lanthanum oxide, yttrium oxide, niobium oxide, praseodymium oxide, neodymium oxide, magnesium oxide, barium oxide, erbium oxide, rubidium oxide and aluminum oxide.

[0063] The rare earth oxygen storage material has a specific surface area of ​​not less than 60m after aging at 1000°C for 4 hours. 2 / g, and the oxygen storage capacity is not less than 200μmol / g.

[0064] The lanthanum-modified alumina material includes aluminum oxide and lanthanum oxide, and one or more selected from the group consisting of neodymium oxide, magnesium oxide, barium oxide, silicon dioxide, and calcium oxide.

[0065] It should be noted that the rare earth oxygen storage material in the active reaction layer 4 and the rare earth oxygen storage material in the heat conducting layer 3 may be the same or different.

[0066] It should be noted that the lanthanum-modified alumina material in the active reaction layer 4 and the lanthanum-modified alumina material in the heat conducting layer 3 may be the same or different.

[0067] See also Figure 1 、 Figure 2 、 Figure 3 and Figure 4 As shown, an embodiment of the present application also provides a three-way catalyst for automobile exhaust purification, which includes a carrier 1 and a catalyst composite coating 2, wherein the heat-conducting layer 3 in the catalyst composite coating 2 is arranged on the carrier 1, so that the heat-conducting layer 3 is located between the carrier 1 and the active reaction layer 4.

[0068] See also Figure 3 As shown, when the active reaction layer 4 is layered coating, the lower layer 4-1 is a coating layer loaded with precious metals Pt and Pd, and the upper layer 4-2 is a coating layer loaded with precious metals Pt and Rh.

[0069] See also Figure 4 As shown, when the active reaction layer 4 is coated in layers and sections, the lower layer 4-1 is a coating loaded with precious metals Pt and Pd, and the upper layer 4-2 includes a first section 4-3 and a second section 4-4. The first section 4-3 is a coating loaded with precious metals Pt and Rh, and the second section 4-4 is a coating loaded with precious metal Rh.

[0070] It should be noted that the carrier 1 can be a commonly used carrier. For example, as an example, the carrier 1 is a honeycomb ceramic carrier.

[0071] The present application also provides a method for preparing a three-way catalyst for automobile exhaust purification, which comprises the following steps:

[0072] 101: Add 20-50% of a low-content lanthanum-modified alumina material, 20-30% of a high-content lanthanum-modified alumina material, 10-30% of a rare earth oxygen storage material, 5-30% of a thermal conductive agent and 0.1-5% of a processing aid into water, stir evenly, and obtain slurry A.

[0073] Among them, ball milling stirring can be used, and the time is determined according to actual needs, such as 5 to 30 minutes.

[0074] 102: coating the slurry A on the carrier 1, drying it, and then performing a first calcination process to obtain the carrier 1 loaded with the heat conducting layer 3;

[0075] Wherein, slurry A is dried at 100-200°C for 0.5-2h.

[0076] The water mentioned above can be deionized water.

[0077] The first calcination treatment includes: heating to 500-600° C. at a heating rate of 0.5-10° C. / min and calcining for 1-4 hours.

[0078] 103: Weighing a precious metal source, loading the precious metal onto the rare earth oxygen storage material and the lanthanum-modified alumina material by an equal pore volume impregnation method according to a specific layering and segmentation strategy, drying, and then performing a second calcination treatment to obtain a precious metal-loaded rare earth oxygen storage material and a lanthanum-modified alumina material;

[0079] There are many types of precious metal sources. For example, if the precious metal is palladium (Pd), the precious metal source includes palladium nitrate, palladium sulfate, and the like.

[0080] If the noble metal is platinum (Pt), the noble metal source includes platinum nitrate, platinum sulfate, and the like.

[0081] If the noble metal is rhodium Rh, the noble metal source includes rhodium nitrate, rhodium sulfate, and the like.

[0082] When the precious metal is Pd, the Pd loading is 5 to 300 g / ft 3 Weigh the precious metal source;

[0083] When the precious metal is Pt, the Pt loading is between 0 and 100 g / ft. 3 Weigh the precious metal source;

[0084] When the precious metal is Rh, the Rh loading is 0.1 to 50 g / ft 3 Weigh the precious metal source.

[0085] After loading the precious metal onto the rare earth oxygen storage material and the lanthanum-modified alumina material, drying at a temperature of 100 to 200° C. for 0.2 to 2 hours;

[0086] The second calcination treatment includes: heating to 200-400° C. at a heating rate of 5-30° C. / min, and calcining for 1-3 hours.

[0087] 104: adding the rare earth oxygen storage material loaded with precious metals and the lanthanum-modified alumina material to an aluminum sol or zirconium acetate aqueous solution having a solid content of 1-5% to a slurry solidified at 10-30%, and then ball milling for 5-30 minutes to obtain slurry B;

[0088] 105: Slurry B is coated on the carrier 1 loaded with the heat-conducting layer 3 to obtain a three-way catalyst.

[0089] It should be noted that, in actual preparation, the above steps 103 and 104 can be combined, that is, the noble metal source, rare earth oxygen storage material and lanthanum-modified alumina material are directly blended and added to the aluminum sol or zirconium acetate aqueous solution.

[0090] Example 1

[0091] A thermally conductive material for purifying automobile exhaust comprises, by weight, 20% of a low-content lanthanum-modified alumina material, 30% of a high-content lanthanum-modified alumina material, 20% of a rare earth oxygen storage material, 28% of a thermally conductive additive, and 2% of a processing additive.

[0092] The weight ratio of lanthanum oxide in the low-content lanthanum-modified alumina material is not higher than 6%; the weight ratio of lanthanum oxide in the high-content lanthanum-modified alumina material is 6% to 10%. The specific surface area of ​​the high-content lanthanum-modified alumina material after aging at 1100°C for 4 hours is 115m 2 / g.

[0093] The thermal conductive additive includes silicon carbide SiC.

[0094] The thermal conductivity of the thermal conductive additive is not less than 60 W / (m·K).

[0095] The processing aid includes zirconium acetate and polyvinyl alcohol, and the mass ratio is 1:1.

[0096] The rare earth oxygen storage material has a specific surface area of ​​not less than 60m after aging at 1000°C for 4 hours. 2 / g, and the oxygen storage capacity is not less than 200μmol / g.

[0097] The thermal conductive material does not contain Pt, Pd and Rh.

[0098] A catalyst composite coating for automobile exhaust purification comprises a heat-conducting layer 3 and an active reaction layer 4 arranged on the heat-conducting layer 3. The heat-conducting layer 3 adopts the above-mentioned heat-conducting material for automobile exhaust purification.

[0099] The thickness of the heat-conducting layer 3 accounts for 1 / 10 of the thickness of the catalyst composite coating.

[0100] A three-way catalyst for automobile exhaust purification comprises a carrier 1 and the above catalyst composite coating for automobile exhaust purification, wherein a heat conducting layer 3 is provided on the carrier 1. The above carrier 1 is a honeycomb ceramic carrier.

[0101] A method for preparing a three-way catalyst for automobile exhaust purification comprises the following steps:

[0102] 101: 20% of a low-content lanthanum-modified alumina material, 30% of a high-content lanthanum-modified alumina material, 20% of a rare earth oxygen storage material, 28% of a thermal conductive agent, and 2% of a processing aid were added to water and ball-milled for 30 minutes to obtain slurry A.

[0103] 102: coating the slurry A on the carrier 1, drying it, and then performing a first calcination process to obtain the carrier 1 loaded with the heat conducting layer 3;

[0104] Slurry A was dried at 150°C for 1 h.

[0105] The water mentioned above is deionized water.

[0106] The first calcination treatment includes: heating to 550° C. at a heating rate of 5° C. / min and calcining for 2 hours.

[0107] 103: Weighing a precious metal source, loading the precious metal onto the rare earth oxygen storage material and the lanthanum-modified alumina material by an equal pore volume impregnation method according to a specific layering and segmentation strategy, drying, and then performing a second calcination treatment to obtain a precious metal-loaded rare earth oxygen storage material and a lanthanum-modified alumina material;

[0108] After loading the precious metals onto the rare earth oxygen storage material and the lanthanum-modified alumina material, the materials were dried at 150°C for 1 hour.

[0109] The second calcination treatment includes: heating to 30° C. at a heating rate of 200° C. / min and calcining for 2 hours.

[0110] 104: Add the rare earth oxygen storage material loaded with precious metals and the lanthanum-modified alumina material to an aluminum sol or zirconium acetate aqueous solution with a solid content of 5% to a slurry solidified to a concentration of 20%, and then ball mill for 5-30 minutes to obtain slurry B;

[0111] 105: Slurry B is coated on the carrier 1 loaded with the heat-conducting layer 3 to obtain a three-way catalyst.

[0112] Example 2

[0113] A thermally conductive material for purifying automobile exhaust comprises, by weight, 35% of a low-content lanthanum-modified alumina material, 25% of a high-content lanthanum-modified alumina material, 27% of a rare earth oxygen storage material, 10% of a thermal conductive additive, and 3% of a processing additive.

[0114] The weight ratio of lanthanum oxide in the low-content lanthanum-modified alumina material is not higher than 6%; the weight ratio of lanthanum oxide in the high-content lanthanum-modified alumina material is 6% to 10%. The specific surface area of ​​the high-content lanthanum-modified alumina material after aging at 1100°C for 4 hours is 115m 2 / g.

[0115] Thermal conductive additives include silicon carbide SiC, iron powder, chromium powder and aluminum powder.

[0116] The thermal conductivity of the thermal conductive additive is not less than 60 W / (m·K).

[0117] The processing aid includes zirconium acetate and polyvinyl alcohol, and the mass ratio is 1:1.

[0118] The rare earth oxygen storage material has a specific surface area of ​​not less than 60m after aging at 1000°C for 4 hours. 2 / g, and the oxygen storage capacity is not less than 200μmol / g.

[0119] The thermal conductive material does not contain Pt, Pd and Rh.

[0120] A catalyst composite coating for automobile exhaust purification comprises a heat-conducting layer 3 and an active reaction layer 4 arranged on the heat-conducting layer 3. The heat-conducting layer 3 adopts the above-mentioned heat-conducting material for automobile exhaust purification.

[0121] The thickness of the heat-conducting layer 3 accounts for 1 / 4 of the thickness of the catalyst composite coating.

[0122] A three-way catalyst for automobile exhaust purification comprises a carrier 1 and the above catalyst composite coating for automobile exhaust purification, wherein a heat conducting layer 3 is provided on the carrier 1. The above carrier 1 is a honeycomb ceramic carrier.

[0123] A method for preparing a three-way catalyst for automobile exhaust purification comprises the following steps:

[0124] 101: 35% of a low-content lanthanum-modified alumina material, 25% of a high-content lanthanum-modified alumina material, 27% of a rare earth oxygen storage material, 10% of a thermal conductive agent, and 3% of a processing aid were added to water and ball-milled for 30 minutes to obtain slurry A.

[0125] 102: coating the slurry A on the carrier 1, drying it, and then performing a first calcination process to obtain the carrier 1 loaded with the heat conducting layer 3;

[0126] Slurry A was dried at 150°C for 1 h.

[0127] The water mentioned above is deionized water.

[0128] The first calcination treatment includes: heating to 550° C. at a heating rate of 5° C. / min and calcining for 2 hours.

[0129] 103: Weighing a precious metal source, loading the precious metal onto the rare earth oxygen storage material and the lanthanum-modified alumina material by an equal pore volume impregnation method according to a specific layering and segmentation strategy, drying, and then performing a second calcination treatment to obtain a precious metal-loaded rare earth oxygen storage material and a lanthanum-modified alumina material;

[0130] After loading the precious metals onto the rare earth oxygen storage material and the lanthanum-modified alumina material, the materials were dried at 150°C for 1 hour.

[0131] The second calcination treatment includes: heating to 30° C. at a heating rate of 200° C. / min and calcining for 2 hours.

[0132] 104: Add the rare earth oxygen storage material loaded with precious metals and the lanthanum-modified alumina material to an aluminum sol or zirconium acetate aqueous solution with a solid content of 5% to a slurry solidified to a concentration of 20%, and then ball mill for 5-30 minutes to obtain slurry B;

[0133] 105: Slurry B is coated on the carrier 1 loaded with the heat-conducting layer 3 to obtain a three-way catalyst.

[0134] Example 3

[0135] A thermally conductive material for purifying automobile exhaust comprises, by weight, 35% of a low-content lanthanum-modified alumina material, 25% of a high-content lanthanum-modified alumina material, 27% of a rare earth oxygen storage material, 10% of a thermal conductive additive, and 3% of a processing additive.

[0136] The weight ratio of lanthanum oxide in the low-content lanthanum-modified alumina material is not higher than 6%; the weight ratio of lanthanum oxide in the high-content lanthanum-modified alumina material is 6% to 10%. The specific surface area of ​​the high-content lanthanum-modified alumina material after aging at 1100°C for 4 hours is 115m 2 / g.

[0137] Thermal conductive additives include silicon carbide SiC, iron powder, chromium powder and aluminum powder.

[0138] The thermal conductivity of the thermal conductive additive is not less than 60 W / (m·K).

[0139] Processing aids include polyvinyl alcohol.

[0140] The rare earth oxygen storage material has a specific surface area of ​​not less than 60m after aging at 1000°C for 4 hours. 2 / g, and the oxygen storage capacity is not less than 200μmol / g.

[0141] The thermal conductive material does not contain Pt, Pd and Rh.

[0142] A catalyst composite coating for automobile exhaust purification comprises a heat-conducting layer 3 and an active reaction layer 4 arranged on the heat-conducting layer 3. The heat-conducting layer 3 adopts the above-mentioned heat-conducting material for automobile exhaust purification.

[0143] The thickness of the heat-conducting layer 3 accounts for 1 / 4 of the thickness of the catalyst composite coating.

[0144] A three-way catalyst for automobile exhaust purification comprises a carrier 1 and the above catalyst composite coating for automobile exhaust purification, wherein a heat conducting layer 3 is provided on the carrier 1. The above carrier 1 is a honeycomb ceramic carrier.

[0145] A method for preparing a three-way catalyst for automobile exhaust purification comprises the following steps:

[0146] 101: 35% of a low-content lanthanum-modified alumina material, 25% of a high-content lanthanum-modified alumina material, 27% of a rare earth oxygen storage material, 10% of a thermal conductive agent, and 3% of a processing aid were added to water and ball-milled for 30 minutes to obtain slurry A.

[0147] 102: coating the slurry A on the carrier 1, drying it, and then performing a first calcination process to obtain the carrier 1 loaded with the heat conducting layer 3;

[0148] Slurry A was dried at 150°C for 1 h.

[0149] The water mentioned above is deionized water.

[0150] The first calcination treatment includes: heating to 550° C. at a heating rate of 5° C. / min and calcining for 2 hours.

[0151] 103: Weighing a precious metal source, loading the precious metal onto the rare earth oxygen storage material and the lanthanum-modified alumina material by an equal pore volume impregnation method according to a specific layering and segmentation strategy, drying, and then performing a second calcination treatment to obtain a precious metal-loaded rare earth oxygen storage material and a lanthanum-modified alumina material;

[0152] After loading the precious metals onto the rare earth oxygen storage material and the lanthanum-modified alumina material, the materials were dried at 150°C for 1 hour.

[0153] The second calcination treatment includes: heating to 30° C. at a heating rate of 200° C. / min and calcining for 2 hours.

[0154] 104: Add the rare earth oxygen storage material loaded with precious metals and the lanthanum-modified alumina material to an aluminum sol or zirconium acetate aqueous solution with a solid content of 5% to a slurry solidified to a concentration of 20%, and then ball mill for 5-30 minutes to obtain slurry B;

[0155] 105: Slurry B is coated on the carrier 1 loaded with the heat-conducting layer 3 to obtain a three-way catalyst.

[0156] Example 4

[0157] A thermally conductive material for purifying automobile exhaust comprises, by weight, 35% of a low-content lanthanum-modified alumina material, 25% of a high-content lanthanum-modified alumina material, 27% of a rare earth oxygen storage material, 10% of a thermal conductive additive, and 3% of a processing additive.

[0158] The weight ratio of lanthanum oxide in the low-content lanthanum-modified alumina material is not higher than 6%; the weight ratio of lanthanum oxide in the high-content lanthanum-modified alumina material is 6% to 10%. The specific surface area of ​​the high-content lanthanum-modified alumina material after aging at 1100°C for 4 hours is 130m 2 / g.

[0159] Thermal conductive additives include silicon carbide SiC, iron powder, chromium powder and aluminum powder.

[0160] The thermal conductivity of the thermal conductive additive is not less than 60 W / (m·K).

[0161] The processing aid includes zirconium acetate and polyvinyl alcohol, and the mass ratio is 1:1.

[0162] The rare earth oxygen storage material has a specific surface area of ​​not less than 60m after aging at 1000°C for 4 hours. 2 / g, and the oxygen storage capacity is not less than 200μmol / g.

[0163] The thermal conductive material does not contain Pt, Pd and Rh.

[0164] A catalyst composite coating for automobile exhaust purification comprises a heat-conducting layer 3 and an active reaction layer 4 arranged on the heat-conducting layer 3. The heat-conducting layer 3 adopts the above-mentioned heat-conducting material for automobile exhaust purification.

[0165] The thickness of the heat-conducting layer 3 accounts for 1 / 4 of the thickness of the catalyst composite coating.

[0166] A three-way catalyst for automobile exhaust purification comprises a carrier 1 and the above catalyst composite coating for automobile exhaust purification, wherein a heat conducting layer 3 is provided on the carrier 1. The above carrier 1 is a honeycomb ceramic carrier.

[0167] A method for preparing a three-way catalyst for automobile exhaust purification comprises the following steps:

[0168] 101: 35% of a low-content lanthanum-modified alumina material, 25% of a high-content lanthanum-modified alumina material, 27% of a rare earth oxygen storage material, 10% of a thermal conductive agent, and 3% of a processing aid were added to water and ball-milled for 30 minutes to obtain slurry A.

[0169] 102: coating the slurry A on the carrier 1, drying it, and then performing a first calcination process to obtain the carrier 1 loaded with the heat conducting layer 3;

[0170] Slurry A was dried at 150°C for 1 h.

[0171] The water mentioned above is deionized water.

[0172] The first calcination treatment includes: heating to 550° C. at a heating rate of 5° C. / min and calcining for 2 hours.

[0173] 103: Weighing a precious metal source, loading the precious metal onto the rare earth oxygen storage material and the lanthanum-modified alumina material by an equal pore volume impregnation method according to a specific layering and segmentation strategy, drying, and then performing a second calcination treatment to obtain a precious metal-loaded rare earth oxygen storage material and a lanthanum-modified alumina material;

[0174] After loading the precious metals onto the rare earth oxygen storage material and the lanthanum-modified alumina material, the materials were dried at 150°C for 1 hour.

[0175] The second calcination treatment includes: heating to 30° C. at a heating rate of 200° C. / min and calcining for 2 hours.

[0176] 104: Add the rare earth oxygen storage material loaded with precious metals and the lanthanum-modified alumina material to an aluminum sol or zirconium acetate aqueous solution with a solid content of 5% to a slurry solidified to a concentration of 20%, and then ball mill for 5-30 minutes to obtain slurry B;

[0177] 105: Slurry B is coated on the carrier 1 loaded with the heat-conducting layer 3 to obtain a three-way catalyst.

[0178] Example 5

[0179] A thermally conductive material for purifying automobile exhaust comprises, by weight, 44% of a low-content lanthanum-modified alumina material, 20% of a high-content lanthanum-modified alumina material, 30% of a rare earth oxygen storage material, 5% of a thermal conductive additive, and 1% of a processing aid.

[0180] The weight ratio of lanthanum oxide in the low-content lanthanum-modified alumina material is not higher than 6%; the weight ratio of lanthanum oxide in the high-content lanthanum-modified alumina material is 6% to 10%. The specific surface area of ​​the high-content lanthanum-modified alumina material after aging at 1100°C for 4 hours is 115m 2 / g.

[0181] Thermal conductive additives include silicon carbide SiC, iron powder, chromium powder and aluminum powder.

[0182] The thermal conductivity of the thermal conductive additive is not less than 60 W / (m·K).

[0183] The processing aid includes zirconium acetate and polyvinyl alcohol, and the mass ratio is 1:1.

[0184] The rare earth oxygen storage material has a specific surface area of ​​not less than 60m after aging at 1000°C for 4 hours. 2 / g, and the oxygen storage capacity is not less than 200μmol / g.

[0185] The thermal conductive material does not contain Pt, Pd and Rh.

[0186] A catalyst composite coating for automobile exhaust purification comprises a heat-conducting layer 3 and an active reaction layer 4 arranged on the heat-conducting layer 3. The heat-conducting layer 3 adopts the above-mentioned heat-conducting material for automobile exhaust purification.

[0187] The thickness of the heat-conducting layer 3 accounts for 1 / 4 of the thickness of the catalyst composite coating.

[0188] A three-way catalyst for automobile exhaust purification comprises a carrier 1 and the above catalyst composite coating for automobile exhaust purification, wherein a heat conducting layer 3 is provided on the carrier 1. The above carrier 1 is a honeycomb ceramic carrier.

[0189] A method for preparing a three-way catalyst for automobile exhaust purification comprises the following steps:

[0190] 101: 44% of a low-content lanthanum-modified alumina material, 20% of a high-content lanthanum-modified alumina material, 30% of a rare earth oxygen storage material, 5% of a thermal conductive agent, and 1% of a processing aid were added to water and ball-milled for 30 minutes to obtain slurry A.

[0191] 102: coating the slurry A on the carrier 1, drying it, and then performing a first calcination process to obtain the carrier 1 loaded with the heat conducting layer 3;

[0192] Slurry A was dried at 150°C for 1 h.

[0193] The water mentioned above is deionized water.

[0194] The first calcination treatment includes: heating to 550° C. at a heating rate of 5° C. / min and calcining for 2 hours.

[0195] 103: Weighing a precious metal source, loading the precious metal onto the rare earth oxygen storage material and the lanthanum-modified alumina material by an equal pore volume impregnation method according to a specific layering and segmentation strategy, drying, and then performing a second calcination treatment to obtain a precious metal-loaded rare earth oxygen storage material and a lanthanum-modified alumina material;

[0196] After loading the precious metals onto the rare earth oxygen storage material and the lanthanum-modified alumina material, the materials were dried at 150°C for 1 hour.

[0197] The second calcination treatment includes: heating to 30° C. at a heating rate of 200° C. / min and calcining for 2 hours.

[0198] 104: Add the rare earth oxygen storage material loaded with precious metals and the lanthanum-modified alumina material to an aluminum sol or zirconium acetate aqueous solution with a solid content of 5% to a slurry solidified to a concentration of 20%, and then ball mill for 5-30 minutes to obtain slurry B;

[0199] 105: Slurry B is coated on the carrier 1 loaded with the heat-conducting layer 3 to obtain a three-way catalyst.

[0200] Table 1

[0201]

[0202]

[0203] Among them, Al2O3-1 in Table 1 is an alumina material modified with a low content of lanthanum, and Al2O3-2 is an alumina material modified with a low content of lanthanum.

[0204] Comparative Example 1

[0205] A thermal conductive material for purifying automobile exhaust comprises, by weight, 60% of a low-content lanthanum-modified alumina material, 27% of a rare earth oxygen storage material, 10% of a thermal conductive additive, and 3% of a processing additive.

[0206] The weight ratio of lanthanum oxide in the low-content lanthanum-modified alumina material is not higher than 6%.

[0207] Thermal conductive additives include silicon carbide SiC, iron powder, chromium powder and aluminum powder.

[0208] The thermal conductivity of the thermal conductive additive is not less than 60 W / (m·K).

[0209] The processing aid includes zirconium acetate and polyvinyl alcohol, and the mass ratio is 1:1.

[0210] The rare earth oxygen storage material has a specific surface area of ​​not less than 60m after aging at 1000°C for 4 hours. 2 / g, and the oxygen storage capacity is not less than 200μmol / g.

[0211] The thermal conductive material does not contain Pt, Pd and Rh.

[0212] A catalyst composite coating for automobile exhaust purification comprises a heat-conducting layer 3 and an active reaction layer 4 arranged on the heat-conducting layer 3. The heat-conducting layer 3 adopts the above-mentioned heat-conducting material for automobile exhaust purification.

[0213] The thickness of the heat-conducting layer 3 accounts for 1 / 4 of the thickness of the catalyst composite coating.

[0214] A three-way catalyst for automobile exhaust purification comprises a carrier 1 and the above catalyst composite coating for automobile exhaust purification, wherein a heat conducting layer 3 is provided on the carrier 1. The above carrier 1 is a honeycomb ceramic carrier.

[0215] A method for preparing a three-way catalyst for automobile exhaust purification comprises the following steps:

[0216] 101: 60% of a low-content lanthanum-modified alumina material, 27% of a rare earth oxygen storage material, 10% of a thermal conductive agent, and 3% of a processing aid were added to water and ball-milled for 30 minutes to obtain slurry A.

[0217] 102: coating the slurry A on the carrier 1, drying it, and then performing a first calcination process to obtain the carrier 1 loaded with the heat conducting layer 3;

[0218] Slurry A was dried at 150°C for 1 h.

[0219] The water mentioned above is deionized water.

[0220] The first calcination treatment includes: heating to 550° C. at a heating rate of 5° C. / min and calcining for 2 hours.

[0221] 103: Weighing a precious metal source, loading the precious metal onto the rare earth oxygen storage material and the lanthanum-modified alumina material by an equal pore volume impregnation method according to a specific layering and segmentation strategy, drying, and then performing a second calcination treatment to obtain a precious metal-loaded rare earth oxygen storage material and a lanthanum-modified alumina material;

[0222] After loading the precious metals onto the rare earth oxygen storage material and the lanthanum-modified alumina material, the materials were dried at 150°C for 1 hour.

[0223] The second calcination treatment includes: heating to 30° C. at a heating rate of 200° C. / min and calcining for 2 hours.

[0224] 104: Add the rare earth oxygen storage material loaded with precious metals and the lanthanum-modified alumina material to an aluminum sol or zirconium acetate aqueous solution with a solid content of 5% to a slurry solidified to a concentration of 20%, and then ball mill for 5-30 minutes to obtain slurry B;

[0225] 105: Slurry B is coated on the carrier 1 loaded with the heat-conducting layer 3 to obtain a three-way catalyst.

[0226] Comparative Example 2

[0227] A thermally conductive material for purifying automobile exhaust comprises, by weight, 35% of a low-content lanthanum-modified alumina material, 25% of a high-content lanthanum-modified alumina material, 27% of a rare earth oxygen storage material, 10% of a thermal conductive additive, and 3% of a processing additive.

[0228] The weight ratio of lanthanum oxide in the low-content lanthanum-modified alumina material is not higher than 6%; the weight ratio of lanthanum oxide in the high-content lanthanum-modified alumina material is 6% to 10%. The specific surface area of ​​the high-content lanthanum-modified alumina material after aging at 1100°C for 4 hours is 90m 2 / g.

[0229] Thermal conductive additives include silicon carbide SiC, iron powder, chromium powder and aluminum powder.

[0230] The thermal conductivity of the thermal conductive additive is not less than 60 W / (m·K).

[0231] The processing aid includes zirconium acetate and polyvinyl alcohol, and the mass ratio is 1:1.

[0232] The rare earth oxygen storage material has a specific surface area of ​​not less than 50m after aging at 1000°C for 4 hours. 2 / g, and the oxygen storage capacity is 150μmol / g.

[0233] The thermal conductive material does not contain Pt, Pd and Rh.

[0234] A catalyst composite coating for automobile exhaust purification comprises a heat-conducting layer 3 and an active reaction layer 4 arranged on the heat-conducting layer 3. The heat-conducting layer 3 adopts the above-mentioned heat-conducting material for automobile exhaust purification.

[0235] The thickness of the heat-conducting layer 3 accounts for 1 / 4 of the thickness of the catalyst composite coating.

[0236] A three-way catalyst for automobile exhaust purification comprises a carrier 1 and the above catalyst composite coating for automobile exhaust purification, wherein a heat conducting layer 3 is provided on the carrier 1. The above carrier 1 is a honeycomb ceramic carrier.

[0237] A method for preparing a three-way catalyst for automobile exhaust purification comprises the following steps:

[0238] 101: 35% of a low-content lanthanum-modified alumina material, 25% of a high-content lanthanum-modified alumina material, 27% of a rare earth oxygen storage material, 10% of a thermal conductive agent, and 3% of a processing aid were added to water and ball-milled for 30 minutes to obtain slurry A.

[0239] 102: coating the slurry A on the carrier 1, drying it, and then performing a first calcination process to obtain the carrier 1 loaded with the heat conducting layer 3;

[0240] Slurry A was dried at 150°C for 1 h.

[0241] The water mentioned above is deionized water.

[0242] The first calcination treatment includes: heating to 550° C. at a heating rate of 5° C. / min and calcining for 2 hours.

[0243] 103: Weighing a precious metal source, loading the precious metal onto the rare earth oxygen storage material and the lanthanum-modified alumina material by an equal pore volume impregnation method according to a specific layering and segmentation strategy, drying, and then performing a second calcination treatment to obtain a precious metal-loaded rare earth oxygen storage material and a lanthanum-modified alumina material;

[0244] After loading the precious metals onto the rare earth oxygen storage material and the lanthanum-modified alumina material, the materials were dried at 150°C for 1 hour.

[0245] The second calcination treatment includes: heating to 30° C. at a heating rate of 200° C. / min and calcining for 2 hours.

[0246] 104: Add the rare earth oxygen storage material loaded with precious metals and the lanthanum-modified alumina material to an aluminum sol or zirconium acetate aqueous solution with a solid content of 5% to a slurry solidified to a concentration of 20%, and then ball mill for 5-30 minutes to obtain slurry B;

[0247] 105: Slurry B is coated on the carrier 1 loaded with the heat-conducting layer 3 to obtain a three-way catalyst.

[0248] Comparative Example 3

[0249] Compared to Example 2, no heat conducting layer is provided.

[0250] The above embodiments and comparative examples were tested for ignition temperature and coating shedding rate, wherein the ignition temperature is the temperature at which the conversion rate of hydrocarbons THC, CO, and NOx reaches 50%.

[0251] Coating peeling rate test

[0252] This application uses ultrasonic vibration and thermal shock methods to measure the coating's firmness. The average of the shedding rates obtained by the two methods is used as the final coating shedding rate. Shedding rate = (mass after coating - mass after testing) / (mass after coating - mass before coating) × 100%

[0253] (1) Ultrasonic vibration

[0254] The sample coated with the three-way catalyst coating material was placed in a sealed container filled with petroleum ether, and then the container was placed in an ultrasonic cleaner for 30 minutes. The sample was then taken out and dried, and the mass of the sample was weighed and the shedding rate was calculated.

[0255] (2) Thermal shock

[0256] Place the sample coated with the three-way catalyst coating material in a muffle furnace at 1000°C for 20 minutes, take out the sample and quickly immerse it in cold water at 0-10°C, then subject the sample to ultrasonic treatment to promote the separation of the detached material (the action time is not longer than 1 minute), repeat this operation several times until the mass no longer decreases, weigh the mass of the sample and calculate the shedding rate.

[0257] The test results are shown in Tables 2 and 3 below.

[0258] Table 2: Ignition Temperature

[0259] pollutants Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 THC 270 261 267 255 259 313 308 340 CO 269 261 264 254 259 310 300 330 <![CDATA[NO X ]]> 259 255 258 250 253 307 298 322

[0260] Table 3 Coating shedding rate

[0261] Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 1.2％ 1.4％ 2.2％ 1.6％ 1.3％ 1.5％ 1.4％ 1.5％

[0262] It can be seen from the data in Table 2 and Table 3 that the catalyst prepared in the present application has a very low ignition temperature and a relatively low coating shedding rate.

[0263] Comparing Example 2 and Example 3, it can be seen that the use of a two-component processing aid can reduce the coating shedding rate. Zirconium acetate and polyvinyl alcohol themselves have high viscosity and both have the effect of improving coating adhesion. One of them is a small molecule and the other is a polymer. The zirconium acetate small molecule mainly relies on high-valent ion solvation to increase the viscosity of the coating slurry, while polyvinyl alcohol can increase the viscosity of the slurry itself. The hydroxyl groups on it can form a coating on the solute, and the long chain structure of the polymer forms a network structure, stabilizing the slurry composition. After baking, it forms good adhesion to the ceramic carrier. The two effects synergistically can improve the anti-shedding performance.

[0264] Comparing Examples 2 and 4, it can be seen that increasing the specific surface area of ​​Al2O3-2 can further improve the thermal conductivity of the coating and reduce the ignition temperature. This is because it provides mechanical support for the thermal conductive additive at the microscopic level, reduces the agglomeration of the thermal conductive additive, and forms a thermal conductive path.

[0265] Comparison of Example 2 and Comparative Example 1 shows that the addition of a certain amount of alumina material modified with a high content of lanthanum helps the thermal conductive material to perform its thermal conductivity without affecting the chemical reaction of the active reaction layer.

[0266] It can be seen from Comparative Examples 1-3 that only by setting the heat-conducting layer described in this application and complying with the parameter range proposed in this application can a better ignition effect be obtained to cope with the frequent ignition of hybrid models.

[0267] In the description of this application, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 a direct connection, or an indirect connection through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0268] It should be noted that, in this application, relational terms such as "first" and "second" are used only 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 "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0269] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A thermally conductive material for automobile exhaust purification, characterized by: By weight, the thermal conductive material comprises 20-50% of a low-content lanthanum-modified alumina material, 20-30% of a high-content lanthanum-modified alumina material, 10-30% of a rare earth oxygen storage material, 5-30% of a thermal conductive additive, and 0.1-5% of a processing aid; The weight ratio of lanthanum oxide in the low-content lanthanum-modified alumina material is not higher than 6%; the weight ratio of lanthanum oxide in the high-content lanthanum-modified alumina material is 6% to 10%. The weight ratio of lanthanum oxide in the low-content lanthanum-modified alumina material and the weight ratio of lanthanum oxide in the high-content lanthanum-modified alumina material are different from each other and are both 6%; The thermal conductivity of the thermal conductive additive is not less than 60W / (m·K); The processing aid is used to disperse the components of the thermal conductive material and to increase the adhesion between the thermal conductive material and the carrier.

2. The thermally conductive material for automobile exhaust purification according to claim 1, wherein: The rare earth oxygen storage material includes cerium oxide and zirconium oxide.

3. The thermally conductive material for automobile exhaust purification according to claim 2, wherein: The rare earth oxygen storage material further comprises one or more of lanthanum oxide, yttrium oxide, niobium oxide, praseodymium oxide, neodymium oxide, magnesium oxide, barium oxide, erbium oxide, rubidium oxide and aluminum oxide.

4. The thermally conductive material for automobile exhaust purification according to claim 1, wherein: The lanthanum-modified alumina material includes aluminum oxide and lanthanum oxide, and one or more selected from the group consisting of neodymium oxide, magnesium oxide, barium oxide, silicon dioxide, and calcium oxide.

5. The thermally conductive material for automobile exhaust purification according to claim 1, wherein: The thermal conductive additive includes one or more of boron nitride BN, silicon carbide SiC, and metal powder.

6. The thermally conductive material for automobile exhaust purification according to claim 1, wherein: The processing aid includes one or more of zirconium acetate, pseudo-boehmite, polyvinyl alcohol, and polyethylene glycol.

7. The thermally conductive material for purifying automobile exhaust gas according to claim 1, wherein: The specific surface area of ​​the high-content lanthanum-modified alumina material after aging at 1100℃ for 4 hours is not less than 110m 2 / g.

8. The thermally conductive material for purifying automobile exhaust gas according to claim 1, wherein: The rare earth oxygen storage material has a specific surface area of ​​not less than 60m after aging at 1000°C for 4 hours. 2 / g, and the oxygen storage capacity is not less than 200μmol / g.

9. A catalyst composite coating for automobile exhaust purification, characterized in that: It includes: A heat-conducting layer (3) and an active reaction layer (4) provided on the heat-conducting layer (3), wherein the heat-conducting layer (3) is made of the heat-conducting material for automobile exhaust purification according to any one of claims 1 to 8.

10. The catalyst composite coating according to claim 9, characterized in that: The active reaction layer (4) contains at least one noble metal selected from the group consisting of Pt, Pd, and Rh, as well as a rare earth oxygen storage material and a lanthanum-modified aluminum oxide material.

11. The catalyst composite coating according to claim 9, characterized in that: The thickness of the heat-conducting layer (3) accounts for 1 / 10 to 1 / 3 of the thickness of the catalyst composite coating.

12. A three-way catalyst for automobile exhaust purification, characterized in that: It comprises a carrier (1) and a catalyst composite coating for automobile exhaust purification according to any one of claims 9 to 11, wherein the heat-conducting layer (3) is provided on the carrier (1).

13. A method for preparing a three-way catalyst for automobile exhaust purification according to claim 12, characterized in that: It includes the following steps: Adding a low-content lanthanum-modified alumina material, a high-content lanthanum-modified alumina material, a rare earth oxygen storage material, a thermal conductive additive, and a processing aid into water, and stirring uniformly to obtain slurry A; The slurry A is coated on the carrier (1), dried, and then subjected to a first calcination treatment to obtain the carrier (1) loaded with the heat-conducting layer (3); Weighing a precious metal source, loading the precious metal onto the rare earth oxygen storage material and the lanthanum-modified alumina material by an equal pore volume impregnation method, drying, and then performing a second calcination treatment to obtain a precious metal-loaded rare earth oxygen storage material and a lanthanum-modified alumina material; Adding a rare earth oxygen storage material loaded with noble metals and a lanthanum-modified alumina material to an aluminum sol or zirconium acetate aqueous solution with a solid content of 1-5%, and then ball milling to obtain slurry B; The slurry B is coated on a carrier (1) loaded with a heat-conducting layer (3) to obtain a three-way catalyst for purifying automobile exhaust gas.

14. The method for preparing a three-way catalyst for purifying automobile exhaust gas according to claim 13, wherein: Slurry A is dried at 100-200°C for 0.5-2h; The first calcination treatment includes: heating to 500-600° C. at a heating rate of 0.5-10° C. / min and calcining for 1-4 hours.

15. The method for preparing a three-way catalyst for purifying automobile exhaust gas according to claim 13, wherein: After loading the precious metal onto the rare earth oxygen storage material and the lanthanum-modified alumina material, drying at 100-200°C for 0.2-2h; The second calcination treatment includes: heating to 200-400° C. at a heating rate of 5-30° C. / min and calcining for 1-3 hours.

16. The method for preparing a three-way catalyst for purifying automobile exhaust gas according to claim 13, wherein: The noble metal source includes one or more of palladium nitrate, platinum nitrate and rhodium nitrate.

17. The method for preparing a three-way catalyst for purifying automobile exhaust gas according to claim 13, wherein: When the precious metal is Pd, the Pd loading is 5 to 300 g / ft 3 Weigh the precious metal source; When the precious metal is Pt, the Pt loading is between 0 and 100 g / ft. 3 Weigh the precious metal source; When the precious metal is Rh, the Rh loading is 0.1 to 50 g / ft 3 Weigh the precious metal source.

18. The method for preparing a three-way catalyst for purifying automobile exhaust gas according to claim 13, wherein: When rare earth oxygen storage materials loaded with precious metals and lanthanum-modified alumina materials are added to aluminum sol or zirconium acetate aqueous solution with a solid content of 1-5%, the amount of slurry solids is made to be 10-30%.

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