WO2023151688A1 - Catalyst for loading noble metal on grain boundary and surface, preparation method therefor, and use thereof - Google Patents

Abstract

The present invention relates to a catalyst for loading a noble metal on a grain boundary and a surface, a preparation method therefor, and the use thereof. The catalyst is used to load a noble metal on a grain boundary and a surface of an active coating containing aluminum oxide and/or a cerium-zirconium composite oxide, thereby improving the anchoring effect of the noble metal, avoiding the migration, agglomeration and growth of noble-metal particles, maintaining the catalytic activity and high-temperature stability performance of a noble-metal catalyst, and reducing the amount of noble metal used.

Description

A kind of catalyst of grain boundary and surface loading noble metal and its preparation method and application

cross reference

This application is based on a Chinese patent application with application number 202210135425.8 and a filing date of February 14, 2022, and claims the priority of this Chinese patent application. The entire content of this Chinese patent application is hereby incorporated by reference into this application.

technical field

The invention relates to the technical field of noble metal catalysts, in particular to a catalyst loaded with noble metals on grain boundaries and surfaces, as well as its preparation method and application.

Background technique

According to the research, with the increase of global car ownership year by year, automobile exhaust pollution has become the primary source of urban air pollution, and the environmental problems caused by automobile exhaust emissions are becoming increasingly serious. Automobile exhaust catalytic converter is an effective solution for automobile exhaust purification, and its core is a three-way catalyst loaded with precious metals. Usually, the three-way catalyst for automobile exhaust gas is composed of honeycomb carrier, precious metal, active coating, etc., and its service life is mainly determined by the active coating material and preparation process of the three-way catalyst. The active coating material includes cerium-zirconium composite oxide and Alumina, etc., precious metals are loaded on the active coating. Due to the harsh environment of automobile exhaust three-way catalysts in practical applications, it not only contains water vapor, but also has a high temperature, sometimes reaching above 900 ° C, which requires catalysts, coating materials and precious metals to have high temperature stability. Therefore, in order to ensure the conversion efficiency of automobile exhaust catalysts and maintain the catalytic activity of cerium-zirconium composite oxide-supported noble metal catalysts, it is necessary to prevent high-temperature aging of coating materials containing cerium-zirconium-supported noble metals in high-temperature environments: on the one hand, try to prevent Cerium-zirconium is sintered at high temperature. On the other hand, noble metal particles should be prevented from migrating, agglomerating, growing up or being wrapped by cerium-zirconium, alumina and other coating materials at high temperature to reduce or lose their catalytic activity. Oxidative catalysts such as catalytic combustion of natural gas and organic waste gas treatment also require noble metal catalysts to have high high temperature stability.

Contents of the invention

Based on the above-mentioned situation of prior art, the object of the present invention is to provide a kind of catalyst of grain boundary and surface loading precious metal and its preparation method and application, by precious metal being dispersed in the grain boundary of alumina and/or cerium-zirconium composite oxide and The surface is used to prevent or slow down the diffusion of elements between the grains and the surface, inhibit the migration, agglomeration and growth of noble metal particles at high temperatures, and make a more high-temperature-resistant and stable cerium-zirconium-based noble metal catalyst; it will be prepared as above The alumina and/or cerium-zirconium composite oxide grain boundaries and surface-supported noble metal catalysts are used for the preparation of honeycomb-type noble metal catalyst slurry, and then the slurry is coated on the honeycomb to make a honeycomb-type noble metal catalyst, thereby effectively improving the honeycomb type. The high temperature resistance and stability of the type noble metal catalyst can maintain the catalytic activity of the catalyst under high temperature and long-term use conditions, and reduce the amount of noble metal.

In order to achieve the above object, according to the first aspect of the present invention, there is provided a grain boundary and surface-loaded noble metal catalyst, the catalyst includes noble metal G, alumina and/or cerium-zirconium composite oxide, and the noble metal G is dispersed At the grain boundaries and surfaces of alumina and/or cerium-zirconium composite oxides, the general chemical formula of cerium-zirconium composite oxides is C _{x Zry} M _z O _2-α D _δ ; where,

M is a cation doping element, and D is an anion doping element;

0≤x≤1, 0≤y≤1, 0≤z<0.5, and x, y, z satisfy x+y+z=1;

0≤α≤0.1; 0≤δ≤0.1.

According to the second aspect of the present invention, a kind of honeycomb type noble metal catalyst is provided, and described catalyst comprises honeycomb carrier, noble metal G and active coat, active coat contains alumina and/or cerium-zirconium composite oxide C _{x Zry} M _z O _2-α D _δ ; the noble metal G is dispersed at the grain boundaries and surfaces of alumina and/or cerium-zirconium composite oxides; wherein,

M is a cation doping element, and D is an anion doping element;

0≤x≤1, 0≤y≤1, 0≤z<0.5, and x, y, z satisfy x+y+z=1; 0≤α≤0.1; 0≤δ≤0.1.

Further, the percentage of the cerium-zirconium composite oxide in the total mass of the active coating is 0-100%, preferably 30-70%.

Further, the noble metal G at the grain boundaries and surfaces is in a metallic state, or a metallic state and an oxidized state.

Further, the noble metal G includes a combination of one or more of Pt, Pd, Rh, Ir, Os, Ru, Au and Ag, preferably one or more of Pt, Pd, Rh and Ru The combination.

Further, the doping element M is one or more combinations of non-cerium rare earth elements, transition metal elements other than zirconium and rare earth elements, alkaline earth metal elements, Al, Si, Ga, Sn, Bi, Cerium rare earth elements include La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, preferably La, Pr, Nd, Sm, Eu, Gd, Tm, Yb, Y; transition metal elements include Sc, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo, Hf, Ta, W, preferably Ti, Mn, Fe, Co, Ni, Cu, Nb, Hf, W, Mo; alkaline earth metal elements include Be, Mg, Ca, Sr, Ba, preferably Mg, Sr, Ba; the doping element D includes one or more of anions N, F, and P combination.

Further, the cerium-zirconium composite oxide in the catalyst contains a core-shell structure, the core contains rare earth and zirconium elements, and the content of yttrium oxide in the shell is higher than that of the overall yttrium oxide in the composite oxide. According to the difference between the surface energy of elements and the formation energy of oxygen vacancies calculated in theory, the present invention designs the types and contents of elements in the outer shell or/and inner core, and comprehensively improves the thermal stability and oxygen storage and release performance of the cerium-zirconium composite oxide.

Further, the cerium-zirconium composite oxide in the catalyst contains cerium-zirconium oxide with a gradient element distribution structure. According to the difference between element surface energy and oxygen vacancy formation energy calculated in theory, the present invention designs the types and contents of elements in the gradient structure, so that the content of specific elements in the grain radial direction gradually increases or decreases from the inside to the outside, and comprehensively improves the cerium-zirconium composite. Thermal stability and oxygen storage and release properties of oxides.

Further, the material of the honeycomb carrier is porous ceramic or metal.

Further, the loading amount of noble metal G in the catalyst is 0.01%-3%, preferably 0.1%-2%.

Further, the loading amount of noble metal G in the catalyst is 0.01-2.8 g/L, preferably 0.1-2 g/L.

According to a third aspect of the present invention, there is provided a method for preparing a catalyst of a grain boundary and a surface loaded noble metal as described in the first aspect of the present invention, comprising the following steps:

S1, uniformly mixing the cerium-zirconium composite oxide and/or activated alumina with the liquid salt of noble metal G;

S2. Carrying out one or two heat treatments to the product obtained in step S1;

S3. Carrying out one or two reduction calcinations on the product obtained in step S2 under air or a reducing atmosphere to obtain cerium-zirconium composite oxide and/or active alumina grain boundaries and a catalyst loaded with precious metals on the surface.

According to a fourth aspect of the present invention, there is provided a method for preparing a honeycomb-type noble metal catalyst as described in the second aspect of the present invention, the honeycomb-type noble metal catalyst is layered or partitioned and coated with one or more coatings Material, the coating material is cerium-zirconium composite oxide, alumina, grain boundary and surface of cerium-zirconium composite oxide loaded with precious metals, grain boundary and surface of alumina loaded with noble metal, grains of cerium-zirconium composite oxide and alumina The mixture of boundary and surface loading noble metal, the preparation of described honeycomb type noble metal catalyst comprises the following steps:

B1, mixing the coating material with adhesive, acidity regulator and water in one or more steps to make a coating slurry;

B2, coating the coating slurry obtained in step B1 on the honeycomb carrier in one or more steps, or coating the honeycomb carrier in partitions or layers, and drying;

B3, heat-treating or/and roasting the product obtained in step B2 in air or a reducing atmosphere to obtain a noble metal honeycomb catalyst.

According to a fifth aspect of the present invention, there is provided a method for preparing a honeycomb-type noble metal catalyst as described in the second aspect of the present invention, wherein the cerium-zirconium composite oxide and/or alumina, liquid salt of noble metal, and binder , acidity regulator and water are mixed uniformly in one or more steps to make a coating slurry; the obtained product is coated on the honeycomb carrier through one or more steps, or coated on the honeycomb carrier in partitions or layers, and carried out Drying; the dried honeycomb carrier is subjected to heat treatment or/and reduction roasting in a reducing atmosphere to obtain a honeycomb type noble metal catalyst.

Further, the heat treatment temperature is 200-800°C, and the heat treatment time is 0.5-24h; preferably, the heat treatment temperature is 400-700°C, and the heat treatment time is preferably 1-12h.

Further, the calcination temperature is 400-700°C, and the time is 0.5h-24h; the preferred calcination temperature is 450-600°C, and the preferred calcination time is 1h-12h.

Further, the reducing atmosphere includes one or more of CO and H ₂ .

Further, the liquid salt of noble metal G includes one or more combinations of molten salts or aqueous solutions of chloride salts, nitrates and acetates.

According to the sixth aspect of the present invention, there is provided the use of the catalyst as described in the first and second aspects of the present invention in the fields of motor vehicle exhaust purification, industrial organic waste gas treatment, catalytic combustion of natural gas, petrochemical industry, hydrogen energy and batteries application.

In summary, the present invention provides a grain boundary and surface-supported noble metal catalyst, a honeycomb type noble metal catalyst, and a preparation method and application thereof. The grain boundary and surface-loaded noble metal catalyst and the honeycomb noble metal catalyst provided by the present invention improve the anchoring effect of the noble metal by dispersing the noble metal G on the grain boundaries and surfaces of alumina and/or cerium-zirconium composite oxides, and avoid the noble metal particles. Migration, agglomeration and growth, maintaining the catalytic activity and high temperature stability of noble metal catalysts, and reducing the amount of noble metals used.

Description of drawings

Fig. 1 is the preparation method flowchart of the catalyst of grain boundary and surface loading noble metal of the embodiment of the present invention;

Fig. 2 is a flow chart of the preparation method of the honeycomb type noble metal catalyst according to the embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in combination with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are exemplary only, and are not intended to limit the scope of the present invention. Also, in the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concept of the present invention.

An embodiment of the present invention provides a grain boundary and surface supported noble metal catalyst, the catalyst is to load noble metal G on the grain boundary and surface of alumina and/or cerium-zirconium composite oxide, wherein the chemical generality of the cerium-zirconium composite oxide is The formula is C _{x Zry} M _z O _2-α D _δ ; M is a cation doping element, D is an anion doping element; the value range of each element is as follows:

0≤x≤1, 0≤y≤1, 0≤z≤0.5 and x, y, z satisfy x+y+z=1;

0≤α≤0.1; 0≤δ≤0.1.

The embodiment of the present invention also provides a honeycomb type noble metal catalyst, the catalyst includes a honeycomb carrier, a noble metal G and an active coating, the active coating contains alumina and/or cerium-zirconium composite oxide C _{x Zry} M _z O _{2 -α} D _δ , the precious metal G dispersed in alumina and/or cerium-zirconium composite oxide At the grain boundaries and surfaces of _{CexZryMzO2 -αDδ ,} the noble metal G is in _a metallic state, or in _a metallic state and an oxidized state, preferably in a metallic state, and the noble metal G is dispersed in alumina and/or cerium-zirconium The grain boundary and the surface of the active coating of the composite oxide Ce _{x Zry} M _z O _2-α D _δ are in a metallic state, which will be more conducive to the catalytic effect. The noble metal G can be Pt, Pd, Rh, Ir, Os, One or more combinations of Ru, Au and Ag, preferably noble metal G is one or more combinations of Pt, Pd, Rh, Ru, and the loading of noble metal G in the catalyst is calculated as 0.01-3%, preferably 0.1-2%.

The doping element M of the cerium-zirconium composite oxide in the present invention is one or more combinations of non-cerium rare earth elements, transition metal elements other than zirconium and rare earth elements, alkaline earth metal elements, Al, Si, Ga, Sn, Bi , non-cerium rare earth elements include La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, preferably La, Pr, Nd, Sm, Eu, Gd, Tm, Yb, Y; transition metal elements include Sc, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo, Hf, Ta, W, preferably Ti, Mn, Fe, Co, Ni, Cu, Nb, Hf, W, Mo; alkaline earth metal elements include Be, Mg, Ca, Sr, Ba, preferably Mg, Sr, Ba; doping element D can be one or more of anions N, F, P The combination.

The cerium-zirconium composite oxide in the catalyst provided in the embodiment of the present invention contains a core-shell structure. For other features and advantages of the core-shell structure of cerium-zirconium composite oxides, please refer to the application number CN202010982980.5 filed on September 17, 2020, and the title of the invention is "a core-shell structure cerium-zirconium-based composite oxide and its "Preparation method" Chinese patent application and its entire content description. According to the difference between the surface energy of elements and the formation energy of oxygen vacancies calculated in theory, the present invention designs the types and contents of elements in the outer shell or/and inner core, and comprehensively improves the thermal stability and oxygen storage and release performance of the cerium-zirconium composite oxide.

The cerium-zirconium composite oxide in the catalyst provided in the embodiment of the present invention includes a cerium-zirconium composite oxide with a gradient element distribution structure. For other features and advantages of the element gradient distribution structure of the cerium-zirconium composite oxide, please refer to the application number CN202010982979.2 filed on September 17, 2020, and the title of the invention is "A cerium-zirconium-based composite oxide with gradient element distribution" and its preparation method" Chinese patent application and its entire content description. According to the difference between element surface energy and oxygen vacancy formation energy calculated theoretically, the present invention designs and controls the type and content of elements in the gradient structure, so that the content of specific elements in the radial direction of the crystal grains gradually increases or decreases from the inside to the outside, and comprehensively improves the cerium Thermal stability and storage capacity of zirconium composite oxides Oxygen evolution performance.

The embodiment of the present invention also provides a preparation method of the above-mentioned catalyst with noble metals loaded on grain boundaries and surfaces. Fig. 1 shows the flow chart of the preparation method of the catalyst of grain boundary and surface loading noble metal of the embodiment of the present invention, comprises the following steps:

S1. Uniformly mix alumina and/or cerium-zirconium composite oxide _{Cex Zry} M _z O _2-α D _δ with the liquid salt of noble metal G according to the predetermined composition ratio; the liquid salt of noble metal G includes chloride salt One or more combinations of molten salts or solutions of nitrates and acetates; in this step, alumina and/or cerium-zirconium composite oxides C _{x Zry} M _z O _2-α D _δ and precious metal G The ratio is 0.01-3%, preferably 0.1-2%, in terms of mass fraction according to the loaded amount of noble metal G.

S2. Perform one or two heat treatments on the product obtained in step S1; the heat treatment temperature can be 200-800°C, and the time is 0.5h-24h; preferably, the heat treatment temperature is 400-700°C, and the heat treatment time is 1h-12h .

S3. The product obtained in step S2 is reduced and roasted once or twice under air or reducing atmosphere to obtain alumina and/or cerium-zirconium composite oxide C _{x Zry} M _z O _2-α D _δ grain boundaries and surfaces A catalyst for dispersing precious metals; the calcination temperature can be 400-800°C, and the time is 0.5h-24h; preferably, the calcination temperature is 450-600°C, and the calcination time is 1h-12h; the reducing atmosphere can include CO, _H2 One or a combination of more than one, the reducing atmosphere can also contain a small amount of O ₂ , and the O ₂ volume percentage does not exceed 10%.

In the embodiment of the present invention, when the heat treatment is performed in step S2, by controlling the appropriate temperature, the grain boundaries of the matrix are activated to become channels for the diffusion of noble metals. By controlling the heat treatment time, the depth and distribution of the diffusion of noble metals along the grain boundaries can be controlled. In step S3, by controlling the reducing atmosphere, reducing temperature, and reducing time, the noble metals at the grain boundaries and surfaces can be reduced or partially reduced. Through steps S2 and S3, the precious metal is distributed on the grain boundary and surface of the cerium-zirconium composite oxide, on the one hand, it is used to prevent or slow down the element diffusion between the grains of the cerium-zirconium composite oxide or on the surface, and to prevent the sintering and aging of the cerium-zirconium composite oxide , The specific surface area is reduced, which increases the thermal stability of the cerium-zirconium composite oxide; on the other hand, due to the anchoring effect of the noble metal on the grain boundary and surface of the cerium-zirconium composite oxide, the migration, agglomeration and grown to make more high temperature stable alumina and/or cerium-zirconium composite oxides _{CexZryMzO 2-αDδ Grain} Boundary and _{Surface Supported} Noble Metal Catalysts.

The embodiment of the present invention also provides the preparation method of the above-mentioned honeycomb-type noble metal catalyst, the honeycomb-type noble metal catalyst is layered or partition-coated with one or more coating materials, and the coating material is cerium-zirconium composite oxide, oxide Aluminum, grain boundary and surface-loaded cerium-zirconium composite oxide of noble metal, grain boundary and surface-loaded alumina, cerium-zirconium composite oxide and alumina grain boundary and surface-loaded noble metal mixture, Figure 2 shows the mixture of the present invention The preparation method flowchart of embodiment honeycomb type precious metal catalyst, comprises the following steps:

B1, mixing the coating material with adhesive, acidity regulator and water in one or more steps to make a coating slurry;

B2, coating the coating slurry obtained in step B1 on the honeycomb carrier in one or more steps, or coating the honeycomb carrier in partitions or layers, and drying;

B3. Heat-treat or/and roast the product obtained in step B2 to obtain a noble metal honeycomb catalyst. The heat-treatment temperature in this step can be 200-800°C, and the time is 0.5h-24h; the preferred heat-treatment temperature is 400-700°C, and the heat-treatment time 1h-12h; the roasting temperature in this step can be 400-800°C, and the time is 0.5h-24h; the preferred roasting temperature is 450-600°C, and the roasting time is 1h-12h; the roasting atmosphere in this step can be roasted in air atmosphere or reduced Atmosphere roasting, the atmosphere of reduction roasting can choose one or more of CO and _H2 .

The embodiment of the present invention also provides another preparation method of the above-mentioned honeycomb-type noble metal catalyst, which includes the following steps: loading noble metal on the grain boundaries of cerium-zirconium composite oxide, alumina, cerium-zirconium composite oxide and/or activated alumina and the surface One or more combinations of the catalysts are layered or/and partition-coated on the honeycomb carrier, through a heat treatment step and a calcination step, and by controlling the atmosphere, temperature and time of the heat treatment and calcination, alumina and/or Or a honeycomb-type noble metal catalyst loaded with precious metal G on the grain boundary and surface of the cerium-zirconium composite oxide, through the anchoring effect of the grain boundary and surface on the noble metal, the migration and growth of noble metal particles are avoided, so that the catalytic performance of the noble metal catalyst can be maintained. Activity and high-temperature stability, improve the thermal stability of the honeycomb-type precious metal catalyst under long-term high-temperature environmental conditions, ensure the catalytic activity of the catalyst, and reduce the amount of precious metals used.

The embodiment of the present invention also provides the above-mentioned grain boundary and surface-loaded noble metal catalyst and the above-mentioned honeycomb The application of type noble metal catalysts in the purification of motor vehicle exhaust, industrial organic waste gas treatment, catalytic combustion of natural gas, petrochemical industry, hydrogen energy, and batteries. The grain boundary and surface-supported noble metal catalyst and the honeycomb type noble metal catalyst provided by the embodiments of the present invention have good high temperature stability and can meet the application requirements of various related fields.

The present invention will be further described by specific examples below.

Comparative example 1

Take a certain volume of palladium nitrate and platinum nitrate solution and 200g _{Ce 0.52} Zr _0.36 La _0.05 Y _0.07 O ₂ powder according to the load of palladium 0.9% and platinum 0.3%, mix evenly, dry the sample at 110°C for 4 hours, and then dry the The dry sample was calcined at 500° C. for 5 hours in an air atmosphere to obtain a cerium-zirconium supported noble metal catalyst sample.

An appropriate amount of cerium-zirconium composite oxide-supported noble metal catalyst sample prepared above was aged at 1000° C. for 4 hours. Then, the cerium-zirconium composite oxide-supported noble metal catalyst powder was pressed into tablets, crushed, and sieved to obtain a granular cerium-zirconium composite oxide-supported noble metal catalyst of 30 to 40 meshes, and then the catalytic performance of the granular catalyst was tested. The catalytic test adopts the mixed gas of simulated automobile exhaust, and the content (volume ratio) of each component is as follows: CO content is 1.5%, NO content is 900ppm, HC content is 900ppm, _O2 content is 1.2%, _CO2 content is 12%, and the rest It is N ₂ ; the space velocity is 50000/h. The light-off temperature (T50) of the test sample for the catalytic conversion of CO, NO, and HC; the results showed that the light-off temperature of CO was 325°C, that of NO was 339°C, and that of HC was 318°C.

Comparative example 2

Take 200g Ce _0.52 Zr _0.36 La _0.05 Y _0.07 O ₂ powder, 200g activated alumina and an appropriate amount of deionized water to make a slurry, add palladium nitrate according to the loading amount of palladium 0.45% and platinum 0.15% in the total mass of the honeycomb support active coating and platinum nitrate and mix evenly, then add binders, acidity regulators, etc. Then, the coated honeycomb carrier was dried at 110° C. for 4 hours, and finally the honeycomb carrier was calcined at 500° C. in an air atmosphere for 5 hours to obtain a honeycomb type noble metal catalyst.

The honeycomb-type noble metal catalyst prepared above was aged at 1000°C for 4 hours, and then a small section of the honeycomb-type noble metal catalyst sample with a diameter of 0.5-1 cm was cut off, and then the cut-off small piece of honeycomb-type noble metal catalyst sample was tested for catalytic performance. The catalytic test adopts the mixed gas of simulated automobile exhaust, The content (volume ratio) of each component is as follows: CO content is 1.5%, NO content is 900ppm, HC content is 900ppm, _O2 content is 1.2%, _CO2 content is 12%, and the rest is _N2 . The air speed is 50000/h. The light-off temperature (T50) of the test sample for the catalytic conversion of CO, NO, and HC; the results showed that the light-off temperature of CO was 314°C, that of NO was 329°C, and that of HC was 311°C.

Comparative example 3

Take a certain volume of palladium nitrate and rhodium nitrate solution and 200g Ce _0.16 Zr _0.78 La _0.02 Nd _0.04 O ₂ powders according to the loading capacity of palladium 1.2% and rhodium 0.2%, mix evenly, then dry the sample at 110°C for 4 hours, Then, the dried sample was calcined at 500° C. for 5 hours in an air atmosphere to obtain a cerium-zirconium-supported noble metal catalyst sample. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 330°C, that of NO was 323°C, and that of HC was 331°C.

Comparative example 4

Take 200g Ce _0.16 Zr _0.78 La _0.02 Nd _0.04 O ₂ powder, 200g activated alumina and an appropriate amount of deionized water to make a slurry, add nitric acid according to the loading capacity of palladium 0.6% and rhodium 0.1% in the total mass of the honeycomb support active coating Mix palladium and rhodium nitrate evenly, then add binder, acidity regulator, etc. to make coating slurry, and coat the prepared slurry on ceramic Then, the coated honeycomb carrier was dried at 110° C. for 4 hours, and finally the honeycomb carrier was fired at 500° C. in an air atmosphere for 5 hours to obtain a honeycomb-type noble metal catalyst. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 2. The test results showed that the light-off temperature of CO was 326°C, the light-off temperature of NO was 319°C, and the light-off temperature of HC was 327°C.

Example 1

Measure a certain volume of palladium nitrate and platinum nitrate solution and _{200g Ce 0.52} Zr _0.36 La _0.05 Y _0.07 O ₂ powder according to the loading capacity of 0.9% palladium and 0.3% platinum, and then dry the sample at 110°C for 4 hours, then The sample was heat-treated at 550°C for 4 hours, and finally the sample was reduced and roasted at 500°C for 5 hours under a hydrogen atmosphere to obtain a catalyst sample PdPt/Ce _0.52 Zr _0.36 La _0.05 with cerium-zirconium composite oxide grain boundaries and surface-loaded noble metals Pd and Pt Y _0.07 O ₂ . The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 290°C, and the light-off temperature of NO was 320°C, the light-off temperature of HC is 295°C.

Example 2

Take the cerium-zirconium composite oxide supported noble metal catalyst PdPt/Ce _0.52 Zr _0.36 La _0.05 Y _0.07 O ₂ 200g prepared according to Example 1 and an appropriate amount of alumina and a certain amount of binder, acidity regulator, deionized water, etc. into a coating slurry; then the prepared slurry is coated on the ceramic honeycomb carrier according to the coating amount of the honeycomb catalyst precious metal total loading of 1.2g/L, and then the coated honeycomb carrier is dried at 110°C for 4 hours , then heat-treat the honeycomb carrier at 300°C for 5 hours, and finally bake the honeycomb carrier at 500°C for 5 hours to obtain a honeycomb-type noble metal catalyst; precious metals Pd and Pt are loaded on the honeycomb-type noble metal catalyst. The cerium-zirconium composite oxide and alumina grain boundaries and surfaces. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 2. The test results showed that the light-off temperature of CO was 270°C, that of NO was 300°C, and that of HC was 284°C.

Example 3

According to the loading capacity of palladium 1.2%, rhodium 0.2%, take a certain volume of palladium nitrate, rhodium nitrate solution and 200g Ce _0.16 Zr _0.78 La _0.02 Nd _0.04 O ₂ powder mix evenly, then the sample is dried at 110 ℃ for 4 hours, and then The sample was heat-treated at 550°C for 4 hours, and finally the sample was reduced and roasted at 500°C for 5 hours in a hydrogen atmosphere to obtain a catalyst sample PdRh/Ce _0.16 Zr _0.78 La _0.02 with cerium-zirconium composite oxide grain boundaries and surface-loaded noble metals Pd and Rh Nd _0.04 O ₂ . The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 278°C, the light-off temperature of NO was 279°C, and the light-off temperature of HC was 313°C.

Example 4

Take the cerium-zirconium composite oxide supported noble metal catalyst PdRh/Ce _0.16 Zr _0.78 La _0.02 Nd _0.04 O ₂ 200g prepared according to Example 3, an appropriate amount of activated alumina and a certain amount of binder, acidity regulator, deionized water, etc. Prepare the coating slurry; then coat the prepared slurry on the ceramic honeycomb carrier according to the coating amount of the honeycomb catalyst precious metal total load of 1.4g/L, and dry the coated honeycomb carrier at 110°C for 4 Hours, then heat-treat the honeycomb carrier at 300°C for 5 hours, and finally bake the honeycomb carrier at 500°C for 5 hours to obtain a honeycomb-type noble metal catalyst; precious metals Pd and Rh are supported on the cerium-zirconium composite oxide and alumina of the honeycomb-type noble metal catalyst grain boundaries and surfaces. Challenging the sample Chemical performance test, sample preparation steps and catalytic test conditions are the same as in Comparative Example 2. The test results show that the light-off temperature of CO is 261°C, the light-off temperature of NO is 250°C, and the light-off temperature of HC is 287°C.

Example 5

Take a certain volume of palladium nitrate, platinum nitrate, rhodium nitrate solution and 200g Ce _0.38 Zr _0.53 La _0.071 Pr _0.01 Y _0.01 O according to the loading capacity of palladium 0.4%, platinum 0.3%, and _rhodium 0.01%. The sample was dried at 110°C for 4 hours, and then heat-treated at 550°C for 4 hours. Finally, the sample was reduced and roasted at 500°C for 4 hours in a hydrogen atmosphere to obtain grain boundaries of cerium-zirconium composite oxides and surface loaded noble metals Pd, Pt, Rh catalyst sample PdPtRh/Ce _0.38 Zr _0.53 La _0.071 Pr _0.01 Y _0.01 O ₂ . The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 260°C, that of NO was 287°C, and that of HC was 286°C.

Example 6

Take a certain volume of palladium nitrate, platinum nitrate, rhodium nitrate solution and 200g _{Ce 0.33} Zr _0.58 La _0.033 Nd _0.032 Y _0.025 O according to the loading capacity of palladium 0.7%, platinum 0.2%, rhodium 0.1%. The sample was dried at 110°C for 4 hours, and then heat-treated at 200°C for 4 hours, and finally the sample was reduced and roasted at 500°C for 4 hours under a hydrogen atmosphere to obtain grain boundaries of cerium-zirconium composite oxides and surface loaded noble metals Pd, Pt, Rh catalyst sample PdPtRh/Ce _0.33 Zr _0.58 La _0.033 Nd _0.032 Y _0.025 O ₂ . The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 315°C, that of NO was 324°C, and that of HC was 327°C.

Example 7

Take a certain volume of palladium nitrate, platinum nitrate, rhodium nitrate solution and 200g _{Ce 0.33} Zr _0.58 La _0.033 Nd _0.032 Y _0.025 O according to the loading capacity of palladium 0.7%, platinum 0.2%, rhodium 0.1%. The sample was dried at 110°C for 4 hours, and then heat-treated at 400°C for 4 hours. Finally, the sample was reduced and roasted at 500°C for 4 hours in a hydrogen atmosphere to obtain grain boundaries of cerium-zirconium composite oxides and surface loaded noble metals Pd, Pt, Rh catalyst sample PdPtRh/Ce _0.33 Zr _0.58 La _0.033 Nd _0.032 Y _0.025 O ₂ . The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 278°C, that of NO was 310°C, and that of HC was 290°C.

Example 8

Take a certain volume of palladium nitrate, platinum nitrate, rhodium nitrate solution and 200g _{Ce 0.33} Zr _0.58 La _0.033 Nd _0.032 Y _0.025 O according to the loading capacity of palladium 0.7%, platinum 0.2%, rhodium 0.1%. The sample was dried at 110°C for 4 hours, and then heat-treated at 600°C for 4 hours. Finally, the sample was reduced and roasted at 500°C for 4 hours under a hydrogen atmosphere to obtain grain boundaries of cerium-zirconium composite oxides and surface loaded noble metals Pd, Pt, Rh catalyst sample PdPtRh/Ce _0.33 Zr _0.58 La _0.033 Nd _0.032 Y _0.025 O ₂ . The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 259°C, that of NO was 277°C, and that of HC was 278°C.

Example 9

Take the cerium-zirconium composite oxide supported noble metal catalyst PdPtRh/Ce _0.33 Zr _0.58 La _0.033 Nd _0.032 Y _0.025 O ₂ 200g prepared according to Example 8 and an appropriate amount of activated alumina and a certain amount of binder, acidity regulator, deionized Adjust the coating slurry with water, etc.; then coat the prepared slurry on the ceramic honeycomb carrier according to the coating amount of the honeycomb catalyst precious metal total loading amount of 1g/L, and then dry the coated honeycomb carrier at 110°C 4 hours, then heat-treat the honeycomb carrier at 400°C for 12 hours, and finally bake the honeycomb carrier at 500°C for 5 hours to obtain a honeycomb-type noble metal catalyst; noble metals Pd, Pt, and Rh are loaded on the honeycomb-type noble metal catalyst. The cerium-zirconium composite oxide and alumina grain boundaries and surfaces. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 2. The test results showed that the light-off temperature of CO was 257°C, the light-off temperature of NO was 283°C, and the light-off temperature of HC was 267°C.

Example 10

Take a certain volume of palladium, platinum, rhodium chloride liquid salt and 200g Ce _0.33 Zr _0.58 La _0.033 Nd _0.032 Y _{0.025 O} powder according to the loading capacity of palladium 0.7%, platinum 0.2%, and rhodium 0.1%. Dry at 110°C for 4 hours, then perform the first heat treatment at 450°C for 4 hours, then conduct the second heat treatment at 800°C for 4 hours, and finally reduce and roast the sample at 500°C for 4 hours in a hydrogen atmosphere to obtain Catalyst sample PdPtRh/Ce _0.33 Zr _0.58 La _0.033 Nd _0.032 Y _0.025 O ₂ supported on the grain boundary of cerium-zirconium composite oxide and the surface of noble metals Pd, Pt and Rh. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 264°C, that of NO was 291°C, and that of HC was 275°C.

Example 11

Take 200g of activated alumina and a certain amount of adhesive, acidity regulator, deionized water, etc. to make a coating slurry; then apply the alumina slurry to the ceramic according to the amount of alumina contained in the honeycomb carrier on the honeycomb carrier, and dry the coated honeycomb carrier at 110°C for 4 hours; take the cerium-zirconium composite oxide-supported noble metal catalyst PdPtRh/Ce _0.33 Zr _0.58 La _0.033 Nd _0.032 Y _0.025 O ₂ 200g prepared according to Example 10 and a certain amount of adhesive, acidity regulator, deionized water, etc. to prepare a coating slurry; then apply the prepared slurry to the above-mentioned coated On the alumina-coated ceramic honeycomb carrier, dry the coated honeycomb carrier at 110°C for 4 hours, then heat-treat the honeycomb carrier at 600°C for 4 hours, and finally bake the honeycomb carrier at 500°C for 5 hours to obtain a honeycomb-type noble metal catalyst ; Precious metals Pd, Pt, Rh are mainly supported on the grain boundary and surface of the cerium-zirconium composite oxide of the honeycomb-type precious metal catalyst, and a small amount is loaded on the grain boundary and surface of the cerium-zirconium composite oxide and alumina. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 2. The test results showed that the light-off temperature of CO was 267°C, the light-off temperature of NO was 279°C, and the light-off temperature of HC was 274°C.

Example 12

Take a certain volume of palladium and rhodium liquid acetate and 200g of cerium-zirconium composite oxide Ce _0.18 Zr _0.64 La _0.03 Y _0.15 O ₂ powder with a core-shell structure that is rich in yttrium on the surface according to the loading capacity of palladium 0.8% and rhodium 0.08%. Mix the body evenly, dry the sample at 110°C for 4 hours, then conduct the first heat treatment at 600°C for 6 hours, and then conduct the second heat treatment at 580°C for 5 hours to obtain the grain boundaries and surface of the cerium-zirconium composite oxide. Catalyst sample PdRh/Ce _0.18 Zr _0.64 La _0.03 Y _0.15 O ₂ loaded with noble metals Pd and Rh. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 251°C, that of NO was 264°C, and that of HC was 239°C.

Example 13

Take the cerium-zirconium composite oxide grain boundary prepared according to Example 12 and the surface-loaded noble metal catalyst PdRh/Ce _0.18 Zr _0.64 La _0.03 Y _0.15 O ₂ 200g and an appropriate amount of activated alumina and a certain amount of binder, acidity regulator, Deionized water, etc. were used to prepare the coating slurry; then the prepared slurry was coated on the ceramic honeycomb carrier according to the coating amount of the honeycomb catalyst precious metal total loading of 0.88g/L, and the coated honeycomb The honeycomb carrier was dried at 110°C for 4 hours, then the honeycomb carrier was heat-treated at 600°C for 6 hours, and finally the honeycomb carrier was fired at 580°C for 5 hours to obtain a honeycomb-type noble metal catalyst; precious metals Pd and Rh were loaded on the cerium of the honeycomb-type noble metal catalyst Grain boundaries and surfaces of zirconium complex oxides and alumina. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as those in Comparative Example 2. The test results showed that the light-off temperature of CO was 243°C, that of NO was 250°C, and that of HC was 235°C.

Example 14

Take a certain volume of platinum, rhodium liquid acetate and 200g surface cerium-rich gradient cerium-zirconium composite oxide Ce _0.33 Zr _0.57 La _0.04 Y _0.06 O according to the loading capacity of platinum 0.3%, rhodium 0.02% The powder is mixed _evenly , The sample was dried at 110°C for 4 hours, then the first heat treatment was performed at 550°C for 4 hours, and then the sample was subjected to the second heat treatment at 500°C for 5 hours to obtain grain boundaries of cerium-zirconium composite oxides and surface loaded noble metal Pt, Rh catalyst sample PtRh/Ce _0.33 Zr _0.57 La _0.04 Y _0.06 O ₂ . The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 241°C, that of NO was 246°C, and that of HC was 251°C.

Example 15

Take the cerium-zirconium composite oxide-supported noble metal catalyst PtRh/Ce _0.33 Zr _0.57 La _0.04 Y _0.06 O ₂ 200g prepared according to Example 14, an appropriate amount of activated alumina and a certain amount of binder, acidity regulator, deionized water, etc. Adjust the coating slurry; then coat the prepared slurry on the ceramic honeycomb carrier according to the coating amount of the honeycomb catalyst precious metal total loading of 0.32g/L, and dry the coated honeycomb carrier at 110°C for 4 hour, then heat-treat the honeycomb carrier at 550°C for 4 hours, and finally bake the honeycomb carrier at 500°C for 5 hours to obtain a honeycomb-type noble metal catalyst; precious metals Pt and Rh are loaded on the cerium-zirconium composite oxide and alumina of the honeycomb-type noble metal catalyst grain boundaries and surfaces. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 2. The test results showed that the light-off temperature of CO was 235°C, that of NO was 230°C, and that of HC was 243°C.

Example 16

Take a certain volume of palladium and platinum liquid nitrate and 200g of cerium-zirconium composite oxide Ce _0.42 Zr _0.47 La _0.045 Y _0.064 O ₂ powder with a core-shell structure and a surface rich in cerium and yttrium according to the loading capacity of palladium 0.2% and platinum 0.5%. Mix the body evenly, dry the sample at 110°C for 4 hours, and then conduct the first heat treatment at 610°C for 7 hours. Then the sample was subjected to a second heat treatment at 470°C for 4 hours to obtain a catalyst sample PdPt/Ce _0.42 Zr _0.47 La _0.045 Y _0.064 O ₂ with grain boundaries of cerium-zirconium composite oxide and noble metals Pd and Pt supported on the surface. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 243°C, that of NO was 259°C, and that of HC was 239°C.

Example 17

Take the cerium-zirconium composite oxide-supported noble metal catalyst PdPt/Ce _0.42 Zr _0.47 La _0.045 Y _0.064 O ₂ 200g prepared according to Example 16, an appropriate amount of activated alumina and a certain amount of binder, acidity regulator, deionized water, etc. Adjust the coating slurry; then coat the prepared slurry on the ceramic honeycomb carrier according to the coating amount of the honeycomb catalyst precious metal total loading of 0.7g/L, and dry the coated honeycomb carrier at 110°C for 4 hours, then heat-treat the honeycomb carrier at 490°C for 7 hours, and finally bake the honeycomb carrier at 570°C for 4 hours to obtain a honeycomb-type noble metal catalyst; precious metals Pd and Pt are loaded on the honeycomb-type noble metal catalyst. The cerium-zirconium composite oxide and alumina grain boundaries and surfaces. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 2. The test results showed that the light-off temperature of CO was 237°C, the light-off temperature of NO was 248°C, and the light-off temperature of HC was 227°C.

Example 18

Take a certain volume of liquid nitrate of palladium and rhodium and 200g of cerium-zirconium composite oxide Ce _0.24 Zr _0.7 La _0.017 Nd _0.043 O ₂ powder with core-shell structure rich in neodymium on the surface according to the loading capacity of palladium 0.1% and rhodium 0.02%. Mix evenly, dry the sample at 110°C for 4 hours, then conduct the first heat treatment at 520°C for 3 hours, and then conduct the second heat treatment at 630°C for 6 hours to obtain the grain boundaries and surface loading of the cerium-zirconium composite oxide Catalyst samples of noble metals Pd and Rh: PdRh/Ce _0.24 Zr _0.7 La _0.017 Nd _0.043 O ₂ . The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 233°C, that of NO was 211°C, and that of HC was 225°C.

Example 19

Take the cerium-zirconium composite oxide-supported noble metal catalyst PdRh/Ce _0.24 Zr _0.7 La _0.017 Nd _0.043 O ₂ 200g prepared according to Example 18, an appropriate amount of activated alumina and a certain amount of binder, acidity regulator, deionized water, etc. Adjust the coating slurry; then the prepared slurry is coated on the ceramic honeycomb carrier according to the coating amount of the honeycomb catalyst precious metal total loading of 0.12g/L, and the coated honeycomb The honeycomb carrier was dried at 110°C for 4 hours, then the honeycomb carrier was heat-treated at 510°C for 3 hours, and finally the honeycomb carrier was fired at 600°C for 5 hours to obtain a honeycomb-type noble metal catalyst; precious metals Pd and Rh were loaded on the cerium of the honeycomb-type noble metal catalyst Grain boundaries and surfaces of zirconium complex oxides and alumina. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 2. The test results showed that the light-off temperature of CO was 230°C, that of NO was 205°C, and that of HC was 222°C.

Example 20

Take a certain volume of palladium nitrate, platinum nitrate solution and _200g CeO powder according to the loading of palladium 1% and platinum 0.01%, mix evenly, then dry the sample at 110°C for 4 hours, then heat treat the sample at 500°C for 4.5 hours, Finally, the sample was reduced and calcined at 400° C. for 24 hours under a hydrogen atmosphere to obtain a catalyst sample PdPt/CeO ₂ with grain boundaries of cerium oxide and noble metals Pd and Pt supported on the surface. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 304°C, that of NO was 339°C, and that of HC was 317°C.

Example 21

Take _200g of the cerium oxide-supported noble metal catalyst PdPt/CeO2 prepared according to Example 20, an appropriate amount of activated alumina, and a certain amount of binder, acidity regulator, deionized water, etc. to make a coating slurry; then press the honeycomb catalyst The coating amount of the total precious metal loading is 0.61g/L. The prepared slurry is coated on the ceramic honeycomb carrier, and the coated honeycomb carrier is dried at 110°C for 4 hours, and then the honeycomb carrier is heat-treated at 300°C for 18 hours, and finally the honeycomb carrier was calcined at 400° C. for 12 hours to obtain a honeycomb-type noble metal catalyst; noble metals Pd and Pt were supported on the grain boundaries and surfaces of ceria and alumina of the honeycomb-type noble metal catalyst. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 2. The test results showed that the light-off temperature of CO was 288°C, that of NO was 329°C, and that of HC was 303°C.

Example 22

According to the load of palladium 1.2% and rhodium 0.08%, take a certain volume of palladium and rhodium acetate solution and 200g Ce _0.38 Zr _0.53 La _0.045 Sm _0.03 Tm _0.015 O ₂ powder and mix evenly, and dry the sample at 110°C for 4 Then the sample was heat-treated at 600°C for 4 hours, then the sample was subjected to the first reduction roasting at 500°C for 5 hours under hydrogen atmosphere, and finally the sample was subjected to the second reduction roasting at 650°C for 2 hours under hydrogen atmosphere , the catalyst sample PdRh/Ce _0.38 Zr _0.53 La _0.045 Sm _0.03 Tm _0.015 O ₂ with the grain boundaries of the cerium-zirconium composite oxide and the noble metals Pd and Rh supported on the surface was obtained. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as those in Comparative Example 1. The test results showed that the light-off temperature of CO was 254°C, that of NO was 257°C, and that of HC was 260°C.

Example 23

Take a certain volume of platinum nitrate, rhodium nitrate solution and 200g Ce _0.13 Zr _0.64 La _0.03 Nd _0.03 Mn _0.17 O ₂ powder according to the loading of platinum 1.9% and rhodium 0.1%, mix evenly, and then dry the sample at 110°C for 4 hours , then heat-treated the sample at 200°C for 24 hours, and finally reduced and roasted the sample at 700°C for 0.5 hour under CO atmosphere to obtain the catalyst sample PtRh/Ce _0.13 Zr _0.64 La _0.03 Nd _0.03 Mn _0.17 O ₂ . The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 286°C, that of NO was 280°C, and that of HC was 293°C.

Example 24

Take the cerium-zirconium composite oxide supported noble metal catalyst PdRh/Ce _0.38 Zr _0.53 La _0.045 Sm _0.03 Tm _0.015 O ₂ 200g prepared according to Example 23, an appropriate amount of activated alumina and a certain amount of binder, acidity regulator, deionized Prepare coating slurry a with water, etc.; take the cerium-zirconium composite oxide supported noble metal catalyst PtRh/Ce _0.13 Zr _0.64 La _0.03 Nd _0.03 Mn _0.17 O ₂ 200g prepared according to Example 15, an appropriate amount of activated alumina and a certain amount of Adhesive, acidity regulator, deionized water, etc. are adjusted into another coating slurry b; then the prepared slurry a is coated on half of the honeycomb carrier according to the coating amount of the total precious metal loading of 0.64g/L and dry the half-coated honeycomb carrier at 110°C for 4 hours; then apply the prepared slurry b to the other half of the honeycomb carrier according to the coating amount of the total precious metal loading of 1g/L, and apply The coated honeycomb carrier was dried at 110°C for 4 hours; then the honeycomb carrier was heat-treated at 450°C for 3 hours, and finally the honeycomb carrier was calcined at 550°C for 6 hours to obtain a honeycomb-type noble metal catalyst with a total precious metal loading of 1.64g/L; Noble metals Pd, Pt and Rh are supported on the grain boundaries and surfaces of the cerium-zirconium composite oxide and alumina of the honeycomb-type noble metal catalyst. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 2. The test results showed that the light-off temperature of CO was 245°C, that of NO was 249°C, and that of HC was 247°C.

Example 25

Take a certain volume of rhodium nitrate solution and 200g Ce _0.78 Zr _0.16 La _0.02 Y _0.02 Fe _0.02 O ₂ powder according to the load of rhodium 0.01%, mix evenly, dry the sample at 110°C for 4 hours, and then heat-treat the sample at 300°C for 20 hour, then the sample was roasted at 450°C for 4 hours in an air atmosphere, and finally the sample was reduced and roasted at 570°C for 5 hours under a hydrogen atmosphere to obtain a catalyst sample Rh/Ce _0.78 Zr _0.16 La _0.02 Y _0.02 Fe _0.02 O ₂ . The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 313°C, that of NO was 291°C, and that of HC was 305°C.

Example 26

Take the cerium-zirconium composite oxide supported noble metal catalyst Rh/Ce _0.78 Zr _0.16 La _0.02 Y _0.02 Fe _0.02 O ₂ 200g prepared according to Example 25, an appropriate amount of activated alumina and a certain amount of binder, acidity regulator, deionized Adjust the coating slurry with water, etc.; then apply the prepared slurry on the ceramic honeycomb carrier according to the coating amount of the honeycomb catalyst precious metal total loading of 0.01g/L, and put the coated honeycomb carrier at 110°C Drying for 4 hours, and finally calcining the honeycomb carrier at 500° C. for 5 hours to obtain a honeycomb-type noble metal catalyst; the noble metal Rh is supported on the grain boundaries and surfaces of the cerium-zirconium composite oxide and alumina of the honeycomb-type noble metal catalyst. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 2. The test results showed that the light-off temperature of CO was 296°C, the light-off temperature of NO was 281°C, and the light-off temperature of HC was 293°C.

Example 27

Take a certain volume of palladium nitrate solution according to the loading capacity of 0.5% palladium, mix with 200g Ce _0.38 Zr _0.5 La _0.07 Pr _0.03 Y _0.01 Si _0.01 O _1.999 N _0.001 and 200g activated alumina powder, and then dry the sample at 110°C After 4 hours, the sample was heat-treated at 550°C for 3 hours, and finally the sample was reduced and roasted at 470°C for 16 hours under a hydrogen atmosphere to obtain a catalyst sample Pd/ Ce _0.38 Zr _0.5 La _0.07 Pr _0.03 Y _0.01 Si _0.01 O _1.999 N _0.001 & Al ₂ O ₃ . The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 265°C, that of NO was 270°C, and that of HC was 270°C.

Example 28

Take the cerium-zirconium composite oxide prepared according to Example 27 and the alumina-supported noble metal catalyst Pd/Ce _0.38 Zr _0.5 La _0.07 Pr _0.03 Y _0.01 Si _0.01 O _1.999 N _0.001 & Al ₂ O ₃ 200g and an appropriate amount of binder and acidity Regulator, deionized water, etc. were adjusted into a coating slurry; then the prepared slurry was coated on the ceramic honeycomb carrier according to the coating amount of the honeycomb catalyst precious metal total loading of 1g/L, and the coated honeycomb The carrier was dried at 110°C for 4 hours, and then the honeycomb carrier was heat-treated at 750°C for 1 hour, and finally the honeycomb carrier was calcined at 600°C for 5 hours to obtain a honeycomb-type noble metal catalyst; precious metal Pd was loaded on the honeycomb-type noble metal catalyst. grain boundaries and surfaces of the material and alumina. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 2. The test results showed that the light-off temperature of CO was 260°C, the light-off temperature of NO was 263°C, and the light-off temperature of HC was 258°C.

Example 29

Take a certain volume of palladium nitrate, platinum nitrate solution and 200g Ce _0.18 Zr _0.64 La _0.03 Y _0.13 Yb _0.02 O _1.995 F _0.005 powder according to the load of palladium 0.5% and platinum 1.8%, mix evenly, and then dry the sample at 110°C After 4 hours, the sample was heat-treated at 600°C for 4 hours, and finally the sample was reduced and roasted at 600°C for 4 hours in a hydrogen atmosphere to obtain a catalyst sample PdPt/Ce _0.18 with grain boundaries of cerium-zirconium composite oxide and noble metals Pd and Pt on the surface. Zr _0.64 La _0.03 Y _0.13 Yb _0.02 O _1.995 F _0.005 . The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 243°C, that of NO was 261°C, and that of HC was 242°C.

Example 30

Take a certain volume of platinum nitrate and rhodium nitrate solution and 200g Ce _0.33 Zr _0.5 La _0.033 Nd _0.032 Y _0.025 Sr _0.04 Ba _0.04 O ₂ powder according to the loading of platinum 0.9% and rhodium 0.01%, mix evenly, and then put the sample at 110°C Dry the sample for 4 hours, then heat-treat the sample at 600°C for 6.5 hours, and finally reduce and roast the sample at 500°C for 12 hours under a hydrogen atmosphere to obtain the catalyst sample PtRh/ Ce _0.33 Zr _0.5 La _0.033 Nd _0.032 Y _0.025 Sr _0.04 Ba _0.04 O ₂ . The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 256°C, that of NO was 261°C, and that of HC was 263°C.

Example 31

The cerium-zirconium composite oxide-supported noble metal catalyst PtRh/Ce _0.33 Zr _0.5 La _0.033 Nd _0.032 Y _0.025 Sr _0.04 Ba prepared according to Example 30 was taken according to the cerium-zirconium content of 90% and the alumina content of 10% in the honeycomb-type noble metal catalyst coating _0.04 O ₂ 200g and an appropriate amount of activated alumina and a certain amount of binder, acidity regulator, deionized water, etc. to prepare a coating slurry; The good slurry is coated on the ceramic honeycomb carrier, and the coated honeycomb carrier is dried at 110°C for 4 hours, then the honeycomb carrier is heat-treated at 800°C for 0.5 hour, and finally the honeycomb carrier is fired at 700°C for 0.5 hour to obtain A honeycomb type noble metal catalyst; noble metals Pt and Rh are loaded on the grain boundaries and surfaces of the cerium-zirconium composite oxide and alumina of the honeycomb type noble metal catalyst. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 2. The test results showed that the light-off temperature of CO was 265°C, the light-off temperature of NO was 271°C, and the light-off temperature of HC was 274°C.

Example 32

Take a certain volume of platinum nitrate and rhodium nitrate solution and 200g _{Ce 0.16} Zr _0.6 La _0.02 Nd _0.04 Mn _0.12 Ba _0.06 O ₂ powder according to the load of platinum 0.5% and rhodium 0.4%, mix evenly, and then dry the sample at 110°C for 4 hours, then heat-treated the sample at 700°C for 8 hours, and finally reduced and roasted the sample at 600°C for 4 hours in a hydrogen atmosphere to obtain the catalyst sample PtRh/Ce _0.16 Zr with cerium-zirconium composite oxide grain boundaries and surface-supported noble metals Pt and Rh _0.6 La _0.02 Nd _0.04 Mn _0.12 Ba _0.06 O ₂ . The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 251°C, that of NO was 248°C, and that of HC was 260°C.

Example 33

Take the cerium-zirconium composite oxide supported noble metal catalyst PtRh/Ce _0.16 Zr _0.6 La _0.02 Nd _0.04 Mn _0.12 Ba _0.06 O ₂ 200g prepared according to Example 32, an appropriate amount of activated alumina and a certain amount of binder, acidity regulator, Deionized water, etc. are adjusted into the coating slurry; then the prepared slurry is coated on the ceramic honeycomb carrier according to the coating amount of the honeycomb catalyst precious metal total loading of 1.08g/L, and then the coated honeycomb carrier is placed on the Dry at 110°C for 4 hours, then heat-treat the honeycomb carrier at 430°C for 3 hours, and finally bake the honeycomb carrier at 650°C for 6 hours to obtain a honeycomb-type noble metal catalyst; precious metals Pt and Rh are loaded on the honeycomb-type noble metal catalyst. The cerium-zirconium composite oxidation grain boundaries and surfaces of AlO and AlO place. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 2. The test results showed that the light-off temperature of CO was 247°C, that of NO was 242°C, and that of HC was 253°C.

Example 34

Take a certain volume of rhodium nitrate solution and 200g Zr _0.86 La _0.09 Y _0.04 Ti _0.01 O ₂ powder according to the load of rhodium 0.1%, mix evenly, then dry the sample at 110°C for 4 hours, and then heat-treat the sample at 420°C for 6 Finally, the sample was reduced and roasted at 630°C for 4 hours under a hydrogen atmosphere to obtain a catalyst sample Rh/Zr _0.86 La _0.09 Y _0.04 Ti _0.01 O ₂ with cerium-zirconium composite oxide grain boundaries and noble metal Rh supported on the surface. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 271°C, that of NO was 248°C, and that of HC was 277°C.

Example 35

According to the 70% cerium-zirconium content and 30% alumina content in the honeycomb-type noble metal catalyst coating, take the cerium-zirconium composite oxide-supported noble metal catalyst Rh/Zr _0.86 La _0.09 Y _0.04 Ti _0.01 O ₂ 200g prepared according to Example 34 and an appropriate amount of Activated alumina and a certain amount of adhesives, acidity regulators, deionized water, etc. were adjusted to prepare a coating slurry; then the prepared slurry was coated according to the coating amount of the honeycomb catalyst with a total loading of precious metals of 0.14g/L onto the ceramic honeycomb carrier, and dry the coated honeycomb carrier at 110°C for 4 hours, then heat-treat the honeycomb carrier at 550°C for 3 hours, and finally bake the honeycomb carrier at 700°C for 1.5 hours to obtain a honeycomb-type noble metal catalyst; precious metal Rhodium is supported at the grain boundaries and surfaces of the cerium-zirconium composite oxide and alumina of the honeycomb type noble metal catalyst. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 2. The test results showed that the light-off temperature of CO was 268°C, that of NO was 233°C, and that of HC was 272°C.

Example 36

Take a certain volume of rhodium nitrate solution and 200g Zr _0.86 La _0.095 Y _0.045 O ₂ powder according to the load of rhodium 0.1%, mix evenly, then dry the sample at 110°C for 4 hours, then heat-treat the sample at 630°C for 5 hours, Finally, the sample was reduced and calcined at 700°C for 5 hours in a hydrogen atmosphere to obtain a catalyst sample Rh/Zr _0.86 La _0.095 Y _0.045 O ₂ with grain boundaries of cerium-zirconium composite oxide and noble metal Rh supported on the surface. For samples The catalytic performance test was carried out. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 270°C, the light-off temperature of NO was 264°C, and the light-off temperature of HC was 274°C.

Example 37

According to the 70% cerium-zirconium content and 30% alumina content in the honeycomb-type noble metal catalyst coating, the cerium-zirconium composite oxide-supported noble metal catalyst Rh/Zr _0.86 La _0.095 Y _0.045 O ₂ 200 g prepared according to Example 34 and an appropriate amount of active oxidation Aluminum and a certain amount of adhesives, acidity regulators, deionized water, etc. are adjusted into a coating slurry; then the prepared slurry is coated on the ceramic according to the coating amount of the honeycomb catalyst precious metal total loading of 0.14g/L on the honeycomb carrier, and dry the coated honeycomb carrier at 110°C for 4 hours, then heat-treat the honeycomb carrier at 600°C for 3 hours, and finally bake the honeycomb carrier at 660°C for 5 hours to obtain a honeycomb-type precious metal catalyst; precious metal rhodium At the grain boundary and surface of the cerium-zirconium composite oxide and alumina of the honeycomb type noble metal catalyst. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 2. The test results showed that the light-off temperature of CO was 265°C, the light-off temperature of NO was 251°C, and the light-off temperature of HC was 268°C.

Example 38

Take a certain volume of palladium nitrate, platinum nitrate, rhodium nitrate solution and 200g Ce _0.25 Zr _{0.6 La 0.05} Y _0.05 Nb _0.02 Sn _0.03 O according to the load of palladium 0.1%, platinum 0.2%, rhodium 0.1% The powder is mixed uniformly, and then The sample was dried at 110°C for 4 hours, and then heat-treated at 620°C for 4 hours. Finally, the sample was reduced and roasted at 520°C for 7 hours in a hydrogen atmosphere to obtain grain boundaries of cerium-zirconium composite oxides and surface loaded noble metals Pd, Pt, Rh catalyst sample PdPtRh/Ce _0.25 Zr _0.6 La _0.05 Y _0.05 Nb _0.02 Sn _0.03 O ₂ . The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 276°C, that of NO was 257°C, and that of HC was 273°C.

Example 39

Take a certain volume of rhodium nitrate solution and 200g Ce _0.18 Zr _0.62 La _0.03 Y _0.13 Er _0.02 Ni _0.02 O ₂ powder according to the load of rhodium 0.1%, mix evenly, then dry the sample at 110 ° C for 4 hours, and then dry the sample in Heat treatment at 710°C for 2 hours, and finally reduce and roast the sample at 650°C for 3 hours in a hydrogen atmosphere to obtain a catalyst sample Rh/Ce _0.18 Zr _0.62 La _0.03 Y _0.13 Er _0.02 Ni with grain boundaries of cerium-zirconium composite oxide and noble metal Rh supported on the surface _0.02 O ₂ . The samples were tested for catalytic performance, sample preparation steps and catalytic The chemical test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 291°C, that of NO was 258°C, and that of HC was 285°C.

Example 40

Take a certain volume of palladium nitrate and platinum nitrate solution and 200g of Al _0.48 Ce _0.175 Zr _0.3 La _0.018 Nd _0.018 Y _0.009 O ₂ powder according to the load of palladium 0.9% and platinum 0.5% and mix evenly, then dry the sample at 110°C After 4 hours, the sample was heat-treated at 650°C for 5 hours, and finally the sample was reduced and roasted at 500°C for 5 hours under a hydrogen atmosphere to obtain a catalyst sample PdPt/Al _0.48 with grain boundaries of cerium-zirconium composite oxide and noble metals Pd and Pt on the surface. Ce _0.175 Zr _0.3 La _0.018 Nd _0.018 Y _0.009 O ₂ . The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 1. The test results showed that the light-off temperature of CO was 273°C, the light-off temperature of NO was 285°C, and the light-off temperature of HC was 277°C.

Example 41

Take the cerium-zirconium composite oxide supported noble metal catalyst PdPt/Al _0.48 Ce _0.175 Zr _0.3 La _0.018 Nd _0.018 Y _0.009 O ₂ 200g prepared according to Example 40, an appropriate amount of activated alumina and a certain amount of binder, acidity regulator, Deionized water and the like are adjusted into the coating slurry; then the prepared slurry is coated on the ceramic honeycomb carrier according to the coating amount of the honeycomb catalyst precious metal total loading of 1.4g/L, and the coated honeycomb carrier is placed on the Dry at 110°C for 4 hours, then heat-treat the honeycomb carrier at 250°C for 4 hours, and finally bake the honeycomb carrier at 470°C for 16 hours to obtain a honeycomb-type noble metal catalyst; precious metals Pd and Pt are loaded on the honeycomb-type noble metal catalyst. grain boundaries and surfaces of the material and alumina. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 2. The test results showed that the light-off temperature of CO was 253°C, that of NO was 264°C, and that of HC was 269°C.

Example 42

Take a certain volume of palladium nitrate, platinum nitrate solution and 200g Ce _0.30 Zr _0.61 La _0.044 Gd _0.04 Cu _0.006 O ₂ powder according to the load of palladium 0.01% and platinum 2%, mix evenly, and then dry the sample at 110°C for 4 hours , then heat-treated the sample at 270°C for 12 hours, then fired the sample for the first time at 440°C for 3 hours in an air atmosphere, and finally fired the sample for a second time at 620°C for 3 hours in an air atmosphere to obtain cerium-zirconium Composite oxide grain boundary and surface supported noble metal Pd, Pt catalyst sample PdPt/Ce _0.30 Zr _0.61 La _0.044 Gd _0.04 Cu _0.006 O ₂ . Catalytic performance test on samples, sample preparation steps The catalytic test conditions are the same as in Comparative Example 1. The test results show that the light-off temperature of CO is 283°C, the light-off temperature of NO is 272°C, and the light-off temperature of HC is 278°C.

Example 43

Take a certain volume of platinum nitrate solution and mix with 200g activated alumina powder according to the load of 0.5% platinum, then dry the sample at 110°C for 4 hours, then heat-treat the sample at 350°C for 7 hours, and finally dry the sample under hydrogen Reduction roasting at 500° C. for 5 hours under atmosphere to obtain a catalyst sample Pt/Al ₂ O ₃ with alumina grain boundaries and noble metal Pt supported on the surface.

According to the mass ratio of Pt/Al ₂ O ₃ and cerium-zirconium powder of 4:1, take the prepared Pt/Al ₂ O ₃ 320g, Ce _0.13 Zr _0.64 La _0.03 Nd _0.03 Mn _0.17 O ₂ 80g and a certain amount of viscose Adjuvant, acidity regulator, deionized water, etc. were adjusted into a coating slurry; then the above prepared slurry was coated on the honeycomb carrier according to the coating amount of the honeycomb catalyst precious metal total loading of 0.8g/L, and the coated The covered honeycomb carrier was dried at 110°C for 4 hours, then the honeycomb carrier was heat-treated at 270°C for 7 hours, and finally the honeycomb carrier was fired at 500°C for 5 hours to obtain a honeycomb-type noble metal catalyst; precious metal Pt was loaded on the honeycomb-type noble metal catalyst. Grain boundaries and surfaces of cerium-zirconium composite oxides and alumina. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 2. The test results showed that the light-off temperature of CO was 277°C, the light-off temperature of NO was 273°C, and the light-off temperature of HC was 281°C.

Example 44

Take the cerium-zirconium composite oxide supported noble metal catalyst PtRh/Ce _0.13 Zr _0.64 La _0.03 Nd _0.03 Mn _0.17 O ₂ 200g prepared according to Example 23, take the Pt/Al ₂ O ₃ 200g prepared according to Example 43, and mix PtRh /Ce _0.13 Zr _0.64 La _0.03 Nd _0.03 Mn _0.17 O ₂ and Pt/Al ₂ O ₃ and a certain amount of binder, acidity regulator, deionized water, etc. to prepare coating slurry; The coating amount of 2.5g/L will coat the prepared slurry on the ceramic honeycomb carrier, dry the coated honeycomb carrier at 110°C for 4 hours, then heat-treat the honeycomb carrier at 400°C for 3 hours, and finally apply the The honeycomb support is calcined at 550° C. for 6 hours to obtain a honeycomb-type noble metal catalyst; noble metals Pt and Rh are loaded on the grain boundaries and surfaces of the cerium-zirconium composite oxide and alumina of the honeycomb-type noble metal catalyst. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 2. The test results showed that the light-off temperature of CO was 253°C, that of NO was 249°C, and that of HC was 255°C.

Example 45

Take 200g of Pt/Al ₂ O ₃ prepared according to Example 43 and a certain amount of adhesive, acidity regulator, deionized water, etc. to make a coating slurry; Coat the alumina slurry on the ceramic honeycomb support, and dry the coated honeycomb support at 110°C for 4 hours; take 200g of cerium-zirconium composite oxide Ce _0.30 Zr _0.61 La _0.044 Gd _0.04 Cu _0.006 O ₂ , and mix Ce _0.30 Zr _0.61 La _0.044 Gd _0.04 Cu _0.006 O ₂ and a certain amount of binder, acidity regulator, deionized water, etc. to prepare coating slurry; then the slurry containing Ce _0.30 Zr _0.61 La _0.044 Gd _0.04 Cu _0.006 O ₂ The material was coated on the above-mentioned honeycomb carrier coated with Pt/Al ₂ O ₃ at a coating amount of 100g/L, and the coated honeycomb carrier was dried at 110°C for 4 hours, and then the honeycomb carrier was heat-treated at 530°C for 7 hours, and finally the honeycomb support was calcined at 640°C for 5 hours to obtain a honeycomb-type noble metal catalyst; the noble metal Pt was mainly supported on the grain boundaries and surfaces of the Pt/Al ₂ O ₃ of the honeycomb-type noble metal catalyst, and a small amount was supported on the cerium-zirconium composite oxidation grain boundaries and surfaces of the material and alumina. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 2. The test results showed that the light-off temperature of CO was 293°C, that of NO was 288°C, and that of HC was 287°C.

Example 46

Take 200g of cerium-zirconium composite oxide Ce _0.3 Zr _0.6 La _0.05 Pr _0.05 O ₂ and activated alumina respectively, add a certain amount of deionized water and mix evenly, according to the honeycomb support active coating contains palladium 0.45%, platinum 0.13%, rhodium Add a certain amount of palladium, platinum, and rhodium nitrates to the slurry at a loading capacity of 0.01%, and then add a certain amount of binder, acidity regulator, deionized water, etc. to make a coating slurry; then press the honeycomb catalyst The coating amount of the total precious metal loading is 1.18g/L. The prepared slurry is coated on the ceramic honeycomb carrier, and then the coated honeycomb carrier is dried at 110°C for 4 hours, and then the honeycomb carrier is heat-treated at 650°C for 4 hours. Hours, and finally the honeycomb support was reduced and roasted at 550°C for 6 hours under a hydrogen atmosphere to obtain a honeycomb-type noble metal catalyst; noble metals Pd, Pt, and Rh were loaded on the grain boundaries and at the surface. The catalytic performance test was carried out on the sample. The sample preparation steps and catalytic test conditions were the same as in Comparative Example 2. The test results showed that the light-off temperature of CO was 281°C, that of NO was 294°C, and that of HC was 287°C.

As can be seen from the above comparative examples and examples, the grain boundary and surface loading provided by the examples of the present invention The preparation method of the noble metal catalyst and the honeycomb type noble metal catalyst, through the control of the atmosphere, temperature and time of the heat treatment and roasting steps, the obtained grain boundary and surface loaded noble metal catalyst and the honeycomb type noble metal catalyst can be passed through 1000 ° C for 4 hours After aging, the light-off temperatures for CO, NO _X , and HC are significantly lower than those of the catalyst prepared by the conventional method of the comparative example, and have good high temperature resistance stability and catalytic activity. This embodiment of the present invention prevents the migration, agglomeration and growth of noble metal particles by diffusing the noble metal to the grain boundaries and surfaces of the cerium-zirconium composite oxide or the active coating containing cerium-zirconium composite oxide and alumina, thereby better The catalytic activity of the noble metal catalyst is maintained, the high temperature stability is improved, and the consumption amount of the noble metal is reduced.

In summary, the present invention relates to a grain boundary and surface-loaded noble metal catalyst, a honeycomb type noble metal catalyst, and a preparation method and application thereof. The noble metal is dispersed at the grain boundaries and surfaces of the alumina and/or cerium-zirconium composite oxide. The present invention supports and diffuses the noble metal to the grain boundary and surface of the catalyst, and there are abundant defect sites at the grain boundary and the surface, which can improve the activity of the noble metal, realize the anchoring effect of the noble metal, and avoid the migration, agglomeration and growth of the noble metal particles. Large, maintain the catalytic activity and high temperature stability of the noble metal catalyst, and reduce the amount of noble metal used.

It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principle of the present invention, and not to limit the present invention. Therefore, any modification, equivalent replacement, improvement, etc. made without departing from the spirit and scope of the present invention shall fall within the protection scope of the present invention. Furthermore, it is intended that the appended claims of the present invention embrace all changes and modifications that come within the scope and metesques of the appended claims, or equivalents of such scope and metes and bounds.

Claims (19)

A catalyst for carrying precious metals on grain boundaries and surfaces, characterized in that the catalyst comprises noble metal G, alumina and/or cerium-zirconium composite oxides, and the precious metal G is dispersed in alumina and/or cerium-zirconium composite oxides At the grain boundary and surface, the general chemical formula of cerium-zirconium composite oxide is _{Cex Zry} M _z O _2-α D _δ ; where, M is a cation doping element, and D is an anion doping element; 0≤x≤1, 0≤y≤1, 0≤z<0.5, and x, y, z satisfy x+y+z=1; 0≤α≤0.1; 0≤δ≤0.1. A kind of honeycomb type precious metal catalyst, it is characterized in that, described catalyst comprises honeycomb carrier, noble metal G and active coating, active coating contains aluminum oxide and/or cerium zirconium composite oxide C _{x Zry} M _z O _2-α D _δ ; the noble metal G is dispersed at the grain boundaries and surfaces of the active coating; wherein, M is a cation doping element, and D is an anion doping element; 0≤x≤1, 0≤y≤1, 0≤z<0.5, and x, y, z satisfy x+y+z=1; 0≤α≤0.1; 0≤δ≤0.1. The catalyst according to claim 2, characterized in that the percentage of the cerium-zirconium composite oxide in the total mass of the active coating is 0-100%, preferably 30-70%. The catalyst according to any one of claims 1-3, characterized in that the noble metal G at the grain boundaries and surfaces is in a metallic state, or in a metallic state and an oxidized state. The catalyst according to any one of claims 1-4, wherein the noble metal G comprises one or more combinations of Pt, Pd, Rh, Ir, Os, Ru, Au and Ag, It preferably includes one or a combination of more than one of Pt, Pd, Rh and Ru. The catalyst according to any one of claims 1-5, wherein the doping element M includes non-cerium rare earth elements, transition metal elements other than zirconium and rare earth elements, alkaline earth metal elements, and Al, Si, One or more combinations of Ga, Sn and Bi, non-cerium rare earth elements include La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc and Y , preferably including La, Pr, Nd, Sm, Eu, Gd, Tm, Yb and Y; transition metal elements include Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo, Hf, Ta and W , preferably including Ti, Mn, Fe, Co, Ni, Cu, Nb, Hf, W and Mo; alkaline earth metal elements include Be, Mg, Ca, Sr, Ba, preferably Mg, Sr, Ba. The catalyst according to any one of claims 1-6, characterized in that, the doping element D includes one or a combination of anions N, F and P. The honeycomb carrier catalyst according to claim 2, characterized in that the material of the honeycomb carrier is porous ceramics or metal. The catalyst supporting noble metals on grain boundaries and surfaces according to claim 1, characterized in that the loading amount of noble metal G in the catalyst is 0.01%-3%, preferably 0.1%-2%, in terms of mass fraction. The honeycomb carrier catalyst according to claim 2, characterized in that the loading amount of noble metal G in the catalyst is 0.01-2.8 g/L, preferably 0.1-2 g/L. The catalyst according to any one of claims 1-10, characterized in that the cerium-zirconium composite oxide in the catalyst comprises a cerium-zirconium composite oxide with a gradient distribution of elements and/or a cerium-zirconium composite oxide with a core-shell structure. A kind of preparation method of the catalyst of grain boundary and surface load noble metal as claimed in claim 1,4-7,9 or 11, it is characterized in that, preparation steps are as follows: S1, uniformly mixing the cerium-zirconium composite oxide and/or activated alumina with the liquid salt of noble metal G; S2. Carrying out one or two heat treatments to the product obtained in step S1; S3. Carrying out one or two reduction calcinations on the product obtained in step S2 under air or a reducing atmosphere to obtain cerium-zirconium composite oxide and/or active alumina grain boundaries and a catalyst loaded with precious metals on the surface. A method for preparing a honeycomb type noble metal catalyst as claimed in claim 2-8, 10 or 11, wherein the honeycomb type noble metal catalyst is layered or partitioned and coated with one or more coating materials, so The above-mentioned coating materials include cerium-zirconium composite oxides, alumina, grain boundaries and surface-loaded cerium-zirconium composite oxides, grain boundaries and surface-loaded noble metals, cerium-zirconium composite oxides, and grain boundaries and surfaces of alumina a mixture of loaded noble metals, the honeycomb-type noble metal Catalyst preparation steps are as follows: B1. Mix one or more coating materials with adhesive, acidity regulator and water in one or more steps to make a coating slurry; B2, coating the coating slurry obtained in step B1 on the honeycomb carrier in one or more steps, or coating the honeycomb carrier in partitions or layers, and drying; B3. Heat-treating or/and roasting the product obtained in step B2 under air or a reducing atmosphere to obtain a honeycomb-type noble metal catalyst. A preparation method of the honeycomb type noble metal catalyst as claimed in claim 2-8, 10, 11 or 13, characterized in that, the liquid salt, acidity The conditioner, adhesive and water are uniformly mixed in one or more steps to make a coating slurry; the obtained slurry is coated on the honeycomb carrier in one or more steps, or the obtained slurry is coated in partitions or layers to the honeycomb carrier and dried; the dried honeycomb carrier is subjected to heat treatment or/and reduction roasting in a reducing atmosphere. The method according to any one of claims 12-14, characterized in that, the heat treatment temperature is 200-800°C, and the heat treatment time is 0.5-24h; the preferred heat treatment temperature is 400-700°C, and the preferred heat treatment time is 1 -12h. The method according to claims 12-14, characterized in that the calcination temperature is 400-700°C, and the time is 0.5h-24h; the preferred calcination temperature is 450-600°C, and the preferred calcination time is 1h-12h. The method according to claims 12-14, characterized in that the reducing atmosphere includes one or more of CO and _H2 . The method according to claims 12 and 14, characterized in that the liquid salt of noble metal G includes one or more combinations of molten salts or aqueous solutions of chloride salts, nitrates and acetates. The application of the catalyst according to any one of claims 1-12 in the fields of motor vehicle tail gas purification, industrial organic waste gas treatment, catalytic combustion of natural gas, petrochemical industry, hydrogen energy and batteries.