Preparation method of internal combustion engine tail gas purification catalyst

Abstract

The invention relates to a preparation method of an internal combustion engine tail gas purification catalyst. The preparation method of the internal combustion engine tail gas purification catalyst comprises the following steps: providing a ceramic carrier, a supporting carrier material, an oxygen storage material and a noble metal precursor; mixing the oxygen storage material with carbon powder, and roasting to obtain a prefabricated oxygen storage body; preparing the precious metal precursor into a solution, and dipping the solution on the surface of the prefabricated oxygen storage body to obtain a prefabricated oxygen storage catalytic body; calcining the prefabricated oxygen storage catalytic body to obtain an oxygen storage catalytic material; the oxygen storage catalytic material and the support carrier material are prepared into slurry, the slurry is arranged on the ceramic carrier, the slurry on the surface of the carrier is dried and sintered, and the internal combustion engine tail gas purification catalyst is obtained. According to the preparation method, the oxygen storage material and the carbon powder are mixed and then roasted, and oxygen vacancies are formed on the oxygen storage material, so that the noble metal can be loaded on more dispersion sites, and the dispersion degree of the noble metal is relatively high.

Description

Technical Field

[0001] The present application relates to energy conservation and environmental protection, and in particular to tail gas treatment. Background Art

[0002] Most exhaust aftertreatment systems in the world are made by coating a catalytic coating with a certain proportion on a honeycomb ceramic carrier. The raw materials of the catalytic coating mostly include aluminum oxide, and the oxygen storage materials are mostly cerium oxide, zirconium oxide or cerium-zirconium solid solution, other metal oxides and some additives. The prepared catalyst is installed in the front exhaust pipe, and when the exhaust gas flows through, it converts the main pollutants such as carbon monoxide (CO), hydrocarbons (HCs) and nitrogen oxides (NOx) into carbon dioxide (CO2), water (H2O) and nitrogen (N2).

[0003] Traditional catalyst preparation technology usually directly loads precious metals such as platinum (Pt), rhodium (Rh), palladium (Pd) on the raw material powder of the catalytic coating through a simple impregnation method, and then dries it as a catalyst raw material and mixes it with water and additives such as a binder to make a slurry, which is coated on a honeycomb ceramic carrier in a single layer or two to three layers. After drying, calcining, labeling and other steps, the catalyst is made. The catalyst made by traditional technology has low dispersion of precious metals, resulting in low catalytic efficiency. Summary of the invention

[0004] The embodiment of the present application provides a method for preparing an internal combustion engine exhaust gas purification catalyst to solve the technical problem of low dispersion of precious metals in the exhaust gas purification catalyst.

[0005] The present invention provides a method for preparing an internal combustion engine exhaust gas purification catalyst, and the method for preparing an internal combustion engine exhaust gas purification catalyst comprises the following steps:

[0006] Provide ceramic carriers, support carrier materials, oxygen storage materials and precious metal precursors;

[0007] The oxygen storage material is mixed with carbon powder and then calcined to obtain a prefabricated oxygen storage body;

[0008] The noble metal precursor is prepared into a solution and then impregnated onto the surface of the prefabricated oxygen storage body to obtain a prefabricated oxygen storage catalyst body;

[0009] calcining the prefabricated oxygen storage catalyst to obtain an oxygen storage catalyst material;

[0010] The oxygen storage catalytic material and the supporting carrier material are made into slurry, the slurry is set on the ceramic carrier, and the slurry on the surface of the carrier is dried and sintered to obtain the internal combustion engine exhaust gas purification catalyst.

[0011] In some embodiments of the present application, the mass of the carbon powder accounts for 1% to 5% of the mass of the oxygen storage material; and / or,

[0012] The particle size of the carbon powder is between 0.5 and 20 μm; and / or,

[0013] The carbon powder is at least one of graphene and carbon black.

[0014] In some embodiments of the present application, the calcination temperature is 500-900° C.; and / or,

[0015] The duration of the calcination is 1 to 2 hours.

[0016] In some embodiments of the present application, the calcination temperature is 450-550° C.; and / or,

[0017] The calcination duration is 0.5 to 2 hours.

[0018] In some embodiments of the present application, the sintering temperature is 500-550° C.; and / or,

[0019] The sintering duration is 1 to 5 hours.

[0020] In some embodiments of the present application, the slurry further includes a binder and carboxymethyl cellulose.

[0021] In some embodiments of the present application, in the slurry, the mass ratio of the oxygen storage catalytic material, the supporting carrier material, the binder, and the carboxymethyl cellulose is 30-50:50-70:3-7:0.7-7.

[0022] In some embodiments of the present application, the ceramic carrier includes cordierite; and / or,

[0023] The support carrier material comprises at least one of alumina and silica; and / or,

[0024] The oxygen storage material comprises at least one of ceria and zirconium oxide; and / or,

[0025] The precious metal precursor includes at least one of H2PdCl6, K2PdCl6, Na2PdCl6, H2PtCl6, K2PtCl6, Na2PtCl6, H2RhCl6, K2RhCl6, and Na2RhCl6.

[0026] In some embodiments of the present application, the noble metal precursor includes a platinum precursor, a palladium precursor and a rhodium precursor, and the loading amount of Pd in ​​the internal combustion engine exhaust purification catalyst is 10 to 90 g / ft 3 , Pt loading is 10~140g / ft 3 , Rh loading is 1~40g / ft 3 .

[0027] In some embodiments of the present application, the internal combustion engine exhaust gas purification catalyst includes a front-stage catalyst and a rear-stage catalyst, the carrier includes a front-stage carrier and a rear-stage carrier, the front-stage catalyst includes the front-stage carrier, the rear-stage catalyst includes the rear-stage carrier, the front-stage catalyst also includes a first catalytic section and a second catalytic section distributed in sequence according to the exhaust gas flow direction, wherein the first catalytic section includes a palladium-rhodium catalytic layer arranged on the surface of the carrier and a platinum catalytic layer arranged on the surface of the palladium-rhodium catalytic layer, the second catalytic section includes a palladium catalytic layer arranged on the surface of the carrier and a platinum catalytic layer arranged on the surface of the palladium catalytic layer, and the rear-stage catalyst includes a platinum catalytic layer arranged on the surface of the carrier,

[0028] Wherein, the palladium-rhodium catalyst layer is formed by the slurry including palladium and rhodium, the palladium catalyst layer is formed by the slurry including palladium, and the platinum catalyst layer is formed by the slurry including platinum.

[0029] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0030] The preparation method of the internal combustion engine exhaust gas purification catalyst provided in the embodiment of the present application forms oxygen vacancies on the oxygen storage material by mixing the oxygen storage material with carbon powder and then calcining the mixture, so that the precious metal can be loaded on more dispersed sites, resulting in a higher dispersion degree of the precious metal. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0032] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0033] Figure 1 A schematic flow chart of a method for preparing an internal combustion engine exhaust purification catalyst provided in an embodiment of the present application. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0035] Unless otherwise specified, the terms used herein should be understood as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. In the event of a conflict, this specification takes precedence.

[0036] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0037] Existing exhaust gas purification catalysts have the technical problem of low dispersion of precious metals.

[0038] The technical solution provided by the embodiments of the present application is to solve the above technical problems, and the overall idea is as follows:

[0039] The present invention provides a method for preparing an internal combustion engine exhaust gas purification catalyst, and the method for preparing an internal combustion engine exhaust gas purification catalyst comprises the following steps:

[0040] S1: Provide ceramic carrier, support carrier material, oxygen storage material and precious metal precursor;

[0041] S2: mixing the oxygen storage material and carbon powder and then calcining them to obtain a prefabricated oxygen storage body;

[0042] S3: preparing the noble metal precursor into a solution and impregnating the solution onto the surface of the prefabricated oxygen storage body to obtain a prefabricated oxygen storage catalyst;

[0043] S4: calcining the prefabricated oxygen storage catalyst to obtain an oxygen storage catalyst material;

[0044] S5: preparing the oxygen storage catalytic material and the supporting carrier material into slurry, placing the slurry on the ceramic carrier, and drying and sintering the slurry on the surface of the carrier to obtain the internal combustion engine exhaust gas purification catalyst.

[0045] It is easy to understand that the ceramic carrier is a conventional material in the art, and is usually a ceramic member having a porous structure at the microscopic level and a tubular shape at the macroscopic level.

[0046] It is easy to understand that the supporting carrier material is a conventional material in this field. The supporting carrier is usually alumina, silica and other materials, which have good thermal stability and mechanical strength and can provide good support for the dispersion and fixation of oxygen storage materials and precious metals.

[0047] It is easy to understand that the oxygen storage material is a conventional material in the art, which can release or absorb oxygen when the external oxygen concentration changes. The oxygen storage material is usually a material such as cerium dioxide and zirconium oxide.

[0048] It is easy to understand that the role of precious metals in the internal combustion engine exhaust purification catalyst is to catalyze the oxidation of nitrogen oxides, carbon monoxide, and hydrocarbons in the exhaust gas. The precious metal precursor is used to form precious metals, and the precious metals in the internal combustion engine exhaust purification catalyst are usually Pt, Pd, Rh, etc.

[0049] In step S2, the oxygen storage material is mixed with carbon powder and then calcined to cause a reduction reaction in the oxygen storage material, so that crystal defects in the form of oxygen vacancies are formed on the surface of the oxygen storage material. The size of the oxygen vacancies is very small and the surface energy is very high. When the noble metal precursor decomposes into noble metals, it will first nucleate at the oxygen vacancies. The more oxygen vacancies there are, the more sites the noble metal can nucleate, and the dispersion increases accordingly. The oxygen vacancies formed on the surface of the oxygen storage material can provide more dispersion sites for the noble metal load, which is conducive to increasing the dispersion of the noble metal.

[0050] The present application forms oxygen vacancies on the oxygen storage material by mixing the oxygen storage material with carbon powder and then calcining the mixture, so that the noble metal can be loaded on more dispersed sites, resulting in a higher dispersion degree of the noble metal.

[0051] In some embodiments of the present application, the mass of the carbon powder accounts for 1% to 5% of the mass of the oxygen storage material; and / or,

[0052] The particle size of the carbon powder is between 0.5 and 20 μm; and / or,

[0053] The carbon powder is at least one of graphene and carbon black.

[0054] It is easy to understand that the beneficial effect of the carbon powder accounting for 1% to 5% of the mass of the oxygen storage material is that it can form enough oxygen vacancies without causing some oxygen vacancies to expand due to excessive carbon powder, resulting in a decrease in surface energy, which is not conducive to the nucleation of precious metals.

[0055] It is easy to understand that the beneficial effect of the carbon powder having a particle size of 0.5 to 20 μm is to reduce the particle size of the carbon powder as much as possible within the cost-permitted range and to minimize the size of oxygen vacancies.

[0056] It is easy to understand that graphene and carbon black are both small-particle carbon materials that are easily available in the market.

[0057] In some embodiments of the present application, the calcination temperature is 500-900° C.; and / or,

[0058] The duration of the calcination is 1 to 2 hours.

[0059] As an example, the calcination temperature may be 500°C, 600°C, 700°C, 800°C, or 900°C.

[0060] As an example, the calcination duration may be 1 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h, or 2 h.

[0061] In some embodiments of the present application, the calcination temperature is 450-550° C.; and / or,

[0062] The calcination duration is 0.5 to 2 hours.

[0063] As an example, the calcination temperature may be 450 to 550°C.

[0064] As an example, the calcination duration may be 0.5 to 2 hours.

[0065] In some embodiments of the present application, the sintering temperature is 500-550° C.; and / or,

[0066] The sintering duration is 1 to 5 hours.

[0067] As an example, the sintering temperature may be 450-550°C.

[0068] As an example, the sintering duration may be 0.5 to 2 hours.

[0069] In some embodiments of the present application, the slurry further includes a binder and carboxymethyl cellulose.

[0070] As an example, the binder may be an aluminate binder, a polymer binder, etc. Carboxymethyl cellulose also acts as a binder to a certain extent.

[0071] In some embodiments of the present application, based on the total mass of the non-solvent materials in the slurry, the non-solvent materials in the slurry include: 30wt% to 50wt% of oxygen storage catalytic material, 50wt% to 70wt% of supporting carrier material, 3wt% to 7wt% of binder, and 0.07wt% to 0.7wt% of carboxymethyl cellulose.

[0072] In some embodiments of the present application, the ceramic carrier includes cordierite; and / or,

[0073] The support carrier material comprises at least one of alumina and silica; and / or,

[0074] The oxygen storage material comprises at least one of ceria and zirconium oxide; and / or,

[0075] The precious metal precursor includes at least one of H2PdCl6, K2PdCl6, Na2PdCl6, H2PtCl6, K2PtCl6, Na2PtCl6, H2RhCl6, K2RhCl6, and Na2RhCl6.

[0076] It is easy to understand that the above-mentioned precious metal precursors are different from chloride salts and nitrates which are widely used in the field. The precious metal elements in the above-mentioned precious metal precursors are all present in anions. This is because the oxygen vacancies are positively charged centers with positive charges, which makes it easier for anions containing precious metal elements to be adsorbed on the oxygen vacancies, thereby increasing the dispersibility of the precious metals.

[0077] It should be noted that even if the noble metal precursor is a reagent such as chloride, nitrate, etc. in which the noble metal element exists in the cation, many oxygen vacancies can still load the noble metal due to the high surface energy of oxygen vacancies.

[0078] In some embodiments of the present application, the noble metal precursor includes a platinum precursor, a palladium precursor and a rhodium precursor, and the loading amount of Pd in ​​the internal combustion engine exhaust purification catalyst is 10 to 90 g / ft 3 , Pt loading is 10~140g / ft 3 , Rh loading is 1~40g / ft 3 .

[0079] In some embodiments of the present application, the internal combustion engine exhaust gas purification catalyst includes a front-stage catalyst and a rear-stage catalyst, the carrier includes a front-stage carrier and a rear-stage carrier, the front-stage catalyst includes the front-stage carrier, the rear-stage catalyst includes the rear-stage carrier, the front-stage catalyst also includes a first catalytic section and a second catalytic section distributed in sequence according to the exhaust gas flow direction, wherein the first catalytic section includes a palladium-rhodium catalytic layer arranged on the surface of the carrier and a platinum catalytic layer arranged on the surface of the palladium-rhodium catalytic layer, the second catalytic section includes a palladium catalytic layer arranged on the surface of the carrier and a platinum catalytic layer arranged on the surface of the palladium catalytic layer, and the rear-stage catalyst includes a platinum catalytic layer arranged on the surface of the carrier,

[0080] Wherein, the palladium-rhodium catalyst layer is formed by the slurry including palladium and rhodium, the palladium catalyst layer is formed by the slurry including palladium, and the platinum catalyst layer is formed by the slurry including platinum.

[0081] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to industry standards. If there is no corresponding industry standard, then the conditions recommended by the manufacturer are followed.

[0082] Example 1

[0083] This embodiment provides a method for preparing an internal combustion engine exhaust gas purification catalyst, comprising the following steps:

[0084] Sa: Provide ceramic carriers, support carrier materials, oxygen storage materials and precious metal precursors;

[0085] Sb: the oxygen storage material is mixed with carbon powder and then calcined to obtain a prefabricated oxygen storage body;

[0086] Sc: preparing the noble metal precursor into a solution and then impregnating the solution onto the surface of the prefabricated oxygen storage body to obtain a prefabricated oxygen storage catalyst;

[0087] Sd: calcining the prefabricated oxygen storage catalyst to obtain an oxygen storage catalyst material;

[0088] Se: The oxygen storage catalytic material and the supporting carrier material are made into slurry, the slurry is set on the ceramic carrier, and the slurry on the surface of the carrier is dried and sintered to obtain the internal combustion engine exhaust gas purification catalyst.

[0089] Among them, the material of the ceramic carrier is cordierite, the material of the supporting carrier is alumina, the oxygen storage material is cerium dioxide, and the precious metal precursors include H2PdCl6, H2PtCl6, and H2RhCl6.

[0090] The step Sc comprises the following steps:

[0091] Sc1: After preparing H2PdCl6 into a solution, immersing the prefabricated oxygen storage body into the obtained H2PdCl6 solution, and evaporating the solvent to obtain a palladium-supported prefabricated oxygen storage catalyst;

[0092] Sc2: preparing H2PtCl6 into a solution and impregnating it onto the surface of the prefabricated oxygen storage body to obtain a platinum-loaded prefabricated oxygen storage catalyst body;

[0093] Sc3: Prepare H2RhCl6 into a solution and then impregnate it onto the surface of the prefabricated oxygen storage body to obtain a rhodium-loaded prefabricated oxygen storage catalyst.

[0094] The step Sd comprises the following steps:

[0095] Sd1: calcining the palladium-supported prefabricated oxygen storage catalyst to obtain a palladium-supported oxygen storage catalyst material;

[0096] Sd2: calcining the platinum-supported prefabricated oxygen storage catalyst to obtain a palladium-supported oxygen storage catalyst material;

[0097] Sd3: calcining the rhodium-supported prefabricated oxygen storage catalyst to obtain a palladium-supported oxygen storage catalyst material;

[0098] The ceramic carrier includes a front-stage carrier and a rear-stage carrier, and the front-stage carrier is divided into a first load section and a second load section according to the gas flow direction of the exhaust gas. The step Se includes the following steps:

[0099] Se1: ball-milling the palladium-supported oxygen storage catalytic material, the rhodium-supported oxygen storage catalytic material, the support carrier material, the binder, the carboxymethyl cellulose and water to prepare a first slurry, placing the first slurry on the first loading section, and drying to obtain a first prefabricated catalyst;

[0100] Se2: ball-milling the palladium-supported oxygen storage catalytic material, supporting carrier material, binder, carboxymethyl cellulose and water to prepare a second slurry, placing the second slurry on the second loading section, and drying to obtain a second prefabricated catalyst;

[0101] Se3: ball-milling the platinum-supported oxygen storage catalytic material, supporting carrier material, binder, carboxymethyl cellulose and water to prepare a third slurry, setting the third slurry on the surface formed by drying the first slurry and the second slurry, and drying to obtain a third prefabricated catalyst;

[0102] Se4: placing the third slurry on the subsequent carrier and drying to form a fourth prefabricated catalyst;

[0103] Se5: Sintering the fourth prefabricated catalyst to obtain the internal combustion engine exhaust gas purification catalyst.

[0104] Among them, in the first slurry, the mass ratio of the palladium-supported oxygen storage catalytic material, the rhodium-supported oxygen storage catalytic material, the supporting carrier material, the binder, and the carboxymethyl cellulose is 25:25:50:3:0.7.

[0105] In the second slurry, the mass ratio of the palladium-supported oxygen storage catalytic material, the supporting carrier material, the binder, and the carboxymethyl cellulose is 50:50:3:0.7.

[0106] In the third slurry, the mass ratio of the platinum-supported oxygen storage catalytic material, the supporting carrier material, the binder, and the carboxymethyl cellulose is 50:50:3:0.7.

[0107] The internal combustion engine exhaust gas purification catalyst includes a front-stage catalyst and a rear-stage catalyst, the front-stage catalyst also includes a first catalytic section and a second catalytic section distributed in sequence according to the exhaust gas flow direction, wherein the first catalytic section includes a palladium-rhodium catalytic layer arranged on the surface of the first load section and a platinum catalytic layer arranged on the surface of the palladium-rhodium catalytic layer, the second catalytic section includes a palladium catalytic layer arranged on the surface of the second load section and a platinum catalytic layer arranged on the surface of the palladium catalytic layer, and the rear-stage catalyst includes a platinum catalytic layer arranged on the surface of the rear-stage carrier.

[0108] The noble metal precursor includes a platinum precursor, a palladium precursor and a rhodium precursor. In the internal combustion engine exhaust purification catalyst, the loading amount of Pd is 14 g / ft 3 , the Pt loading is 17 g / ft 3 , the Rh loading is 5g / ft 3 .

[0109] The mass of the carbon powder accounts for 1% of the mass of the oxygen storage material, the average particle size of the carbon powder is between 0.5 and 5 um, and the carbon powder is graphene.

[0110] The calcination temperature is 500° C. and the calcination duration is 2 hours.

[0111] The calcination temperature is 500° C., and the calcination duration is 2 h.

[0112] The sintering temperature is 500° C., and the sintering duration is 2 hours.

[0113] Example 2

[0114] This embodiment provides a method for preparing an internal combustion engine exhaust gas purification catalyst, comprising the following steps:

[0115] Sa: Provide ceramic carriers, support carrier materials, oxygen storage materials and precious metal precursors;

[0116] Sb: the oxygen storage material is mixed with carbon powder and then calcined to obtain a prefabricated oxygen storage body;

[0117] Sc: preparing the noble metal precursor into a solution and then impregnating the solution onto the surface of the prefabricated oxygen storage body to obtain a prefabricated oxygen storage catalyst;

[0118] Sd: calcining the prefabricated oxygen storage catalyst to obtain an oxygen storage catalyst material;

[0119] Se: The oxygen storage catalytic material and the supporting carrier material are made into slurry, the slurry is set on the ceramic carrier, and the slurry on the surface of the carrier is dried and sintered to obtain the internal combustion engine exhaust gas purification catalyst.

[0120] Among them, the material of the ceramic carrier is cordierite, the material of the supporting carrier is alumina, the oxygen storage material is zirconia, and the precious metal precursors include H2PdCl6, H2PtCl6, and H2RhCl6.

[0121] The step Sc comprises the following steps:

[0122] Sc1: After preparing H2PdCl6 into a solution, immersing the prefabricated oxygen storage body into the obtained H2PdCl6 solution, and evaporating the solvent to obtain a palladium-supported prefabricated oxygen storage catalyst;

[0123] Sc2: preparing H2PtCl6 into a solution and impregnating it onto the surface of the prefabricated oxygen storage body to obtain a platinum-loaded prefabricated oxygen storage catalyst body;

[0124] Sc3: Prepare H2RhCl6 into a solution and then impregnate it onto the surface of the prefabricated oxygen storage body to obtain a rhodium-loaded prefabricated oxygen storage catalyst.

[0125] The step Sd comprises the following steps:

[0126] Sd1: calcining the palladium-supported prefabricated oxygen storage catalyst to obtain a palladium-supported oxygen storage catalyst material;

[0127] Sd2: calcining the platinum-supported prefabricated oxygen storage catalyst to obtain a palladium-supported oxygen storage catalyst material;

[0128] Sd3: calcining the rhodium-supported prefabricated oxygen storage catalyst to obtain a palladium-supported oxygen storage catalyst material;

[0129] The ceramic carrier includes a front-stage carrier and a rear-stage carrier, and the front-stage carrier is divided into a first load section and a second load section according to the gas flow direction of the exhaust gas. The step Se includes the following steps:

[0130] Se1: ball-milling the palladium-supported oxygen storage catalytic material, the rhodium-supported oxygen storage catalytic material, the support carrier material, the binder, the carboxymethyl cellulose and water to prepare a first slurry, placing the first slurry on the first loading section, and drying to obtain a first prefabricated catalyst;

[0131] Se2: ball-milling the palladium-supported oxygen storage catalytic material, supporting carrier material, binder, carboxymethyl cellulose and water to prepare a second slurry, placing the second slurry on the second loading section, and drying to obtain a second prefabricated catalyst;

[0132] Se3: ball-milling the platinum-supported oxygen storage catalytic material, supporting carrier material, binder, carboxymethyl cellulose and water to prepare a third slurry, setting the third slurry on the surface formed by drying the first slurry and the second slurry, and drying to obtain a third prefabricated catalyst;

[0133] Se4: placing the third slurry on the subsequent carrier and drying to form a fourth prefabricated catalyst;

[0134] Se5: Sintering the fourth prefabricated catalyst to obtain the internal combustion engine exhaust gas purification catalyst.

[0135] Among them, in the first slurry, the mass ratio of the palladium-supported oxygen storage catalytic material, the rhodium-supported oxygen storage catalytic material, the supporting carrier material, the binder, and the carboxymethyl cellulose is 15:15:70:3:0.07.

[0136] In the second slurry, the mass ratio of the palladium-supported oxygen storage catalytic material, the supporting carrier material, the binder, and the carboxymethyl cellulose is 30:70:3:0.7.

[0137] In the third slurry, the mass ratio of the platinum-supported oxygen storage catalytic material, the supporting carrier material, the binder, and the carboxymethyl cellulose is 30:70:3:0.7.

[0138] The internal combustion engine exhaust gas purification catalyst includes a front-stage catalyst and a rear-stage catalyst, the front-stage catalyst also includes a first catalytic section and a second catalytic section distributed in sequence according to the exhaust gas flow direction, wherein the first catalytic section includes a palladium-rhodium catalytic layer arranged on the surface of the first load section and a platinum catalytic layer arranged on the surface of the palladium-rhodium catalytic layer, the second catalytic section includes a palladium catalytic layer arranged on the surface of the second load section and a platinum catalytic layer arranged on the surface of the palladium catalytic layer, and the rear-stage catalyst includes a platinum catalytic layer arranged on the surface of the rear-stage carrier.

[0139] The noble metal precursor includes a platinum precursor, a palladium precursor and a rhodium precursor. In the internal combustion engine exhaust purification catalyst, the loading amount of Pd is 14 g / ft 3 , the Pt loading is 17 g / ft 3 , the Rh loading is 5g / ft 3 .

[0140] The mass of the carbon powder accounts for 2% of the mass of the oxygen storage material, the particle size of the carbon powder is between 10 and 20 um, and the carbon powder is carbon black.

[0141] The calcination temperature is 900° C. and the calcination duration is 1 hour.

[0142] The calcination temperature is 450° C., and the calcination duration is 0.5 h.

[0143] The sintering temperature is 550° C., and the sintering duration is 1 hour.

[0144] Example 3

[0145] This embodiment provides a method for preparing an internal combustion engine exhaust gas purification catalyst, comprising the following steps:

[0146] Sa: Provide ceramic carriers, support carrier materials, oxygen storage materials and precious metal precursors;

[0147] Sb: the oxygen storage material is mixed with carbon powder and then calcined to obtain a prefabricated oxygen storage body;

[0148] Sc: preparing the noble metal precursor into a solution and then impregnating the solution onto the surface of the prefabricated oxygen storage body to obtain a prefabricated oxygen storage catalyst;

[0149] Sd: calcining the prefabricated oxygen storage catalyst to obtain an oxygen storage catalyst material;

[0150] Se: The oxygen storage catalytic material and the supporting carrier material are made into slurry, the slurry is set on the ceramic carrier, and the slurry on the surface of the carrier is dried and sintered to obtain the internal combustion engine exhaust gas purification catalyst.

[0151] Among them, the material of the ceramic carrier is cordierite, the supporting carrier material is alumina, the oxygen storage material includes cerium dioxide and zirconium oxide, wherein the mass ratio of cerium dioxide to zirconium oxide is 1:1, and the precious metal precursors include H2PdCl6, H2PtCl6, and H2RhCl6.

[0152] The step Sc comprises the following steps:

[0153] Sc1: After preparing H2PdCl6 into a solution, immersing the prefabricated oxygen storage body into the obtained H2PdCl6 solution, and evaporating the solvent to obtain a palladium-supported prefabricated oxygen storage catalyst;

[0154] Sc2: preparing H2PtCl6 into a solution and impregnating it onto the surface of the prefabricated oxygen storage body to obtain a platinum-loaded prefabricated oxygen storage catalyst body;

[0155] Sc3: Prepare H2RhCl6 into a solution and then impregnate it onto the surface of the prefabricated oxygen storage body to obtain a rhodium-loaded prefabricated oxygen storage catalyst.

[0156] The step Sd comprises the following steps:

[0157] Sd1: calcining the palladium-supported prefabricated oxygen storage catalyst to obtain a palladium-supported oxygen storage catalyst material;

[0158] Sd2: calcining the platinum-supported prefabricated oxygen storage catalyst to obtain a palladium-supported oxygen storage catalyst material;

[0159] Sd3: calcining the rhodium-supported prefabricated oxygen storage catalyst to obtain a palladium-supported oxygen storage catalyst material;

[0160] The ceramic carrier includes a front-stage carrier and a rear-stage carrier, and the front-stage carrier is divided into a first load section and a second load section according to the gas flow direction of the exhaust gas. The step Se includes the following steps:

[0161] Se1: ball-milling the palladium-supported oxygen storage catalytic material, the rhodium-supported oxygen storage catalytic material, the support carrier material, the binder, the carboxymethyl cellulose and water to prepare a first slurry, placing the first slurry on the first loading section, and drying to obtain a first prefabricated catalyst;

[0162] Se2: ball-milling the palladium-supported oxygen storage catalytic material, supporting carrier material, binder, carboxymethyl cellulose and water to prepare a second slurry, placing the second slurry on the second loading section, and drying to obtain a second prefabricated catalyst;

[0163] Se3: ball-milling the platinum-supported oxygen storage catalytic material, supporting carrier material, binder, carboxymethyl cellulose and water to prepare a third slurry, setting the third slurry on the surface formed by drying the first slurry and the second slurry, and drying to obtain a third prefabricated catalyst;

[0164] Se4: placing the third slurry on the subsequent carrier and drying to form a fourth prefabricated catalyst;

[0165] Se5: Sintering the fourth prefabricated catalyst to obtain the internal combustion engine exhaust gas purification catalyst.

[0166] Among them, in the first slurry, the mass ratio of the palladium-supported oxygen storage catalytic material, the rhodium-supported oxygen storage catalytic material, the supporting carrier material, the binder, and the carboxymethyl cellulose is 20:20:60:5:0.4.

[0167] In the second slurry, the mass ratio of the palladium-supported oxygen storage catalytic material, the supporting carrier material, the binder, and the carboxymethyl cellulose is 40:60:5:0.4.

[0168] In the third slurry, the mass ratio of the platinum-supported oxygen storage catalytic material, the supporting carrier material, the binder, and the carboxymethyl cellulose is 40:60:5:0.4.

[0169] The internal combustion engine exhaust gas purification catalyst includes a front-stage catalyst and a rear-stage catalyst, the front-stage catalyst also includes a first catalytic section and a second catalytic section distributed in sequence according to the exhaust gas flow direction, wherein the first catalytic section includes a palladium-rhodium catalytic layer arranged on the surface of the first load section and a platinum catalytic layer arranged on the surface of the palladium-rhodium catalytic layer, the second catalytic section includes a palladium catalytic layer arranged on the surface of the second load section and a platinum catalytic layer arranged on the surface of the palladium catalytic layer, and the rear-stage catalyst includes a platinum catalytic layer arranged on the surface of the rear-stage carrier.

[0170] The noble metal precursor includes a platinum precursor, a palladium precursor and a rhodium precursor. In the internal combustion engine exhaust purification catalyst, the loading amount of Pd is 14 g / ft 3 , the Pt loading is 17 g / ft 3 , the Rh loading is 5g / ft 3 .

[0171] The mass of the carbon powder accounts for 5% of the mass of the oxygen storage material, the particle size of the carbon powder is between 0.5 and 20 um, and the carbon powder is a mixture of graphene and carbon black, wherein the mass ratio of graphene to carbon black is 1:1.

[0172] The calcination temperature is 700° C. and the calcination duration is 1.5 h.

[0173] The calcination temperature is 550° C., and the calcination duration is 2 h.

[0174] The sintering temperature is 530° C., and the sintering duration is 3 hours.

[0175] Comparative Example

[0176] The only difference between this comparative example and Example 1 is that no carbon powder is used in step Sb.

[0177] Step Sb is:

[0178] The oxygen storage material is calcined to obtain a prefabricated oxygen storage body.

[0179] Related experiments and effect data:

[0180] The ignition temperature and complete conversion temperature of Examples 1 to 3 and the comparative example were tested in accordance with the national standard GB / T 34248-2017. The results are shown in Table 1.

[0181] Table 1 Ignition temperature and complete conversion temperature test results

[0182] Catalyst No. Ignition temperature / ℃ Complete conversion temperature / ℃ Example 1 348 370 Example 2 343 368 Example 3 337 357 Comparative Example 351 375

[0183] The catalytic efficiency of a three-way catalyst is usually characterized by the ignition temperature and complete conversion temperature in the ignition curve of the three-way catalyst. The lower the ignition temperature and complete conversion temperature, the higher the catalytic efficiency. As can be seen from Table 1, the ignition temperature and complete conversion temperature of Examples 1 to 3 are significantly lower than those of the comparative example, which indicates that the addition of carbon powder during the calcination process of the present application may help increase the catalytic efficiency of the three-way catalyst by increasing the dispersion of the precious metal.

[0184] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0185] In the present application, in the absence of any contrary description, the directional words used, such as "upper" and "lower", are specifically the directions of the drawings in the accompanying drawings. In addition, in the description of the present application specification, the terms "including", "comprising", etc. refer to "including but not limited to". Moreover, the terms "including", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of further restrictions, the elements defined by the sentence "including..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements. In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. For the association relationship of more than three associated objects described by "and / or", it means that any one of the three associated objects can exist alone, or any at least two of them can exist at the same time. For example, for A, and / or B, and / or C, it can mean that any one of A, B, and C exists alone, or any two of them exist at the same time, or three of them exist at the same time. In this article, "at least one" means one or more, and "multiple" means two or more. "At least one", "the following at least one (one)" or similar expressions refer to any combination of these items, including any combination of single (one) or plural (one). For example, "at least one (one) of a, b, or c", or "at least one (one) of a, b, and c", can all represent: a, b, c, a~b (i.e. a and b), a~c, b~c, or a~b~c, where a, b, and c can be single or multiple, respectively.

[0186] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for preparing an internal combustion engine exhaust gas purification catalyst, characterized in that: The preparation method of the internal combustion engine exhaust gas purification catalyst comprises the following steps: Provide ceramic carriers, support carrier materials, oxygen storage materials and precious metal precursors; The oxygen storage material is mixed with carbon powder and then calcined to obtain a prefabricated oxygen storage body; The noble metal precursor is prepared into a solution and then impregnated onto the surface of the prefabricated oxygen storage body to obtain a prefabricated oxygen storage catalyst body; calcining the prefabricated oxygen storage catalyst to obtain an oxygen storage catalyst material; The oxygen storage catalytic material and the supporting carrier material are made into slurry, the slurry is set on the ceramic carrier, and the slurry on the surface of the carrier is dried and sintered to obtain the internal combustion engine exhaust gas purification catalyst.

2. The method for preparing an internal combustion engine exhaust gas purification catalyst according to claim 1, characterized in that: The mass of the carbon powder accounts for 1% to 5% of the mass of the oxygen storage material; and / or, The particle size of the carbon powder is between 0.5 and 20 μm; and / or, The carbon powder is at least one of graphene and carbon black.

3. The method for preparing an internal combustion engine exhaust gas purification catalyst according to claim 1, characterized in that: The calcination temperature is 500-900° C.; and / or, The duration of the calcination is 1 to 2 hours.

4. The method for preparing an internal combustion engine exhaust gas purification catalyst according to claim 1, characterized in that: The calcination temperature is 450-550° C.; and / or, The calcination duration is 0.5 to 2 hours.

5. The method for preparing an internal combustion engine exhaust gas purification catalyst according to claim 1, characterized in that: The sintering temperature is 500-550° C.; and / or, The sintering duration is 1 to 5 hours.

6. The method for preparing an internal combustion engine exhaust gas purification catalyst according to claim 1, characterized in that: The slurry also includes a binder and carboxymethyl cellulose.

7. The method for preparing an internal combustion engine exhaust gas purification catalyst according to claim 6, characterized in that: In the slurry, the mass ratio of the oxygen storage catalytic material, the supporting carrier material, the binder and the carboxymethyl cellulose is 30-50:50-70:3-7:0.7-7.

8. The method for preparing an internal combustion engine exhaust gas purification catalyst according to claim 1, characterized in that: The ceramic carrier comprises cordierite; and / or, The support carrier material comprises at least one of alumina and silica; and / or, The oxygen storage material comprises at least one of ceria and zirconium oxide; and / or, The precious metal precursor includes at least one of H2PdCl6, K2PdCl6, Na2PdCl6, H2PtCl6, K2PtCl6, Na2PtCl6, H2RhCl6, K2RhCl6, and Na2RhCl6.

9. The method for preparing an internal combustion engine exhaust gas purification catalyst according to claim 1, characterized in that: The noble metal precursor includes a platinum precursor, a palladium precursor and a rhodium precursor. In the internal combustion engine exhaust purification catalyst, the loading amount of Pd is 10 to 90 g / ft 3 , Pt loading is 10~140g / ft 3 , Rh loading is 1~40g / ft 3 .

10. The method for preparing an internal combustion engine exhaust gas purification catalyst according to claim 9, characterized in that: The internal combustion engine exhaust gas purification catalyst comprises a front-stage catalyst and a rear-stage catalyst, the carrier comprises a front-stage carrier and a rear-stage carrier, the front-stage catalyst comprises the front-stage carrier, the rear-stage catalyst comprises the rear-stage carrier, the front-stage catalyst further comprises a first catalytic section and a second catalytic section sequentially distributed according to the exhaust gas flow direction, wherein the first catalytic section comprises a palladium-rhodium catalytic layer arranged on the surface of the carrier and a platinum catalytic layer arranged on the surface of the palladium-rhodium catalytic layer, the second catalytic section comprises a palladium catalytic layer arranged on the surface of the carrier and a platinum catalytic layer arranged on the surface of the palladium catalytic layer, and the rear-stage catalyst comprises a platinum catalytic layer arranged on the surface of the carrier, Wherein, the palladium-rhodium catalyst layer is formed by the slurry including palladium and rhodium, the palladium catalyst layer is formed by the slurry including palladium, and the platinum catalyst layer is formed by the slurry including platinum.

Images