WO2025035850A1 - 一种尾气处理用改性氧化铝材料、制备方法及三元催化剂 - Google Patents

一种尾气处理用改性氧化铝材料、制备方法及三元催化剂 Download PDF

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WO2025035850A1
WO2025035850A1 PCT/CN2024/092563 CN2024092563W WO2025035850A1 WO 2025035850 A1 WO2025035850 A1 WO 2025035850A1 CN 2024092563 W CN2024092563 W CN 2024092563W WO 2025035850 A1 WO2025035850 A1 WO 2025035850A1
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gas treatment
bao
mgo
alumina material
modified
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熊芬
赵浩远
刘丹丹
陈超
吴旭
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Dongfeng Motor Group Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9445—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC]
    • B01D53/945—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC] characterised by a specific catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/002—Mixed oxides other than spinels, e.g. perovskite
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/02—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the alkali- or alkaline earth metals or beryllium
    • B01J23/04—Alkali metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/902—Multilayered catalyst
    • B01D2255/9025—Three layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/92—Dimensions
    • B01D2255/9207—Specific surface
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/01—Engine exhaust gases
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2523/00—Constitutive chemical elements of heterogeneous catalysts
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the present application relates to the technical field of tail gas treatment, and in particular to a modified alumina material for tail gas treatment, a preparation method and a three-way catalyst.
  • Automobile exhaust purification catalysts are the main strategy for converting pollutants such as carbon monoxide, hydrocarbons, and nitrogen oxides into non-toxic gases such as carbon dioxide and water vapor.
  • Automobile exhaust purification catalysts are generally composed of honeycomb carriers and catalytic coatings.
  • the catalytic coatings are mainly composed of catalytic materials such as rare earth oxides and alumina and precious metal active components.
  • Alumina materials play the role of dispersing precious metal active components and increasing specific surface area.
  • Alumina materials have various crystal forms such as ⁇ , ⁇ , ⁇ , ⁇ , ⁇ , and ⁇ .
  • ⁇ -Al 2 O 3 is the most widely used in automobile exhaust purification catalysts.
  • ⁇ -Al 2 O 3 is also called activated alumina. It is a porous, highly dispersed solid material with a high specific surface area, excellent thermal stability and adsorption properties. It is generally considered to be a defective spinel structure. Oxygen and aluminum atoms occupy the positions of octahedrons and tetrahedrons respectively, and trivalent aluminum ions form the defects and acidity of spinel.
  • ⁇ -Al 2 O 3 is a metastable structure. During the operation of the car, the instantaneous temperature of the exhaust gas sometimes reaches above 1000°C.
  • ⁇ -Al 2 O 3 (cubic) gradually transforms into ⁇ -Al 2 O 3 (tetragonal) and ⁇ -Al 2 O 3 (monoclinic), and finally transforms into ⁇ -Al 2 O 3 (hexagonal), resulting in a sharp decrease in the specific surface area of the alumina material, causing the active components of the dispersed load to aggregate, thereby causing the catalyst activity to weaken sharply. Therefore, increasing the specific surface area and thermal stability of the alumina material is crucial to improving the performance of automobile exhaust purification catalysts.
  • Rare earth oxygen storage materials and precious metal active components need to be dispersed on carriers such as cordierite and metals through alumina coating.
  • Mechanical shocks such as bumps are inevitable during the driving of the car, and high and low temperature thermal shocks will occur during the operation of the exhaust gas processor. This requires alumina
  • the material has good resistance to shedding during mechanical and thermal shock.
  • ⁇ -Al 2 O 3 is usually prepared by dehydrating boehmite or pseudo-boehmite precursor (AlOOH) at 500-600°C.
  • Alkaline earth and rare earth elements can change the thermal stability of alumina to a certain extent.
  • CN100484621C discloses a preparation method of a modified alumina with a large specific surface area and high temperature resistance, by adding nitrates of alkali metals, alkaline earth metals, rare earth elements and tetraethyl orthosilicate to modify the structure of the alumina material.
  • CN109772289A discloses a method for preparing lanthanum-modified alumina, wherein the size and pore volume of alumina are regulated by adding NaBr, and the alumina material is modified by adding lanthanum nitrate as a lanthanum source and polyethylene glycol as a dispersant.
  • the specific surface area of the fresh sample is 200-250m2 /g, and the specific surface area after calcination at 1000°C for 12h is 160-200m2 /g.
  • CN103599768A discloses a method for preparing a modified alumina material, wherein the crystal structure of ⁇ - Al2O3 is stabilized by adding lanthanum oxide and zirconium oxide, and the specific surface area of the fresh material is 237m2 /g, and the specific surface area after calcination at 1200°C for 4h is 59m2 /g.
  • CN 113233484 A discloses a method for preparing high-temperature resistant and high-specific surface active alumina.
  • the active alumina material is prepared by a low-heat solid-phase precursor method combined with a freeze-drying method.
  • the specific surface area of the fresh sample of the active alumina is about 300m 2 /g, and the specific surface area is still 110m 2 /g after aging at 1100°C for 4 hours.
  • CN 102962047A discloses an aluminum-cerium-zirconium composite oxide catalytic material and a preparation method thereof.
  • the cerium-zirconium doped active alumina is prepared by a precipitation method.
  • the maximum specific surface area can reach 145m 2 /g after being kept at 1000°C for 4 hours.
  • the phosphorus-modified alumina prepared by an equal volume impregnation method in the "Study on the Preparation of Modified Active Alumina by Impregnation Method" has a specific surface area of 75.69m 2 /g after calcination at 1200°C for 3h.
  • ⁇ -Al 2 O 3 materials are those modified with rare earth elements such as lanthanum.
  • the heat resistance and anti-shedding performance of ⁇ -Al 2 O 3 materials need to be further improved.
  • ⁇ -Al 2 O 3 materials that are not modified with rare earth elements such as the introduction of silicon sources, It usually involves multiple organic solvents, complex process flows, harsh drying conditions, etc., making industrial-scale production difficult, and there is currently little research on the anti-shedding properties of alumina materials.
  • the embodiments of the present application provide a modified alumina material for exhaust gas treatment, a preparation method and a three-way catalyst, which can improve the specific surface area and high temperature resistance of the alumina material, inhibit the phase transformation process of the ⁇ - Al2O3 material at high temperature, thereby improving the high temperature aging resistance of the alumina material, and at the same time improve the anti-shedding performance of the alumina material when used as a coating material.
  • a method for preparing a modified alumina material for tail gas treatment comprising:
  • Secondary growth is performed on the activated alumina prestructure MgO-BaO- Al2O3 to obtain a modified alumina material SiO2- MgO -BaO- Al2O3 for tail gas treatment, wherein the molar ratio of Si to Mg in the modified alumina material SiO2- MgO - BaO - Al2O3 for tail gas treatment is (3-7.5):1.
  • the content of MgO is 0.2-4.0wt%
  • the content of BaO is 0.5-5.0wt%
  • Al2O3 accounts for 5-30wt% of the total weight of Al2O3 in the modified alumina material SiO2 - MgO - BaO - Al2O3 for tail gas treatment.
  • a growth is performed on alumina to obtain an active alumina pre-structure MgO-BaO-Al 2 O 3 , which specifically includes the following steps:
  • the slurry A2 is subjected to low temperature calcination and grinding to obtain an activated alumina pre-structure MgO-BaO-Al 2 O 3 .
  • the addition amount of the soluble aluminum salt, soluble magnesium salt, and soluble barium salt is as follows:
  • the soluble aluminum salt includes one or more of aluminum nitrate, aluminum sulfate, and aluminum chloride;
  • the soluble magnesium salt includes one or more of magnesium nitrate, magnesium sulfate, magnesium acetate and magnesium chloride;
  • the soluble barium salt includes one or more of barium nitrate, barium acetate and barium chloride;
  • the soluble ammonium salt includes ammonium sulfate and/or ammonium nitrate;
  • the alkali solution includes aqueous ammonia and/or ammonium carbonate.
  • the first aging treatment includes: aging at 20-30° C. for 2-4 hours.
  • the low temperature calcination treatment includes: calcination at 350-420° C. for 1-3 hours.
  • the slurry A2 before the slurry A2 is subjected to low-temperature calcination, it further comprises: drying at 60-100°C.
  • the drying is carried out by spraying at 60-100°C.
  • the grinding is performed to a particle size D 90 of 5-15 ⁇ m.
  • secondary growth is performed on the activated alumina pre-structure MgO-BaO-Al 2 O 3 to obtain a modified alumina material SiO 2 -MgO-BaO-Al 2 O 3 for tail gas treatment, which specifically includes the following steps:
  • Pseudo-boehmite powder and polyether-modified siloxane are dissolved in a second solvent, and nitric acid is added. Acid, after ball milling, a second solvent is added to obtain solution B2;
  • the solution B1 is heated to 70-90°C, and the solution B2 is added while stirring, and an alkali solution is added at the same time to adjust the pH to 8-9. After stirring evenly, a second aging treatment is performed to obtain a slurry B3;
  • the slurry B3 is subjected to a first high temperature roasting treatment at a preset air flow rate;
  • a second high-temperature calcination treatment is then performed to obtain a modified alumina material SiO 2 —MgO—BaO—Al 2 O 3 for tail gas treatment.
  • the mass fraction of the ammonia water is 5 to 10 wt %
  • the polyether-modified siloxane is one or more of polyether-modified polydimethylsiloxane, polyether-modified trisiloxane, and polyether-modified heptamethylsiloxane.
  • the activated alumina pre-structure MgO-BaO-Al 2 O 3 when added to aqueous ammonia, one or more of polyhydroxyethyl acrylate, hydroxypropyl methylcellulose, hydroxypropyl cellulose and polyvinyl alcohol are also added.
  • solution B2 is added while stirring under ultrasonic dispersion conditions.
  • the slurry before the slurry B3 is subjected to the first high-temperature roasting treatment, the slurry further includes: drying at 100-120°C.
  • the second aging treatment comprises: aging at 40-60° C. for 3-5 hours.
  • the first high temperature calcination treatment includes: calcining at 300-500° C. for 1-2 hours.
  • the second high temperature calcination treatment includes: calcining at 600-800° C. for 2-5 hours.
  • the preset air flow rate is 50-250 L/min.
  • a modified alumina material for exhaust gas treatment is provided, which is prepared by any of the above-described methods for preparing a modified alumina material for exhaust gas treatment.
  • a three-way catalyst which includes the modified alumina material for exhaust gas treatment as described above.
  • the embodiments of the present application provide a modified alumina material, preparation method and three-way catalyst for tail gas treatment.
  • the current main strategy is to form a porous structure with a high specific surface area in the alumina material during the material preparation and molding process, while inhibiting the phase change process of the alumina material under high temperature conditions to prevent sintering between alumina particles.
  • the most commonly used method is to dope and modify with rare earth oxides ( La2O3 , etc. ), and there are also reports of auxiliary doping with alkaline earth metal oxides and silicon dioxide for modification.
  • FIG1 is a flow chart of a method for preparing a modified alumina material for tail gas treatment provided in an embodiment of the present application
  • FIG2 is a flow chart of obtaining an activated alumina pre-structure according to an embodiment of the present application.
  • FIG3 is a flow chart of performing secondary growth on an activated alumina prestructure to obtain a modified alumina material for exhaust gas treatment, as provided in an embodiment of the present application.
  • the present embodiment provides a method for preparing a modified alumina material for tail gas treatment, which comprises the following steps:
  • the molar ratio of Si and Mg was determined to be (3-7.5):1. This ratio can improve the adhesion between the alumina material and the ceramic carrier, improve the coating's anti-shedding performance, and also increase the specific surface area.
  • the current main strategy is to form a porous structure with a high specific surface area in the alumina material during the material preparation and molding process, while inhibiting the phase change process of the alumina material under high temperature conditions to prevent sintering between alumina particles.
  • the most commonly used method is to dope and modify with rare earth oxides ( La2O3 , etc. ), and there are also reports of auxiliary doping with alkaline earth metal oxides and silica for modification. These doping techniques usually involve one or more metal salts, oxides, etc. to directly modify alumina through coprecipitation, sol-gel methods, etc., and the specific surface area and high temperature resistance need to be further improved.
  • the present application has found through a large number of studies that by first preparing Mg, Ba The modified activated alumina prestructure, i.e., MgO-BaO-Al 2 O 3 , is then grown on the basis of the structure to form a Si-modified activated alumina structure (secondary growth), and the molar ratio of Si to Mg is controlled to be (3-7.5):1, and a modified alumina material with high temperature resistance and high specific surface area can be obtained without doping rare earth oxides.
  • the modified alumina material prepared by this method can significantly improve the anti-shedding performance of the three-way catalyst coating when it is prepared into a slurry and coated on a ceramic carrier.
  • the content of MgO in the activated alumina prestructure MgO-BaO- Al2O3 is 0.2-4.0wt%, and the content of BaO is 0.5-5.0wt%.
  • the Al2O3 in the activated alumina prestructure accounts for 5-30wt% of the total weight of Al2O3 in the modified alumina material SiO2 -MgO-BaO- Al2O3 for tail gas treatment.
  • step 101 in order to prepare the required activated alumina prestructure, in the above step 101 , a growth is performed on alumina to obtain the activated alumina prestructure MgO—BaO—Al 2 O 3 , which specifically includes the following steps:
  • 201 Dissolve a soluble aluminum salt, a soluble magnesium salt, a soluble barium salt and a soluble ammonium salt in a first solvent to prepare a solution A1.
  • the added amounts of the soluble aluminum salt, the soluble magnesium salt, and the soluble barium salt can be determined according to the molar ratios of Al 3+ , Mg 2+ , and Ba 2+ in the corresponding soluble salts.
  • the role of the soluble ammonium salt is to gradually decompose into gas during the roasting process, which helps to form a porous structure with a high specific surface area. Therefore, the soluble ammonium salt can be added according to actual preparation needs.
  • the soluble aluminum salt includes one or more of aluminum nitrate, aluminum sulfate and aluminum chloride.
  • the soluble magnesium salt includes one or more of magnesium nitrate, magnesium sulfate, magnesium acetate and magnesium chloride.
  • the soluble barium salt includes one or more of barium nitrate, barium acetate and barium chloride.
  • the soluble ammonium salt includes one or more of ammonium nitrate and ammonium sulfate.
  • the function of the first solvent is to dissolve and mix the various soluble salts.
  • the first solvent includes one or more of deionized water and distilled water.
  • the first aging treatment comprises: aging at 20-30° C. for 2-4 hours.
  • the alkali solution includes aqueous ammonia and/or ammonium carbonate.
  • the low temperature calcination treatment includes: calcination at 350-420° C. for 1-3 hours.
  • the slurry A2 is preferably dried by spray drying.
  • the alumina is doped and modified by adding magnesium salt, barium salt and soluble ammonium salt in appropriate proportions.
  • the doped magnesium and barium can react with alumina to generate aluminates with high thermal stability during the high-temperature solid phase reaction and disperse in the alumina material, inhibiting the bulk diffusion and ⁇ phase transition of alumina under high temperature conditions, thereby improving the aging resistance/high temperature resistance of the activated alumina.
  • the added soluble ammonium salt will decompose and release gases such as ammonia near the roasting temperature (if ammonium sulfate is used, ammonia will be generated).
  • ammonium nitrate is used, ammonia and nitrogen will be generated.
  • the diffusion of ammonia gas in the system can promote the formation of porous structure in the activated alumina pre-structure and increase the specific surface area of the material.
  • the control of some process parameters in this preparation process is also different from the conventional preparation method, such as pH needs to be 7-8, the aging temperature needs to be lower than the conventional aging temperature, and the roasting temperature needs to reach the formation temperature of ⁇ -Al 2 O 3 on the one hand, and on the other hand, it needs to prevent ammonium bisulfate or ammonium nitrate from continuing to decompose violently.
  • ammonium sulfate it is selected to be roasted at 350-420°C; and for ammonium nitrate, it is selected to be roasted at 200-250°C for 1-2h for pre-decomposition to prevent explosion, and then the temperature is raised to 350-420°C.
  • step 102 secondary growth is performed on the activated alumina prestructure MgO—BaO—Al 2 O 3 to obtain the modified alumina material SiO 2 —MgO—BaO—Al 2 O 3 for tail gas treatment, which specifically includes the following steps:
  • the mass fraction of the ammonia water is 5-10wt%, and the pH value of the solution is adjusted by using the ammonia water.
  • the activated alumina pre-structured MgO-BaO- Al2O3 is added to the ammonia water, one or more of polyhydroxyethyl acrylate, hydroxypropyl methylcellulose, hydroxypropyl cellulose and polyvinyl alcohol are also added.
  • nitric acid The role of nitric acid is to promote the formation of pseudo-boehmite gel network.
  • This application is a method of preparing aluminum oxide by peptization: taking advantage of the large peptization index of pseudo-boehmite, an acid is used as a peptizer to prepare aluminum oxide.
  • H + ions in the peptizer are adsorbed on the pseudo-boehmite particles to form new particles.
  • new particles continuously absorb other pseudo-boehmite particles.
  • the "acid bridge" of H + ions multiple pseudo-boehmite particles are connected together in a network form, so that the pseudo-boehmite particles lose fluidity and the pseudo-boehmite solution becomes a peptized state. After that, the peptized pseudo-boehmite is calcined to obtain alumina.
  • the second solvent includes deionized water and/or distilled water.
  • the polyether-modified siloxane is one or more of polyether-modified polydimethylsiloxane, polyether-modified trisiloxane, and polyether-modified heptamethylsiloxane.
  • step 302 the amount of polyether-modified siloxane added can be calculated by reverse calculation based on the Si content in the final product , the modified alumina material SiO2- MgO -BaO- Al2O3 for tail gas treatment.
  • the Al 2 O 3 in the activated alumina prestructure MgO-BaO-Al 2 O 3 accounts for a small proportion of the total weight of Al 2 O 3 in the final product, modified alumina material SiO 2 -MgO-BaO-Al 2 O 3 for exhaust gas treatment.
  • modified alumina material SiO 2 -MgO-BaO-Al 2 O 3 for exhaust gas treatment is not high.
  • the difference is provided by another source of Al 2 O 3 , namely, pseudo-boehmite powder. Therefore, the amount of pseudo-boehmite powder added can be reversed from the two.
  • the solution B1 is heated to 70-90° C., and the solution B2 is added while stirring, and an alkali solution is added at the same time to adjust the pH to 8-9. After stirring evenly, a second aging treatment is performed to obtain a slurry B3.
  • the second aging treatment comprises: aging at 40-60° C. for 3-5 hours.
  • ultrasonic dispersion is preferably increased.
  • the slurry B3 is subjected to a first high-temperature roasting treatment.
  • the process further comprises: Dry at 100-120°C.
  • the first high temperature calcination treatment includes: calcining at 300-500° C. for 1-2 hours.
  • the preset air flow rate is 50-250 L/min.
  • the second high temperature calcination treatment includes: calcining at 600-800° C. for 2-5 hours.
  • the activated alumina pre-structure is first ground into a powder of suitable particle size to provide a growth substrate of suitable size for the secondary growth, and then the corresponding powder is uniformly dispersed into the ammonia solution by ultrasound.
  • the present application adopts the method of adding polyether modified siloxane to pseudo-boehmite for modification. Avoiding the introduction of organic solvents can make the material preparation process greener on the one hand, and on the other hand, it is conducive to the secondary growth of activated alumina in the aqueous activated alumina pre-structure system to prevent phase separation.
  • the activated alumina pre-structured powder is added to the ammonia solution, it is preferred to add polyhydroxyethyl acrylate, hydroxypropyl methylcellulose, hydroxypropyl cellulose, polyvinyl alcohol, etc. to regulate the viscosity of the solution; by adding ultrasonic dispersion in the secondary growth process, the uniform growth and dispersion of the particles are further promoted.
  • the roasting process proposed in this application is similar to the conventional roasting process, and its main purpose is to completely convert pseudo-boehmite into ⁇ -Al 2 O 3.
  • the difference is that for ammonium sulfate, the incompletely converted ammonium sulfate and the generated ammonium bisulfate will further decompose to generate gases such as ammonia, nitrogen, sulfur dioxide and water vapor in the process.
  • the incompletely converted ammonium nitrate will further decompose to generate gases such as ammonia, nitrogen and water vapor in the process.
  • appropriate gas flow rate control allows the diffused gas to form a porous structure in the alumina material, further increasing the specific surface area.
  • waste gases such as sulfur dioxide are removed from the system to prevent them from remaining therein and poisoning the precious materials when preparing the coating slurry.
  • Metal catalyst
  • the embodiments of the present application also provide a modified alumina material for exhaust gas treatment, which is prepared by any of the above-described methods for preparing a modified alumina material for exhaust gas treatment.
  • the embodiment of the present application also provides a three-way catalyst, which includes the modified alumina material for tail gas treatment as described above.
  • the three-way catalyst also includes a cerium-zirconium-based oxygen storage material, an auxiliary material, and at least one precious metal selected from Pt, Pd, and Rh.
  • the modified alumina material samples of each embodiment and comparative example were characterized by specific surface area when freshly prepared (before aging) and after high-temperature aging at 1100°C (after aging).
  • the specific surface area test method is as follows: first, the sample is pretreated under vacuum conditions at 300°C for 3h, and then an adsorption test is performed at -196°C (liquid nitrogen) with high-purity N2 as the adsorption gas, and a desorption test is performed at 25°C.
  • the specific surface area of the sample is calculated using the BET method (Autosorb SI fully automatic specific surface-pore size analyzer, Quantachrome).
  • the retention rate of specific surface area specific surface area after aging/specific surface area before aging ⁇ 100%.
  • the three-way catalyst coating slurry is prepared according to this application.
  • this application adopts two methods, ultrasonic vibration and thermal shock, to measure the firmness of the coating.
  • Shedding rate (mass after coating - mass after test) / (mass after coating - mass before coating) ⁇ 100%.
  • the sample coated with the three-way catalyst coating material was placed in a sealed container filled with petroleum ether, and then the container was placed in an ultrasonic cleaner for 30 minutes. The sample was then taken out and dried, the mass of the sample was weighed and the shedding rate was calculated.
  • a method for preparing a modified alumina material for tail gas treatment :
  • Step (1) weigh 33.48 g of Al(NO 3 ) 3 ⁇ 9H 2 O (including about 10 g of Al 2 O 3 ) and 3.35 g of (NH 4 ) 2 SO 4 , weigh Mg(NO 3 ) 2 ⁇ 6H 2 O and Ba(NO 3 ) 2 according to the MgO content of 1 wt% and the BaO content of 2 wt % in MgO-BaO-Al 2 O 3, dissolve the corresponding soluble salts in deionized water to prepare solution A1, add ammonia water dropwise to the uniformly mixed solution to adjust the pH value of the solution to 7, stir evenly and age at 25° C. for 2 hours to obtain slurry A2;
  • Step (2) spray drying the slurry A2 at 80°C, and then low-temperature calcining at 350°C for 3h, and grinding the calcined sample into P powder (MgO-BaO-Al 2 O 3 ) with a particle size D 90 of 10 ⁇ m;
  • Step (3) adding the P powder prepared in step (2) to an ammonia solution with a mass fraction of 10 wt%, stirring and ultrasonicating at 25°C for 60 min to prepare solution B1; weighing pseudo-boehmite powder according to an Al2O3 content of 90 g, weighing a polyether-modified polydimethylsiloxane solution according to a molar ratio of Si to Mg of 6:1, dissolving them in deionized water, adding nitric acid, ball milling for 1 h twice, and then adding a certain amount of deionized water to prepare solution B2;
  • Step (4) heating solution B1 to 70° C., adding solution B2 to solution B1 at this temperature while stirring, using ultrasonic dispersion during the process of adding solution B2, and adjusting the pH of the slurry to 8 by adding ammonia water, stirring evenly, and aging at 40° C. for 3 hours;
  • Step (5) The slurry obtained by aging in step (4) was dried at 100°C, and then calcined at 400°C for 2h, during which the gas flow rate was maintained at 200L/min.
  • the modified alumina material (SiO 2 -MgO-BaO-Al 2 O 3 ) for tail gas treatment was obtained by calcining at 800°C for 4 hours.
  • a method for preparing a modified alumina material for tail gas treatment :
  • Step (1) weigh 33.48 g of Al(NO 3 ) 3 ⁇ 9H 2 O (including about 10 g of Al 2 O 3 ) and 3.35 g of (NH 4 ) 2 SO 4 , weigh Mg(NO 3 ) 2 ⁇ 6H 2 O and Ba(NO 3 ) 2 according to the MgO-BaO-Al 2 O 3 content of 4 wt% and the BaO content of 2 wt %, dissolve the corresponding soluble salts in deionized water to prepare solution A1, add ammonia water dropwise to the uniformly mixed solution to adjust the pH value of the solution to 7, stir evenly and age at 25° C. for 2 hours to obtain slurry A2;
  • Step (2) spray drying the slurry A2 at 80°C, and then low-temperature calcining at 350°C for 3h, and grinding the calcined sample into P powder (MgO-BaO-Al 2 O 3 ) with a particle size D 90 of 10 ⁇ m;
  • Step (3) adding the P powder prepared in step (2) to an ammonia solution with a mass fraction of 10 wt%, stirring and ultrasonicating at 25°C for 60 min to prepare solution B1; weighing pseudo-boehmite powder according to an Al2O3 content of 90 g, weighing a polyether-modified polydimethylsiloxane solution according to a molar ratio of Si to Mg of 3:1, dissolving them in deionized water, adding nitric acid, ball milling for 1 h twice, and then adding a certain amount of deionized water to prepare solution B2;
  • Step (4) heating solution B1 to 70° C., adding solution B2 to solution B1 at this temperature while stirring, using ultrasonic dispersion during the process of adding solution B2, and adjusting the pH of the slurry to 8 by adding ammonia water, stirring evenly, and aging at 40° C. for 3 hours;
  • Step (5) drying the slurry obtained by aging in step (4) at 100°C, then calcining at 400°C for 2h, during which the gas flow rate is maintained at 200L/min, and finally calcining at 800°C for 4h to obtain a modified alumina material ( SiO2 -MgO-BaO- Al2O3 ) for tail gas treatment.
  • a method for preparing a modified alumina material for tail gas treatment :
  • Step (1) weigh 33.48 g of Al(NO 3 ) 3 ⁇ 9H 2 O (including about 10 g of Al 2 O 3 ) and 3.35 g of (NH 4 ) 2 SO 4 , weigh Mg(NO 3 ) 2 ⁇ 6H 2 O and Ba(NO 3 ) 2 according to the MgO content of 1 wt% and the BaO content of 2 wt % in MgO-BaO-Al 2 O 3, dissolve the corresponding soluble salts in deionized water to prepare solution A1, add ammonia water dropwise to the uniformly mixed solution to adjust the pH value of the solution to 7, stir evenly and age at 25° C. for 2 hours to obtain slurry A2;
  • Step (2) spray drying the slurry A2 at 80°C, and then low-temperature calcining at 350°C for 3h, and grinding the calcined sample into P powder (MgO-BaO-Al 2 O 3 ) with a particle size D 90 of 10 ⁇ m;
  • Step (3) adding the P powder prepared in step (2) to an ammonia solution with a mass fraction of 10 wt%, and adding polyhydroxyethyl acrylate, stirring, and ultrasonicating at 25° C. for 60 min to prepare solution B1; weighing pseudo-boehmite powder according to an Al 2 O 3 content of 90 g, and weighing a polyether-modified polydimethylsiloxane solution according to a molar ratio of Si to Mg of 6:1, dissolving them in deionized water, adding nitric acid, ball milling for 1 h twice, and then adding a certain amount of deionized water to prepare solution B2;
  • Step (4) heating solution B1 to 70° C., adding solution B2 to solution B1 at this temperature while stirring, using ultrasonic dispersion during the process of adding solution B2, and adjusting the pH of the slurry to 8 by adding ammonia water, stirring evenly, and aging at 40° C. for 3 hours;
  • Step (5) drying the slurry obtained by aging in step (4) at 100°C, then calcining at 400°C for 2h, during which the gas flow rate is maintained at 200L/min, and finally calcining at 800°C for 4h to obtain a modified alumina material ( SiO2 -MgO-BaO- Al2O3 ) for tail gas treatment.
  • a method for preparing a modified alumina material for tail gas treatment :
  • Step (1) weigh 33.48 g of Al(NO 3 ) 3 ⁇ 9H 2 O (including about 10 g of Al 2 O 3 ) and 3.35 g of (NH 4 ) 2 SO 4 , weigh Mg(NO 3 ) 2 ⁇ 6H 2 O and Ba(NO 3 ) 2 according to the MgO content of 4 wt% and the BaO content of 2 wt % in MgO-BaO-Al 2 O 3, dissolve the corresponding soluble salts in deionized water to prepare solution A1, add ammonia water dropwise to the uniformly mixed solution to adjust the pH value of the solution to 7, stir evenly and age at 30° C. for 4 hours to obtain slurry A2;
  • Step (2) spray drying the slurry A2 at 80°C, then low-temperature calcining at 420°C for 1 h, and grinding the calcined sample into P powder (MgO-BaO-Al 2 O 3 ) with a particle size D 90 of 15 ⁇ m;
  • Step (3) adding the P powder prepared in step (2) to an ammonia solution with a mass fraction of 10 wt%, and adding polyhydroxyethyl acrylate, stirring, and ultrasonicating at 25° C. for 60 min to prepare solution B1; weighing pseudo-boehmite powder according to an Al 2 O 3 content of 50 g, and measuring a polyether-modified polydimethylsiloxane solution according to a molar ratio of Si to Mg of 3:1, dissolving them in deionized water, adding nitric acid, ball milling for 1 h twice, and then adding a certain amount of deionized water to prepare solution B2;
  • Step (4) heating solution B1 to 70° C., adding solution B2 to solution B1 at this temperature while stirring, using ultrasonic dispersion during the process of adding solution B2, and adjusting the pH of the slurry to 8 by adding ammonia water, stirring evenly, and aging at 60° C. for 5 hours;
  • Step (5) drying the slurry obtained by aging in step (4) at 100°C, then calcining at 400°C for 2h, during which the gas flow rate is maintained at 200L/min, and finally calcining at 800°C for 4h to obtain a modified alumina material ( SiO2 -MgO-BaO- Al2O3 ) for tail gas treatment.
  • a method for preparing a modified alumina material for tail gas treatment :
  • Step (1) weigh 33.48 g of Al(NO 3 ) 3 ⁇ 9H 2 O (including about 10 g of Al 2 O 3 ) and 3.35 g of (NH 4 ) 2 SO 4 , weigh Mg(NO 3 ) 2 ⁇ 6H 2 O and Ba(NO 3 ) 2 according to the MgO content of 1 wt% and the BaO content of 2 wt % in MgO-BaO-Al 2 O 3, dissolve the corresponding soluble salts in deionized water to prepare solution A1, add ammonia water dropwise to the uniformly mixed solution to adjust the pH value of the solution to 7, stir evenly and age at 50° C. for 2 hours to obtain slurry A2;
  • Step (2) spray drying the slurry A2 at 80°C, then calcining at 600°C for 3h, and grinding the calcined sample into P powder (MgO-BaO-Al 2 O 3 ) with a particle size D 90 of 10 ⁇ m;
  • Step (3) adding the P powder prepared in step (2) to an ammonia solution with a mass fraction of 10 wt%, stirring and ultrasonicating at 25°C for 60 min to prepare solution B1; weighing pseudo-boehmite powder according to an Al2O3 content of 90 g, weighing a polyether-modified polydimethylsiloxane solution according to a molar ratio of Si to Mg of 12:1, dissolving them in deionized water, adding nitric acid, ball milling for 1 h twice, and then adding a certain amount of deionized water to prepare solution B2;
  • Step (4) heating solution B1 to 70° C., adding solution B2 to solution B1 at this temperature while stirring, using ultrasonic dispersion during the process of adding solution B2, and adjusting the pH of the slurry to 8 by adding ammonia water, stirring evenly, and aging at 40° C. for 3 hours;
  • Step (5) drying the slurry obtained by aging in step (4) at 100°C, then calcining at 400°C for 2h, during which the gas flow rate is maintained at 200L/min, and finally calcining at 800°C for 4h to obtain a modified alumina material ( SiO2 -MgO-BaO- Al2O3 ) for tail gas treatment.
  • a method for preparing a modified alumina material for tail gas treatment :
  • Step (1) weigh 33.48 g of Al(NO 3 ) 3 ⁇ 9H 2 O (including about 10 g of Al 2 O 3 ), Mg(NO 3 ) 2 ⁇ 6H 2 O and Ba(NO 3 ) 2 were weighed according to the content of MgO in MgO-BaO-Al 2 O 3 being 1wt% and the content of BaO being 2wt%, and the corresponding soluble salts were dissolved in deionized water to prepare solution A1, and aqueous ammonia was added dropwise to the uniformly mixed solution to adjust the pH value of the solution to 7, and the solution was stirred uniformly and aged at 25°C for 2 hours to obtain slurry A2;
  • Step (2) spray drying the slurry A2 at 80°C, and then low-temperature calcining at 350°C for 3h, and grinding the calcined sample into P powder (MgO-BaO-Al 2 O 3 ) with a particle size D 90 of 10 ⁇ m;
  • Step (3) adding the P powder prepared in step (2) to an ammonia solution with a mass fraction of 10 wt%, stirring and ultrasonicating at 25°C for 60 min to prepare solution B1; weighing pseudo-boehmite powder according to an Al2O3 content of 90 g, weighing a polyether-modified polydimethylsiloxane solution according to a molar ratio of Si to Mg of 6:1, dissolving them in deionized water, adding nitric acid, ball milling for 1 h twice, and then adding a certain amount of deionized water to prepare solution B2;
  • Step (4) heating solution B1 to 70° C., adding solution B2 to solution B1 at this temperature while stirring, using ultrasonic dispersion during the process of adding solution B2, and adjusting the pH of the slurry to 8 by adding ammonia water, stirring evenly, and aging at 40° C. for 3 hours;
  • Step (5) drying the slurry obtained by aging in step (4) at 100°C, then calcining at 400°C for 2h, during which the gas flow rate is maintained at 200L/min, and finally calcining at 800°C for 4h to obtain a modified alumina material ( SiO2 -MgO-BaO- Al2O3 ) for tail gas treatment.
  • a method for preparing a modified alumina material for tail gas treatment :
  • Step (1) weigh 33.48 g of Al(NO 3 ) 3 ⁇ 9H 2 O (of which Al 2 O 3 is about 10 g) and 3.35 g of (NH 4 ) 2 SO 4 , weigh Mg(NO 3 ) 2 ⁇ 6H 2 O according to the MgO content in MgO-Al 2 O 3 being 1 wt %, dissolve the corresponding soluble salt in deionized water to prepare solution A1, add ammonia water dropwise to the uniformly mixed solution to adjust the pH value of the solution to 7, and stir evenly. Then, the mixture was aged at 25°C for 2 hours to obtain slurry A2;
  • Step (2) spray drying the slurry A2 at 80°C, and then low-temperature calcining at 350°C for 3h, and grinding the calcined sample into P powder (MgO- Al2O3 ) with a particle size D90 of 10 ⁇ m;
  • Step (3) adding the P powder prepared in step (2) to an ammonia solution with a mass fraction of 10 wt%, stirring and ultrasonicating at 25°C for 60 min to prepare solution B1; weighing pseudo-boehmite powder according to an Al2O3 content of 90 g, weighing a polyether-modified polydimethylsiloxane solution according to a molar ratio of Si to Mg of 6:1, dissolving them in deionized water, adding nitric acid, ball milling for 1 h twice, and then adding a certain amount of deionized water to prepare solution B2;
  • Step (4) heating solution B1 to 70° C., adding solution B2 to solution B1 at this temperature while stirring, using ultrasonic dispersion during the process of adding solution B2, and adjusting the pH of the slurry to 8 by adding ammonia water, stirring evenly, and aging at 40° C. for 3 hours;
  • Step (5) drying the slurry obtained by aging in step (4) at 100°C, then calcining at 400°C for 2h, during which the gas flow rate is maintained at 200L/min, and finally calcining at 800°C for 4h to obtain a modified alumina material ( SiO2 -MgO- Al2O3 ) for tail gas treatment.
  • a method for preparing a modified alumina material for tail gas treatment :
  • Step (1) weigh 33.48 g of Al(NO 3 ) 3 ⁇ 9H 2 O (including about 10 g of Al 2 O 3 ) and 3.35 g of (NH 4 ) 2 SO 4 , weigh Mg(NO 3 ) 2 ⁇ 6H 2 O and Ba(NO 3 ) 2 according to the MgO content of 1 wt% and the BaO content of 2 wt % in MgO-BaO-Al 2 O 3, dissolve the corresponding soluble salts in deionized water to prepare solution A1, add ammonia water dropwise to the uniformly mixed solution to adjust the pH value of the solution to 7, stir evenly and age at 25° C. for 2 hours to obtain slurry A2;
  • Step (2) spray drying the slurry A2 at 80°C and then low temperature drying at 350°C. After calcination for 3 h, the calcined sample was ground into P powder (MgO-BaO-Al 2 O 3 ) with a particle size D 90 of 10 ⁇ m;
  • Step (3) adding the P powder prepared in step (2) to an ammonia solution with a mass fraction of 10 wt%, and adding polyhydroxyethyl acrylate, stirring, and ultrasonicating at 25°C for 60 min to prepare solution B1; weighing pseudo-boehmite powder according to an Al2O3 content of 90 g, and weighing a polyether-modified polydimethylsiloxane solution according to a molar ratio of Si to Mg of 8:1, dissolving them in deionized water, adding nitric acid, ball milling for 1 h twice, and then adding a certain amount of deionized water to prepare solution B2;
  • Step (4) heating solution B1 to 70° C., adding solution B2 to solution B1 at this temperature while stirring, using ultrasonic dispersion during the process of adding solution B2, and adjusting the pH of the slurry to 8 by adding ammonia water, stirring evenly, and aging at 40° C. for 3 hours;
  • Step (5) drying the slurry obtained by aging in step (4) at 100°C, then calcining at 400°C for 2h, during which the gas flow rate is maintained at 200L/min, and finally calcining at 800°C for 4h to obtain a modified alumina material ( SiO2 -MgO-BaO- Al2O3 ) for tail gas treatment.
  • the aluminum oxide material prepared in the embodiment has a very high specific surface area and a very low shedding rate, and the attenuation degree after high temperature aging is also relatively low.
  • Example 3 Compared with Example 1, the difference of Example 3 is that polyhydroxyethyl acrylate is added.
  • the specific surface area after aging is also higher than that when polyhydroxyethyl acrylate is not added, and the ultrasonic vibration shedding rate is also lower than that when polyhydroxyethyl acrylate is not added; it means that when the activated alumina pre-structured MgO-BaO-Al 2 O 3 is added to ammonia water, adding polyhydroxyethyl acrylate, hydroxypropyl methylcellulose, hydroxypropyl cellulose, polyvinyl alcohol, etc. can adjust the viscosity of the solution, thereby promoting the uniform growth and dispersion of the particles.
  • Example 4 Compared with Example 2, the difference of Example 4 is that polyhydroxyethyl acrylate is added.
  • the specific surface area after aging is also higher than that when polyhydroxyethyl acrylate is not added, and the thermal shock shedding rate is also lower than that when polyhydroxyethyl acrylate is not added; it shows that when the activated alumina pre-structured MgO-BaO-Al 2 O 3 is added to ammonia water, adding polyhydroxyethyl acrylate, hydroxypropyl methylcellulose, hydroxypropyl cellulose, polyvinyl alcohol, etc. can adjust the viscosity of the solution, thereby promoting the uniform growth and dispersion of the particles.
  • Comparative Example 1 Compared with Example 1, the difference of Comparative Example 1 is that the molar ratio of Si to Mg is 12:1, and the calcination temperature of step (2) is 600°C. At this time, the molar ratio of Si to Mg in Comparative Example 1 exceeds (3-7.5):1, and its specific surface area is greatly reduced after aging, while the shedding rate is greatly improved, indicating that by controlling the molar ratio of Si to Mg to (3-7.5):1, a modified alumina material with high temperature resistance and high specific surface area can be obtained without doping with rare earth oxides. At the same time, the anti-shedding performance of the three-way catalyst coating can be significantly improved.
  • Example 2 Compared with Example 1, the difference of Comparative Example 2 is that no ammonium sulfate is added. At this time, the specific surface area after aging is greatly reduced, while the shedding rate is greatly increased, indicating that the addition of ammonium sulfate gradually decomposes into gas during the roasting process, which helps to form a porous high specific surface area structure, which is beneficial to increase the specific surface area of the alumina material.
  • Example 3 Compared with Example 1, the difference of Comparative Example 3 is that no barium nitrate is added. After oxidization, the specific surface area is greatly reduced, while the shedding rate is greatly increased, indicating that the appropriate content of BaO can improve the aging resistance of alumina materials.
  • Comparative Example 4 Compared with Example 1, the difference of Comparative Example 4 is that polyhydroxyethyl acrylate is added, and the molar ratio of Si to Mg is 8:1. At this time, the specific surface area is greatly reduced after aging, and the shedding rate is greatly increased, but relative to Comparative Example 1, its shedding rate is relatively low, indicating that when the activated alumina pre-structured MgO-BaO-Al 2 O 3 is added to ammonia water, adding polyhydroxyethyl acrylate, hydroxypropyl methylcellulose, hydroxypropyl cellulose, polyvinyl alcohol, etc. can adjust the viscosity of the solution, thereby promoting the uniform growth and dispersion of the particles, which is beneficial to reducing the shedding rate.
  • the alumina material for exhaust gas treatment provided in the present application can improve the specific surface area and high temperature resistance of the alumina material, inhibit the phase transformation process of the ⁇ -Al 2 O 3 material at high temperature, thereby improving the high temperature aging resistance of the alumina material, and at the same time improve the anti-shedding performance of the alumina material when used as a coating material.
  • the preparation method has a simple process flow and high production efficiency, and can be introduced into the existing alumina material production line.
  • the gasoline engine exhaust after-treatment module based on the alumina material has very good application prospects in the field of automobile exhaust treatment.
  • the terms “installed”, “connected”, and “connected” should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements.
  • installed should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements.

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Abstract

本申请涉及一种尾气处理用改性氧化铝材料、制备方法及三元催化剂，其包括：在氧化铝上进行一次生长，以获得活性氧化铝预结构MgO-BaO-Al2O3；在活性氧化铝预结构MgO-BaO-Al2O3上进行二次生长，以获得尾气处理用改性氧化铝材料SiO2-MgO-BaO-Al2O3，其中，尾气处理用改性氧化铝材料SiO2-MgO-BaO-Al2O3中的Si和Mg的摩尔比为(3～7.5)：1。本申请可以提高氧化铝材料的比表面积和耐高温性能，抑制γ-Al2O3材料在高温下的相转变过程，从而提高氧化铝材料的高温耐老化性能，同时提高氧化铝材料作为涂层材料时的抗脱落性能。

Description

一种尾气处理用改性氧化铝材料、制备方法及三元催化剂 技术领域
本申请涉及尾气处理技术领域，特别涉及一种尾气处理用改性氧化铝材料、制备方法及三元催化剂。
背景技术
随着汽车年保有量的逐年增加，汽车尾气排放已经成为大气污染的主要来源之一。汽车尾气净化催化剂是将一氧化碳、碳氢化合物、氮氧化物等污染物转化为二氧化碳、水蒸气等无毒害气体的主要策略。汽车尾气净化催化剂一般由蜂窝载体和催化涂层构成，催化涂层主要由稀土氧化物、氧化铝等催化材料及贵金属活性组分组成。氧化铝材料在其中起到分散贵金属活性组分、提高比表面积等作用。氧化铝材料有α、β、γ、δ、η、θ等多种晶型，其中汽车尾气净化催化剂中应用最广泛是γ-Al2O3。γ-Al2O3也称活性氧化铝，它是一种多孔性、高分散度的固体材料，具有高的比表面积，优良的热稳定性和吸附性能等，其通常被认为是缺陷尖晶石的结构，氧和铝原子分别占据八面体和四面体的位置，三价的铝离子形成了尖晶石的缺陷和酸性。γ-Al2O3是一种亚稳态结构，汽车运行过程中尾气温度瞬时温度有时会达到1000℃以上，γ-Al2O3(立方)随着温度的升高逐渐转变为δ-Al2O3(四方)和θ-Al2O3(单斜)，最终转变为α-Al2O3(六方)，导致氧化铝材料比表面积急剧降低，引起分散负载的活性组分聚集从而致使催化剂活性急剧减弱。因此，提高氧化铝材料的比表面积及热稳定性对于提高汽车尾气净化催化剂性能至关重要。
稀土储氧材料、贵金属活性组分需要通过氧化铝材料涂敷分散到堇青石、金属等载体上，而汽车行驶过程不可避免的会出现颠簸等机械冲击，尾气处理器运行过程会出现高低温热冲击，这就要求氧化铝 材料在机械冲击和热冲击过程中具有良好抗脱落性能。
目前，γ-Al2O3通常由薄水铝石或拟薄水铝石前驱体(AlOOH)在500-600℃下脱水制备得到，前人围绕氧化铝及其热稳定性的提高进行了大量研究，主要集中在改进制备方法以及加入不同金属元素进行改性等，碱土和稀土元素可一定程度改变氧化铝的热稳定性。CN100484621C中公开了一种具有耐高温性能的大比表面改性氧化铝的制备方法，通过添加碱金属、碱土金属、稀土元素的的硝酸盐以及正硅酸乙酯对氧化铝材料进行结构改性。CN109772289A中公开了一种镧改性氧化铝的制备方法，通过添加NaBr调控氧化铝的尺寸及孔容，通过添加硝酸镧作为澜源、聚乙二醇作为分散剂对氧化铝材料进行改性，新鲜样的比表面积为200-250m2/g，1000℃焙烧12h后比表面为160-200m2/g。CN103599768A中公开了一种改性氧化铝材料的制备方法，通过添加氧化镧和氧化锆来稳定γ-Al2O3的晶体结构，材料新鲜态比表面积为237m2/g，1200焙烧4h后比表面积为59m2/g。CN 113233484 A中公开了一种耐高温高比表面活性氧化铝的制备方法，通过引入结构稳定剂为硝酸铈、硝酸镧、氢氧化钡以及表面修饰剂为碳酸氢铵，采用低热固相前驱物法结合冷冻干燥法制备了活性氧化铝材料，活性氧化铝新鲜样的比表面在300m2/g左右，在1100℃老化4小时后比表面积仍有110m2/g。如CN 102962047A公布了一种铝铈锆复合氧化物催化材料及其制备方法，采用沉淀法制备铈锆掺杂的活性氧化铝，1000℃保温4小时后最大比表面积可达145m2/g。《浸渍法制备改性活性氧化铝的研究》中通过等体积浸渍法制备得到的磷改性氧化铝，在1200℃下煅烧3h后，比表面积为75.69m2/g。
结合γ-Al2O3工业化的应用现状以及系统分析上述研究，目前最常使用的是加镧等稀土元素改性的γ-Al2O3材料，随着排放法规的不断严格以及混动汽车占比的逐渐提升，γ-Al2O3材料的耐热性和抗脱落性能需要进一步提高。对于非稀土元素改性的γ-Al2O3材料，如引入硅源， 通常涉及多种有机溶剂、复杂的工艺流程、苛刻的干燥条件等，工业化规模生产困难，且目前对于氧化铝材料的抗脱落性能研究较少。
因此，亟需开发出一种具有耐高温高比表面积、优异抗脱落性能的氧化铝材料。
发明内容
本申请实施例提供一种尾气处理用改性氧化铝材料、制备方法及三元催化剂，可以提高氧化铝材料的比表面积和耐高温性能，抑制γ-Al2O3材料在高温下的相转变过程从而提高氧化铝材料的高温耐老化性能，同时提高氧化铝材料作为涂层材料时的抗脱落性能。
第一方面，提供了一种尾气处理用改性氧化铝材料的制备方法，其包括：
在氧化铝上进行一次生长，以获得活性氧化铝预结构MgO-BaO-Al2O3；
在活性氧化铝预结构MgO-BaO-Al2O3上进行二次生长，以获得尾气处理用改性氧化铝材料SiO2-MgO-BaO-Al2O3，其中，尾气处理用改性氧化铝材料SiO2-MgO-BaO-Al2O3中的Si和Mg的摩尔比为(3～7.5)：1。
一些实施例中，活性氧化铝预结构MgO-BaO-Al2O3中，MgO的含量为0.2-4.0wt％，BaO的含量为0.5-5.0wt％，Al2O3占尾气处理用改性氧化铝材料SiO2-MgO-BaO-Al2O3中Al2O3总重量的5-30wt％。
一些实施例中，在氧化铝上进行一次生长，以获得活性氧化铝预结构MgO-BaO-Al2O3，具体包括如下步骤：
将可溶性铝盐、可溶性镁盐、可溶性钡盐和可溶性铵盐溶于第一溶剂中制备成溶液A1；
向溶液A1中滴加碱液，使溶液A1的pH调节至7-8，搅拌均匀 后进行第一陈化处理，得到浆液A2；
将浆液A2进行低温焙烧处理，并研磨，以获得活性氧化铝预结构MgO-BaO-Al2O3。
一些实施例中，所述可溶性铝盐、可溶性镁盐、可溶性钡盐的加入量如下：
Al3+、Mg2+和Ba2+的摩尔比为Al3+：Mg2+：Ba2+＝(90～95)：(0.2～5)：(0.1～2)。
一些实施例中，所述可溶性铝盐包括硝酸铝、硫酸铝和氯化铝中的一种或多种；
所述可溶性镁盐包括硝酸镁、硫酸镁、醋酸镁和氯化镁中的一种或多种；
所述可溶性钡盐包括硝酸钡、醋酸钡和氯化钡中的一种或多种；
所述可溶性铵盐包括硫酸铵和/或硝酸铵；
所述碱液包括氨水和/或碳酸铵。
一些实施例中，所述第一陈化处理包括：20-30℃下陈化2-4小时。
一些实施例中，所述低温焙烧处理包括：350-420℃下焙烧1-3h。
一些实施例中，所述浆液A2进行低温焙烧处理之前，还包括：在60-100℃下烘干。
一些实施例中，在60-100℃下采用喷雾的方式烘干。
一些实施例中，研磨至粒度D90为5-15μm。
一些实施例中，在活性氧化铝预结构MgO-BaO-Al2O3上进行二次生长，以获得尾气处理用改性氧化铝材料SiO2-MgO-BaO-Al2O3，具体包括如下步骤：
将活性氧化铝预结构MgO-BaO-Al2O3加入到氨水中，混合均匀，得到溶液B1；
将拟薄水铝石粉末和聚醚改性硅氧烷溶于第二溶剂中，并加入硝 酸，球磨之后再加入第二溶剂，得到溶液B2；
将溶液B1升温至70-90℃，并边搅拌边加入溶液B2，同时加入碱液，以调节pH至8-9，搅拌均匀后进行第二陈化处理，得到浆液B3；
在预设气流流速下，将浆液B3进行第一高温焙烧处理；
再进行第二高温焙烧处理，以获得尾气处理用改性氧化铝材料SiO2-MgO-BaO-Al2O3。
一些实施例中，所述氨水的质量分数为5～10wt％；
所述聚醚改性硅氧烷为聚醚改性聚二甲基硅氧烷、聚醚改性三硅氧烷、聚醚改性七甲基硅氧烷中的一种或多种。
一些实施例中，将活性氧化铝预结构MgO-BaO-Al2O3加入到氨水中时，还加入聚丙烯酸羟乙酯、羟丙基甲基纤维素、羟丙基纤维素和聚乙烯醇中的一种或多种。
一些实施例中，在超声波分散条件下，边搅拌边加入溶液B2。
一些实施例中，所述浆液B3进行第一高温焙烧处理之前，还包括：在100-120℃下烘干。
一些实施例中，所述第二陈化处理包括：在40-60℃下陈化3-5小时。
一些实施例中，所述第一高温焙烧处理包括：在300-500℃下焙烧1-2h。
一些实施例中，所述第二高温焙烧处理包括：在600-800℃下焙烧2-5h。
一些实施例中，所述预设气流流速为50-250L/min。
第二方面，提供了一种尾气处理用改性氧化铝材料，其采用如上任一所述的尾气处理用改性氧化铝材料的制备方法制备而成。
第三方面，提供了一种三元催化剂，其包括如上所述的尾气处理用改性氧化铝材料。
本申请提供的技术方案带来的有益效果包括：
本申请实施例提供了一种尾气处理用改性氧化铝材料、制备方法及三元催化剂，为了提高活性氧化铝材料的耐高温性能和比表面积，目前的主要策略是在材料制备成型过程中使得氧化铝材料中形成具有高比表面积的多孔结构，同时抑制氧化铝材料在高温条件的相变过程，阻止氧化铝粒子之间的烧结。目前最常用的是进行稀土氧化物(La2O3等)掺杂改性，也有辅助掺杂碱土金属氧化物和二氧化硅进行改性的报道。而这些掺杂技术通常是一种或多种金属盐、氧化物等通过共沉淀法、溶胶-凝胶法等直接对氧化铝进行改性，比表面积和耐高温性能需要进一步提高。本申请通过大量研究发现：通过首先制备Mg、Ba改性的活性氧化铝预结构，即MgO-BaO-Al2O3，然后再在该结构的基础上生长形成Si改性的活性氧化铝结构(二次生长)，控制Si和Mg的摩尔比为(3～7.5)：1，在不掺杂稀土氧化物的情况下可以获得具有耐高温、高比表面积的改性氧化铝材料。同时意外的发现，由该方法制备的改性氧化铝材料在制备成浆料涂覆到陶瓷载体上时，可以显著提高三元催化剂涂层的抗脱落性能。
附图说明
为了更清楚地说明本申请实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本申请实施例提供的尾气处理用改性氧化铝材料的制备方法流程图；
图2为本申请实施例提供的获得活性氧化铝预结构的流程图；
图3为本申请实施例提供的在活性氧化铝预结构上进行二次生长，以获得尾气处理用改性氧化铝材料的流程图。
具体实施方式
为使本申请实施例的目的、技术方案和优点更加清楚，下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本申请的一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有做出创造性劳动的前提下所获得的所有其他实施例，都属于本申请保护的范围。
参见图1所示，本申请实施例提供了一种尾气处理用改性氧化铝材料的制备方法，其包括如下步骤：
101：在氧化铝上进行一次生长，以获得活性氧化铝预结构MgO-BaO-Al2O3。
102：在活性氧化铝预结构MgO-BaO-Al2O3上进行二次生长，以获得尾气处理用改性氧化铝材料SiO2-MgO-BaO-Al2O3，其中，尾气处理用改性氧化铝材料SiO2-MgO-BaO-Al2O3中的Si和Mg的摩尔比为(3～7.5)：1。
SiO2过高会在形成致密的玻璃相，SiO2过低难以抑制氧化铝材料的高温老化相变，因此，通过大量试验研究后，将Si和Mg的摩尔比确定为(3～7.5)：1，这个比例下可以提高氧化铝材料与陶瓷载体之间的附着力，提高涂层抗脱落性能，同时也提高比表面积。
为了提高活性氧化铝材料的耐高温性能和比表面积，目前的主要策略是在材料制备成型过程中使得氧化铝材料中形成具有高比表面积的多孔结构，同时抑制氧化铝材料在高温条件的相变过程，阻止氧化铝粒子之间的烧结。目前最常用的是进行稀土氧化物(La2O3等)掺杂改性，也有辅助掺杂碱土金属氧化物和二氧化硅进行改性的报道。而这些掺杂技术通常是一种或多种金属盐、氧化物等通过共沉淀法、溶胶-凝胶法等直接对氧化铝进行改性，比表面积和耐高温性能需要进一步提高。本申请通过大量研究发现：通过首先制备Mg、Ba 改性的活性氧化铝预结构，即MgO-BaO-Al2O3，然后再在该结构的基础上生长形成Si改性的活性氧化铝结构(二次生长)，控制Si和Mg的摩尔比为(3～7.5)：1，在不掺杂稀土氧化物的情况下可以获得具有耐高温、高比表面积的改性氧化铝材料。同时意外的发现，由该方法制备的改性氧化铝材料在制备成浆料涂覆到陶瓷载体上时，可以显著提高三元催化剂涂层的抗脱落性能。
其中，活性氧化铝预结构MgO-BaO-Al2O3中，MgO的含量为0.2-4.0wt％，BaO的含量为0.5-5.0wt％，而该活性氧化铝预结构中的Al2O3占尾气处理用改性氧化铝材料SiO2-MgO-BaO-Al2O3中Al2O3总重量的5-30wt％。
参见图2所示，为了制备出所需要的活性氧化铝预结构，上述步骤101中，在氧化铝上进行一次生长，以获得活性氧化铝预结构MgO-BaO-Al2O3，具体包括如下步骤：
201：将可溶性铝盐、可溶性镁盐、可溶性钡盐和可溶性铵盐溶于第一溶剂中制备成溶液A1。
在步骤201中，所述可溶性铝盐、可溶性镁盐、可溶性钡盐的加入量，可以按照对应的可溶性盐中的Al3+、Mg2+和Ba2+的摩尔比来确定，比如，作为示例，所述可溶性铝盐、可溶性镁盐、可溶性钡盐的加入量如下：所述可溶性铝盐中的Al3+、可溶性镁盐中的Mg2+和可溶性钡盐中的Ba2+的摩尔比为Al3+：Mg2+：Ba2+＝(90～95)：(0.2～5)：(0.1～2)。
可溶性铵盐的作用是在焙烧的过程中逐渐分解成气体，有助于形成多孔高比表面积结构，故可溶性铵盐可以根据实际制备需要进行添加。
需要说明的是，所述可溶性铝盐有多种选择，可以根据实际制备需要选择，比如，作为示例，所述可溶性铝盐包括硝酸铝、硫酸铝和氯化铝中的一种或多种。
需要说明的是，所述可溶性镁盐有多种选择，可以根据实际制备需要选择，比如，作为示例，所述可溶性镁盐包括硝酸镁、硫酸镁、醋酸镁和氯化镁中的一种或多种。
需要说明的是，所述可溶性钡盐有多种选择，可以根据实际制备需要选择，比如，作为示例，所述可溶性钡盐包括硝酸钡、醋酸钡和氯化钡中的一种或多种。
需要说明的是，所述可溶性铵盐有多种选择，可以根据实际制备需要选择，比如，作为示例，所述可溶性铵盐包括硝酸铵和硫酸铵中的一种或多种。
需要说明的是，第一溶剂的作用是将各个可溶性盐溶解混匀，所述第一溶剂有多种选择，可以根据实际制备需要选择，比如，作为示例，所述第一溶剂包括去离子水、蒸馏水中的一种或多种。
202：向溶液A1中滴加碱液，使溶液A1的pH调节至7-8，搅拌均匀后进行第一陈化处理，得到浆液A2；
所述第一陈化处理包括：20-30℃下陈化2-4小时。
所述碱液包括氨水和/或碳酸铵。
203：将浆液A2在60-100℃下烘干后，进行低温焙烧处理，并研磨至粒度D90为5-15μm，以获得活性氧化铝预结构MgO-BaO-Al2O3。
所述低温焙烧处理包括：350-420℃下焙烧1-3h。
其中，浆液A2的干燥方式优选为喷雾干燥的方式进行烘干。
为了制备合适结构的活性氧化铝预结构，通过添加合适比例的镁盐、钡盐以及可溶性铵盐对氧化铝进行掺杂改性，掺杂的镁、钡可以在高温固相反应过程中与氧化铝生成高热稳定性的铝酸盐分散在氧化铝材料中，抑制氧化铝在高温条件下的体相扩散和γ→δ→α相变过程，从而提高活性氧化铝的耐老化/耐高温性能。添加的可溶性铵盐在焙烧温度附近会分解释放出氨气等气体(若采用硫酸铵，则生成氨 气和硫酸氢铵等；若采用硝酸铵，则生成氨气和氮气等)，氨气气体在体系中的扩散可以促进活性氧化铝预结构中生成多孔结构，提升材料的比表面积。由于需要与二次生长过程相匹配，该制备过程中部分工艺参数控制也不同于常规的制备方法，如pH需要在7-8，陈化温度需要低于常规的陈化温度，焙烧温度一方面要达到γ-Al2O3的生成温度，另一方面又需要防止硫酸氢铵或硝酸铵继续剧烈分解。因此，对于硫酸铵而言，选择在350-420℃下焙烧；而对于硝酸铵而言，选择在200～250℃焙烧1～2h进行预分解，以防止爆炸，之后，再升温至350-420℃。
参见图3所示，为了能够在活性氧化铝预结构上进行二次生长，上述步骤102中，在活性氧化铝预结构MgO-BaO-Al2O3上进行二次生长，以获得尾气处理用改性氧化铝材料SiO2-MgO-BaO-Al2O3，具体包括如下步骤：
301：将活性氧化铝预结构MgO-BaO-Al2O3加入到氨水中，混合均匀，得到溶液B1。
其中，搅拌后在25-35℃超声30-60min，得到混合均匀的溶液B1。
所述氨水的质量分数为5～10wt％，利用氨水调节溶液pH值。
将活性氧化铝预结构MgO-BaO-Al2O3加入到氨水中时，还加入聚丙烯酸羟乙酯、羟丙基甲基纤维素、羟丙基纤维素和聚乙烯醇中的一种或多种。
302：将拟薄水铝石粉末和聚醚改性硅氧烷溶于第二溶剂中，并加入硝酸，球磨一段时间(比如0.5～1h)之后再加入第二溶剂，以将得到的溶胶状态的粘稠物进行稀释，得到溶液B2。
硝酸的作用是促进形成拟薄水铝石凝胶网络。
本申请是利用胶溶法制备氧化铝：利用拟薄水铝石胶溶指数较大的特点，采用酸作胶溶剂而制备氧化铝的一种方法。在胶溶过程中，胶溶剂中的H+离子吸附在拟薄水铝石颗粒上，形成新的颗粒。在搅 拌/球磨的作用下，新颗粒不断吸附其它拟薄水铝石颗粒。通过H+离子这种“酸性桥”将多个拟薄水铝石颗粒以网状的形式连接在一起，从而使拟薄水铝石颗粒失去流动性，使拟薄水铝石溶液变为胶溶状态，后将胶溶后的拟薄水铝石焙烧即可以得到氧化铝。
所述第二溶剂有多种选择，可以根据实际制备需要选择，比如，作为示例，所述第二溶剂包括去离子水和/或蒸馏水。
所述聚醚改性硅氧烷为聚醚改性聚二甲基硅氧烷、聚醚改性三硅氧烷、聚醚改性七甲基硅氧烷中的一种或多种。
步骤302中，聚醚改性硅氧烷的加入量，可以根据最终产物尾气处理用改性氧化铝材料SiO2-MgO-BaO-Al2O3中的Si的含量反算得到。
另外，需要说明的是，活性氧化铝预结构MgO-BaO-Al2O3中的Al2O3在最终产物尾气处理用改性氧化铝材料SiO2-MgO-BaO-Al2O3中的Al2O3总重量的占比并不多，也就是说，活性氧化铝预结构MgO-BaO-Al2O3中的Al2O3对最终产物尾气处理用改性氧化铝材料SiO2-MgO-BaO-Al2O3中的Al2O3的贡献并不高，其中的差值是由Al2O3的另一个来源即拟薄水铝石粉末提供的，故拟薄水铝石粉末的加入量可以由二者反算出来。
需要说明的是，上述步骤301和302并无严格的时间先后顺序，也即二者可以同时进行，也可以先制备溶液B2再制备溶液B1。
303：将溶液B1升温至70-90℃，并边搅拌边加入溶液B2，同时加入碱液，以调节pH至8-9，搅拌均匀后进行第二陈化处理，得到浆液B3。
所述第二陈化处理包括：在40-60℃下陈化3-5小时。
在加入溶液B2的过程中，优选增加超声波分散。
304：在预设气流流速下，将浆液B3进行第一高温焙烧处理。
其中，所述浆液B3进行第一高温焙烧处理之前，还包括：在 100-120℃下烘干。
所述第一高温焙烧处理包括：在300-500℃下焙烧1-2h。
所述预设气流流速为50-250L/min。
305：再进行第二高温焙烧处理，以获得尾气处理用改性氧化铝材料SiO2-MgO-BaO-Al2O3。
所述第二高温焙烧处理包括：在600-800℃下焙烧2-5h。
在进行二次生长之前，首先将活性氧化铝预结构研磨成合适粒径大小的粉末，以利于为二次生长提供合适尺寸的生长基底，然后将相应粉末通过超声均匀分散到氨水溶液中。为了引入Si掺杂改性，又要避免在制备过程中引入有机溶剂，本申请采用将聚醚改性硅氧烷添加到拟薄水铝石中进行改性。避免有机溶剂的引入，一方面可以使得材料制备过程中更加绿色，另一方面有利于活性氧化铝在水性的活性氧化铝预结构体系中进行二次生长，防止出现分相。为了使得掺杂硅改性的活性氧化铝能够均匀的在活性氧化铝预结构粒子的表面进行二次生长，防止活性氧化铝预结构粒子发生团聚，活性氧化铝预结构粉末加入到氨水溶液中时优选添加聚丙烯酸羟乙酯、羟丙基甲基纤维素、羟丙基纤维素、聚乙烯醇等调控溶液的粘度；通过在二次生长过程增加超声分散，进一步促进粒子的均生长和分散。
本申请提出的焙烧工艺与常规的焙烧工艺类似，主要目的是使得拟薄水铝石完全转化成γ-Al2O3，不同之处在于：对于硫酸铵而言，未完全转化的硫酸铵以及生成的硫酸氢铵会在该过程中进一步分解生成氨气、氮气、二氧化硫及水蒸汽等气体，对于硝酸铵而言，未完全转化硝酸铵会在该过程中进一步分解生成氨气、氮气及水蒸汽等气体。为了防止气体的非均匀扩散和局部聚集，需要在300-500℃时调控气体的流速。合适的气体流速控制一方面可以让扩散的气体在氧化铝材料中形成多孔结构，进一步提高比表面积，另一方面也保证二氧化硫等废气从体系中排除，防止残留在其中在制备涂层浆料时毒害贵 金属催化剂。
本申请实施例还提供了一种尾气处理用改性氧化铝材料，其采用如上任一所述的尾气处理用改性氧化铝材料的制备方法制备而成。
本申请实施例还提供了一种三元催化剂，其包括如上所述的尾气处理用改性氧化铝材料。该三元催化剂还包括铈锆基储氧材料、助剂材料以及Pt、Pd、Rh中至少一种贵金属。
以下通过几个实施例和对比例对本申请进行详细说明。
表征方法
1、比表面积表征
对各实施例和对比例的改性氧化铝材料样品分别进行新鲜制得(老化前)以及1100℃高温老化后(老化后)的比表面积表征。比表面积测试方法如下：首先将样品在300℃真空条件下预处理3h，然后以高纯N2为吸附气体，在-196℃(液氮)下进行吸附测试，在25℃下进行脱附测试，采用BET法计算样品的比表面积(Autosorb SI型全自动比表面-孔径分析仪，Quantachrome)。比表面积的保留率＝老化后的比表面积/老化前的比表面积×100％。
2、抗脱落性能表征
首先按照本申请制备三元催化剂涂层浆料，为了更好评价涂层材料在实际应用过程中在高低温环境、机械冲击等条件下的抗脱落性能，本申请采取超声振动和热冲击两种方法来衡量涂层的牢固度。脱落率＝(涂覆后质量-测试后质量)/(涂覆后质量-涂覆前质量)×100％。
(1)超声振动
将涂覆有三元催化剂涂层材料的样品放置在盛有石油醚的密封容器中，然后将该容器放置在超声清洗器中超声波作用30分钟，然后将样品取出并烘干，称量样品的质量并计算脱落率。
(2)热冲击
将涂覆有三元催化剂涂层材料的样品放置在1000℃的马弗炉中保持20min，取出样品迅速浸于0～10℃的冷水中，然后将样品再进行超声波作用促进脱落材料的分离(作用时间不长于1分钟)，如此反复操作多次后至质量不再减少，称量样品的质量并计算脱落率。
实施例1
一种尾气处理用改性氧化铝材料的制备方法：
步骤(1)：称取33.48g的Al(NO3)3·9H2O(其中Al2O3约10g)和3.35g的(NH4)2SO4，按照MgO-BaO-Al2O3中MgO的含量为1wt％、BaO的含量为2wt％称取Mg(NO3)2·6H2O和Ba(NO3)2，将相应的可溶性盐溶解于去离子水中制备成溶液A1，均匀混合的溶液中滴加氨水，使溶液的pH调节至7，搅拌均匀后在25℃下陈化2小时，得到浆液A2；
步骤(2):将浆液A2在80℃下喷雾干燥，然后在350℃下低温焙烧3h，将焙烧后的样品研磨成粒度D90为10μm的P粉末(MgO-BaO-Al2O3)；
步骤(3)：将步骤(2)制备的P粉末添加至质量分数为10wt％的氨水溶液中，搅拌后在25℃超声60min制备成溶液B1；按照Al2O3含量为90g称取拟薄水铝石粉末、按照Si和Mg的摩尔比为6：1量取聚醚改性聚二甲基硅氧烷溶液，将其溶解于去离子水中并加入硝酸，分两次球磨1h，再加入一定量的去离子水制备得到溶液B2；
步骤(4)：将溶液B1升温至70℃，在该温度下向溶液B1中边搅拌边加入溶液B2，在加入溶液B2的过程中使用超声波分散，同时通过添加氨水使浆液的pH调节至8，搅拌均匀后在40℃下陈化3小时；
步骤(5)：将步骤(4)陈化得到的浆液在100℃下烘干，然后在400℃下焙烧2h，该过程中保持气体流速在200L/min，最后在 800℃下焙烧4h，得到尾气处理用改性氧化铝材料(SiO2-MgO-BaO-Al2O3)。
实施例2
一种尾气处理用改性氧化铝材料的制备方法：
步骤(1)：称取33.48g的Al(NO3)3·9H2O(其中Al2O3约10g)和3.35g的(NH4)2SO4，按照MgO-BaO-Al2O3中MgO的含量为4wt％、BaO的含量为2wt％称取Mg(NO3)2·6H2O和Ba(NO3)2，将相应的可溶性盐溶解于去离子水中制备成溶液A1，均匀混合的溶液中滴加氨水，使溶液的pH调节至7，搅拌均匀后在25℃下陈化2小时，得到浆液A2；
步骤(2):将浆液A2在80℃下喷雾干燥，然后在350℃下低温焙烧3h，将焙烧后的样品研磨成粒度D90为10μm的P粉末(MgO-BaO-Al2O3)；
步骤(3)：将步骤(2)制备的P粉末添加至质量分数为10wt％的氨水溶液中，搅拌后在25℃超声60min制备成溶液B1；按照Al2O3含量为90g称取拟薄水铝石粉末、按照Si和Mg的摩尔比为3:1量取聚醚改性聚二甲基硅氧烷溶液，将其溶解于去离子水中并加入硝酸，分两次球磨1h，再加入一定量的去离子水制备得到溶液B2；
步骤(4)：将溶液B1升温至70℃，在该温度下向溶液B1中边搅拌边加入溶液B2，在加入溶液B2的过程中使用超声波分散，同时通过添加氨水使浆液的pH调节至8，搅拌均匀后在40℃下陈化3小时；
步骤(5)：将步骤(4)陈化得到的浆液在100℃下烘干，然后在400℃下焙烧2h，该过程中保持气体流速在200L/min，最后在800℃下焙烧4h，得到尾气处理用改性氧化铝材料(SiO2-MgO-BaO-Al2O3)。
实施例3
一种尾气处理用改性氧化铝材料的制备方法：
步骤(1)：称取33.48g的Al(NO3)3·9H2O(其中Al2O3约10g)和3.35g的(NH4)2SO4，按照MgO-BaO-Al2O3中MgO的含量为1wt％、BaO的含量为2wt％称取Mg(NO3)2·6H2O和Ba(NO3)2，将相应的可溶性盐溶解于去离子水中制备成溶液A1，均匀混合的溶液中滴加氨水，使溶液的pH调节至7，搅拌均匀后在25℃下陈化2小时，得到浆液A2；
步骤(2):将浆液A2在80℃下喷雾干燥，然后在350℃下低温焙烧3h，将焙烧后的样品研磨成粒度D90为10μm的P粉末(MgO-BaO-Al2O3)；
步骤(3)：将步骤(2)制备的P粉末添加至质量分数为10wt％的氨水溶液中，并加入聚丙烯酸羟乙酯，搅拌后在25℃超声60min制备成溶液B1；按照Al2O3含量为90g称取拟薄水铝石粉末、按照Si和Mg的摩尔比为6：1量取聚醚改性聚二甲基硅氧烷溶液，将其溶解于去离子水中并加入硝酸，分两次球磨1h，再加入一定量的去离子水制备得到溶液B2；
步骤(4)：将溶液B1升温至70℃，在该温度下向溶液B1中边搅拌边加入溶液B2，在加入溶液B2的过程中使用超声波分散，同时通过添加氨水使浆液的pH调节至8，搅拌均匀后在40℃下陈化3小时；
步骤(5)：将步骤(4)陈化得到的浆液在100℃下烘干，然后在400℃下焙烧2h，该过程中保持气体流速在200L/min，最后在800℃下焙烧4h，得到尾气处理用改性氧化铝材料(SiO2-MgO-BaO-Al2O3)。
实施例4
一种尾气处理用改性氧化铝材料的制备方法：
步骤(1)：称取33.48g的Al(NO3)3·9H2O(其中Al2O3约10g)和3.35g的(NH4)2SO4，按照MgO-BaO-Al2O3中MgO的含量为4wt％、BaO的含量为2wt％称取Mg(NO3)2·6H2O和Ba(NO3)2，将相应的可溶性盐溶解于去离子水中制备成溶液A1，均匀混合的溶液中滴加氨水，使溶液的pH调节至7，搅拌均匀后在30℃下陈化4小时，得到浆液A2；
步骤(2):将浆液A2在80℃下喷雾干燥，然后在420℃下低温焙烧1h，将焙烧后的样品研磨成粒度D90为15μm的P粉末(MgO-BaO-Al2O3)；
步骤(3)：将步骤(2)制备的P粉末添加至质量分数为10wt％的氨水溶液中，并加入聚丙烯酸羟乙酯，搅拌后在25℃超声60min制备成溶液B1；按照Al2O3含量为50g称取拟薄水铝石粉末、按照Si和Mg的摩尔比为3：1量取聚醚改性聚二甲基硅氧烷溶液，将其溶解于去离子水中并加入硝酸，分两次球磨1h，再加入一定量的去离子水制备得到溶液B2；
步骤(4)：将溶液B1升温至70℃，在该温度下向溶液B1中边搅拌边加入溶液B2，在加入溶液B2的过程中使用超声波分散，同时通过添加氨水使浆液的pH调节至8，搅拌均匀后在60℃下陈化5小时；
步骤(5)：将步骤(4)陈化得到的浆液在100℃下烘干，然后在400℃下焙烧2h，该过程中保持气体流速在200L/min，最后在800℃下焙烧4h，得到尾气处理用改性氧化铝材料(SiO2-MgO-BaO-Al2O3)。
对比例1
一种尾气处理用改性氧化铝材料的制备方法：
步骤(1)：称取33.48g的Al(NO3)3·9H2O(其中Al2O3约10g)和3.35g的(NH4)2SO4，按照MgO-BaO-Al2O3中MgO的含量为1wt％、BaO的含量为2wt％称取Mg(NO3)2·6H2O和Ba(NO3)2，将相应的可溶性盐溶解于去离子水中制备成溶液A1，均匀混合的溶液中滴加氨水，使溶液的pH调节至7，搅拌均匀后在50℃下陈化2小时，得到浆液A2；
步骤(2):将浆液A2在80℃下喷雾干燥，然后在600℃下焙烧3h，将焙烧后的样品研磨成粒度D90为10μm的P粉末(MgO-BaO-Al2O3)；
步骤(3)：将步骤(2)制备的P粉末添加至质量分数为10wt％的氨水溶液中，搅拌后在25℃超声60min制备成溶液B1；按照Al2O3含量为90g称取拟薄水铝石粉末、按照Si和Mg的摩尔比为12：1量取聚醚改性聚二甲基硅氧烷溶液，将其溶解于去离子水中并加入硝酸，分两次球磨1h，再加入一定量的去离子水制备得到溶液B2；
步骤(4)：将溶液B1升温至70℃，在该温度下向溶液B1中边搅拌边加入溶液B2，在加入溶液B2的过程中使用超声波分散，同时通过添加氨水使浆液的pH调节至8，搅拌均匀后在40℃下陈化3小时；
步骤(5)：将步骤(4)陈化得到的浆液在100℃下烘干，然后在400℃下焙烧2h，该过程中保持气体流速在200L/min，最后在800℃下焙烧4h，得到尾气处理用改性氧化铝材料(SiO2-MgO-BaO-Al2O3)。
对比例2
一种尾气处理用改性氧化铝材料的制备方法：
步骤(1)：称取33.48g的Al(NO3)3·9H2O(其中Al2O3约10g)， 按照MgO-BaO-Al2O3中MgO的含量为1wt％、BaO的含量为2wt％称取Mg(NO3)2·6H2O和Ba(NO3)2，将相应的可溶性盐溶解于去离子水中制备成溶液A1，均匀混合的溶液中滴加氨水，使溶液的pH调节至7，搅拌均匀后在25℃下陈化2小时，得到浆液A2；
步骤(2):将浆液A2在80℃下喷雾干燥，然后在350℃下低温焙烧3h，将焙烧后的样品研磨成粒度D90为10μm的P粉末(MgO-BaO-Al2O3)；
步骤(3)：将步骤(2)制备的P粉末添加至质量分数为10wt％的氨水溶液中，搅拌后在25℃超声60min制备成溶液B1；按照Al2O3含量为90g称取拟薄水铝石粉末、按照Si和Mg的摩尔比为6：1量取聚醚改性聚二甲基硅氧烷溶液，将其溶解于去离子水中并加入硝酸，分两次球磨1h，再加入一定量的去离子水制备得到溶液B2；
步骤(4)：将溶液B1升温至70℃，在该温度下向溶液B1中边搅拌边加入溶液B2，在加入溶液B2的过程中使用超声波分散，同时通过添加氨水使浆液的pH调节至8，搅拌均匀后在40℃下陈化3小时；
步骤(5)：将步骤(4)陈化得到的浆液在100℃下烘干，然后在400℃下焙烧2h，该过程中保持气体流速在200L/min，最后在800℃下焙烧4h，得到尾气处理用改性氧化铝材料(SiO2-MgO-BaO-Al2O3)。
对比例3
一种尾气处理用改性氧化铝材料的制备方法：
步骤(1)：称取33.48g的Al(NO3)3·9H2O(其中Al2O3约10g)和3.35g的(NH4)2SO4，按照MgO-Al2O3中MgO的含量为1wt％称取Mg(NO3)2·6H2O，将相应的可溶性盐溶解于去离子水中制备成溶液A1，均匀混合的溶液中滴加氨水，使溶液的pH调节至7，搅拌均匀 后在25℃下陈化2小时，得到浆液A2；
步骤(2):将浆液A2在80℃下喷雾干燥，然后在350℃下低温焙烧3h，将焙烧后的样品研磨成粒度D90为10μm的P粉末(MgO-Al2O3)；
步骤(3)：将步骤(2)制备的P粉末添加至质量分数为10wt％的氨水溶液中，搅拌后在25℃超声60min制备成溶液B1；按照Al2O3含量为90g称取拟薄水铝石粉末、按照Si和Mg的摩尔比为6：1量取聚醚改性聚二甲基硅氧烷溶液，将其溶解于去离子水中并加入硝酸，分两次球磨1h，再加入一定量的去离子水制备得到溶液B2；
步骤(4)：将溶液B1升温至70℃，在该温度下向溶液B1中边搅拌边加入溶液B2，在加入溶液B2的过程中使用超声波分散，同时通过添加氨水使浆液的pH调节至8，搅拌均匀后在40℃下陈化3小时；
步骤(5)：将步骤(4)陈化得到的浆液在100℃下烘干，然后在400℃下焙烧2h，该过程中保持气体流速在200L/min，最后在800℃下焙烧4h，得到尾气处理用改性氧化铝材料(SiO2-MgO-Al2O3)。
对比例4
一种尾气处理用改性氧化铝材料的制备方法：
步骤(1)：称取33.48g的Al(NO3)3·9H2O(其中Al2O3约10g)和3.35g的(NH4)2SO4，按照MgO-BaO-Al2O3中MgO的含量为1wt％、BaO的含量为2wt％称取Mg(NO3)2·6H2O和Ba(NO3)2，将相应的可溶性盐溶解于去离子水中制备成溶液A1，均匀混合的溶液中滴加氨水，使溶液的pH调节至7，搅拌均匀后在25℃下陈化2小时，得到浆液A2；
步骤(2):将浆液A2在80℃下喷雾干燥，然后在350℃下低温 焙烧3h，将焙烧后的样品研磨成粒度D90为10μm的P粉末(MgO-BaO-Al2O3)；
步骤(3)：将步骤(2)制备的P粉末添加至质量分数为10wt％的氨水溶液中，并加入聚丙烯酸羟乙酯，搅拌后在25℃超声60min制备成溶液B1；按照Al2O3含量为90g称取拟薄水铝石粉末、按照Si和Mg的摩尔比为8：1量取聚醚改性聚二甲基硅氧烷溶液，将其溶解于去离子水中并加入硝酸，分两次球磨1h，再加入一定量的去离子水制备得到溶液B2；
步骤(4)：将溶液B1升温至70℃，在该温度下向溶液B1中边搅拌边加入溶液B2，在加入溶液B2的过程中使用超声波分散，同时通过添加氨水使浆液的pH调节至8，搅拌均匀后在40℃下陈化3小时；
步骤(5)：将步骤(4)陈化得到的浆液在100℃下烘干，然后在400℃下焙烧2h，该过程中保持气体流速在200L/min，最后在800℃下焙烧4h，得到尾气处理用改性氧化铝材料(SiO2-MgO-BaO-Al2O3)。
表1由实施例和对比例制备的改性氧化铝材料的性能指标
由表1中的数据可得，实施例制备得到的氧化铝材料具有非常高的比表面积和非常低的脱落率，同时在高温老化后的衰减程度也相对较低。
与实施例1相比，实施例3的区别在于：加入了聚丙烯酸羟乙酯。老化后比表面积也比未加入聚丙烯酸羟乙酯时的高，且超声振动脱落率也低于未加入聚丙烯酸羟乙酯时的超声振动脱落率；说明在将活性氧化铝预结构MgO-BaO-Al2O3加入到氨水中时，添加聚丙烯酸羟乙酯、羟丙基甲基纤维素、羟丙基纤维素、聚乙烯醇等，可以调整溶液的粘度，进而促进粒子的均生长和分散。
与实施例2相比，实施例4的区别在于：加入了聚丙烯酸羟乙酯。老化后比表面积也比未加入聚丙烯酸羟乙酯时的高，且热冲击脱落率也低于未加入聚丙烯酸羟乙酯时的热冲击脱落率；说明在将活性氧化铝预结构MgO-BaO-Al2O3加入到氨水中时，添加聚丙烯酸羟乙酯、羟丙基甲基纤维素、羟丙基纤维素、聚乙烯醇等，可以调整溶液的粘度，进而促进粒子的均生长和分散。
与实施例1相比，对比例1的区别在于：Si和Mg的摩尔比为12：1，步骤(2)的焙烧温度为600℃。此时对比例1的Si和Mg的摩尔比超出(3～7.5)：1，其老化后比表面积大幅降低，而脱落率大幅提高，说明控制Si和Mg的摩尔比为(3～7.5)：1，在不掺杂稀土氧化物的情况下可以获得具有耐高温高比表面积的改性氧化铝材料。同时可以显著提高三元催化剂涂层的抗脱落性能。
与实施例1相比，对比例2的区别在于：不添加硫酸铵。此时老化后比表面积大幅降低，而脱落率大幅提高，说明添加硫酸铵，在焙烧的过程中逐渐分解成气体，有助于形成多孔高比表面积结构，有利于提高氧化铝材料的比表面积。
与实施例1相比，对比例3的区别在于：不添加硝酸钡。此时老 化后比表面积大幅降低，而脱落率大幅提高，说明合适含量BaO可以提高氧化铝材料的耐老化性能。
与实施例1相比，对比例4的区别在于：加入了聚丙烯酸羟乙酯，Si和Mg的摩尔比为8：1。此时老化后比表面积大幅降低，而脱落率大幅提高，但是相对于对比例1而言，其脱落率相对低一些，说明在将活性氧化铝预结构MgO-BaO-Al2O3加入到氨水中时，添加聚丙烯酸羟乙酯、羟丙基甲基纤维素、羟丙基纤维素、聚乙烯醇等，可以调整溶液的粘度，进而促进粒子的均生长和分散，有利于降低脱落率。
综上所述，本申请提供的一种尾气处理用氧化铝材料，可以提高氧化铝材料的比表面积和耐高温性能，抑制γ-Al2O3材料在高温下的相转变过程从而提高氧化铝材料的高温耐老化性能，同时提高氧化铝材料作为涂层材料时的抗脱落性能，并且在制备方法上工艺流程简便，生产效率高，可导入到现有的氧化铝材料生产线中，基于该氧化铝材料的汽油机尾气后处理模块在汽车尾气处理领域具有非常良好的应用前景。
在本申请的描述中，需要说明的是，术语“上”、“下”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本申请和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请的限制。除非另有明确的规定和限定，术语“安装”、“相连”、“连接”应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体地连接；可以是机械连接，也可以是电连接；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本申请中的具体含义。
需要说明的是，在本申请中，诸如“第一”和“第二”等之类的关系术语仅仅用来将一个实体或者操作与另一个实体或操作区分开来，而不一定要求或者暗示这些实体或操作之间存在任何这种实际的关系或者顺序。而且，术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含，从而使得包括一系列要素的过程、方法、物品或者设备不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种过程、方法、物品或者设备所固有的要素。在没有更多限制的情况下，由语句“包括一个……”限定的要素，并不排除在包括所述要素的过程、方法、物品或者设备中还存在另外的相同要素。
以上所述仅是本申请的具体实施方式，使本领域技术人员能够理解或实现本申请。对这些实施例的多种修改对本领域的技术人员来说将是显而易见的，本文中所定义的一般原理可以在不脱离本申请的精神或范围的情况下，在其它实施例中实现。因此，本申请将不会被限制于本文所示的这些实施例，而是要符合与本文所申请的原理和新颖特点相一致的最宽的范围。

Claims (21)

  1. 一种尾气处理用改性氧化铝材料的制备方法，其特征在于，其包括：
    在氧化铝上进行一次生长，以获得活性氧化铝预结构MgO-BaO-Al2O3；
    在活性氧化铝预结构MgO-BaO-Al2O3上进行二次生长，以获得尾气处理用改性氧化铝材料SiO2-MgO-BaO-Al2O3，其中，尾气处理用改性氧化铝材料SiO2-MgO-BaO-Al2O3中的Si和Mg的摩尔比为(3～7.5)：1。
  2. 如权利要求1所述的尾气处理用改性氧化铝材料的制备方法，其特征在于，
    活性氧化铝预结构MgO-BaO-Al2O3中，MgO的含量为0.2-4.0wt％，BaO的含量为0.5-5.0wt％，Al2O3占尾气处理用改性氧化铝材料SiO2-MgO-BaO-Al2O3中Al2O3总重量的5-30wt％。
  3. 如权利要求1所述的尾气处理用改性氧化铝材料的制备方法，其特征在于，在氧化铝上进行一次生长，以获得活性氧化铝预结构MgO-BaO-Al2O3，具体包括如下步骤：
    将可溶性铝盐、可溶性镁盐、可溶性钡盐和可溶性铵盐溶于第一溶剂中制备成溶液A1；
    向溶液A1中滴加碱液，使溶液A1的pH调节至7-8，搅拌均匀后进行第一陈化处理，得到浆液A2；
    将浆液A2进行低温焙烧处理，并研磨，以获得活性氧化铝预结构MgO-BaO-Al2O3。
  4. 如权利要求3所述的尾气处理用改性氧化铝材料的制备方法，其特征在于，所述可溶性铝盐、可溶性镁盐、可溶性钡盐的加入量如下：
    Al3+、Mg2+和Ba2+的摩尔比为Al3+：Mg2+：Ba2+＝(90～95)：(0.2～5)：(0.1～2)。
  5. 如权利要求3所述的尾气处理用改性氧化铝材料的制备方法，其特征在于：
    所述可溶性铝盐包括硝酸铝、硫酸铝和氯化铝中的一种或多种；
    所述可溶性镁盐包括硝酸镁、硫酸镁、醋酸镁和氯化镁中的一种或多种；
    所述可溶性钡盐包括硝酸钡、醋酸钡和氯化钡中的一种或多种；
    所述可溶性铵盐包括硫酸铵和/或硝酸铵；
    所述碱液包括氨水和/或碳酸铵。
  6. 如权利要求3所述的尾气处理用改性氧化铝材料的制备方法，其特征在于，所述第一陈化处理包括：20-30℃下陈化2-4小时。
  7. 如权利要求3所述的尾气处理用改性氧化铝材料的制备方法，其特征在于，所述低温焙烧处理包括：350-420℃下焙烧1-3h。
  8. 如权利要求3所述的尾气处理用改性氧化铝材料的制备方法，其特征在于，所述浆液A2进行低温焙烧处理之前，还包括：在60-100℃下烘干。
  9. 如权利要求8所述的尾气处理用改性氧化铝材料的制备方法，其特征在于：在60-100℃下采用喷雾的方式烘干。
  10. 如权利要求3所述的尾气处理用改性氧化铝材料的制备方法，其特征在于：研磨至粒度D90为5-15μm。
  11. 如权利要求1所述的尾气处理用改性氧化铝材料的制备方法，其特征在于，在活性氧化铝预结构MgO-BaO-Al2O3上进行二次生长，以获得尾气处理用改性氧化铝材料SiO2-MgO-BaO-Al2O3，具体包括如下步骤：
    将活性氧化铝预结构MgO-BaO-Al2O3加入到氨水中，混合均匀，得到溶液B1；
    将拟薄水铝石粉末和聚醚改性硅氧烷溶于第二溶剂中，并加入硝酸，球磨之后再加入第二溶剂，得到溶液B2；
    将溶液B1升温至70-90℃，并边搅拌边加入溶液B2，同时加入碱液，以调节pH至8-9，搅拌均匀后进行第二陈化处理，得到浆液B3；
    在预设气流流速下，将浆液B3进行第一高温焙烧处理；
    再进行第二高温焙烧处理，以获得尾气处理用改性氧化铝材料SiO2-MgO-BaO-Al2O3。
  12. 如权利要求11所述的尾气处理用改性氧化铝材料的制备方法，其特征在于：所述氨水的质量分数为5～10wt％；
    所述聚醚改性硅氧烷为聚醚改性聚二甲基硅氧烷、聚醚改性三硅氧烷、聚醚改性七甲基硅氧烷中的一种或多种。
  13. 如权利要求11所述的尾气处理用改性氧化铝材料的制备方法，其特征在于：将活性氧化铝预结构MgO-BaO-Al2O3加入到氨水中时，还加入聚丙烯酸羟乙酯、羟丙基甲基纤维素、羟丙基纤维素和聚乙烯醇中的一种或多种。
  14. 如权利要求11所述的尾气处理用改性氧化铝材料的制备方法，其特征在于：在超声波分散条件下，边搅拌边加入溶液B2。
  15. 如权利要求11所述的尾气处理用改性氧化铝材料的制备方法，其特征在于，所述浆液B3进行第一高温焙烧处理之前，还包括：在100-120℃下烘干。
  16. 如权利要求11所述的尾气处理用改性氧化铝材料的制备方法，其特征在于，所述第二陈化处理包括：在40-60℃下陈化3-5小时。
  17. 如权利要求11所述的尾气处理用改性氧化铝材料的制备方法，其特征在于，所述第一高温焙烧处理包括：在300-500℃下焙烧1-2h。
  18. 如权利要求11所述的尾气处理用改性氧化铝材料的制备方法，其特征在于，所述第二高温焙烧处理包括：在600-800℃下焙烧2-5h。
  19. 如权利要求11所述的尾气处理用改性氧化铝材料的制备方法，其特征在于：所述预设气流流速为50-250L/min。
  20. 一种尾气处理用改性氧化铝材料，其特征在于，其采用如权利要求1至19中任一所述的尾气处理用改性氧化铝材料的制备方法制备而成。
  21. 一种三元催化剂，其特征在于，其包括如权利要求20所述的尾气处理用改性氧化铝材料。
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CN109772289A (zh) 2019-02-28 2019-05-21 江苏国盛新材料有限公司 一种镧改性氧化铝的制备方法
CN110540222A (zh) * 2019-08-30 2019-12-06 中国铝业股份有限公司 一种耐高温活性氧化铝的制备方法
CN113233484A (zh) 2021-06-02 2021-08-10 西南石油大学 一种耐高温高比表面活性氧化铝的制备方法
CN117123207A (zh) * 2023-08-16 2023-11-28 东风汽车集团股份有限公司 一种尾气处理用改性氧化铝材料、制备方法及三元催化剂

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