Supported catalyst based on carrier modification and preparation method and application thereof

Abstract

The invention discloses a supported catalyst based on carrier modification and a preparation method and application thereof, and relates to the technical field of supported catalysts, the supported catalyst comprises an inert ceramic material and catalyst powder coating the inert ceramic material, and the catalyst powder comprises a modified carrier and an active component supported on the modified carrier; the modified carrier comprises a carrier material and a modifier, the carrier is one or more of pure aluminum oxide or an aluminum-based composite material, and the modifier is a mixture of an M source and a P source; the modified carrier is prepared by carrying out surface modification on a carrier through a mixture formed by an M source and a P source, and the modified carrier is an M3 (PO4) delta carrier or an M3 (PO4) delta carrier; the active component includes noble metal particles dispersed in a modified carrier material. The catalyst can be directly applied to three-way catalysis of a motor vehicle, and the catalyst prepared by adopting the method disclosed by the invention can be used for effectively improving the ignition performance and the durability by taking a natural gas vehicle equivalence ratio combustion reaction as an application case.

Description

Technical Field

[0001] This invention relates to the field of supported catalyst technology, specifically to a supported catalyst based on support modification, its preparation method, and its application. Background Technology

[0002] Noble metal (Pt / Pd / Rh) catalysts have become the core of many important catalytic systems due to their excellent redox properties. However, the full realization of their catalytic conversion performance is highly dependent on the supported material. Among them, aluminum-based composite materials with Al2O3 as the main component, with their high specific surface area, controllable pore structure, and suitable interaction with the active components, have become an ideal support platform for loading noble metals and are widely used in some key environmental catalysis fields.

[0003] 1) Stoichiometric three-way catalyst (TWC)

[0004] In the exhaust gas purification reactions of internal combustion engines in motor vehicles such as gasoline cars, natural gas (CNG), and motorcycles, the catalyst needs to synergistically and efficiently catalyze the oxidation of CO, HC, and NO at an air-fuel ratio close to the stoichiometric ratio. x The reduction of aluminum-based carriers, especially aluminum-based composite materials modified with rare earth elements (Ce, La, etc.), not only provides a highly dispersed environment for precious metal nanoparticles, but their oxygen storage / release capacity (OSC) can also effectively buffer fluctuations in the air-fuel ratio window, thereby widening the three-effect window and meeting the current stringent emission standards such as China VI and Euro VI.

[0005] 2) Lean combustion oxidation catalyst

[0006] Under lean-burn conditions, such as diesel engine oxidation catalysts (DOC) and natural gas lean-burn engine oxidation catalysts (MOC), aluminum-based supports, especially γ-Al₂O₃ with certain high thermal stability, utilize their surface acidic sites to facilitate the adsorption and activation of long-chain HC, thereby improving overall purification efficiency.

[0007] 3) Catalysts for the catalytic oxidation of volatile organic compounds (VOCs)

[0008] In industrial waste gas treatment, precious metal / aluminum-based catalysts have high low-temperature activity and low ignition temperature, and have the ability to oxidize various VOCs (such as benzene compounds, esters, aldehydes and ketones). For different VOC components and complex working conditions, specific aluminum-based composite supports can be designed to modulate the electronic state of precious metals and the surface properties of the support, thereby enhancing the activity, selectivity and anti-poisoning ability of the catalyst.

[0009] However, despite the widespread use of precious metal / aluminum-based catalysts, ongoing challenges remain:

[0010] 1. The surface properties of traditional pure alumina or alkali / alkaline earth / rare earth metal modified alumina carriers mainly rely on alumina as an inert support carrier, resulting in a single function, insufficient redox performance, and difficulty in constructing efficient multifunctional active sites.

[0011] 2. The doped metal in the carrier cannot form a solid solution structure with strong interaction with alumina. Under high temperature and steam environment, the carrier surface is prone to hydroxylation and rapid sintering and deactivation.

[0012] 3. The lack of redox sites on the support that strongly interact with precious metals results in insufficient low-temperature ignition activity and poor high-temperature durability of the catalyst.

[0013] Furthermore, the prices of precious metals (Pt, Pd, Rh) have been fluctuating and rising in recent years, leading to market demands for continuous cost reduction. Therefore, developing new support materials has gradually become the core of cost reduction and efficiency improvement. To overcome limitations, researchers have developed various strategies to enhance catalytic performance, among which phosphorus / phosphate modification technology has attracted much attention due to its high-temperature stability, electronic structure regulation, and surface acidity. For example, a mesoporous metal phosphate catalyst (CN120205183A) with high crystallinity, large specific surface area, and good thermal stability was prepared by modifying inorganic metal salts with phosphoric acid as the phosphorus source; a Ni-based catalyst was prepared by modifying alumina with organophosphorus to enhance the support AlPO4. x - The metal-support interaction between Al2O3 and Ni (CN117816208A); using phosphorus compounds to modify the support for loading active metals, optimizing the surface acidity of the support, and thus improving the thermal stability of the catalyst (CN120695857A). However, existing phosphorus / phosphate modification technologies present significant contradictions, often sacrificing catalytic activity and support texture in pursuit of stability. Therefore, developing a strategy for synergistic modification of aluminum-based supports with metals and phosphates to improve the low-temperature ignition performance and durability of noble metal catalysts is of great significance for addressing vehicle exhaust emissions and industrial waste gas treatment. Summary of the Invention

[0014] The existing technology suffers from insufficient low-temperature ignition activity and poor high-temperature durability due to the lack of redox sites on the support that strongly interact with precious metals. The present invention aims to provide a supported catalyst based on support modification, its preparation method, and its application. This supported catalyst can be directly applied to the field of motor vehicle exhaust purification. Using the method of this invention, the supported catalyst prepared in the equivalence combustion exhaust purification reaction of a natural gas vehicle is used as an application example, demonstrating that it can effectively improve its ignition performance and durability.

[0015] This invention is achieved through the following technical solution:

[0016] Firstly, this application provides a supported catalyst based on support modification.

[0017] The invention includes an inert ceramic material and a catalyst powder coated on the inert ceramic material, wherein the catalyst powder includes a modified support and an active component supported on the modified support;

[0018] The modified carrier includes a carrier material and a modifier. The carrier is one or more of pure alumina or aluminum-based composite materials, and the modifier is a mixture of M source and P source. The modified carrier is prepared by surface modification of the carrier using a mixture of M source and P source, and its composition is M3(PO4). δ —Carrier or M3 (PO4) δ / carrier;

[0019] The M includes any one or more combinations of alkali metals, alkaline earth metals, transition metals, or rare earth metals; the P source includes any one or more combinations of phosphorus oxides, orthophosphoric acid, orthophosphate, phosphorous acid, phosphite, hypophosphoric acid, hypophosphite, and halides.

[0020] The active component includes a noble metal composition dispersed on the surface of the modified carrier material.

[0021] In an embodiment of the present invention, in the mixture composed of the M source and the P source, M δ+ With PO4 3- The molar ratio is 1:(0.36~1.5), which makes M δ+ M3(PO4) is fully formed. δ It should be noted that this molar ratio is the process feed ratio, and the actual stoichiometric ratio should be adjusted according to the metal valence state: for example, a +1 valence metal corresponds to PO4. 3- The molar ratio is 1:(0.36-0.5).

[0022] In an embodiment of the present invention, the M3(PO4) on the modified carrier... δ The mass percentage of the carrier is 0.1wt% to 30wt%. Preferably, it is 1wt%, 3wt%, 5wt%, 8wt%, 10wt%, 20wt%, or 30wt%.

[0023] In an embodiment of the present invention, the carrier material is Al2O3, and the content of Al2O3 accounts for 40% or more of the total amount of the carrier material;

[0024] Alternatively, the carrier material may be an aluminum-based composite material, comprising Al2O3 and one or more components selected from rare earth oxides, alkaline earth metal oxides, silicon oxides, titanium oxides, and zirconium oxides.

[0025] In an embodiment of the present invention, the noble metal composition is mainly Pd and contains Pt and / or Rh; wherein the noble metal source in the noble metal composition includes any one or more of Pt / Pd / Rh oxides, chlorides, nitrate compounds, acetic acid compounds, and acetylacetone compounds.

[0026] In an embodiment of the present invention, the loading of noble metal in the supported catalyst is 15 g / ft. 3 ~80g / ft 3 , at 50g / ft 3 For example, the ratio between Pt / Pd / Rh is (0~15):(25:50):(0~10).

[0027] Secondly, this application provides a method for preparing a supported catalyst based on a modified support, comprising the following steps:

[0028] (1) Under acidic conditions, the M source and the P source are impregnated together onto the carrier powder, and after standing and aging, they are dried and calcined to obtain the modified carrier.

[0029] (2) The modified support is added to the precious metal impregnation solution for loading to obtain catalyst powder;

[0030] (3) The catalyst powder and binder solution are mixed and ball-milled to obtain a slurry. The slurry is coated on a ceramic material, dried, calcined and aged to obtain a supported catalyst.

[0031] The specific preparation method of the modified support is as follows:

[0032] The M precursor, P precursor, and water are mixed evenly to obtain an impregnation solution;

[0033] Mix the acidic reagent and water thoroughly to obtain an acidic solution;

[0034] The carrier and water are mixed evenly to obtain a carrier suspension;

[0035] The impregnation solution and acidic solution are simultaneously added dropwise to the carrier suspension while stirring, with the stirring speed controlled at 100-400 rpm and the dropping rate controlled at 0.5-3.0 mL / min. Under acidic conditions, the M source and P source are co-impregnated onto the carrier. Specifically, in the impregnation complex solution containing M and P, M... δ+ With PO4 3- The molar ratio is 1:(0.36~1.5). It should be noted that the P source content is slightly higher than the M source to ensure that M... δ+ M3(PO4) is fully formed. δ .

[0036] The carrier material is Al2O3, and the Al2O3 content accounts for 40% or more of the total carrier material; or the carrier material is an aluminum-based composite material, including Al2O3 and one or more components selected from rare earth oxides, alkaline earth metal oxides, silicon oxides, titanium oxides, and zirconium oxides. In a specific embodiment of the present invention, it is preferable to transfer the carrier powder to a beaker, add deionized water, and then uniformly disperse the carrier powder to obtain a carrier solution. The mass fraction of the carrier in the carrier solution is generally 10% to 20%.

[0037] The impregnation solution containing M and P is obtained by dissolving the precursors of the M source and the P source in water. The M source is any one or more of the following: alkali metals Li, Na, K, Rb, Cs or alkaline earth metals Mg, Ca, Sr, Ba or transition metals Fe, Co, Ni, Cu, Zn, Y, Zr or rare earth metals La, Ce, Pr, Nd, Sm, Eu; and the P source is a phosphorus source.

[0038] The M source includes any one or more of the following: oxides, chlorides, nitrates, sulfates, carbonates, oxalates, and acetates of M; the P source includes any one or more of the following: oxides of P, orthophosphoric acid, orthophosphate, phosphorous acid, phosphite, hypophosphorous acid, hypophosphite, and halides. The modified support contains M3(PO4). δ The mass percentage of the carrier is 0.1wt to 30wt%.

[0039] The acidic solution is obtained by dispersing an acidic substance in water. The acidic substance, as an auxiliary agent, includes one or more of HCOOH, CH3COOH, HNO3, HCl, H3PO4, or H2SO4. In a specific embodiment of the present invention, the mass concentration of the acidic solution is generally 1% to 10%, and the amount of acidic solution used depends on the pH of the reaction solution, which is generally 4.5 to 6.5.

[0040] In an embodiment of the present invention, it is preferable to allow the obtained product to stand and age after the above impregnation is completed, so as to ensure that the M source and P source can exist stably and grow on the carrier, and then dry and calcinate.

[0041] In an embodiment of the present invention, the aging temperature is 30~80℃, preferably 50~60℃; the aging time is 1~6h, preferably 3~5h.

[0042] In embodiments of the present invention, the drying method is not particularly limited. After drying, grinding and sieving are preferably performed, and the grinding and sieving are not particularly limited.

[0043] In an embodiment of the present invention, the calcination temperature is 500~900℃, such as 500℃, 550℃, 600℃, 650℃, 700℃ or 750℃; the calcination time is 2~5h; the calcination heating rate is 3~10℃ / min; and the calcination atmosphere is an air atmosphere.

[0044] In an embodiment of the present invention, during the calcination process of the modified support, M and P undergo precursor decomposition, phosphate nucleus formation, hydrate formation, dehydration and crystal orientation transformation, and crystal and interface strengthening on the support, ultimately forming a stable phosphate-support complex.

[0045] The specific preparation method of the catalyst powder is as follows:

[0046] The precious metal precursor and water are mixed evenly to obtain a precious metal impregnation solution;

[0047] The impregnation solution was transferred to a beaker, and the modified carrier powder described above was added for loading.

[0048] The impregnation method is selected from any one of the following: over-impregnation method, impregnation precipitation method, equal-volume impregnation method, co-impregnation method, ultrasonic / microwave assisted impregnation method, or step-by-step multiple impregnation method.

[0049] The impregnation solution containing the noble metal source is obtained by dissolving the precursor of the noble metal source in water.

[0050] The noble metal component is mainly Pd, and contains a combination of Pt and / or Rh. The noble metal source includes any one or more of the following: oxides of Pt / Pd / Rh, chlorides, nitrate compounds, acetic acid compounds, and acetylacetone compounds.

[0051] In an embodiment of the present invention, it is preferable to dry and calcine the obtained product after the loading is completed.

[0052] In the embodiments of the present invention, there are no particular restrictions on the drying method, and the product is roasted after drying.

[0053] In an embodiment of the present invention, the calcination temperature is 500~900℃, such as 500℃, 550℃, 600℃, 650℃, 700℃ or 750℃; the calcination time is 2~5h; the calcination heating rate is 3~10℃ / min; and the calcination atmosphere is an air atmosphere.

[0054] In an embodiment of the present invention, during the calcination process, the noble metal undergoes precursor decomposition, oxide crystal phase formation, and oxide reduction on the modified carrier, and the resulting noble metal particles are uniformly dispersed on the surface of the modified carrier.

[0055] The specific preparation method of the supported catalyst is as follows:

[0056] Mix the adhesive with water until homogeneous to obtain an adhesive complex solution.

[0057] The modified catalyst powder and binder solution described above were mixed, ball-milled to obtain a slurry, which was then coated onto a ceramic material, dried, and calcined to obtain a fresh catalyst sample.

[0058] In an embodiment of the present invention, during the coating process, the loading amount of the slurry is 50~150g / L, preferably 80~130g / L.

[0059] In the embodiments of the present invention, there are no particular restrictions on the drying method, and the product is roasted after drying.

[0060] In an embodiment of the present invention, the calcination temperature is 500~900℃, such as 500℃, 550℃, 600℃, 650℃, 700℃ or 750℃; the calcination time is 2~5h; the calcination heating rate is 3~10℃ / min; and the calcination atmosphere is an air atmosphere.

[0061] The fresh catalyst sample described above was calcined and aged under aging conditions to obtain an aged catalyst sample.

[0062] In an embodiment of the present invention, the hydrothermal aging temperature is 500~1100℃; the aging time is 5~100h; and the aging atmosphere is 5vol%~30vol% H2O / Air.

[0063] The method for preparing the supported catalyst with the surface-modified support provided by the present invention is simple. By controlling the calcination temperature of the modified support and the proportion of the modified material, a modified catalyst with effectively improved performance can be obtained, and it is suitable for large-scale industrial production.

[0064] Thirdly, this application provides an application of a supported catalyst based on carrier modification, including its use in the purification reaction of exhaust gas from equivalence ratio combustion in motor vehicle internal combustion engines.

[0065] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0066] (1) The preparation method of the carrier-modified-supported catalyst provided by the present invention is simple and low in cost. It can be scaled up or produced without complex processes. When applied to the field of exhaust gas purification of natural gas vehicles, the catalyst can effectively improve its low-temperature activity and hydrothermal durability.

[0067] (2) The present invention uses an over-impregnation method to precisely dope phosphate onto the carrier. By combining over-impregnation with specific drying control technology, the modified components are fully adsorbed and uniformly dispersed on the complex carrier surface. The strong interaction between phosphate and the carrier surface is used to anchor the active components and enhance the structural stability of the material. After high-temperature hydrothermal aging treatment, it can still maintain excellent activity, providing an efficient and feasible technical path for the precise modification and functional design of multi-component oxide carriers.

[0068] (3) The present invention uses a specific ratio of phosphate to modify the support. Through the process of "excessive impregnation + step-by-step roasting", the phosphate and the support form a stable "phosphate mineral phase-support" interface, anchoring the active components, thereby inhibiting the sintering deactivation problem of the catalyst after being treated in a high-temperature water and gas environment.

[0069] (4) After the modified carrier in this invention is loaded with precious metals, the CH4 / NO ratio in the natural gas tail gas treatment is reduced. x The ignition performance is improved, and the resistance to high-temperature hydrothermal aging is significantly enhanced, while maintaining the levels of CH4 and NO. x The conversion rate of CO is >90%.

[0070] (5) By optimizing the phosphate doping ratio and the calcination temperature of the support, this invention not only solves the problems of poor compatibility between phosphate and support and catalyst poisoning in traditional modification processes, but also significantly improves the problem of easy agglomeration and deactivation of active components, which is conducive to realizing industrial scale-up production. Detailed Implementation

[0071] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0072] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known materials or methods have not been specifically described in order to avoid obscuring the invention.

[0073] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described herein, as well as the features of those different embodiments or examples.

[0074] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0075] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0076] Example 1

[0077] Step S1: Dissolve lithium hydroxide and phosphoric acid in deionized water to form 0.3 mol / L impregnation solutions for later use. Dilute the acidic additive in deionized water to form a 10% acidic solution for later use. Transfer 24.25 g of carrier powder to another beaker, add 108 mL of deionized water to evenly disperse the carrier powder and form a carrier suspension, and stir continuously. Then, add the impregnation solution and acidic solution to the above carrier suspension at a dropping rate of 2 mL / min, and adjust the pH of the solution to 5.5. After stirring evenly, age the mixed solution at 50 °C for 5 h. Then transfer it to an oven to dry at 120 °C for 2 h, grind, sieve, and calcine in a muffle furnace in air atmosphere at a temperature of 5 °C / min to 800 °C for 2 h to obtain a modified carrier with a Li3PO4 mass fraction of 3 wt%.

[0078] Step S2: The noble metal (Pt / Pd / Rh) precursor solution is mixed with the modified support powder for loading, and the total content of Pt / Pd / Rh is 40 g / ft. 3 The proportion of precious metals is (Pt / Pd / Rh=9 / 30 / 1). After loading, the catalyst is dried at 90 °C and then calcined in an air atmosphere in a muffle furnace at 5 °C / min to 500 °C for 2 hours to obtain catalyst powder.

[0079] Step S3: Dissolve 2g of binder (boehmite) in 4mL of water to form an aluminum sol. Then, weigh 18.60g of the catalyst powder obtained in step S2, mix it with the aluminum sol, and transfer it to a ball mill jar. Add 23.64mL of deionized water and ball mill for 25min to obtain a slurry. Coat the slurry onto a ceramic carrier at a coating amount of 130g / L, then dry it and calcine it at 500℃ for 2h to obtain catalyst S1 of this embodiment.

[0080] Example 2

[0081] Step S1: This embodiment uses a preparation method similar to Example 1, the difference being the selection of the M source and P source. Specifically: Magnesium nitrate and ammonium dihydrogen phosphate are dissolved in deionized water to form a 0.3 mol / L impregnation solution for later use. The acidic auxiliary agent is diluted in deionized water to form a 10% acidic solution for later use. 24.25 g of carrier powder is transferred to another beaker, and 108 mL of deionized water is added to uniformly disperse the carrier powder to form a carrier suspension, and the mixture is continuously stirred. Then, the impregnation solution and the acidic solution are added to the above carrier suspension at a dropping rate of 2 mL / min, and the pH of the solution is adjusted to 5.5. After stirring evenly, the mixed solution is aged at 50°C for 5 h. Subsequently, it is transferred to an oven and dried at 120°C for 2 h, ground, sieved, and then calcined in a muffle furnace in an air atmosphere at a temperature of 5°C / min to 800°C for 2 h to obtain a modified carrier with a Mg3(PO4)2 mass fraction of 3 wt%.

[0082] Step S2: The noble metal (Pt / Pd / Rh) precursor solution is mixed with the modified support powder for loading, and the total content of Pt / Pd / Rh is 40 g / ft. 3 The proportion of precious metals is (Pt / Pd / Rh=7 / 30 / 3). After loading, the catalyst is dried at 90 °C and then calcined in an air atmosphere in a muffle furnace at 5 °C / min to 500 °C for 2 hours to obtain catalyst powder.

[0083] Step S3 is the same as in Example 1, and the catalyst S2 of this example is obtained.

[0084] Example 3

[0085] Step S1: This embodiment uses a preparation method similar to Example 1, the difference being the selection of the M source and P source. Specifically: Strontium carbonate and sodium phosphate are dissolved in deionized water to form a 0.3 mol / L impregnation solution for later use. The acidic auxiliary agent is diluted in deionized water to form a 10% acidic solution for later use. 24.25 g of carrier powder is transferred to another beaker, and 108 mL of deionized water is added to uniformly disperse the carrier powder to form a carrier suspension, and the mixture is continuously stirred. Then, the impregnation solution and the acidic solution are added to the above carrier suspension at a dropping rate of 2 mL / min, and the pH of the solution is adjusted to 5.5. After stirring evenly, the mixed solution is aged at 50°C for 5 h. Subsequently, it is transferred to an oven and dried at 120°C for 2 h, ground, sieved, and then calcined in a muffle furnace in an air atmosphere at a temperature of 5°C / min to 800°C for 2 h to obtain a modified carrier with a Sr3(PO4)2 mass fraction of 3 wt%.

[0086] Step S2: The noble metal (Pt / Pd / Rh) precursor solution is mixed with the modified support powder for loading, and the total content of Pt / Pd / Rh is 40 g / ft. 3 The proportion of precious metals is (Pt / Pd / Rh=2 / 35 / 3). After loading, the catalyst is dried at 90 °C and then calcined in an air atmosphere in a muffle furnace at 5 °C / min to 500 °C for 2 hours to obtain catalyst powder.

[0087] Step S3 is the same as in Example 1, and the catalyst S3 of this example is obtained.

[0088] Example 4

[0089] Step S1: This embodiment uses a preparation method similar to Example 1, the difference being the selection of the M source and P source. Specifically: Yttrium nitrate and diammonium hydrogen phosphate are dissolved in deionized water to form a 0.3 mol / L impregnation solution for later use. The acidic auxiliary agent is diluted in deionized water to form a 10% acidic solution for later use. 24.25 g of carrier powder is transferred to another beaker, and 108 mL of deionized water is added to uniformly disperse the carrier powder to form a carrier suspension, and the mixture is continuously stirred. Then, the impregnation solution and the acidic solution are added to the above carrier suspension at a dropping rate of 2 mL / min, and the pH of the solution is adjusted to 5.5. After stirring evenly, the mixed solution is aged at 50°C for 5 h. Subsequently, it is transferred to an oven and dried at 120°C for 2 h, ground, sieved, and then calcined in a muffle furnace in an air atmosphere at a temperature of 5°C / min to 800°C for 2 h to obtain a modified carrier with a YPO4 mass fraction of 3 wt%.

[0090] Step S2: The noble metal (Pt / Pd / Rh) precursor solution is mixed with the modified support powder for loading, and the total content of Pt / Pd / Rh is 40 g / ft. 3 The proportion of precious metals is (Pt / Pd / Rh=8 / 30 / 2). After loading, the catalyst is dried at 90 °C and then calcined in an air atmosphere in a muffle furnace at 5 °C / min to 500 °C for 2 hours to obtain catalyst powder.

[0091] Step S3 is the same as in Example 1, and the catalyst S4 of this example is obtained.

[0092] Example 5

[0093] Step S1: This embodiment uses a similar preparation method to Example 1, the difference being the selection of the M source and P source. Specifically: Zirconium oxychloride and hypophosphoric acid are dissolved in deionized water to form a 0.3 mol / L impregnation solution for later use. The acidic auxiliary agent is diluted in deionized water to form a 10% acidic solution for later use. 24.25 g of carrier powder is transferred to another beaker, and 108 mL of deionized water is added to uniformly disperse the carrier powder to form a carrier suspension, and the mixture is continuously stirred. Then, the impregnation solution and the acidic solution are added to the above carrier suspension at a dropping rate of 2 mL / min, and the pH of the solution is adjusted to 5.5. After stirring evenly, the mixed solution is aged at 50 °C for 5 h. Subsequently, it is transferred to an oven and dried at 120 °C for 2 h, ground, sieved, and then calcined in a muffle furnace in an air atmosphere at a temperature of 5 °C / min to 800 °C for 2 h to obtain a modified carrier with a Zr3(PO4)4 mass fraction of 3 wt%.

[0094] Step S2: The noble metal (Pt / Pd / Rh) precursor solution is mixed with the modified support powder for loading, and the total content of Pt / Pd / Rh is 40 g / ft. 3The proportion of precious metals is (Pt / Pd / Rh=10 / 27 / 3). After loading, the catalyst is dried at 90 °C and then calcined in an air atmosphere in a muffle furnace at 5 °C / min to 500 °C for 2 hours to obtain catalyst powder.

[0095] Step S3 is the same as in Example 1, and the catalyst S5 of this example is obtained.

[0096] Example 6

[0097] Step S1: This embodiment uses a preparation method similar to Example 1, the difference being the selection of the M source and P source and the different doping concentrations. Specifically: Yttrium nitrate and diammonium hydrogen phosphate are dissolved in deionized water to form a 0.3 mol / L impregnation solution for later use. The acidic auxiliary agent is diluted in deionized water to form a 10% acidic solution for later use. 24.75 g of carrier powder is transferred to another beaker, and 108 mL of deionized water is added to uniformly disperse the carrier powder to form a carrier suspension, and the mixture is continuously stirred. Then, the impregnation solution and the acidic solution are added to the above carrier suspension at a dropping rate of 2 mL / min, and the pH of the solution is adjusted to 5.5. After stirring evenly, the mixed solution is aged at 50°C for 5 h. Subsequently, it is transferred to an oven and dried at 120°C for 2 h, ground, sieved, and then calcined in a muffle furnace in an air atmosphere at a temperature of 5°C / min to 800°C for 2 h to obtain a modified carrier with a YPO4 mass fraction of 1 wt%.

[0098] Step S2: The noble metal (Pt / Pd / Rh) precursor solution is mixed with the modified support powder for loading, and the total content of Pt / Pd / Rh is 40 g / ft. 3 The proportion of precious metals is (Pt / Pd / Rh=14 / 25 / 1). After loading, the catalyst is dried at 90 °C and then calcined in an air atmosphere in a muffle furnace at 5 °C / min to 500 °C for 2 hours to obtain catalyst powder.

[0099] Step S3 is the same as in Example 1, and the catalyst S6 of this example is obtained.

[0100] Example 7

[0101] Step S1: This embodiment uses a preparation method similar to Example 1, the difference being the selection of the M source and P source and the different doping concentrations. Specifically: Yttrium nitrate and diammonium hydrogen phosphate are dissolved in deionized water to form a 0.3 mol / L impregnation solution for later use. The acidic auxiliary agent is diluted in deionized water to form a 10% acidic solution for later use. 20g of carrier powder is transferred to another beaker, and 108mL of deionized water is added to uniformly disperse the carrier powder to form a carrier suspension, and the mixture is continuously stirred. Then, the impregnation solution and the acidic solution are added to the above carrier suspension at a dropping rate of 2mL / min, and the pH of the solution is adjusted to 5.5. After stirring evenly, the mixed solution is aged at 50℃ for 5h. Subsequently, it is transferred to an oven and dried at 120℃ for 2h, ground, sieved, and then calcined in a muffle furnace in an air atmosphere at a temperature of 5℃ / min to 800℃ for 2h to obtain a modified carrier with a YPO4 mass fraction of 20wt%.

[0102] Step S2: The noble metal (Pt / Pd / Rh) precursor solution is mixed with the modified support powder for loading, and the total content of Pt / Pd / Rh is 40 g / ft. 3 The proportion of precious metals is (Pt / Pd / Rh=16 / 23 / 1). After loading, the catalyst is dried at 90 °C and then calcined in an air atmosphere in a muffle furnace at 5 °C / min to 500 °C for 2 hours to obtain catalyst powder.

[0103] Step S3 is the same as in Example 1, and the catalyst S7 of this example is obtained.

[0104] Example 8

[0105] Step S1: This embodiment uses a preparation method similar to Example 1, the difference being the selection of the M source and P source and the different calcination temperature of the modified support. Specifically: Yttrium nitrate and diammonium hydrogen phosphate are dissolved in deionized water to form a 0.3 mol / L impregnation solution for later use. The acidic auxiliary agent is diluted in deionized water to form a 10% acidic solution for later use. 24.25 g of support powder is transferred to another beaker, and 108 mL of deionized water is added to uniformly disperse the support powder to form a support suspension, and the mixture is continuously stirred. Then, the impregnation solution and the acidic solution are added to the above support suspension at a dropping rate of 2 mL / min, and the pH of the solution is adjusted to 5.5. After stirring evenly, the mixed solution is aged at 50°C for 5 h. Subsequently, it is transferred to an oven and dried at 120°C for 2 h, ground, sieved, and then calcined in a muffle furnace in an air atmosphere at a temperature of 5°C / min to 500°C for 2 h to obtain a modified support with a YPO4 mass fraction of 3 wt%.

[0106] Step S2: The noble metal (Pt / Pd / Rh) precursor solution is mixed with the modified support powder for loading, and the total content of Pt / Pd / Rh is 40 g / ft. 3The proportion of precious metals is (Pt / Pd / Rh=17 / 22 / 1). After loading, the catalyst is dried at 90 °C and then calcined in an air atmosphere in a muffle furnace at 5 °C / min to 500 °C for 2 hours to obtain catalyst powder.

[0107] Step S3 is the same as in Example 1, and the catalyst S8 of this example is obtained.

[0108] Example 9

[0109] Step S1: This embodiment uses a preparation method similar to Example 1, the difference being the selection of the M source and P source and the different calcination temperature of the modified support. Specifically: Yttrium nitrate and diammonium hydrogen phosphate are dissolved in deionized water to form a 0.3 mol / L impregnation solution for later use. The acidic auxiliary agent is diluted in deionized water to form a 10% acidic solution for later use. 24.25 g of support powder is transferred to another beaker, and 108 mL of deionized water is added to uniformly disperse the support powder to form a support suspension, and the mixture is continuously stirred. Then, the impregnation solution and the acidic solution are added to the above support suspension at a dropping rate of 2 mL / min, and the pH of the solution is adjusted to 5.5. After stirring evenly, the mixed solution is aged at 50°C for 5 h. Subsequently, it is transferred to an oven and dried at 120°C for 2 h, ground, sieved, and then calcined in a muffle furnace in an air atmosphere at a temperature of 5°C / min to 900°C for 2 h to obtain a modified support with a YPO4 mass fraction of 3 wt%.

[0110] Step S2: The noble metal (Pt / Pd / Rh) precursor solution is mixed with the modified support powder for loading, and the total content of Pt / Pd / Rh is 40 g / ft. 3 The proportion of precious metals is (Pt / Pd / Rh=13 / 26 / 1). After loading, the catalyst is dried at 90 °C and then calcined in an air atmosphere in a muffle furnace at 5 °C / min to 500 °C for 2 hours to obtain catalyst powder.

[0111] Step S3 is the same as in Example 1, and the catalyst S9 of this example is obtained.

[0112] Comparative Example 1

[0113] Step S1: Transfer 25g of carrier powder directly to a muffle furnace in an air atmosphere and calcine at 500℃ for 2 hours.

[0114] Steps S2 and S3 are the same as in Example 8, and catalyst D1 of this example is obtained.

[0115] Comparative Example 2

[0116] Step S1: Transfer 25g of carrier powder directly to a muffle furnace in an air atmosphere and calcine at 800℃ for 2 hours at a rate of 5℃ / min.

[0117] Steps S2 and S3 are the same as in Example 4, and catalyst D2 of this example is obtained.

[0118] Comparative Example 3

[0119] In this embodiment, step S1 is omitted, and the carrier powder is directly subjected to the noble metal loading in step S2.

[0120] Steps S2 and S3 are the same as in Example 4, resulting in catalyst D3 of this example.

[0121] Comparative Example 4

[0122] Step S1: This embodiment uses the same preparation method as Example 4, except that in Step S1, only the M source is added as the modifier. Specifically, the M source is dissolved in deionized water to form a 0.3 mol / L impregnation solution for later use. The acidic auxiliary agent is diluted in deionized water to form a 10% acidic solution for later use. 24.25 g of carrier powder is transferred to another beaker, and 108 mL of deionized water is added to uniformly disperse the carrier powder to form a carrier suspension, and the mixture is continuously stirred. Then, the impregnation solution and the acidic solution are added to the above carrier suspension at a dropping rate of 2 mL / min, and the pH of the solution is adjusted to 5.5. After stirring evenly, the mixed solution is aged at 50°C for 5 h. Subsequently, it is transferred to an oven and dried at 120°C for 2 h. After grinding and sieving, it is calcined in a muffle furnace in an air atmosphere at a temperature of 5°C / min to 800°C for 2 h to obtain a modified carrier containing 3 wt% M species.

[0123] Steps S2 and S3 are the same as in Example 4, and catalyst D4 of this example is obtained.

[0124] Comparative Example 5

[0125] Step S1: This embodiment uses the same preparation method as Example 4, except that in Step S1, only the P source is added as the modifier. Specifically, the P source is dissolved in deionized water to form a 0.3 mol / L impregnation solution for later use. The acidic auxiliary agent is diluted in deionized water to form a 10% acidic solution for later use. 24.25 g of carrier powder is transferred to another beaker, and 108 mL of deionized water is added to uniformly disperse the carrier powder to form a carrier suspension, and the mixture is continuously stirred. Then, the impregnation solution and the acidic solution are added to the above carrier suspension at a dropping rate of 2 mL / min, and the pH of the solution is adjusted to 5.5. After stirring evenly, the mixed solution is aged at 50°C for 5 h. Subsequently, it is transferred to an oven and dried at 120°C for 2 h. After grinding and sieving, it is calcined in a muffle furnace in an air atmosphere at a temperature of 5°C / min to 800°C for 2 h to obtain a modified carrier with a phosphorus-containing species mass fraction of 3 wt%.

[0126] Steps S2 and S3 are the same as in Example 4, and catalyst D5 of this example is obtained.

[0127] Test Example 1

[0128] The catalysts prepared in Examples 1-9 and Comparative Examples 1-5 were tested for activity under stoichiometric air-fuel ratios. The atmosphere concentrations were: CO 4000 ppm, NO 1000 ppm, CH4 1000 ppm, CO2 8%, H2O 10%, with N2 as the balance gas, and a space velocity of 40000 h⁻¹. -1 The air-fuel ratio λ was adjusted to the stoichiometric air-fuel ratio by regulating the O2 concentration. The results of the activity test are shown in Table 1.

[0129] Test Example 2

[0130] The catalysts prepared in Examples 1-9 and Comparative Examples 1-5 were subjected to hydrothermal aging in a tube furnace. The hydrothermal aging atmosphere was 10 vol% H2O, with air as the balance gas, and the aging time was 20 h. The aged catalysts were then subjected to activity tests under the same atmosphere as in Test Example 1. The activity test results are shown in Table 1.

[0131] Table 1 Catalyst activity test data results

[0132]

[0133] Among them, T 50 The temperature at which the pollutant conversion rate reaches 50%, T 90 This represents the temperature at which pollutants are completely converted. The better the catalyst activity, the higher its T value. 50 and T 90 The lower the value, the better.

[0134] The data in Table 1 show that Examples 1-9 prepared by the method of this invention all exhibit good resistance to hydrothermal aging, with Example 4 demonstrating the best low-temperature ignition and high-temperature hydrothermal durability. In Table 1, Examples 1-5 are catalysts obtained by modifying the support under the same phosphate concentration and calcination temperature but different M / P source formulations; Examples 4, 6, and 7 are catalysts obtained by modifying the support with the same formulation and calcination temperature but different concentrations of yttrium phosphate; Examples 4, 8, and 9 are catalysts obtained by modifying the support with the same formulation and yttrium phosphate concentration but different calcination temperatures; Comparative Examples 1 and 2 are catalysts obtained by directly calcining the support at different temperatures; Comparative Example 3 is a catalyst obtained by directly loading noble metals onto the support without any treatment; Comparative Examples 4 and 5 are catalysts obtained by modification using only M or P sources. By comparing the sample performance, it can be found that the support modified by M(PO4)… x After modification, CH4 / NO x While achieving a certain improvement in low-temperature activity, the modified samples also exhibited significantly improved durability after hydrothermal aging. All modified samples achieved complete conversion—ignition conversion rate reaching T. 90This indicates that introducing a phosphate mineral phase into the support not only does not destroy the active sites of the catalyst, but also because of the crystalline M(PO4) phase... x The formation of this component contributes to the improved thermal stability of the modified support. Furthermore, when the phosphate doping concentration is insufficient or excessive, the CH4 / NO content of the catalyst... x Low-temperature activity and thermal aging performance decreased, but remained superior to the unmodified comparative example. This indicates that under the same preparation conditions, a suitable concentration of M(PO4) is optimal. x Doping modification can optimally improve catalyst activity. It is worth noting that metal modification alone can improve high-temperature durability, and phosphorus modification alone can improve low-temperature ignition performance, but the improvement effect is significantly lower than that of phosphate modification. This is because phosphate modification possesses both metal and phosphorus properties. δ+ Lattice stability, PO4 3- The acidity regulation and structural support (anti-sintering) effect of the phosphate mineral phase demonstrate that the method employed in this invention can effectively protect the active sites of noble metals by introducing the phosphate structure, significantly improving the hydrothermal stability of the catalyst.

[0135] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A supported catalyst based on support modification, characterized in that: The invention includes an inert ceramic material and a catalyst powder coated on the inert ceramic material, wherein the catalyst powder includes a modified support and an active component supported on the modified support; The modified carrier includes a carrier material and a modifier. The carrier material is one or more of pure alumina or aluminum-based composite materials, and the modifier is a mixture of M source and P source. The modified carrier is prepared by surface modification of the carrier using a mixture of M source and P source, and its composition is M3(PO4). δ —Carrier or M3(PO4) δ / carrier; The M source includes any one or more combinations of alkali metals, alkaline earth metals, transition metals, or rare earth metals; the P source includes any one or more combinations of phosphorus oxides, orthophosphoric acid, orthophosphate, phosphorous acid, phosphite, hypophosphoric acid, hypophosphite, and halides. The active component includes a noble metal composition dispersed on the surface of the modified carrier material.

2. The supported catalyst based on support modification according to claim 1, characterized in that, In the mixture composed of the M source and the P source, M δ+ With PO4 3- The molar ratio is 1:(0.36~1.5), which makes M δ+ M3(PO4) is fully formed. δ .

3. The supported catalyst based on support modification according to claim 1, characterized in that, M3(PO4) on the modified carrier δ The mass percentage of the carrier is 0.1wt% to 30wt%.

4. The supported catalyst based on support modification according to claim 1, characterized in that, The carrier material is Al2O3, and the content of Al2O3 accounts for 40% or more of the total amount of the carrier material; Alternatively, the carrier material may be an aluminum-based composite material, comprising Al2O3 and one or more components selected from rare earth oxides, alkaline earth metal oxides, silicon oxides, titanium oxides, and zirconium oxides.

5. The supported catalyst based on support modification according to claim 1, characterized in that, The noble metal composition is mainly composed of Pd and contains Pt and / or Rh; wherein the noble metal source in the noble metal composition includes any one or more of the following: oxides of Pt / Pd / Rh, chlorides, nitrate compounds, acetic acid compounds, and acetylacetone compounds.

6. The supported catalyst based on support modification according to claim 1, characterized in that, The loading of noble metals in the supported catalyst is 15 g / ft. 3 ~80g / ft 3 , at 50g / ft 3 For example, the ratio between Pt / Pd / Rh is (0~15):(25:50):(0~10).

7. A method for preparing a supported catalyst based on support modification as described in any one of claims 1 to 6, characterized in that, Includes the following steps: (1) Under acidic conditions, the M source and the P source are impregnated together onto the carrier powder, and after standing and aging, they are dried and calcined to obtain the modified carrier. (2) The modified support is added to the precious metal impregnation solution for loading to obtain catalyst powder; (3) The catalyst powder and binder solution are mixed and ball-milled to obtain a slurry. The slurry is coated on a ceramic material, dried, calcined and aged to obtain a supported catalyst.

8. The method for preparing a supported catalyst based on support modification according to claim 7, characterized in that, In step (1), the acidic conditions are obtained by dispersing an acidic substance in water to form an acidic solution. The acidic substance includes any one or more of HCOOH, CH3COOH, HNO3, HCl, H3PO4 or H2SO4.

9. The method for preparing a supported catalyst based on support modification according to claim 7, characterized in that, In the preparation of the modified support and the supported catalyst, the calcination temperature is 500℃~900℃.

10. The method for preparing a supported catalyst based on support modification according to claim 7, characterized in that, In step (3), the loading amount of the slurry is 50g / L~150g / L.

11. The application of a supported catalyst based on a support modification according to any one of claims 1 to 6, or a supported catalyst based on a support modification prepared by the preparation method according to any one of claims 7 to 10, characterized in that, This includes reactions used for purifying exhaust gases from equivalent combustion ratios in motor vehicle internal combustion engines.

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