Palladium immobilization using gallic acid or its derivatives

Abstract

1. A method of making a catalyst article, the method comprising: providing a complex of a compound of formula (I): and a PGM, wherein R1 is H or C1-C6 alkyl, R2 is H, OH, or O-C1-C4 alkyl, and the PGM comprises palladium; providing a support material; applying the complex to the support material to form a supported support material; disposing the supported support material on a substrate; and heating the supported support material to form nanoparticles of the PGM on the support material. [Formula 1] JPEG2026503929000008.jpg25128

Description

[Technical Field]

[0001] The present invention relates to a method for producing a catalytic article, a catalytic article obtainable by this method, an emission treatment system, and a method for treating exhaust gases. [Background technology]

[0002] A three-way catalyst (TWC) removes CO, HC, and NO from the exhaust of a gasoline engine at a stoichiometric air-fuel ratio. x Specifically, the oxidation of CO and HC to CO and water vapor (HO) is primarily catalyzed by Pd, while NO x The reduction of CO to N2 is primarily catalyzed by Rh. Modern TWCs use supported platinum group metal (PGM) catalysts (e.g., Pd, Rh, Pt) deposited on single-, double-, or multi-layer supports. The support materials consist of high-surface-area metal oxides, primarily stabilized gamma alumina, and ceria-containing oxygen storage materials. The supported catalysts are washcoated onto ceramic monolith substrates.

[0003] Conventional preparation of TWC washcoat slurries generally involves depositing PGM elements onto oxide supports by incipient wetness or wet impregnation using solutions of inorganic PGM precursors, such as nitrates, acetates, hydroxides, or chlorides. To improve TWC performance, promoter salts are often added to the washcoat formulation. Once a monolith substrate is washcoated with the as-prepared slurry, subsequent drying and calcination steps are performed to decompose the inorganic salts and immobilize the PGMs and promoter elements on the support material. The performance of supported metal catalysts is known to depend on the structure and composition of the metal nanoparticles and the properties of the support. Conventional TWCs prepared using the above methods often offer limited control over the structure of the catalytically active species (i.e., average PGM particle size and composition, location of the active components, and metal-support interactions). This is primarily due to metal migration and particle growth during the calcination process.

[0004] Increasingly stringent environmental regulations require TWCs with higher emission reduction efficiencies. Meanwhile, increasing PGM costs have created an urgent need to reduce PGM loadings without compromising TWC performance. Better control of PGM particle size and metal-support interactions is essential to optimizing TWC performance. Furthermore, a more homogenized PGM particle size distribution can contribute to reducing the degree of metal sintering due to Ostwald ripening, which often occurs during the fuel cutoff process, an engine strategy used to improve fuel economy.

[0005] U.S. Patent Application Publication No. 2012 / 0077669(A1) describes the polymer-assisted synthesis of supported metal catalysts for automotive applications. The polymers used in the examples include poly(vinylpyrrolidone), poly(acrylic acid), and poly(ethyleneimine). In the described synthesis procedure, a support (alumina powder) is first impregnated with a polymer-containing aqueous solution. The impregnated support is then separated from the solution by filtration and drying. The dried, impregnated support is further impregnated with a PGM precursor solution by incipient wetness impregnation. The described process involves multiple steps for the formation of the claimed supported metal catalyst, which increases the cost and difficulty of commercial-scale production. U.S. Patent Application Publication No. 2012 / 0077669(A1) indicates that lean-burn engines, such as diesel engines or lean-burn gasoline engines, are preferably used to apply this technology. Summary of the Invention

[0006] One aspect of the present disclosure is a method of making a catalytic article, comprising:

[0007] [ka] and a PGM, wherein R1 is H or C1-C6 alkyl and R2 is H, OH, or O-C1-C4 alkyl, and the PGM comprises palladium; providing a support material; applying the complex to the support material to form a supported support material; disposing the supported support material on a substrate; and heating the supported support material to form nanoparticles of the PGM on the support material.

[0008] Another aspect of the present disclosure is directed to a catalyst article obtainable by the method of the first aspect.

[0009] The present invention also includes an exhaust system for an internal combustion engine, comprising the catalytic article of the second aspect.

[0010] Another aspect of the present disclosure relates to a method of treating an exhaust gas, the method comprising providing the catalytic article of the second aspect and contacting the catalytic article with the exhaust gas. [Brief explanation of the drawings]

[0011] [Figure 1] 1 shows Pd uptake onto alumina at various pH values ​​for Comparative Examples 1A and 1B and Example 1C. [Figure 2] 1 shows Pd uptake onto CZO at various pH values ​​for Comparative Examples 2A and 2B and Example 2C. [Figure 3A] 1 shows SEM imaging mapping of Pd for Comparative Example 3A. [Figure 3B] 1 shows an SEM mapping image of Pd in ​​Example 3B. [Figure 3C] 1 shows an SEM mapping image of Pd in ​​Example 3C. [Figure 3D] 1 shows an SEM mapping image of Pd in ​​Example 3C. [Figure 4] 1 shows quantitative element correlations by EPMA for Pd—Al and Pd—Zr for Comparative Example 3A and Examples 3B-3D. [Figure 5A] FIG. 10 shows a comparison of NOx conversion during TWC light-off testing between aged Comparative Example 4A and Examples 4B-4D samples. [Figure 5B] 1 shows a comparison of CO conversion during TWC light-off testing between aged Comparative Example 4A and Examples 4B-4D samples. [Figure 5C] 1 shows a comparison of THC conversion during a TWC light-off test between aged Comparative Example 4A and Examples 4B-4D samples. [Figure 6A] 1 shows cumulative NOx emissions during engine bench testing between aged Comparative Example 5A and Example 5B. [Figure 6B] 1 shows cumulative CO emissions during engine bench testing between aged Comparative Example 5A and Example 5B. [Figure 6C]1 shows cumulative THC emissions during engine bench testing between aged Comparative Example 5A and Example 5B. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention aims to address at least some of the problems associated with the prior art, or at least to provide a commercially acceptable alternative solution.

[0013] In a first aspect, the present invention provides a method of making a catalytic article, the method comprising: Compounds of formula (I):

[0014] [ka] and a PGM complex, wherein R1 is H or C1-C6 alkyl, R2 is H, OH, or O-C1-C4 alkyl, and the PGM comprises palladium; Providing a carrier material; applying the complex to the support material to form a supported support material; disposing the supported support material on a substrate; and heating the loaded support material to form nanoparticles of the PGM on the support material.

[0015] Each aspect or embodiment defined herein may be combined with any other aspect or embodiment unless expressly stated otherwise. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature indicated as being preferred or advantageous.

[0016] Surprisingly, when used in emissions treatment systems, catalyst articles produced by the methods of the present invention may exhibit favorable catalytic activity, particularly favorable three-way catalytic activity. For example, the catalyst article may exhibit favorable light-off performance, particularly NO, CO, and total hydrocarbon conversion, during three-way catalytic emission reduction of a stoichiometric gasoline engine. Such favorable catalytic activity and light-off performance may be superior to that exhibited by conventional catalyst articles having the same / similar PGM species(s), loading(s), support(s), and configuration(s). The catalyst article may be more durable compared to conventional catalyst articles. In other words, such favorable catalytic activity may be exhibited even after aging.

[0017] Advantageously, such superior performance can facilitate the use of lower loadings of PGMs compared to conventional catalyst articles without compromising catalytic performance, which can be beneficial given the high cost of such metals, such as palladium. Furthermore, such superior performance can facilitate partial / full substitution of high-cost PGMs with lower-cost PGMs or other transition metals without compromising catalytic performance.

[0018] Furthermore, due to the improved fixation of Pd to the support material that can be provided by the methods of the present invention, significantly less wicking of Pd or washcoat layers through the substrate and / or mixing of the washcoat layers can be observed. In other words, catalyst articles produced by the methods of the present invention can exhibit stronger / more secure fixation of PGMs to the support material compared to catalyst articles produced by conventional methods. Accordingly, catalyst articles produced by the methods of the present invention can exhibit improved catalytic activity, as well as improved aesthetics in such catalyst articles. This is because, at least, mixing of catalytically active PGMs between any separate washcoat layers in the catalyst article can be reduced, thereby reducing the likelihood of any of the washcoat layers becoming deactivated. This, in turn, can help maintain the catalytic activity of the overall catalyst article as intended, both when the catalyst article is unused and after aging. Keeping the PGMs of any separate washcoat layers within their intended respective layers can be important for maintaining their intended catalytic purpose (e.g., either oxidation or reduction). For example, it is known that direct interaction between Pd and Rh can reduce the catalytic activity of the individual components, particularly the catalytic function of the Rh component.

[0019] Furthermore, depending on the order of steps and the order of addition of the support materials, the method of the present invention can be used to immobilize a PGM, such as Pd, to any standard support material. In other words, if multiple different support materials are present in the washcoat, the method of the present invention can be used to target the PGM, such as Pd, to the desired support material by controlling the order of steps, for example, whether the support material is first combined with a PGM precursor or with a complex of polyphenol and PGM.

[0020] Compared to the method of US Patent Application Publication No. 2012 / 0077669(A1), the method of the present invention is a simpler and more efficient "one-pot" method, for example, without the need for pH adjustment. The method of the present invention does not require separate impregnation, filtration, and drying steps to deposit polymer molecules on the support material. In contrast, in US Patent Application Publication No. 2012 / 0077669(A1), only a limited amount of polymer can remain on the support after the filtration and washing steps. Furthermore, the catalyst article prepared by the method of the present invention can be used, in particular, as a three-way catalyst for stoichiometric gasoline emission reduction. In contrast, the catalyst article produced by the method of US Patent Application Publication No. 2012 / 0077669(A1) has particular application in lean-burn diesel or gasoline engines.

[0021] As used herein, the term "catalytic article" may include an article having a catalyst supported thereon or therein. The article may take the form of, for example, a honeycomb monolith, or a filter, such as a wall-flow filter or a flow-through filter. The catalytic article may be for use in emissions treatment systems, particularly emissions treatment systems for gasoline engines, preferably stoichiometric gasoline engines. The catalytic article may be for use in three-way catalysis.

[0022] Compounds of formula (I):

[0023] [ka] and providing a complex with a PGM typically involves providing the complex in solution, for example an aqueous or alcoholic solution. Providing a complex of a compound of formula (I) with a PGM typically involves mixing an inorganic PGM precursor in pure form or in solution in an aqueous medium with a compound of formula (I), for example mixing a PGM nitrate with a compound of formula (I) in water.

[0024] Preferably, R1 is H. Also preferably, R2 is OH.

[0025] The PGM includes palladium. Palladium may be particularly suitable for three-way catalysis. In addition, palladium is expensive, which means that it is advantageous to be able to provide a similar level of catalytic activity for the same amount of metal. Furthermore, the use of palladium in the method of the present invention may result in particularly favorable perturbation ignition performance. The PGM may be in the form of an alloy. In addition to palladium, the PGM may include other PGMs, such as one or more of rhodium, platinum, ruthenium, osmium, and iridium.

[0026] The complexes may have a PGM atom to ester group ratio of 2:1 to 1:10, preferably 1:1 to 1:8, more preferably 1:2 to 1:5. The complexes may have a palladium atom to ester group ratio of 2:1 to 1:10, preferably 1:1 to 1:8, more preferably 1:2 to 1:5.

[0027] The support material may be any material capable of supporting the composite and nanoparticles thereon or therein. The support material may take any form, but is typically in the form of a powder, more typically a high surface area powder. The powder may be further processed by grinding, either dry or wet, to achieve a desired particle size range. When the method of the present invention is used to prepare a catalytic filter (e.g., a wall-flow filter or a flow-through filter), the support material is typically in the form of a powder, whether in its original, dry-milled, or wet-milled form, having a D50, as measured using TEM, of, for example, 0.1 μm to 30 μm, more typically 0.5 μm to 25 μm, and even more typically 1 μm to 20 μm. Such particle size may facilitate desirable rheological properties of the slurry used to coat the filter. The support material may function as a washcoat. The support material may be the washcoat or may be part of the washcoat.

[0028] The support material may also act as an oxygen storage material, storing and releasing oxygen under fuel-lean and fuel-rich conditions, respectively, to facilitate three-way catalytic conversion.

[0029] Applying the complex to the support material typically involves contacting the complex with the support material in the presence of a solvent (typically water) to produce a slurry. As used herein, the term "slurry" can encompass a liquid containing insoluble material, e.g., insoluble particles. The slurry can include (1) the solvent, (2) soluble content, e.g., unreacted compound of Formula (I), inorganic PGM and promoter precursor, and PGM compound of Formula (I) complex (outside the support), and (3) insoluble content, e.g., support particles, with or without interaction with the compound of Formula (I) and metal precursor. The slurry is typically stirred, more typically for at least 10 minutes, more typically for at least 30 minutes, and even more typically for at least 1 hour. Increasing the contact time and / or stirring time can increase the amount of complex supported on the support material.

[0030] As used herein, the term "supported support material" can include a support material having a complex of Formula (I) supported thereon (e.g., on the surface of a high surface area metal oxide support material) and / or a PGM compound supported therein (e.g., within the pores of a zeolite support material). The complex is typically immobilized on the support by, for example, electrostatic forces, hydrogen bonding, coordinate bonds, covalent bonds, and / or ionic bonds. For example, in the case of oxides, ester functional groups (e.g., carboxylate ester functional groups) in the compound of Formula (I) and surface hydroxyl groups on the support can interact via electrostatic forces or hydrogen bond formation.

[0031] The term "substrate" as used herein can include, for example, ceramic or metal honeycombs, or filter blocks, such as wall-flow or flow-through filters. Substrates can include ceramic monolith substrates. Substrates can vary in their material composition, size and configuration, cell shape and density, and wall thickness. Suitable substrates are known in the art.

[0032] The supported carrier material can be placed on the substrate using techniques known in the art. Typically, the supported carrier material is placed on the substrate by pouring a slurry of the supported carrier material into the inlet of the substrate in a predetermined amount using a specific forming tool. As discussed in more detail below, subsequent vacuum and drying steps may be used during the placement step. If the carrier is a filter block, the supported carrier material may be placed on the filter wall, within the filter wall (if porous), or both.

[0033] Heating of the supported support material is typically carried out in an oven or furnace, more typically in a belt or static oven or furnace, typically in a unidirectional flow of hot air. Heating can include calcination. Heating can also include drying. The drying and calcination steps can be continuous or sequential. For example, a separate washcoat can be applied after the substrate has already been washcoated and dried with the previous washcoat. The washcoated substrate can also be dried and calcined using one continuous heating program once coating is complete. During heating, the complex can at least partially, substantially, or completely decompose. In other words, the ligand of the complex, i.e., the compound of formula (I), is at least partially, substantially, or completely removed or separated from the PGM and removed from the final catalyst article. The thus-separated particles of PGM can then begin to form metal-metal and metal-oxide bonds. As a result of heating (calcination), the substrate is typically substantially free of the compound of formula (I), more typically completely free of the compound of formula (I).

[0034] As used herein, the term "nanoparticle" can encompass particles having a diameter of 0.01 nm to 100 nm as measured by TEM. Nanoparticles can be of any shape, e.g., spheres, plates, cubes, cylinders, hexagons, or rods, but are typically spherical. The largest dimension of a nanoparticle (i.e., the diameter if the nanoparticle is spherical), as measured by TEM, is typically 0.5 to 10 nm, more typically 1 to 5 nm.

[0035] After the heating step, the substrate is typically cooled, more typically to room temperature. Cooling is typically done in air with or without a coolant / cooling medium, typically without a coolant.

[0036] In some preferred embodiments, the compound of formula (I) is gallic acid.

[0037] [ka]

[0038] Gallic acid can coordinate with metal ions through hydrogen or covalent bonds. The PGM-gallic acid complex can be immobilized on a support, such as a metal oxide support, in a washcoat, and the carboxylate functional groups in the gallic acid ligands and surface hydroxyl groups on the support can interact via electrostatic forces or hydrogen bond formation.

[0039] The PGM comprises palladium. Preferably, the PGM consists essentially of palladium, more preferably consists of palladium. Palladium is a particularly expensive PGM and forms a particularly suitable complex with the compound of formula (I), particularly gallic acid. The use of such a metal in the method of the present invention can result in particularly favorable perturbation ignition performance. The PGM may comprise primarily palladium, i.e., at least 50 wt. % palladium, typically at least 80 wt. % palladium, more typically at least 95 wt. % palladium, and even more typically at least 99 wt. % palladium, based on the total weight of the PGM.

[0040] After heating the loaded support material, the substrate preferably has a coating density of 10 g / ft 3 ~200g / ft 3 of PGM, more preferably 30g / ft 3 ~150g / ft 3 of PGM, even more preferably 80 g / ft 3 ~150g / ft 3In other words, the concentration of PGM applied to the substrate via the supported support material is such that after heating the supported support material, the substrate contains 10 g / ft 3 ~200g / ft 3 of PGM, more preferably 30g / ft 3 ~150g / ft 3 of PGM, even more preferably 80 g / ft 3 ~150g / ft 3 The concentration may be such that the PGM comprises 10 g / ft of PGM. Obtaining such a loading of PGM on the substrate would be readily accomplished by one skilled in the art by, for example, using either a higher or lower concentration of the complex of the compound of formula (I) with the PGM and / or a higher or lower ratio of PGM atoms to ester groups. In other words, providing a substrate with a desired level of PGM loading via the method of the present invention is well within the ability of one skilled in the art. For example, a loading of 10 g / ft of PGM may be obtained. 3 ~200g / ft 3 , more preferably 30 g / ft of PGM 3 ~150g / ft 3 , and even more preferably 80 g / ft of PGM 3 ~150g / ft 3 may be applied to the support material in a step where the complex is applied to the support material to form a supported support material.

[0041] The support material comprises an oxide, preferably one or more of Al2O3 (aluminum oxide or alumina), SiO2, TiO2, CeO2, ZrO2, CeO2-ZrO2, VO5, La2O3, and zeolite. The oxide is preferably a metal oxide. The support material more preferably comprises alumina, even more preferably gamma-alumina. The support material preferably comprises ceria-zirconia. The support material preferably comprises alumina and ceria-zirconia. The alumina and / or ceria-zirconia are preferably doped, more preferably doped with one or more oxides of lanthanum, neodymium, yttrium, niobium, praseodymium, hafnium, molybdenum, titanium, vanadium, zinc, cadmium, manganese, iron, copper, calcium, barium, strontium, cesium, magnesium, potassium, or sodium, even more preferably doped with oxides of lanthanum, neodymium, or yttrium. Such doped oxides are particularly useful as support materials. Preferably, the dopant is present in the alumina and / or ceria-zirconia in an amount of 0.001 wt. % to 20 wt. %, and more preferably 0.5 wt. % to 10 wt. %.

[0042] The support material is preferably in the form of a powder having a D90 of 0.1 to 25 μm, more preferably 0.5 to 5 μm.

[0043] The supported support material is preferably disposed on the substrate in the form of a slurry, which is particularly effective in disposing the material on the substrate to maximize gas diffusion and minimize pressure drop during catalytic conversion.

[0044] Providing a complex of a compound of formula (I) and a PGM preferably involves synthesizing the complex in situ in a slurry.

[0045] The slurry preferably comprises: contacting a PGM salt with a compound of formula (I) in water to form a complex of the compound of formula (I) and the PGM in aqueous solution, wherein the PGM salt comprises palladium; applying the complex to the support material by contacting the support material with an aqueous solution to form a supported support material; and optionally adding one or more of an oxygen storage material, preferably ceria-zirconia, a promoter salt, a binder, an acid or base, a thickener, and a reducing agent to the aqueous solution. The optional step of adding one or more of an oxygen storage material, preferably ceria-zirconia, a promoter salt, a binder, an acid or base, a thickener, and a reducing agent to the aqueous solution may occur during any of the steps of the preferred method of preparing the slurry.

[0046] In an alternative preferred embodiment, the slurry comprises: contacting a support material with an aqueous solution of a PGM salt to form a slurry comprising the support material loaded with a PGM salt, the PGM salt comprising palladium; applying a complex of a compound of formula (I) and a PGM to a support material to form a supported support material by contacting the PGM-salt-loaded support material with a slurry comprising the compound of formula (I) in water; and optionally adding one or more of an oxygen storage material, preferably ceria-zirconia, a promoter salt, a binder, an acid or base, a thickener, and a reducing agent to an aqueous solution or slurry comprising the PGM salt-loaded support material. The optional step of adding one or more of an oxygen storage material, preferably ceria-zirconia, a promoter salt, a binder, an acid or base, a thickener, and a reducing agent to the aqueous solution may occur during any of the steps of the preferred method of preparing the slurry, but is preferably carried out during each step in which the support material is provided.

[0047] Preferably, the steps of contacting a PGM salt with a compound of formula (I) in water and contacting a slurry comprising a PGM salt-loaded support material with a compound of formula (I) in water include allowing sufficient reaction time for complex formation to occur between the compound of formula (I) and the PGM cation, in each alternative method of preparing the slurry; for example, such steps are typically carried out for at least 10 minutes, more typically at least 30 minutes, and even more typically at least 1 hour, preferably with stirring. Without wishing to be bound by theory, it is believed that in the second alternative method of preparing the slurry, the step of applying a complex of a compound of formula (I) and a PGM to a support material to form a supported support material by contacting a slurry comprising a PGM-loaded support material and a compound of formula (I) in water can be followed by subsequent reduction and precipitation of the PGM metal species on the support material.

[0048] In other words, the method of preparing the slurry may involve first providing a complex of the compound of formula (I) and the PGM in an aqueous solution, followed by adding the support and other optional ingredients, or may involve first adding the support material and other optional ingredients to an aqueous solution of the PGM precursor (i.e., PGM salt), followed by adding the compound of formula (I).

[0049] Such a "one-pot" preparation method may be simplified and less costly than conventional methods, and may also maximize utilization of the compound of formula (I).

[0050] In other words, the steps of providing a complex of a compound of formula (I) and a PGM, providing a support material, applying the complex to the support material to form a supported support material, and disposing the supported support material on a substrate comprise: contacting a PGM salt with a compound of formula (I) in water to form a complex of the compound of formula (I) and the PGM in aqueous solution, wherein the PGM salt comprises palladium; adding the support material to an aqueous solution to form a slurry of the supported support material; Optionally, adding one or more of an oxygen storage material, preferably ceria-zirconia, a promoter salt, a binder, an acid or base, a thickener, and a reducing agent to the slurry; and disposing the slurry on a substrate.

[0051] Alternatively, the steps of providing a complex of a compound of formula (I) and a PGM, providing a support material, applying the complex to the support material to form a supported support material, and disposing the supported support material on a substrate can include: contacting a support material with an aqueous solution of a PGM salt to form a slurry comprising the support material loaded with a PGM salt, the PGM salt comprising palladium; adding a compound of formula (I) to a slurry comprising a PGM-salt supported support material to form a slurry of the supported support material; Optionally, adding one or more of an oxygen storage material, preferably ceria-zirconia, a promoter salt, a binder, an acid or base, a thickener, and a reducing agent to the aqueous solution or slurry comprising the PGM salt-loaded support material; and disposing the slurry on a substrate.

[0052] The support may include a washcoating.

[0053] The slurry preferably has a solids content of 10-40%, preferably 15-35%. Such a solids content can enable a suitable slurry rheology for disposing the supported support material on a substrate. For example, if the substrate is a honeycomb monolith, such a solids content can enable deposition of a thin layer of washcoat on the inner wall of the substrate. If the substrate is a wall-flow filter, such a solids content can enable the slurry to enter the channels of the wall-flow filter and the walls of the wall-flow filter.

[0054] Preferably, the slurry comprises: an oxygen storage material, preferably ceria-zirconia; promoter salts, binder, Acids or bases, thickeners, and Further comprising one or more of the following reducing agents:

[0055] The promoter may include, for example, a non-PGM transition metal element, a rare earth element, an alkali or alkaline earth group element, and / or a combination of two or more of the foregoing elements in the same or different groups of the periodic table. The promoter salt may be a salt of such an element. A particularly preferred promoter is barium, and particularly preferred salts thereof are barium acetate, barium citrate, and barium sulfate, or combinations thereof, more preferably barium citrate.

[0056] The binder may include, for example, an oxide material having a small particle size to bind together individual insoluble particles in the washcoat slurry. The use of binders in washcoats is well known in the art.

[0057] Thickeners may include, for example, natural polymers with functional hydroxyl groups that interact with insoluble particles in the washcoat slurry. The thickener serves the purpose of thickening the washcoat slurry to improve the coating profile during washcoat application onto a substrate. The thickener is typically burned off during washcoat calcination. Examples of specific thickeners / rheology modifiers for washcoats include glactomanna gum, guar gum, xanthan gum, curdlan schizophyllan, scleroglucan, diutan gum, wheelan gum, hydroxymethylcellulose, carboxymethylcellulose, hydroxyethylcellulose, methylcellulose, methylhydroxyethylcellulose, methylhydroxypropylcellulose, and ethylhydroxycellulose.

[0058] The term "reducing agent" as used herein may include compounds capable of reducing PGM cations to their reduced or even metallic state particles in situ during washcoat preparation.

[0059] Organic acids can be added to act as reducing agents for the PGMs and / or create a reducing environment at ambient or elevated temperatures (<100° C.) for a specific period of time during washcoat preparation. Examples of suitable organic acids include citric acid, succinic acid, oxalic acid, ascorbic acid, acetic acid, formic acid, and combinations thereof.

[0060] In a preferred embodiment, the support material comprises alumina and the slurry further comprises ceria-zirconia. In another preferred embodiment, the support material comprises ceria-zirconia and the slurry further comprises alumina. In another preferred embodiment, the support material comprises alumina and ceria-zirconia.

[0061] The method preferably further includes disposing a further slurry on the substrate, the further slurry comprising one or more of a further support material, an oxygen storage material, a promoter salt, a binder, an acid or base, a thickener, and a reducing agent, before disposing the support material on the substrate and / or after heating the supported support material to form PGM nanoparticles on the support material. This can result in a catalyst article having multiple layers of different washcoats, such as a bottom washcoat containing, among other things, palladium nanoparticles supported on alumina, and a top washcoat containing, among other things, palladium nanoparticles supported on alumina. Further examples of such multiple layers are discussed in more detail below.

[0062] Placing the supported support material on the substrate preferably involves contacting a slurry with the substrate (e.g., injecting the slurry into an inlet of the substrate), and optionally: applying a vacuum to the substrate, and / or and drying the slurry on the substrate.

[0063] This allows for a favorable distribution of the supported support material on the substrate.

[0064] Drying is preferably carried out as follows: at a temperature between 60°C and 200°C, preferably between 70°C and 130°C, and / or The heating is carried out for 10 to 360 minutes, preferably 15 to 60 minutes.

[0065] The substrate may be a "blank," i.e., a substrate that has not been washcoated. Alternatively, the substrate may have one or more washcoats already deposited thereon. In such a situation, the final catalyst article may include multiple layers of different washcoats.

[0066] The substrate preferably comprises cordierite, which is particularly suitable for use in catalytic articles.

[0067] The substrate is preferably in the form of a honeycomb monolith, a wall-flow filter or a flow-through filter.

[0068] The heating is preferably carried out as follows: at a temperature of 400°C to 700°C, preferably 400°C to 600°C, more preferably 450°C to 600°C, and / or The heating is carried out for 10 to 360 minutes, preferably 35 to 120 minutes.

[0069] Lower temperatures and / or shorter heating times may result in insufficient decomposition of the complex and / or high levels of the compound of formula (I) remaining in the substrate. Higher temperatures and / or longer heating times may result in PGM particles with undesirably large particle sizes, possibly due to sintering. Higher temperatures and longer heating times may also result in damage to the catalyst article.

[0070] Heating preferably includes calcination. As used herein, the term "calcination" can include a heat treatment process in the absence or limited supply of air or oxygen to cause thermal decomposition.

[0071] The nanoparticles preferably have a D50 of 0.1 nm to 30 nm, more preferably 0.5 to 25 nm, and even more preferably 1 to 20 nm. D50 can be measured by TEM. Such particle size can provide a desirable level of catalytic activity.

[0072] In a further aspect, the present invention provides a catalyst article obtainable by the methods described herein, the catalyst article being for use in an emissions treatment system.

[0073] Compared to conventional catalyst articles, catalyst articles obtainable by the methods described herein can contain, at each virgin stage, PGM particles having advantageously large particle sizes and favorable particle size distributions (e.g., D50 of 1-20 nm). Furthermore, compared to conventional catalyst articles, catalyst articles obtainable by the methods described herein can exhibit more uniform distribution of PGM particles throughout the substrate.

[0074] When used in emissions treatment systems, the catalytic article can exhibit favorable light-off performance, particularly for NO, CO, and total hydrocarbons, during three-way catalytic conversion for stoichiometric gasoline emission reduction. The catalytic article can also exhibit other advantageous properties described herein, such as lower fresh OSC capacity and lower fresh-to-aged OSC differential (i.e., more stable OSC performance with aging).

[0075] The catalyst is preferably for a three-way catalyst.

[0076] The catalyst article is 1 g / in 3 ~3g / in 3Such catalyst articles may exhibit similar or higher catalytic activity compared to conventional catalyst articles, but may be less expensive given the lower levels of PGM used.

[0077] The substrate preferably comprises a wall-flow filter substrate or a flow-through substrate.

[0078] In a preferred embodiment, the catalyst article includes a bottom layer of support material having rhodium thereon and a top layer of support material having palladium thereon. In such catalyst articles, for example, the bottom layer may be provided by a method similar to the methods described herein or by any conventional method. In another preferred embodiment, the catalyst article includes a bottom layer of support material having palladium thereon and a top layer of support material having rhodium thereon. In such catalyst articles, for example, the top layer may be provided by a method similar to the methods described herein or by any conventional method. As used herein, the term "bottom layer" may include a layer (e.g., a washcoat layer) that is closest to or in contact with the substrate (i.e., the substrate wall). As used herein, the term "top layer" may include a layer (e.g., a washcoat layer) that is further from the substrate (i.e., the substrate wall) than the bottom layer and may be located above the bottom layer. In such layered catalyst articles, the top and / or bottom layers of support material may have an additional PGM thereon, such as platinum. In such layered catalyst articles, the top and / or bottom layers may contain multiple PGMs, i.e., may be bimetallic (e.g., containing Pd—Rh or Pd—Pt) or trimetallic (e.g., Pd—Rh—Pt). The catalyst article may include two or more catalytic zones, e.g., an upstream zone and a downstream zone. The zones may differ from each other by having different PGMs (e.g., Rh upstream and Pd downstream, or vice versa), or may differ by the amount of different types of PGMs, e.g., monometallic, bimetallic, or trimetallic.

[0079] In such a preferred embodiment, the support material preferably comprises alumina and ceria-zirconia.

[0080] The catalyst article, inter alia, in such preferred embodiments, preferably has a surface roughness of 2 g / ft 3 ~15g / ft 3 of rhodium, more preferably 5 g / ft 3 ~10g / ft 3 Advantageously, such rhodium levels can be lower than those of conventional catalyst articles, yet do not impair catalytic activity.

[0081] The catalyst article, particularly in such preferred embodiments, preferably has a coating weight of 50 g / ft 3 ~200g / ft 3 of palladium, more preferably 80 g / ft 3 ~150g / ft 3 Advantageously, such palladium levels can be lower than those of conventional catalyst articles, yet do not impair catalytic activity.

[0082] In a preferred embodiment, the supported support material is disposed on a substrate in the form of a slurry, wherein the PGM comprises palladium, the support material comprises alumina, and the slurry further comprises ceria-zirconia. In another preferred embodiment, the supported support material is disposed on a substrate in the form of a slurry, wherein the PGM comprises palladium, the support material comprises ceria-zirconia, and the slurry further comprises alumina. In another preferred embodiment, the supported support material is disposed on a substrate in the form of a slurry, wherein the PGM comprises palladium, and the support material comprises alumina and ceria-zirconia.

[0083] In a further aspect, the present invention provides an emissions treatment system comprising the catalytic article described herein.

[0084] The emission treatment system is preferably for a gasoline engine.

[0085] Gasoline engines preferably operate under stoichiometric conditions.

[0086] In a further aspect, the present invention provides a method for treating exhaust gases, the method comprising: providing a catalyst article as described herein; contacting the catalytic article with the exhaust gas.

[0087] The exhaust gas is preferably exhaust gas from a gasoline engine. The catalytic article is particularly suitable for treating such exhaust gas. The gasoline engine preferably operates under stoichiometric conditions.

[0088] The invention will now be described with reference to the following non-limiting examples.

[0089] Pd uptake test Comparative Example 1A: Pd incorporation onto alumina at various pHs (2, 4, 6, 8 and 10). 1. Add the required amount of Pd nitrate, water, and alumina to target 3.75 wt% Pd on alumina and 30% solids. Mix for 1 hour. 2. Measure pH and adjust to target pH with ammonium hydroxide. Mix for 1 hour. 3. Centrifuge and collect the supernatant. 4. Subject the supernatant sample to ICP analysis for Pd concentration.

[0090] Comparative Example 1B: Pd uptake onto alumina at various pHs (2, 4, 6, 8 and 10) using tannic acid. 1. Add the required amount of Pd nitrate, water, and alumina to target 3.75 wt% Pd on alumina and 30% solids. Mix for 1 hour. Add tannic acid targeting a TA:Pd mass ratio of 2.2:1. Mix for 2 hours. 3. Measure pH and adjust to target pH with ammonium hydroxide. Mix for 1 hour. 4. Centrifuge and collect the supernatant. 5. Subject the supernatant sample to ICP analysis for Pd concentration.

[0091] Example 1C: Pd incorporation onto alumina at various pHs (2, 4, 6, 8, and 10) using gallic acid. 1. Add the required amount of Pd nitrate, water, and alumina to target 3.75 wt% Pd on alumina and 30% solids. Mix for 1 hour. Add gallic acid targeting a GA:Pd mass ratio of 2.2:1. Mix for 2 hours. 3. Measure pH and adjust to target pH with ammonium hydroxide. Mix for 1 hour. 4. Centrifuge and collect the supernatant. 5. Subject the supernatant sample to ICP analysis for Pd concentration.

[0092] Comparative Example 2A: Pd uptake in CZO at various pHs (2, 4, 6, 8, and 10). 1. Add the required amount of Pd nitrate, water, and CZO to target 3.75 wt% Pd on CZO and 30% solids. Mix for 1 hour. 2. Measure pH and adjust to target pH with ammonium hydroxide. Mix for 1 hour. 3. Centrifuge and collect the supernatant. 4. Subject the supernatant sample to ICP analysis for Pd concentration.

[0093] Comparative Example 2B: Pd uptake in CZO at various pHs (2, 4, 6, 8, and 10) using tannic acid. 1. Add the required amount of Pd nitrate, water, and CZO to target 3.75 wt% Pd on CZO and 30% solids. Mix for 1 hour. Add tannic acid targeting a TA:Pd mass ratio of 2.2:1. Mix for 2 hours. 3. Measure pH and adjust to target pH with ammonium hydroxide. Mix for 1 hour. 4. Centrifuge and collect the supernatant. 5. Subject the supernatant sample to ICP analysis for Pd concentration.

[0094] Example 2C: Pd uptake in CZO at various pHs (2, 4, 6, 8, and 10) using gallic acid. 1. Add the required amount of Pd nitrate, water, and CZO to target 3.75 wt% Pd on CZO and 30% solids. Mix for 1 hour. Add gallic acid targeting a GA:Pd mass ratio of 2.2:1. Mix for 2 hours. 3. Measure pH and adjust to target pH with ammonium hydroxide. Mix for 1 hour. 4. Centrifuge and collect the supernatant. 5. Subject the supernatant sample to ICP analysis for Pd concentration.

[0095] These Pd resorption results on alumina or CZO are shown in Figures 1 and 2. While both tannic acid and gallic acid significantly improved Pd immobilization, the effectiveness of tannic acid was much lower on CZO supports, especially at higher pH conditions. In contrast, gallic acid was much more effective at immobilizing Pd, regardless of the support and pH conditions.

[0096] Pd distribution test Comparative Example 3A: Fully formulated single layer Pd washcoat without Pd anchoring 1. Prepare a solution containing the required amount of Pd nitrate (Pd loading: 130 g / ft 3 ). 2. Stabilized alumina (1 g / in 3 ) and CZO (1g / in 3 ) was added to the batch. 3. Ba acetate (400g / ft 3 ) is added to the batch. 4. Adjust solids content to target (suggests around 30%). 5. Add the appropriate amount of thickener and mix overnight. 6. Coat the single dose target 1.2 inches from the entrance. 7. Fire the bricks in a static oven at 500°C / 30 minutes.

[0097] Example 3B: Fully formulated monolayer Pd washcoat containing Pd immobilized by gallic acid in the presence of both alumina and CZO 1. Prepare a solution containing the required amount of Pd nitrate (Pd loading: 130 g / ft3 ). 2. Stabilized alumina (1 g / in 3 ) and CZO (1g / in 3 ) was added to the batch. 3. Add gallic acid aiming for a GA:Pd mass ratio of 2. 4. Ba acetate (400g / ft 3 ) is added to the batch. 5. Adjust solids content to target (suggested around 30%). 6. Add the appropriate amount of thickener and mix overnight. 7. Coat the single dose target 1.2 inches from the entrance. 8. Fire the bricks in a static oven at 500°C / 30 minutes.

[0098] Example 3C: Fully formulated single layer Pd washcoat with Pd anchored by GA on alumina prior to CZO addition. 1. Prepare a solution containing the required amount of Pd nitrate (Pd loading: 130 g / ft 3 ). 2. Stabilized alumina (1 g / in 3 ) is added to the batch. 3. Add gallic acid aiming for a GA:Pd mass ratio of 2. 4. Add CZO (1g / in) to the batch. 3 ) is added. 5. Ba acetate (400g / ft 3 ) is added to the batch. 6. Adjust solids content to target (suggested around 30%). 7. Add the appropriate amount of thickener and mix overnight. 8. Coat the single dose target 1.2 inches from the entrance. 9. Fire the bricks in a static oven at 500°C / 30 minutes.

[0099] Example 3D: Fully formulated single layer Pd washcoat with Pd anchored by GA on CZO before alumina addition 1. Prepare a solution containing the required amount of Pd nitrate (Pd loading: 130 g / ft 3 ). 2. Add CZO (1g / in) to the batch. 3 ) is added. 3. Add gallic acid aiming for a GA:Pd mass ratio of 2. 4. Stabilized alumina (1 g / in 3 ) is added to the batch. 5. Ba acetate (400g / ft 3 ) is added to the batch. 6. Adjust solids content to target (suggested around 30%). 7. Add the appropriate amount of thickener and mix overnight. 8. Coat the single dose target 1.2 inches from the entrance. 9. Fire the bricks in a static oven at 500°C / 30 minutes.

[0100] Figures 3A-3D show SEM (scanning electron microscope) mapping of Pd in ​​the Pd-TWC monolayer washcoats of Comparative Example 3A and Examples 3B-3D. Comparing Figures 3A and 3B clearly demonstrates that Pd is concentrated on the surface of the washcoat in the reference catalyst, whereas when gallic acid was added, Pd was distributed much more uniformly throughout the washcoat layer. Thus, gallic acid aided in the immobilization of Pd in ​​the washcoat. Figures 3C and 3D show elemental mapping of Pd vs. Al or Pd vs. Zr for the same washcoat samples. This indicates that Pd can be immobilized on either alumina or CZO by adding gallic acid and controlling the order of addition during washcoat preparation.

[0101] EPMA analysis Comparative Example 3A and Examples 3B-3D were analyzed by EPMA for quantitative analysis of elemental proximity. A higher / positive correlation number indicates a higher statistical likelihood that two elements are in close proximity, while a lower / negative correlation number indicates a lower statistical likelihood that two elements are in close proximity. Therefore, the relative amount of Pd on the alumina versus CZO support can be determined by analyzing the Pd-Al and Pd-Zr correlations using this method. The analysis is shown in Figure 4.

[0102] The results suggest that Pd is equally distributed on alumina and CZO in Comparative Example 3A. Also, Pd is preferentially adsorbed onto alumina when immobilized with gallic acid, likely due to the larger surface area and pore volume of alumina compared to CZO. However, by changing the order of addition, Pd can be selectively immobilized to either alumina or CZO using gallic acid.

[0103] Catalyst light-off performance Comparative Example 4A: Fully formulated single layer Pd washcoat without Pd anchoring 1. Prepare a solution containing the required amount of Pd nitrate (Pd loading 100 g / ft 3 ). 2. Stabilized alumina (1 g / in 3 ) and CZO (1g / in 3 ) was added to the batch. 3. Ba acetate (300g / ft 3 ) is added to the batch. 4. Adjust solids content to target (suggests around 30%). 5. Add the appropriate amount of thickener and mix overnight. 6. Coat the single dose target 1.2 inches from the entrance. 7. Fire the bricks in a static oven at 500°C / 30 minutes.

[0104] Example 4B: Fully Formulated Single Layer Pd Washcoat with Pd-GA (GA to Pd Mass Ratio of 1.3) 1. Prepare a solution containing the required amount of Pd nitrate (Pd loading 100 g / ft 3 ). 2. Stabilized alumina (1 g / in 3 ) and CZO (1g / in 3 ) was added to the batch. Gallic acid is added to target a GA:Pd mass ratio of 3.1.3. 4. Ba acetate (300g / ft 3 ) is added to the batch. 5. Adjust solids content to target (suggested around 30%). 6. Add the appropriate amount of thickener and mix overnight. 7. Coat the single dose target 1.2 inches from the entrance. 8. Fire the bricks in a static oven at 500°C / 30 minutes.

[0105] Example 4C: Fully formulated single layer Pd washcoat with Pd-GA x 1.5 (GA to Pd mass ratio 2) 1. Prepare a solution containing the required amount of Pd nitrate (Pd loading 100 g / ft 3 ). 2. Stabilized alumina (1 g / in 3 ) and CZO (1g / in 3 ) was added to the batch. Gallic acid is added to target a GA:Pd mass ratio of 3.2.0. 4. Ba acetate (300g / ft 3 ) is added to the batch. 5. Adjust solids content to target (suggested around 30%). 6. Add the appropriate amount of thickener and mix overnight. 7. Coat the single dose target 1.2 inches from the entrance. 8. Fire the bricks in a static oven at 500°C / 30 minutes.

[0106] Example 4D: Fully formulated single layer Pd washcoat containing Pd-GA x 2.0 (GA to Pd mass ratio of 2.7) 1. Prepare a solution containing the required amount of Pd nitrate (Pd loading 100 g / ft 3 ). 2. Stabilized alumina (1 g / in 3 ) and CZO (1g / in 3 ) was added to the batch. Gallic acid is added to target a GA:Pd mass ratio of 3.2.7. 4. Ba acetate (300g / ft 3 ) is added to the batch. 5. Adjust solids content to target (suggested around 30%). 6. Add the appropriate amount of thickener and mix overnight. 7. Coat the single dose target 1.2 inches from the entrance. 8. Fire the bricks in a static oven at 500°C / 30 minutes.

[0107] 5A, 5B, and 5C show the NO comparison between Comparative Example 4A and Examples 4B, 4C, and 4D after redox aging at 1000° C. for 40 hours. x The comparison of CO and THC light-off conversion was shown. After rich pretreatment, the light-off temperature was between 150 and 600°C, the frequency was 0.96 to 1.04 Hz (with 1 Hz) and the time was 200,000 h. -1 The catalysts were evaluated at varying λ perturbations with GHSV of 1.0, 2.0, and 3.0. Compared to a fully formulated Pd reference catalyst without anchoring (Comparative Example 4A), Pd catalysts with anchoring by different amounts of gallic acid (Examples 4B-4D with GA to Pd mass ratios of 1.3, 2.0, and 2.7, respectively) showed improved low-temperature NO. x Light-off performance, as well as improved CO and THC performance were demonstrated.

[0108] Catalytic Engine Performance Comparative Example 5A: Fully formulated single layer Pd washcoat without Pd anchoring 1. Prepare a solution containing the required amount of Pd nitrate (Pd loading: 149 g / ft 3 ). 2. Stabilized alumina (1 g / in 3 ) and CZO (1g / in 3 ) was added to the batch. 3. Ba acetate (400g / ft 3 ) is added to the batch. 4. Adjust solids content to target (suggests around 30%). 5. Add the appropriate amount of thickener and mix overnight. 6. Coat 50% of the dose length from the inlet and allow to dry by air curing. 7. Then coat 50% of the dose length from the outlet and dry by air curing to obtain the bottom coated portion. 8. The required amount of Rh nitrate (Rh loading 6g / ft 3) solution is prepared. 9. Add stabilized alumina (1 g / in) to the above solution. 3 ) is added. 10. Adjust the pH of the above mixture to 6-7 and mix for at least 1 hour. 11. CZO(1g / in 3 ) is added to the above mixture. 12. Add an appropriate amount of thickener to the above mixture and stir overnight. 13. Coat 50% dose length from the inlet of the coated part from step 7 and air cure to dry. 14. Then coat 50% of the dose length from the outlet and dry by air curing to obtain a double layer coated part. 15. Fire the bricks in a static oven at 500°C / 30 minutes.

[0109] Example 5B: Fully formulated single layer Pd washcoat with Pd immobilization by gallic acid 1. Prepare a solution containing the required amount of Pd nitrate (Pd loading: 149 g / ft 3 ). 2. Stabilized alumina (1 g / in 3 ) and CZO (1g / in 3 ) was added to the batch. Gallic acid is added to target a GA:Pd mass ratio of 3.2.0. 4. Ba acetate (400g / ft 3 ) is added to the batch. 5. Adjust solids content to target (suggested around 30%). 6. Add the appropriate amount of thickener and mix overnight. 7. Coat 50% of the dose length from the inlet and allow to dry by air curing. 8. Then coat 50% of the dose length from the outlet and dry by air curing to obtain the bottom coated portion. 9. The required amount of Rh nitrate (Rh loading 6g / ft 3 ) solution is prepared. 10. Add stabilized alumina (1 g / in) to the above solution. 3 ) is added. 11. Adjust the pH of the above mixture to 6-7 and mix for at least 1 hour. 12. CZO(1g / in 3 ) is added to the above mixture. 13. Add an appropriate amount of thickener to the above mixture and stir overnight. 14. Coat 50% dose length from the inlet of the coated part from step 8 and air cure to dry. 15. Then coat 50% of the dose length from the outlet and dry by air curing to obtain a double layer coated part. 16. Fire the bricks in a static oven at 500°C / 30 minutes.

[0110] 6A, 6B, and 6C show NOx values ​​during engine bench testing for Comparative Example 5A and Example 5B after 50 hours of engine-redox aging at 950° C., respectively. x Compared to the fully formulated Pd-Rh bilayer catalyst without Pd immobilization (Comparative Example 5A), Example 5B exhibited lower NO, CO, and THC emissions. x The results showed improved TWC performance with reduced CO and THC emissions.

[0111] The foregoing detailed description has been provided for purposes of illustration and example, and is not intended to limit the scope of the appended claims. Many variations of the presently preferred embodiments set forth herein will be apparent to those skilled in the art and remain within the scope of the appended claims and their equivalents.

Claims

1. 1. A method of making a catalyst article, said method comprising: Compounds of formula (I): 【Chemistry 1】 and a PGM complex, wherein R1 is H or C １ ~C ６ alkyl, and R2 is H, OH, or O—C １ ~C ４ alkyl, and the PGM comprises palladium; Providing a carrier material; applying the complex to the support material to form a supported support material; placing the supported support material on a substrate; and heating the loaded support material to form nanoparticles of the PGM on the support material.

2. The method of claim 1, wherein R2 is OH.

3. 3. The method of claim 1 or claim 2, wherein R1 is H.

4. The method of any one of claims 1 to 3, wherein the PGM consists of palladium.

5. After heating the loaded support material, the substrate has a surface roughness of 50 g / ft ３ ~200g / ft ３ The method according to any one of claims 1 to 4, wherein the PGM is

6. After heating the loaded support material, the substrate has a surface roughness of 10 g / ft ３ ~150g / ft ３ The method of claim 5 , wherein the PGM is:

7. The support material is an oxide, preferably Al ２ O ３ , SiO ２ , TiO ２ , CeO ２ , ZrO ２ , CeO ２ -ZrO ２ , V ２ O ５ , La ２ O ３ and zeolite.

8. The method of any one of claims 1 to 7, wherein the support material comprises alumina, preferably gamma-alumina.

9. The method of any one of claims 1 to 8, wherein the support material comprises ceria-zirconia.

10. The method of any one of claims 1 to 9, wherein the support material comprises alumina and ceria-zirconia.

11. A method according to any one of claims 8 to 10, wherein the alumina and / or ceria-zirconia is doped.

12. 12. The method of claim 11, wherein the alumina and / or ceria-zirconia is doped with one or more oxides of lanthanum, neodymium, yttrium, niobium, praseodymium, hafnium, molybdenum, titanium, vanadium, zinc, cadmium, manganese, iron, copper, calcium, barium, strontium, cesium, magnesium, potassium, and sodium, preferably with one or more oxides of lanthanum, neodymium, and yttrium.

13. A method according to claim 11 or claim 12, wherein the dopant is present in the alumina and / or ceria-zirconia in an amount of from 0.001% to 20% by weight, preferably from 0.5% to 10% by weight.

14. A method according to any one of the preceding claims, wherein the support material is in the form of a powder having a D90 of 0.1 to 30 μm, preferably 1 to 20 μm.

15. The method of any one of claims 1 to 14, wherein the supported carrier material is disposed on the substrate in the form of a slurry.

16. 16. The method of claim 15, wherein providing the complex of the compound of formula (I) and the PGM comprises synthesizing the complex in situ in the slurry.

17. The slurry contacting a PGM salt with a compound of formula (I) in water to form said complex of the compound of formula (I) and PGM in aqueous solution, wherein said PGM salt comprises palladium; applying the complex to the support material by contacting the support material with the aqueous solution to form a supported support material; and optionally adding one or more of an oxygen storage material, preferably ceria-zirconia, a promoter salt, a binder, an acid or a base, a thickener, and a reducing agent to the aqueous solution.

18. The slurry contacting a support material with an aqueous solution of a PGM salt to form a slurry comprising a PGM salt-loaded support material, the PGM salt comprising palladium; To form a loaded support material by contacting the slurry comprising the PGM-salt loaded support material and the compound of formula (I) in water, the compound of formula (I): 【Chemistry 2】 and applying said complex of said PGM to a support material; and optionally adding one or more of an oxygen storage material, preferably ceria-zirconia, a promoter salt, a binder, an acid or a base, a thickener, and a reducing agent to the aqueous solution or slurry comprising the PGM salt-loaded support material.

19. The method of any one of claims 1 to 18, wherein the supporting comprises a washcoating.

20. A method according to any one of claims 15 to 19, wherein the slurry has a solids content of 10 to 40%, preferably 15 to 35%.

21. The slurry an oxygen storage material, preferably ceria-zirconia; a promoter salt, preferably barium acetate, barium sulfate, barium citrate or a combination thereof; binder, Acids or bases, thickeners, and 21. The method of any one of claims 15 to 20, further comprising one or more of a reducing agent.

22. The method of any one of claims 15 to 21, wherein the support material comprises alumina and the slurry further comprises ceria-zirconia.

23. The method of any one of claims 15 to 21, wherein the support material comprises ceria-zirconia and the slurry further comprises alumina.

24. The method of any one of claims 15 to 21, wherein the support material comprises alumina and ceria-zirconia.

25. 25. The method of any one of claims 15 to 24, further comprising disposing a further slurry on the substrate, the further slurry comprising one or more of a further support material, an oxygen storage material, a promoter salt, preferably barium acetate, barium sulfate, barium citrate or a combination thereof, a binder, an acid or base, a thickener, and a reducing agent, and wherein disposing the further slurry on the substrate occurs before disposing the support material on the substrate and / or after heating the supported support material to form nanoparticles of the PGM on the support material.

26. Disposing the supported support material on a substrate comprises contacting the slurry with the substrate, and optionally applying a vacuum to the substrate; and / or The method of any one of claims 15 to 25, comprising drying the slurry on the substrate.

27. The drying at a temperature of 60°C to 200°C, preferably 70°C to 130°C, and / or 27. The method of claim 26, carried out for 10 to 360 minutes, preferably 15 to 60 minutes.

28. The method of any one of claims 1 to 27, wherein the substrate comprises cordierite.

29. The method of any one of claims 1 to 28, wherein the substrate is in the form of a honeycomb monolith, a wall-flow filter, or a flow-through filter.

30. The heating at a temperature of 400°C to 700°C, preferably 400°C to 600°C, more preferably 450°C to 600°C, and / or 30. The method according to any one of claims 1 to 29, carried out for 10 to 360 minutes, preferably 35 to 120 minutes.

31. The method of any one of claims 1 to 30, wherein the heating comprises calcining.

32. 32. The method of any one of claims 1 to 31, wherein the nanoparticles have a D50 of 0.1 nm to 30 nm, preferably 0.5 to 25 nm, more preferably 1 to 20 nm.

33. A catalytic article obtainable by the method of any one of claims 1 to 32, for use in an emission treatment system.

34. 34. The catalytic article of claim 33 for three-way catalysis.

35. 1 g / in ３ ~3g / in ３ 35. The catalyst article of claim 33 or claim 34, having a washcoat loading of

36. The catalytic article of any one of claims 33 to 35, wherein the substrate comprises a wall-flow filter substrate.

37. The catalytic article of any one of claims 33 to 35, wherein the substrate comprises a flow-through substrate.

38. 38. A catalyst article according to any one of claims 33 to 37, comprising a bottom layer of support material having rhodium thereon and a top layer of support material having palladium thereon.

39. 38. A catalyst article according to any one of claims 33 to 37, comprising a bottom layer of support material having palladium thereon and a top layer of support material having rhodium thereon.

40. 40. The catalytic article of claim 38 or 39, wherein the top and / or bottom layer of the support material also has platinum thereon.

41. 41. The catalyst article of any one of claims 38 to 40, wherein the top and / or bottom layer of the support material has a plurality of PGMs thereon.

42. 42. The catalytic article of any one of claims 38 to 41, comprising two or more catalytic zones, said two or more catalytic zones differing from one another by containing different PGMs or different amounts of PGMs.

43. 43. The catalytic article of claim 38 or claim 42, wherein the support material comprises alumina and ceria-zirconia.

44. 2 g / ft ３ ~15g / ft ３ of rhodium, preferably 5 g / ft ３ ~10g / ft ３ 44. The catalytic article of any one of claims 33 to 43, comprising:

45. 10g / ft ３ ~200g / ft ３ of palladium, preferably 80 g / ft ３ ~150g / ft ３ 45. The catalytic article of any one of claims 38 to 44, comprising palladium of

46. 46. ​​The catalyst article of any one of claims 33-45, wherein the supported support material is disposed on the substrate in the form of a slurry, the PGM comprising palladium, the support material comprising alumina, and the slurry further comprising ceria-zirconia.

47. 46. ​​The catalyst article of any one of claims 33 to 45, wherein the supported support material is disposed on the substrate in the form of a slurry, the PGM comprising palladium, the support material comprising ceria-zirconia, and the slurry further comprising alumina.

48. 46. ​​The catalyst article of any one of claims 34 to 45, wherein the supported support material is disposed on the substrate in the form of a slurry, the PGM comprising palladium, and the support material comprising alumina and ceria-zirconia.

49. An emissions treatment system comprising the catalytic article of any one of claims 33 to 48.

50. 50. The emission treatment system of claim 49 for a gasoline engine.

51. 51. The emission treatment system of claim 50, wherein the gasoline engine operates under stoichiometric conditions.

52. 1. A method for treating an exhaust gas, the method comprising: Providing a catalyst article according to any one of claims 33 to 48; contacting the catalytic article with an exhaust gas.

53. 53. The method of claim 52, wherein the exhaust gas is from a gasoline engine.

54. 54. The method of claim 53, wherein the gasoline engine is operated under stoichiometric conditions.

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