Sulfur-containing organic compounds assisted metal nanoparticle synthesis for improved three-way catalysis applications

Abstract

A method for producing an alkaline earth metal sulfate-loaded support material is provided, the method including: providing a first slurry including a support material, alkaline earth metal ions, and an organic compound, wherein the organic compound includes a functional group selected from a sulfo group (—SOH), a sulfonyl group (—S(═O)—), and a sulfinyl group (—S(═O)—); spray-drying the first slurry to provide a spray-dried powder; and heating the spray-dried powder to form the alkaline earth metal sulfate-loaded support material.

Description

[Technical Field]

[0001] The present invention relates to a method for producing an alkaline earth metal sulfate supported support material, an alkaline earth metal sulfate supported support material, a method for producing a catalyst article, a catalyst article, 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. Conventional TWCs prepared using the above methods often offer limited control over the properties of the catalytically active species (i.e., the average particle size of the PGMs and promoters, the targeted association of these active components with the support material, and the distribution of these active components within the same washcoat ("WC") layer to improve metal-support interactions). This is primarily due to migration and particle growth during the drying and high-temperature calcination processes.

[0004] Alkaline earth metals such as barium are well known to be excellent promoters for the catalytic function of Pd. Ba can donate electrons to Pd, which allows the Pd (II) The electron configuration of NO on Pd becomes more similar to that of Rh, which can improve TWC activity [Non-Patent Document 1]. x Both the adsorption strength of NO and CO were reduced on the Ba-promoted Pd catalyst. x and CO conversion improvement [Non-Patent Document 2, Non-Patent Document 3]. Ba also helps stabilize PdO and inhibit sintering due to high temperature exposure during the life-cycle of three-way catalytic converters. Last but not least, Ba is a good stabilizer for the alumina support material, which helps maintain high dispersion of the Pd species.

[0005] When using a Ba component as an additive, it is important to control the location and size of both palladium and barium to optimize the synergistic interaction with the active Pd, Ba species, and support component. However, in catalysts obtained from known methods, the particle size of the alkaline earth metal-containing species is generally larger compared to the Pd nanoparticles, which may result in a suboptimal interaction. Furthermore, this interaction may deteriorate upon aging in catalysts obtained from known methods. Therefore, there is a need to provide a method for producing a catalyst article that allows for a more optimized interaction between the PGM (e.g., Pd) nanoparticles and the alkaline earth metal-containing species in the resulting catalyst article, ideally with comparable particle size and close proximity that allows for such improved performance and is less susceptible to aging.

[0006] Soluble alkaline earth metal species and Pd precursors migrate to the washcoat layer surface during the drying process after application, resulting in a capillary effect. In this case, the Ba component and Pd species are not uniformly distributed within the washcoat layer, resulting in suboptimal interactions between the Ba / Pd species and the metal oxide support material. Significant grain growth of the Pd and Ba species occurs during typical TWC aging due to high temperatures, which deteriorates the Pd-Ba interaction and leads to TWC catalyst deactivation. Suboptimal metal-support interactions accelerate this grain growth, further reducing catalytic performance. Therefore, increasing the homogeneity of the Pd nanoparticles and alkaline earth metal-containing species in the washcoat layer is as important as maintaining similarly small particle sizes for both, which allows for greater resistance to TWC aging due to optimal metal-support interactions.

[0007] Historically, considerable efforts have been made to reduce the particle size of the barium seeds to facilitate closer contact with the Pd seeds and to control the location of the barium seeds within the washcoat using several insoluble Ba compounds. Ball / bead milling of BaSO4 compounds is not very effective in producing nanoscale barium sulfate seeds [Patent Documents 1 and 6]. To generate barium sulfate seeds during the calcination process, sulfuric acid was added to a Pd washcoat with Ba acetate or Ba hydroxide as precursors. Smaller BaSO4 particle sizes were obtained. However, these were still at the micron level, far from the nanoscale goal [Patent Documents 2-5].

[0008] Citation list: Patent documents: Patent document 1: U.S. Patent No. 8,741,799 Patent Document 2: U.S. Patent Application Publication No. 2012 / 0165185 Patent document 3: U.S. Patent No. 8,545,780 Patent document 4: U.S. Patent No. 8,835,346 Patent Document 5: U.S. Patent Application Publication No. 2014 / 0329669 Patent Document 6: International Publication No. 2014 / 156746

[0009] Non-patent literature: Non-patent document 1: Applied Catalyst B, 30, 2001, 287 Non-patent document 2: Journal of Molecular Catalysis A: Chemical, 349, 2011, 94 Non-patent document 3: Applied Catalysis A: General403, 2011, 12 Summary of the Invention

[0010] One aspect of the present disclosure is directed to a method of producing an alkaline earth metal sulfate-loaded support material, the method including: providing a first slurry including a support material, alkaline earth metal ions, and an organic compound, wherein the organic compound includes a functional group selected from a sulfo group (—SOH), a sulfonyl group (—S(═O)—), and a sulfinyl group (—S(═O)—); spray-drying the first slurry to provide a spray-dried powder; and heating the spray-dried powder to form the alkaline earth metal sulfate-loaded support material.

[0011] Another aspect of the present disclosure is directed to an alkaline earth metal sulfate supported support material obtained or obtainable by the method of the above aspect.

[0012] Another aspect of the present disclosure is directed to a method of making a catalyst article, the method comprising: making an alkaline earth metal sulfate supported support material according to the method of the above aspect, or providing an alkaline earth metal sulfate supported support material according to the above aspect; providing a second slurry comprising the alkaline earth metal sulfate supported support material and platinum group metal (“PGM”) ions; disposing the second slurry on a substrate; and heating the slurry to form PGM nanoparticles on the alkaline earth metal sulfate supported support material.

[0013] Another aspect of the present disclosure is directed to a catalyst article obtained or obtainable by the method of the above aspect.

[0014] Another aspect of the present disclosure is directed to a catalytic article comprising a substrate and a first catalytic region disposed on the substrate, the first catalytic region comprising a support material having PGM nanoparticles and alkaline earth metal sulfate nanoparticles supported thereon, the alkaline earth metal sulfate nanoparticles being uniformly distributed within the first catalytic region.

[0015] Another aspect of the present disclosure relates to an emissions treatment system including the catalytic article of the above-described aspect.

[0016] Another aspect of the present disclosure relates to a method of treating an exhaust gas, the method comprising providing a catalytic article of the above-described aspect and contacting the catalytic article with the exhaust gas. [Brief explanation of the drawings]

[0017] The invention will now be described with reference to the following non-limiting drawings. [Figure 1] FIG. 1 shows an embodiment according to the present invention containing a first catalyst region (single layer) having a length of 100% of the axial length L of the substrate. [Figure 2a] FIG. 1 shows an embodiment according to the invention in which a first catalyst region extends as a bottom layer over 100% of the axial length L, and a second catalyst region extends as a top layer over 100% of the axial length L. [Figure 2b] FIG. 2b shows a variation of FIG. 2a. [Figure 3a] 1 illustrates an embodiment according to the present invention in which the first catalyst region extends from the inlet end for less than 100% of the axial length L, and the second catalyst region extends from the outlet end for less than 100% of the axial length L. The total length of the second catalyst region and the first catalyst region is less than or equal to the axial length L. [Figure 3b] 3b illustrates a variation of FIG. 3a. [Figure 3c] 1 illustrates an embodiment according to the present invention in which the first catalyst region extends from the inlet end for less than 100% of the axial length L, and the second catalyst region extends from the outlet end for less than 100% of the axial length L. The total length of the second catalyst region and the first catalyst region is greater than the axial length L. [Figure 3d] 3c illustrates a variation of FIG. [Figure 4a] 1 illustrates an embodiment according to the present invention in which a first catalyst region extends less than 100% of the axial length L from the inlet end and a second catalyst region extends less than 100% of the axial length L from the outlet end. The combined length of the second catalyst region and the first catalyst region is less than or equal to the axial length L. A third catalyst region extends 100% of the axial length L and is layered as an upper layer on the first and second catalyst regions. [Figure 4b]FIG. 4b shows a variation of FIG. 4a. [Figure 4c] 1 illustrates an embodiment according to the present invention in which a third catalyst region is a bottom layer extending 100% of the axial length L. A first catalyst region extends less than 100% of the axial length L from the inlet end, and a second catalyst region extends less than 100% of the axial length L from the outlet end. The total length of the second catalyst region and the first catalyst region is less than or equal to the axial length L. [Figure 4d] 4c illustrates a variation of FIG. [Figure 5a] 1 illustrates an embodiment according to the present invention, in which the first catalyst region extends less than 100% of the axial length L from the inlet end, and the second catalyst region extends less than 100% of the axial length L from the outlet end. The combined length of the second catalyst region and the first catalyst region can be less than, equal to, or greater than the axial length L. The third catalyst region extends less than 100% of the axial length L from the inlet end, and the fourth catalyst region extends less than 100% of the axial length L from the outlet end. The combined length of the third catalyst region and the fourth catalyst region can be less than, equal to, or greater than the axial length L. The first and second catalyst regions constitute a bottom layer, and the third and fourth catalyst regions constitute a top layer. [Figure 5b] FIG. 5b shows a variation of FIG. 5a. [Figure 5c] FIG. 5b shows a variation of FIG. 5a. [Figure 5d] FIG. 5b shows a variation of FIG. 5a. [Figure 6a] 1 shows an embodiment according to the present invention in which a first catalyst region extends 100% of the axial length L as a bottom layer, a second catalyst region extends 100% of the axial length L as a middle layer, and a third catalyst region extends 100% of the axial length L as a top layer. [Figure 6b] FIG. 6b shows a variation of FIG. 6a. [Figure 6c] FIG. 6b shows a variation of FIG. 6a. [Figure 7a]1 illustrates an embodiment according to the present invention in which a first catalyst region extends less than 100% of the axial length L from the inlet end and a second catalyst region extends less than 100% of the axial length L from the outlet end. The combined length of the second catalyst region and the first catalyst region is greater than the axial length L. A third catalyst region extends 100% of the axial length L and is layered as an upper layer on the first and second catalyst regions. [Figure 7b] FIG. 7b shows a variation of FIG. 7a. [Figure 7c] FIG. 7b shows a variation of FIG. 7a. [Figure 7d] FIG. 7b shows a variation of FIG. 7a. [Figure 7e] FIG. 7b shows a variation of FIG. 7a. [Figure 7f] FIG. 7b shows a variation of FIG. 7a. [Figure 7g] 1 illustrates an embodiment according to the present invention in which a first catalyst region extends less than 100% of the axial length L from the inlet end and a second catalyst region extends less than 100% of the axial length L from the outlet end. The combined length of the second catalyst region and the first catalyst region can be less than, equal to, or greater than the axial length L. A third catalyst region extends less than 100% of the axial length L from the inlet end and is at least partially stacked on the first catalyst region and / or the second catalyst region. [Figure 7h] FIG. 7B shows a variation of FIG. 7G. [Figure 7i] FIG. 7B shows a variation of FIG. 7G. [Figure 7j] 1 illustrates an embodiment according to the present invention in which a first catalyst region extends less than 100% of the axial length L from the inlet end and a second catalyst region extends less than 100% of the axial length L from the outlet end. The combined length of the second catalyst region and the first catalyst region can be less than, equal to, or greater than the axial length L. A third catalyst region extends less than 100% of the axial length L from the outlet end and is at least partially stacked on the second catalyst region and / or the first catalyst region. [Figure 7k] FIG. 7J is a diagram showing a modification of FIG. [Figure 7l] FIG. 7J is a diagram showing a modification of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] 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.

[0019] In a first aspect, the present invention provides a method for producing an alkaline earth metal sulfate-loaded support material, the method comprising: providing a first slurry comprising a support material, alkaline earth metal ions, and an organic compound, wherein the organic compound comprises a functional group selected from a sulfo group (—SOH), a sulfonyl group (—S(═O)—), and a sulfinyl group (—S(═O)—); spray-drying the first slurry to provide a spray-dried powder; and heating the spray-dried powder to form the alkaline earth metal sulfate-loaded support material.

[0020] 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.

[0021] Surprisingly, when the alkaline earth metal sulfate-supported support material produced by the method of the present invention is used as a support material for PGMs (such as Pd) in a catalytic region, such as a washcoat layer, of a catalyst article, the catalyst article may provide favorable catalytic activity, particularly for three-way catalytic activity, when used in an emissions treatment system. 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 than conventional catalyst articles. In other words, such favorable catalytic activity may be exhibited even after aging.

[0022] Advantageously, such superior performance may facilitate the use of lower loadings of PGMs and / or promoter metals (such as alkaline earth metals) compared to conventional catalyst articles without compromising catalytic performance, which may be beneficial given the high cost of such metals, such as palladium. Furthermore, such superior performance may facilitate partial / complete substitution of high-cost PGMs with lower-cost PGMs or other transition metals without compromising catalytic performance.

[0023] As described herein, throughout the description, the PGM (including PGM nanoparticles) can be Pt, Pt, and / or Rh. In some embodiments, the PGM can include Pd. In other embodiments, the PGM can include Pt and / or Rh. In certain embodiments, the PGM can include Pd and Rh or Pd and Pt. In other embodiments, the PGM can include Pd, Pt, and Rh. In some embodiments, the PGM can be only Pd.

[0024] Moreover, such catalyst articles can provide surprisingly efficient TWC performance in "cold start" conditions because the promoter interactions of alkaline earth metals such as barium and, when present, palladium can be particularly effective in such catalyst articles.

[0025] Without being bound by theory, it is hypothesized that such superior performance may be provided by the preferred nanoscale particle size of the alkaline earth metal sulfate, which may include nanoparticles supported on the support material and provided by the method of this embodiment via the organic compound route. This may be because the presence of the organic compound during the calcination step results in a relatively slow rate of alkaline earth metal sulfate formation, resulting in nanoscale particle size of the alkaline earth metal sulfate. Such small particle size may be advantageous in interacting with the PGM, preferably palladium, particle size distribution that may be supported on the support material for use in the catalytic article. Such resulting catalytic articles may also exhibit preferred distributions of PGM or palladium nanoparticles and alkaline earth metal sulfate nanoparticles relative to one another, i.e., may have a high correlation with one another (in other words, have a particularly small particle size and a highly uniformly distributed nanoparticle, i.e., a highly homogeneous distribution of palladium nanoparticles and alkaline earth metal sulfate nanoparticles, thereby having a large number of palladium-alkaline earth metal interactions).

[0026] Without wishing to be bound by theory, it is hypothesized that the process of the present invention, in which a slurry provided in the process comprises alkaline earth metal ions and an organic compound as described herein, and the slurry is then spray dried, may be useful in enabling smaller particle size and uniform distribution of the alkaline earth metal sulfate salt supported on the support material.

[0027] Furthermore, without being bound by theory, it is hypothesized that such a method may enable the particle sizes of the PGM (e.g., Pd) and the alkaline earth metal sulfate to be comparable, i.e., similar in size, when the PGM (e.g., Pd) is supported on the support material. Typically, in conventional methods, alkaline earth metal sulfate nanoparticles may be up to 5, 10, or even 20 times larger than the PGM (e.g., Pd) nanoparticles. Since the method of the present invention may enable small nanoparticles of alkaline earth metal sulfate to be obtained, the interaction and correlation between the PGM (e.g., Pd) and the alkaline earth metal may be increased when the PGM (e.g., Pd) nanoparticles are added. This is because the nanoparticles are therefore closely located adjacent to each other on the support material (e.g., when uniformly distributed) and may, for example, be able to enter pores of the same size in the support material. Therefore, a highly uniform distribution of similarly sized particles may be provided. This may enable the above-mentioned advantageous effects to be achieved while optimizing the possibility of interaction between the PGM (e.g., Pd) and the alkaline earth metal promoter species.

[0028] Without being bound by theory, it is also believed that such a distribution of the resulting alkaline earth metal sulfate nanoparticles, particularly when PGM or palladium nanoparticles may be supported thereon, may help achieve advantageous aging characteristics, i.e., increased resistance to deactivation (e.g., cold-start emission control activity) upon aging. This may be because, due to the more uniform distribution of small nanoparticles that may be formed—i.e., due to the relatively high number of direct interactions between PGM or palladium and alkaline earth metals, and the relatively low number of direct PGM-to-PGM and alkaline earth metal-to-alkaline earth metal interactions (i.e., relative to adjacent nanoparticles)—upon aging, such catalyst articles may be more resistant to sintering / coalescence of the same particles that form the larger nanoparticles, thereby becoming deactivated. This may be due, for example, to the highly uniform distribution of particles, which allows “other” nanoparticles to act as a physical barrier against sintering / coalescence of the same nanoparticles. Thus, advantageously, a catalyst article having higher resistance to deactivation upon aging may be provided. In other words, this may be possible because the alkaline earth metal sulfate nanoparticles, as provided by the method of the present embodiment, may be small and evenly distributed on the support material, and when the PGM or palladium nanoparticles are subsequently supported thereon, the PGM or palladium nanoparticles may be of a similar particle size distribution and evenly distributed among the similarly sized alkaline earth metal nanoparticles.

[0029] A further advantage may be that in situ alkaline earth metal sulfates (such as BaSO) may be formed during the calcination step of the process, taking advantage of the pores of the support material (particularly for lanthanum-doped alumina) so that alkaline earth metal sulfate crystal growth is limited.

[0030] Perhaps most importantly, it has surprisingly been found that by first providing an alkaline earth metal sulfate-supported support material according to the method of the present invention and then supporting, for example, a PGM, particularly, or palladium, thereon, and then using the aforementioned alkaline earth metal sulfate-supported support material in the preparation of a catalytic region, such as a washcoat, of a catalyst article, a catalyst article can be prepared that exhibits the above-mentioned advantageous effects and has a uniform distribution of alkaline earth metal sulfate (nanoparticles) throughout the catalytic region or washcoat. The uniform distribution can also increase the catalytic performance of the catalyst article. In other words, the advantageous effects that can be achieved by a preferred particle size distribution of the alkaline earth metal sulfate can be achieved when the alkaline earth metal sulfate-supported support material of the present invention is used in the catalytic region of a catalyst article, while maintaining a uniform distribution of the alkaline earth metal sulfate in the catalytic region itself.

[0031] This is in contrast to, for example, methods for preparing catalyst articles in which a slurry is washcoated onto a substrate, the slurry including a support material, alkaline earth metal ions, optionally an organic compound, and optionally PGM or palladium ions (i.e., without first preparing an alkaline earth metal sulfate-supported support material by the method of the present invention), and then the slurry is dried and / or heated and / or calcined by conventional methods. Without being bound by theory, this may be because, during the drying step of conventional preparation methods, due to evaporation of the solvent (typically water) in the washcoat and the presence of alkaline earth metal ions, organic compounds, and / or complexes thereof in solution, a higher proportion of alkaline earth metal species (nanoparticles) may form closer to the top of the washcoat, rather than having an even or uniform distribution, as the solvent evaporates and the solute migrates to the surface. Such a method may be a typical washcoat preparation method using such components. This may be particularly true for organic compounds such as taurine, which have relatively low solubility in water and may therefore require relatively large amounts of solvent, i.e., resulting in a dilute slurry.

[0032] In contrast, when the alkaline earth metal sulfate-supported support material of the present invention is used in such a washcoat, the support material already includes alkaline earth metal sulfate nanoparticles of a preferred particle size distribution supported thereon, and therefore, such migration and rearrangement of the alkaline earth metal sulfate can be prevented due to the insolubility of the alkaline earth metal sulfate nanoparticles. In other words, wicking of alkaline earth metal species can be prevented while still achieving the beneficial effects of a preferred particle size distribution of the alkaline earth metal sulfate that can be provided by the use of the organic compounds described herein.

[0033] Advantageously, such catalytic articles are capable of reducing total hydrocarbons (THC), CO, and NO x Improved light-off temperature and TWC activity during warm-up, such as reduced TWC activity. 50 This may indicate a faster time to 50 is the temperature at which a catalyst reaches 50% conversion of a particular pollutant species, as known to those skilled in the art.

[0034] The term "supported" as used herein in the context of an "alkaline earth metal sulfate-supported support material" can include, for example, that the alkaline earth metal sulfate can be directly supported on and / or in the support material. As used herein in the context of the present invention, the term "supported on and / or in" can include that the alkaline earth metal sulfate (typically in the form of nanoparticles) is in direct contact with at least a portion of the surface of the support material and / or, if the support material is porous, is present in at least a portion of the pores of the support material.

[0035] As used herein, the term "support material" can include any material capable of supporting at least an alkaline earth metal sulfate thereon or therein. The support material can be in any form, but is typically in the form of a powder, more typically a high surface area powder. When the method of the present invention is used to prepare a catalyzed filter, such as a wall-flow filter or a flow-through filter, the support material typically has a D of, for example, 0.1 to 30 μm, more typically 2 to 10 μm, and even more typically 4 to 6 μm, as measured using dynamic light scattering. 50 Such particle size can facilitate desirable rheological properties of the slurry used to coat the monolith substrate to reduce backpressure buildup. Preferred support materials are described elsewhere herein.

[0036] Unless otherwise specified or implied, the use of terms such as "first," "second," etc. are intended as labels only and are not intended to indicate the relative position or location of particular features.

[0037] As used herein, the term "slurry" can encompass a liquid containing insoluble materials, e.g., insoluble particles. Slurries described herein can include (1) a solvent, (2) soluble components, e.g., free PGM (e.g., Pd) ions, free alkaline earth metal ions, and free organic compounds (i.e., outside the support), and (3) insoluble components, e.g., support particles that may or may not interact with the components of the solution. Slurries are particularly useful for placing materials on a substrate, particularly to maximize gas diffusion and minimize pressure drop during catalytic conversion.

[0038] As used herein, the term "spray drying" and other derivatives have their ordinary meaning in the art and may include, for example, the rapid drying of a liquid or slurry with a hot gas. The particular method of spray drying is not particularly limited and those skilled in the art will be aware of suitable methods.

[0039] The step of heating the spray-dried powder can typically include the formation of alkaline earth metal sulfate nanoparticles on the support material, which, without being bound by theory, is believed to be due to the presence of the organic compounds described herein.

[0040] The slurry is typically heated in an oven or furnace, more typically in a belt or static oven or furnace, typically in a unidirectional flow of hot air. The heating may include calcination. During heating, any complexes that may have formed in the first slurry may be at least partially, substantially, or completely decomposed. In other words, the ligands of such complexes, e.g., ligands of organic compounds, may be at least partially, substantially, or completely removed or separated from the alkaline earth metal and removed from the final catalyst article. However, it is believed that organic compounds containing sulfur-containing functional groups as described herein may decompose to provide alkaline earth metal sulfates. As a result of heating (calcination), the support material is typically substantially free of organic compounds, more typically completely free of organic compounds.

[0041] As used herein, the term "nanoparticle" generally encompasses particles having a Rietveld crystallite size of 0.01 nm to 100 nm as measured by XRD. Nanoparticles can be of any shape, e.g., spheres, plates, cubes, cylinders, hexagons, or rods, but are typically spherical.

[0042] After the heating step, the support material is typically cooled, more typically to room temperature, typically in air with or without a coolant / cooling medium, typically without a coolant.

[0043] Preferably, the first slurry is substantially free of platinum group metals, such as platinum, palladium, and / or rhodium. Due to limitations of the spray drying process, if PGMs are also present in the first slurry, some yield of PGMs may be lost during the process. This is undesirable, among other reasons, because PGMs are expensive and their loss / waste defeats the purpose of PGM thrifting of the present invention. If the PGMs are supported on a support material for use in a catalyst article, this is preferably after the spray drying process, more preferably after the method of producing an alkaline earth metal sulfate-supported support material of the first embodiment.

[0044] The term "substantially free," as used herein with respect to a material, typically in the context of the content of a slurry, region, layer, or zone, means that the material is present in a small amount, for example, <5 wt.%, preferably <2 wt.%, more preferably <1 wt.%, even more preferably <0.5 wt.%, even more preferably <0.1 wt.%, even more preferably <0.01 wt.%, and even more preferably <0.005 wt.%, based on the total weight of said material. The term "substantially free" encompasses the term "free."

[0045] Preferably, the first slurry consists essentially of, more preferably consists of, a support material, alkaline earth metal ions, an organic compound, and optionally, counterions of the alkaline earth metal ions. Suitable counterions for alkaline earth metal ions are known to those skilled in the art. The counterions of the alkaline earth metal ions may include, for example, hydroxide ions, nitrate ions, and / or acetate ions, for example, preferably acetate ions.

[0046] As used herein, the phrase "consisting essentially of" limits the scope of a feature to include the specified materials or steps and any other materials or steps, e.g., trace impurities, that do not materially affect the basic properties of the feature. The phrase "consisting essentially of" encompasses the phrase "consisting of."

[0047] Preferably, the first slurry contains water. In other words, the first slurry is preferably an aqueous slurry. This is consistent with typical washcoating techniques in the art. Therefore, it would be easy to modify the techniques and equipment used in conventional methods to carry out the method of the present invention by using similar components. Therefore, the organic compound is preferably at least partially water-soluble.

[0048] The organic compound includes a functional group selected from a sulfo group (-SO3H), a sulfonyl group (-S(=O)2-), and a sulfinyl group (-S(=O)-). Without being bound by theory, it is believed that such sulfur-containing groups may interact and / or complex with alkaline earth metal ions in the first slurry. Furthermore, it is the presence of such sulfur-containing groups that allows for the formation of alkaline earth metal sulfate nanoparticles.

[0049] The organic compound preferably further comprises an amine functional group, preferably a primary amine functional group. In this regard, the organic compound preferably comprises a sulfo group and a primary amine group.

[0050] The organic compound may contain 1 to 6 carbon atoms, preferably 2 to 4 carbon atoms, and more preferably 2 carbon atoms. Such organic compounds may provide a good balance between solubility in solution, ability to form complexes with metal species, and ability to decompose upon heating to form nanoparticles of the desired size.

[0051] Specifically, the organic compound preferably comprises one or more of aminomethanesulfonic acid, taurine, homotaurine, 4-aminobutane-1-sulfonic acid, 2-aminopropane-1-sulfonic acid, 2-methyltaurine, dimethyl sulfone, sulfonane, cysteic acid, dimethyl sulfoxide, and aminobenzenesulfonic acid, more preferably taurine. In some embodiments, the molar ratio of the organic compound (e.g., taurine) to barium may be at least 1:1, 1.2:1, 1.5:1, 2:1, or even 3:1. In other embodiments, the molar ratio of the organic compound (e.g., taurine) to barium may be between 3:1 and 1:1, between 2:1 and 1:1, or between 1.5:1 and 1:1.

[0052] Such preferred organic compounds may not be highly soluble in water, and therefore the rapid drying provided by spray drying may help to maintain a uniform distribution of the alkaline earth metal sulfate on the support material.

[0053] The alkaline earth metal ions preferably comprise one or more of calcium ions, strontium ions, and barium ions, more preferably strontium and / or barium ions, and even more preferably barium ions. Barium is known to provide excellent cocatalytic activity in combination with palladium, for example in TWC. Providing the first slurry may typically include contacting the support material and / or organic compound with (a solution containing) an alkaline earth metal salt, and preferably the alkaline earth metal salt comprises one or more of an alkaline earth metal hydroxide, an alkaline earth metal nitrate, and an alkaline earth metal acetate, preferably an alkaline earth metal acetate. Preferably, the alkaline earth metal salt comprises barium acetate.

[0054] Preferably, the support material comprises an inorganic oxide, more preferably a metal oxide, even more preferably a refractory metal oxide. The support material preferably comprises one or more of alumina, silica, titania, ceria, zirconia, ceria-zirconia mixed oxide, vanadia, lanthana, and zeolite. More preferably, the support material comprises alumina and / or ceria-zirconia mixed oxide, even more preferably, the support material comprises alumina and ceria-zirconia mixed oxide. The alumina is preferably gamma alumina. The ceria-zirconia mixed oxide preferably comprises a molar ratio of ceria:zirconia of 10:90 to 90:10, more preferably 30:70 to 70:30, even more preferably 40:60 to 60:40.

[0055] The term "mixed oxide," as used herein, generally refers to a mixture of oxides in a single phase, as conventionally known in the art. The term "complex oxide," as used herein, generally refers to a composition of oxides having two or more phases, as conventionally known in the art.

[0056] It is particularly preferred that the support material comprises both alumina and ceria-zirconia mixed oxide. The presence of an alkaline earth metal sulfate (preferably barium sulfate), typically in combination with a PGM (such as Pd), on the alumina (i) provides particularly good NO x (ii) the presence on a ceria-zirconia mixed oxide may result in, for example, particularly good CO / THC conversion.

[0057] Surprisingly, it has been found that the method of the present invention can simultaneously facilitate the loading of alkaline earth metal sulfate on both alumina and ceria-zirconia mixed oxide. In conventional preparation methods involving slower drying of a slurry containing the components of the slurry, the alkaline earth metal sulfate is typically more easily loaded onto and / or in the alumina on the ceria-zirconia mixed oxide. This is believed to be due, for example, to the relatively high surface area of ​​alumina compared to ceria-zirconia mixed oxide. However, the method of the present invention can facilitate a more uniform distribution of the alkaline earth metal sulfate between two different support materials. Advantageously, this can provide the aforementioned advantageous effects through a single manufacturing method, i.e., rather than loading the alkaline earth metal sulfate separately onto each of the different support materials and then combining the support materials later. In other words, the method of the present invention is surprisingly capable of obtaining an alkaline earth metal sulfate-supported alumina and an alkaline earth metal sulfate-supported ceria-zirconia mixed oxide in a single process by simply including both different support materials in a first slurry and then simultaneously spray-drying the first slurries containing the two different support materials.

[0058] The alumina and / or ceria-zirconia mixed oxide is preferably doped with a dopant. The dopant preferably includes one or more of lanthanum, neodymium, yttrium, niobium, praseodymium, hafnium, molybdenum, titanium, vanadium, zinc, cadmium, manganese, iron, copper, calcium, barium, strontium, cesium, magnesium, potassium, and sodium, preferably one or more of lanthanum, neodymium, and yttrium. The dopant is preferably present in the alumina and / or ceria-zirconia mixed oxide in an amount of 0.001% to 20% by weight, preferably 0.5% to 10% by weight, based on the total weight of the dopant and the alumina and / or ceria-zirconia mixed oxide. Preferably, the support material includes La-doped alumina and ceria-zirconia mixed oxide.

[0059] Throughout this application, "wt. %" with respect to dopants is calculated based on, for example, their metal oxides. If doped, the support material is preferably a mixed oxide.

[0060] Preferably, the support material has a D of 0.1 to 30 μm, preferably 2 to 10 μm, more preferably 4 to 6 μm. 50 It is in the form of a powder having the formula D 50 can be measured by dynamic light scattering. This characteristic is provided in the first slurry, i.e., the D of the support material before the step of spray drying the first slurry. 50 Refers to...

[0061] Accordingly, in a preferred embodiment, there is provided a method for producing a barium sulfate-loaded support material, the method comprising: providing a first slurry comprising a support material, barium ions, and an organic compound, wherein the organic compound comprises a functional group selected from a sulfo group (—SOH), a sulfonyl group (—S(═O)—), and a sulfinyl group (—S(═O)—), and the support material comprises alumina, preferably La-doped alumina and a ceria-zirconia mixed oxide; spray-drying the first slurry to provide a spray-dried powder; and heating the spray-dried powder to form the barium sulfate-loaded support material, wherein preferably the organic compound comprises taurine.

[0062] The step of providing a first slurry may typically include contacting a support material, alkaline earth metal ions, typically in the form of alkaline earth metal salts, and an organic compound with a solvent, preferably comprising water. The components of the slurry may be provided / contacted with each other in any order, sequentially or simultaneously. However, preferably, providing the first slurry includes providing a solution, preferably an aqueous solution, comprising alkaline earth metal ions and an organic compound; providing a support material; and contacting the solution with the support material to form the first slurry. Typically, providing the solution may include contacting alkaline earth metal ions, typically in the form of alkaline earth metal salts, and an organic compound with a solvent, preferably comprising water. Without being bound by theory, it is believed that by first providing a solution comprising alkaline earth metal ions and an organic compound, the presence of the organic compound during the calcination step results in a relatively slow rate of alkaline earth metal sulfate formation, resulting in nanoscale particle sizes for the alkaline earth metal sulfate. Such small particle size may be advantageous in interaction with the PGM, preferably palladium, particle size distribution that may be supported on a support material for use in a catalyst article.

[0063] Preferably, heating the spray-dried powder comprises heating the spray-dried powder at a temperature of 300-700°C for 10 minutes to 5 hours, more preferably at a temperature of 400-600°C for 30 minutes to 4 hours, even more preferably at a temperature of 450-550°C for 1 hour to 3 hours, and even more preferably at a temperature of about 500°C for about 2 hours.

[0064] Preferably, heating the spray-dried powder comprises calcining the spray-dried powder. As used herein, the terms "calcination," "calcine," and "calcining" can include a heat treatment process in the absence or limited supply of air or oxygen to cause thermal decomposition or transformation. Typically, however, calcining in this context involves heating in air in an oven. In some preferred embodiments, calcining involves heating (in an oven, in air) at a temperature of 350-1100°C, preferably 400-900°C, more preferably 450-800°C, for 1-8 hours, preferably 2-5 hours.

[0065] Preferably, the first slurry comprises a solids content of 5-40%, more preferably 10-30%, even more preferably 10-20%, and even more preferably about 15%. Such solids contents may be particularly suitable for use in the spray drying process of the present invention.

[0066] The method preferably further comprises stirring the first slurry prior to the step of spray drying the first slurry, and preferably the first slurry is stirred for at least 10 minutes, more preferably at least 20 minutes, and even more preferably at least 30 minutes. Preferably, the first slurry is stirred for 10 to 90 minutes, more preferably 20 to 60 minutes, and even more preferably 30 to 40 minutes. Stirring may advantageously increase the homogeneity of the slurry and thus enhance the dispersion of the alkaline earth metal sulfate on the support material.

[0067] In another aspect, the present invention provides a method for producing an alkaline earth metal sulfate-loaded support material, the method comprising: providing a first slurry comprising a support material, alkaline earth metal ions, and an organic compound, wherein the organic compound comprises a functional group selected from sulfo (—SOH), sulfonyl (—S(═O)—), and sulfinyl (—S(═O)—); drying the first slurry to provide a dry powder; and heating the dry powder to form the alkaline earth metal sulfate-loaded support material, wherein the first slurry is substantially free of platinum group metals.

[0068] The relevant preferred features and embodiments of the first aspect apply equally to this aspect. The method of this alternative aspect may provide similar advantages to the first aspect, for at least the same reasons. Drying preferably occurs at a temperature of from 60°C to 200°C, more preferably from 70°C to 130°C, and / or for a period of from 10 to 360 minutes, preferably from 15 to 60 minutes.

[0069] In a further aspect, the present invention provides an alkaline earth metal sulfate supported support material obtained or obtainable by the method of the above aspect.

[0070] The relevant preferred features and embodiments of the first aspect apply equally to this aspect. Further, for the avoidance of doubt, the following preferred features apply equally to the methods of the above aspects, where appropriate.

[0071] Preferably, the alkaline earth metal sulfate-loaded support material comprises 1 to 25 wt. % alkaline earth metal sulfate, based on the total weight of the alkaline earth metal sulfate-loaded support material. More preferably, the alkaline earth metal sulfate-loaded support material comprises 2 to 20 wt. % or 5 to 20 wt. % alkaline earth metal sulfate, based on the total weight of the alkaline earth metal sulfate-loaded support material. When two or more different types of support materials are present, the wt. % is based on the total weight of the entire alkaline earth metal sulfate-loaded support material.

[0072] Preferably, the alkaline earth metal sulfate comprises alkaline earth metal sulfate nanoparticles. Preferably, the alkaline earth metal sulfate comprises alkaline earth metal sulfate nanoparticles having a crystallite size of 0.1 nm to 30 nm, preferably 5 to 25 nm or 5 to 20 nm, more preferably 5 to 15 nm. Unless otherwise specified, the crystallite size is preferably the Rietveld crystallite size. The crystallite size may be measured by X-ray diffraction (XRD). Preferably, substantially all of the alkaline earth metal sulfate nanoparticles have such a crystallite size. Such a particle size can advantageously enable the desirable properties discussed above, such as high activity and resistance to deactivation during aging. Furthermore, such a size of the nanoparticles, in combination with a particle size typically similar to that of PGM (e.g., Pd) nanoparticles, can help achieve the advantageous properties discussed above as a result of comparable particle size.

[0073] Unless otherwise specified herein, any crystallite size described herein may be measured by XRD. Suitable techniques are known in the art. For example, such techniques may be described as follows: To obtain X-ray diffraction data, an X'Pert Pro MPD diffractometer was used, manufactured by Bragg Brentano. HDIt can be used with a mirror, a ¼° divergence slit, a 20 mm mask, a sample spinner, and a PIXcel detector. Triple scans can be performed over a range of 5° to 115°, a 0.02° step size, and a total scan time of 50 minutes. Data can be analyzed using HighScore Plus software. Transition alumina phases can be modeled using the partial or unknown crystal structure method (NVYSCARLETT and ICMADSEN, Quantification of phases with partial or unknown crystal structure, Powder Diffraction (2006), 21(4), 278-284, incorporated herein by reference), while all other phases can be modeled using the Rietveld method. Crystallite size and distortion can be measured based on the pseudo-Voight profile function and can be corrected for instrumental broadening. Crystallite size measured by XRD is a common parameter for determining nanoparticle size of such species in the field of the present invention.

[0074] In a further aspect, the present invention provides a method of making a catalyst article, the method comprising: making an alkaline earth metal sulfate supported support material according to the method of the previous aspect, or providing an alkaline earth metal sulfate supported support material according to the previous aspect; providing a second slurry comprising the alkaline earth metal sulfate supported support material and PGM ions; disposing the second slurry on a substrate; and heating the second slurry to form PGM nanoparticles on the alkaline earth metal sulfate supported support material.

[0075] 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 flow-through monolith, or a filter, e.g., a wall-flow filter. The catalytic article may be for use in an emission treatment system, particularly an emission treatment system for a gasoline engine, preferably a stoichiometric gasoline engine. The catalytic article may be for use in three-way catalysis.

[0076] 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. The substrate can include a ceramic monolith substrate. The substrate can vary in its material composition, size and configuration, cell shape and density, and wall thickness. Suitable substrates are known in the art and can be flow-through monoliths or wall-flow filters, preferably flow-through monoliths.

[0077] The step of providing a second slurry may typically comprise contacting an alkaline earth metal sulfate-loaded support material and PGM ions, typically in the form of a PGM salt, for example a PGM (such as Pd) nitrate and / or a PGM (such as Pd) acetate, with a solvent, preferably comprising water.

[0078] Preferably, the second slurry contains water. In other words, the second slurry is preferably an aqueous slurry. This is consistent with typical washcoating techniques in the art. Therefore, by using similar components to carry out the method of the present invention, it is easy to modify the techniques and equipment used in conventional methods to carry out the method of the present invention.

[0079] Preferably, providing a second slurry comprises providing an intermediate slurry comprising an alkaline earth metal sulfate-supported support material and contacting the intermediate slurry with a PGM salt, preferably a solution comprising a PGM salt. The PGM salt preferably comprises one or more of a PGM nitrate and a PGM acetate, more preferably a PGM nitrate. The intermediate slurry comprises an alkaline earth metal sulfate-supported support material and a solvent, preferably water. Preferably, the intermediate slurry consists essentially of, more preferably consists of, the alkaline earth metal sulfate-supported support material and the solvent. The intermediate slurry is preferably provided by contacting the alkaline earth metal sulfate-supported support material with the solvent. Preferably, providing the intermediate slurry comprises providing an intermediate slurry in which the alkaline earth metal sulfate-supported support material has a D of about 5-15 μm, preferably about 4-6 μm. 50 The method includes breaking down the alkaline earth metal sulfate-loaded support material, such as by grinding and / or (vigorous) mixing, preferably using a high shear mixer, so as to have: 50 can be measured by dynamic light scattering.

[0080] Preferably, the method further comprises stirring the second slurry prior to the step of disposing the second slurry on the substrate, and preferably the second slurry is stirred for at least 10 minutes, more preferably at least 20 minutes, and even more preferably at least 30 minutes. Preferably, the second slurry is stirred for 10 to 90 minutes, more preferably 20 to 60 minutes, and even more preferably 30 to 40 minutes. Stirring may advantageously increase the homogeneity of the slurry and thus increase the distribution of the PGM ions on the alkaline earth metal sulfate-loaded support material.

[0081] Preferably, the second slurry further comprises a binder and one or more of an acid or base, a thickener, and / or an additional inorganic oxide. In other words, providing the second slurry preferably further comprises contacting the slurry containing the alkaline earth metal sulfate-supported support material and PGM ions with one or more of a binder; an acid or base; a thickener, and / or an additional inorganic oxide. The additional organic oxide may be as described elsewhere herein, but does not necessarily include an alkaline earth metal sulfate supported thereon.

[0082] 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. A typical binder may include alumina.

[0083] Thickeners may include, for example, natural polymers with functional hydroxyl groups that interact with insoluble particles in the washcoat slurry. Thickeners serve the purpose of thickening the washcoat slurry to improve the coating profile during washcoat application onto a substrate. Thickeners are 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. Thickeners may include natrasol.

[0084] Providing the second slurry may further include adjusting the pH of the second slurry to 6 or greater, preferably 7 or greater, using tetraethylammonium hydroxide (TEAOH) or the like. Such a pH may provide optimal conditions for, for example, washcoating.

[0085] Preferably, the second slurry has a solids content of 10 to 40%, preferably 15 to 35%. Such a solids content may 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 may 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 may enable the slurry to enter the channels of the wall-flow filter and the walls of the wall-flow filter.

[0086] Disposing the second slurry on the substrate can be carried out using techniques known in the art. Typically, the second slurry is injected into the inlet of the substrate using a specific forming tool in a predetermined amount, thereby disposing the supported support material (i.e., preferably again with PGM ions supported) on the substrate. As discussed in more detail below, subsequent vacuum and / or air knife and / or drying steps can be used during the disposing step. If the substrate is a filter block, the supported support material can be disposed on the filter walls, within the filter walls (if porous), or both.

[0087] Heating of the second slurry 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 PGM ions can coalesce and / or sinter to form PGM nanoparticles on the support material. Such PGM particles can also begin to form metal-metal and metal-oxide bonds. Of course, heating the second slurry typically involves simultaneously heating the second slurry and the substrate. Of course, the step of heating the second slurry can therefore typically involve fixing the support material to the substrate, for example, via a binder.

[0088] 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.

[0089] Thus, the method of this aspect typically results in the formation of a PGM and alkaline earth metal sulfate supported support material. The PGM and alkaline earth metal sulfate supported support material is typically disposed on a substrate in the form of a region, zone, washcoat, or layer. In other words, the catalyst article typically includes a first catalytic region comprising a support material having PGM nanoparticles and alkaline earth metal sulfate nanoparticles supported thereon. The first catalytic region is typically disposed on a substrate.

[0090] As used herein, the term "disposed on" can include either having a catalyst composition disposed directly on a substrate, i.e., without intervening materials, and / or having a catalyst composition or catalyst region disposed indirectly on a substrate, i.e., with intervening materials. If the substrate is porous, the term "disposed on" can also include having a catalyst composition or catalyst region disposed internally, e.g., within the pores of the substrate, i.e., the catalyst composition or catalyst region (of the support material) disposed on and / or within. As used herein, the term "washcoat" is well known in the art and typically refers to an adherent coating applied to a substrate during catalyst production.

[0091] Preferably, disposing the second slurry onto the substrate comprises washcoating.

[0092] Preferably, disposing the second slurry on the substrate includes contacting the second slurry with the substrate and, optionally, applying a vacuum and / or an air knife to the substrate and / or drying the second slurry on the substrate. This can result in a favorable distribution of the loaded support material that may be contained in the slurry on the substrate. Drying preferably occurs at a temperature of 60°C to 200°C, more preferably 70°C to 130°C, and / or for a time period of 10 to 360 minutes, preferably 15 to 60 minutes.

[0093] Preferably, heating the slurry to form PGM (e.g., Pd) nanoparticles on the alkaline earth metal sulfate-loaded support material comprises 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 for a period of 10 to 360 minutes, preferably 35 to 120 minutes.

[0094] Preferably, heating the slurry to form PGM nanoparticles on the alkaline earth metal sulfate-supported support material comprises calcination.

[0095] The substrate preferably comprises cordierite. The substrate may be in the form of a honeycomb monolith, a wall-flow filter, or a flow-through filter. The substrate may be a "blank," i.e., a substrate without a washcoat. Alternatively, the substrate may already have one or more washcoats deposited thereon. In such a situation, the final catalyst article may include multiple layers of different washcoats.

[0096] In a further aspect, the present invention provides a catalyst article obtained or obtainable by the method of the above aspect.

[0097] The relevant preferred features and embodiments of the above aspects apply equally to this aspect. Further, for the avoidance of doubt, the following preferred features apply equally to the methods of the above aspects, where appropriate.

[0098] Compared to conventional catalyst articles, such catalyst articles may exhibit favorable light-off performance, particularly for NO, CO, and total hydrocarbons, during three-way catalytic reduction of stoichiometric gasoline engines. The catalyst articles may also exhibit other favorable properties described herein, such as high resistance to deactivation during aging and high activity under "cold start" conditions. Furthermore, such catalyst articles exhibit lower light-off temperatures and T for such pollutants. 50 It may show a shorter time to reach

[0099] Preferably, the alkaline earth metal sulfate-loaded support material comprises 1 to 25 wt. % alkaline earth metal sulfate, based on the total weight of the alkaline earth metal sulfate and support material. More preferably, the alkaline earth metal sulfate-loaded support material comprises 2 to 20 wt. % or 5 to 20 wt. % alkaline earth metal sulfate, based on the total weight of the alkaline earth metal sulfate-loaded support material. When two or more different types of support material are present, the weight percentages are based on the total weight of the entire alkaline earth metal sulfate-loaded support material. However, for the avoidance of doubt, the total weight on which this calculation is based does not include the weight of any PGM (such as Pd) present.

[0100] Preferably, the alkaline earth metal sulfate comprises alkaline earth metal sulfate nanoparticles. Preferably, the alkaline earth metal sulfate comprises alkaline earth metal sulfate nanoparticles having a crystallite size of 0.1 nm to 30 nm, preferably 5 to 25 nm or 5 to 20 nm, more preferably 5 to 15 nm. Preferably, substantially all of the alkaline earth metal sulfate nanoparticles have such a crystallite size. Such a particle size can advantageously enable the desirable properties discussed above, such as high activity and resistance to deactivation during aging. Furthermore, such a size of the nanoparticles, in combination with a particle size typically similar to that of PGM nanoparticles, can help achieve the advantageous properties discussed above as a result of comparable particle size.

[0101] Preferably, the alkaline earth metal sulfate-loaded support material is present in the first catalytic region, and the alkaline earth metal sulfate nanoparticles are uniformly distributed within the first catalytic region. As used herein, the term "uniformly distributed" can encompass a (substantially) uniform concentration of alkaline earth metal sulfate particles throughout the first catalytic region. In other words, preferably, there are no localized regions of alkaline earth metal sulfate particles (i.e., having a higher concentration of alkaline earth metal sulfate particles compared to other regions) within the first catalytic region, such as the surface of the first catalytic region (especially if the first catalytic region is a washcoat). The first catalytic region should be understood to encompass the entire region or volume in which the second slurry is disposed (i.e., not a subset of this region or volume). Such properties can be observed, for example, using SEM. Such properties can provide a catalyst article with the preferred TWC conversion properties described herein. Moreover, as described herein, the method of the present invention surprisingly facilitates such uniform distribution because the alkaline earth metal sulfate particles are already supported on and / or in the support material, compared to other methods that still involve alkaline earth metal ions in the substrate-disposing step of the method. Thus, such wicking of alkaline earth metal species may be reduced, which may provide a catalyst article with improved catalytic performance. However, because the alkaline earth metal sulfate particles are produced by the method described herein, the particle size distribution is also favorable. Such an end product may not be as simply produced via other methods.

[0102] Preferably, the PGM (e.g., Pd) nanoparticles have a crystallite size of 0.1 nm to 20 nm, more preferably 5 to 15 nm. Preferably, substantially all of the PGM (e.g., Pd) nanoparticles have such a crystallite size. The crystallite size is preferably the Rietveld crystallite size measured as described herein. Such particle sizes can advantageously enable the desirable properties discussed above, such as high activity and resistance to deactivation on aging.

[0103] Preferably, M = C ± 70%, preferably M = C ± 50%, more preferably M = C ± 30%, and even more preferably M = C ± 20%, where M is the (Rietveld) crystallite size of the PGM (such as Pd) nanoparticles and C is the (Rietveld) crystallite size of the alkaline earth metal sulfate nanoparticles. In other words, the Rietveld crystallite size of the PGM (such as Pd) nanoparticles and the Rietveld crystallite size of the alkaline earth metal sulfate nanoparticles are preferably comparable in size, i.e., similar in magnitude, for the reasons discussed above.

[0104] Preferably, the alkaline earth metal sulfate-supported support material is present in the first catalyst region, and the support material comprises alumina and ceria-zirconia mixed oxide. When a cross section of the first catalyst region of the catalyst article is area-analyzed by FE-EPMA under conditions of a pixel (cross section) size of 0.34 μm × 0.34 μm and a measurement pixel (cross section) number of 256 × 256, the characteristic X-ray intensity (α: cps) of alkaline earth metal element (Ae) and the characteristic X-ray intensity (γ: cps) of aluminum (Al) are measured for each pixel, and the Pearson correlation coefficient calculated using the obtained α and γ for each pixel is R Ae / Al When specifying R Ae / Al is at least 0.1, preferably at least 0.2, and when a cross section of the first catalyst region of the catalyst article is analyzed by FE-EPMA under the conditions of a pixel (cross section) size of 0.34 μm × 0.34 μm and a measurement pixel (cross section) number of 256 × 256, the characteristic X-ray intensity (α: cps) of alkaline earth metal element (Ae) and the characteristic X-ray intensity (δ: cps) of cerium (Ce) are measured for each pixel, and the Pearson correlation coefficient calculated using the obtained α and δ for each pixel is R Ae / Ce When specifying R Ae / Ce is at least 0.1, preferably at least 0.2. In other words, the alkaline earth metal sulfate is preferably supported on both alumina and ceria-zirconia mixed oxide in the catalyst article. This arrangement can be advantageous for reasons described herein, and its simpler manufacturing process (i.e., involving fewer steps) can be facilitated by the method of the present invention.

[0105] Preferably, the alkaline earth metal sulfate-supported support material is present in the first catalyst region, and when a cross section of the first catalyst region of the catalyst article is analyzed by FE-EPMA under conditions of a pixel (cross section) size of 0.34 μm × 0.34 μm and a measurement pixel (cross section) number of 256 × 256, the characteristic X-ray intensity (α: cps) of the alkaline earth metal element (Ae) and the characteristic X-ray intensity (β: cps) of palladium (Pd) are measured for each pixel, and the Pearson correlation coefficient calculated using the obtained α and β for each pixel is R Ae / Pd When specifying R Ae / Pd The value of is at least 0.1, preferably at least 0.2, and PGM is Pd. The Pearson correlation coefficient (product-moment correlation coefficient) is known to those skilled in the art and is calculated based on the results of area analysis by FE-EPMA. The correlation coefficient R Ae / Pd When the characteristic X-ray intensity of alkaline earth metal elements (Ae) in area analysis by FE-EPMA is the first variable (α) and the characteristic X-ray intensity of palladium (Pd) is the second variable (β), the formula R Ae / Pd = (covariance) / (standard deviation of α×standard deviation of β). Such calculations are known to those skilled in the art. In other words, preferably, in such a catalytic article, the alkaline earth metal element and palladium are highly correlated. That is, the alkaline earth metal can be present in a highly dispersed state based on the distribution of palladium on the substrate. Therefore, the ability of the alkaline earth metal to act as a promoter species for palladium can be optimized. Preferably, R Ae / Pd is at least 0.1, preferably at least 0.2. In other words, the alkaline earth metal and palladium are preferably highly correlated. Such a high correlation may not be easily achieved with the larger alkaline earth metal sulfate nanoparticles of conventional catalytic articles, i.e., those with small palladium nanoparticles but much larger alkaline earth metal sulfate nanoparticles.

[0106] Preferably, the total loading of the alkaline earth metal sulfate supported support material having PGM (e.g., Pd) nanoparticles formed thereon is 0.5 g / in 3 ~5g / in 3is.

[0107] In a further aspect, the present invention provides a catalytic article comprising: a substrate; and a first catalytic region disposed on the substrate, the first catalytic region comprising a support material having PGM nanoparticles and alkaline earth metal sulfate nanoparticles supported thereon, the alkaline earth metal sulfate nanoparticles being uniformly distributed within the first catalytic region.

[0108] The relevant preferred features and embodiments of the above aspect apply equally to this aspect.

[0109] Compared to conventional catalyst articles, such catalyst articles may exhibit favorable light-off performance, particularly for NO, CO, and total hydrocarbons, during three-way catalytic reduction of stoichiometric gasoline engines. The catalyst articles may also exhibit other favorable properties described herein, such as high resistance to deactivation upon aging, and high activity, e.g., lower light-off temperatures and T for such pollutants. 50 It may show a shorter time to reach

[0110] Preferably, the catalyst article is obtained or obtainable by the method of the above aspect.

[0111] Preferably, the catalyst article is for use in an emissions treatment system, preferably the catalyst article is for three-way catalysis, and preferably the catalyst article is for treating exhaust gases from a gasoline engine.

[0112] Preferably, the alkaline earth metal sulfate supported support material is present in a first catalytic region, and the catalytic article further comprises a second catalytic region, the second catalytic region comprising palladium, platinum, and / or rhodium. In certain embodiments, the first catalytic region forms a first layer on the substrate, and the second catalytic region forms a second layer on the substrate, the first layer extending from a first end of the substrate, and the second layer extending from a second end of the substrate. In other embodiments, the second catalytic region forms a first (bottom) layer on the substrate, and the first catalytic region forms a second (top) layer on top of the second catalytic region.

[0113] Preferably, the catalytic article further comprises a third catalytic region, the second catalytic region comprising palladium and / or platinum, and optionally the third catalytic region comprising rhodium, disposed on the first catalytic region and / or the second catalytic region such that the first catalytic region and / or the second catalytic region are each located between the third catalytic region and the substrate.

[0114] In another preferred embodiment, the first catalytic region forms a first layer on the substrate and the second catalytic region forms a second layer on the substrate, the first layer being disposed directly on the substrate and the second layer being disposed directly on the first layer. In another preferred embodiment, the first catalytic region forms a first layer on the substrate and the second catalytic region forms a second layer on the substrate, the second layer being disposed directly on the substrate and the first layer being disposed directly on the first layer. In another preferred embodiment, the catalytic article further comprises a third catalytic region, the third catalytic region being disposed directly on the first layer or the second layer, and optionally the second catalytic region comprising platinum and the third catalytic region comprising rhodium. In yet another preferred embodiment, the catalytic article further comprises a third catalytic region, wherein the first catalytic region is disposed directly on the second and / or third catalytic region, and optionally, the second catalytic region comprises palladium and the third catalytic region comprises rhodium.

[0115] In other words, a catalyst article including a catalytic region formed by the method of the present invention may have such a catalyst layer as, for example, a top layer, a middle layer, or a bottom layer. The term "bottom layer" as used herein may include a layer (e.g., a washcoat layer) that is closest to or in contact with the substrate (i.e., the substrate wall). The term "top layer" as used herein 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 additional PGMs thereon, such as platinum. In such layered catalyst articles, the top and / or bottom layers may include multiple PGMs, i.e., 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, such as an upstream zone and a downstream zone. The zones may differ from one another by having different PGMs (eg, Rh upstream and Pd downstream, or vice versa), or may differ by the amount of different types of PGMs, eg, monometallic, bimetallic, or ternary metallic.

[0116] In any of the above preferred embodiments, the first catalyst region, the second catalyst region, and / or the third catalyst region may be in the form of a zone, where such a zone covers less than 100% of the substrate, for example, 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less. The zone may extend from the inlet end or the outlet end of the substrate.

[0117] The substrate can have a first end and a second end having an axial length L.

[0118] The first catalyst region can extend over 100 percent of the axial length L (see, e.g., FIGS. 1, 2a, 2b, and 6a-6c). In some embodiments, the first catalyst region can extend over 20-99%, 30-90%, or 40-80% of the axial length L. Alternatively, the first catalyst region can extend over 30-70 percent of the axial length L. Preferably, the first catalyst region can extend over 40-60 percent, and more preferably, 45-55 percent of the axial length L (see, e.g., FIGS. 3a-5d and 7a-7l).

[0119] The second catalyst region can extend over 100 percent of the axial length L (see, eg, Figures 2a, 2b, and 6a-6c).

[0120] The second catalyst region can extend over 30 to 70 percent of the axial length L. Preferably, it can extend over 40 to 60 percent, more preferably 45 to 55 percent, of the axial length L, and most preferably, the combined length of the second region and the first region is equal to or greater than the axial length L (see, e.g., Figures 3a-5d and 7a-7l).

[0121] The second catalyst region can overlap the first catalyst region over 0.1 to 99 percent of the axial length L (see, e.g., Figures 3c and 3d; the first catalyst region can be stacked on the second catalyst region, or the second catalyst region can be stacked on the first catalyst region). Alternatively, the combined length of the second catalyst region and the first catalyst region can be equal to the axial length L (see, e.g., Figures 3a and 3b). In yet another alternative, the combined length of the second catalyst region and the first catalyst region can be less than the axial length L, e.g., 95%, 90%, 80%, or 70% or less of the axial length L.

[0122] The third catalyst region can extend over 100 percent of the axial length L (see, eg, Figures 4a-4d and 6a-6c).

[0123] The third catalyst region can be less than the axial length L, for example, 95%, 90%, 80%, or 70% or less of the axial length L (see, for example, Figures 5a-5d and 7g-7l).

[0124] The second catalyst region can overlap the first catalyst region over 0.1 to 99 percent of the axial length L (see, e.g., Figures 7a-7l), the first catalyst region can be stacked on the second catalyst region, or the second catalyst region can be stacked on the first catalyst region). Alternatively, either the second region or the first region can extend over 30 to 70 percent of the axial length L. Preferably, it can extend over 40 to 60 percent, more preferably 45 to 55 percent, of the axial length L, and most preferably, the combined length of the second region and the first region is equal to or less than the axial length L (see, e.g., Figures 4a-4d).

[0125] The catalyst article preferably has a surface area of ​​10 g / ft 3 ~200g / ft 3 of palladium, preferably 50 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.

[0126] In a further aspect, the present invention provides an emissions treatment system comprising the catalytic article described herein.

[0127] The emission treatment system is preferably for a gasoline engine.

[0128] Gasoline engines preferably operate under stoichiometric conditions.

[0129] The present invention may also include a fuel combustion and emissions treatment system, the fuel combustion and emissions treatment system including an engine, preferably a gasoline engine, and an emissions treatment system of the above aspects.

[0130] In a further aspect, the present invention provides a method of treating an exhaust gas, the method comprising providing a catalytic article as described herein and contacting the catalytic article with the exhaust gas.

[0131] The exhaust gas is preferably from a gasoline engine. The catalytic article is particularly suitable for treating such exhaust gas. Furthermore, exhaust from a gasoline engine is typically more severe than exhaust from a diesel engine. Therefore, the advantageous aging characteristics of the catalytic article described herein are particularly beneficial therefor. The gasoline engine preferably operates under stoichiometric conditions.

[0132] The term "region," as used herein, refers to an area on a substrate that is typically obtained by drying and / or calcining a washcoat. A "region" can be disposed or carried on the substrate as, for example, a "layer" or a "zone." The area or arrangement on the substrate is generally controlled during the process of applying the washcoat to the substrate. A "region" typically has a distinct boundary or edge (i.e., it is possible to distinguish one region from another using conventional analytical techniques).

[0133] Typically, a "region" has a substantially uniform length. Reference to a "substantially uniform length" in this context refers to a length that does not deviate from its average value (e.g., the difference between the maximum and minimum length) by more than 10%, preferably a length that does not deviate from its average value by more than 5%, and more preferably a length that does not deviate from its average value by more than 1%.

[0134] Preferably, each "region" has a substantially uniform composition (i.e., there is no substantial difference in the composition of the washcoat when comparing one portion of the region to another portion of the region). Substantially uniform composition in this context refers to a material (e.g., region) where the composition differs by 5% or less, usually 2.5% or less, and most commonly 1% or less when comparing one portion of the region to another portion of the region.

[0135] The term "zone," as used herein, refers to a region having a length less than the entire length of the substrate, such as a length of 75% or less of the entire length of the substrate. A "zone" typically has a length of at least 5% (e.g., 5% or more) of the entire length of the substrate (i.e., a substantially uniform length).

[0136] The overall length of a substrate is the distance between its inlet end and its outlet end (eg, both ends of the substrate).

[0137] As used herein, any reference to a "zone disposed at the inlet end of the substrate" refers to a zone disposed on or carried by a substrate that is closer to the inlet end of the substrate than to the outlet end of the substrate. Thus, the midpoint of the zone (i.e., a point at half its length) is closer to the inlet end of the substrate than to the outlet end of the substrate. Similarly, as used herein, any reference to a "zone disposed at the outlet end of the substrate" refers to a zone disposed on or carried by a substrate that is closer to the outlet end of the substrate than to the inlet end of the substrate. Thus, the midpoint of the zone (i.e., a point at half its length) is closer to the outlet end of the substrate than to the inlet end of the substrate.

[0138] The term "washcoat" is well known in the art and typically refers to an adherent coating applied to a substrate during the production of a catalyst.

[0139] The acronym "PGM" as used herein refers to "platinum group metals." The term "platinum group metals" generally refers to metals selected from the group consisting of Ru, Rh, Pd, Os, Ir, and Pt, preferably metals selected from the group consisting of Ru, Rh, Pd, Ir, and Pt. Generally, the term "PGM" preferably refers to metals selected from the group consisting of Rh, Pt, and Pd.

[0140] The term "loading" as used herein refers to g / ft on a metal weight basis. 3 Refers to a measurement in units of .

[0141] Whenever "a" or "an" is mentioned herein, this includes the singular and the plural.

[0142] The following non-limiting examples are merely illustrative of the present invention, and those skilled in the art will recognize many variations that are within the spirit and scope of the claims.

[0143] Reference catalyst 1 The bottom layer front zone washcoat slurry was prepared by the following: (i) mixing a solution of palladium nitrate and a solution of dilute barium acetate; (ii) adding taurine to the mixed solution (i) and maintaining mixing; (iii) grinding and separately preparing a slurry containing 4% La2O3-doped alumina; (iv) adding and mixing the pre-solution from step (ii) to the pre-milled 4% La2O3-doped alumina slurry (iii); (v) grinding to separately prepare a slurry containing ceria and zirconia mixed oxide; (vi) adding the resulting ceria-zirconia mixed oxide slurry (v) to the batch of step (iv); (vii) The washcoat slurry in (vi) is thickened with a rheology modifier.

[0144] The final composition of the bottom layer front zone washcoat was a ceria-zirconia composite of 0.4 g / in 3 , 4% La2O3 doped alumina 0.8g / in 3 , Ba element 150g / ft 3 , and Pd element 9g / ft 3 It contained:

[0145] The bottom layer rear zone washcoat slurry was prepared by the following: (i) grinding to produce a slurry containing ceria and zirconia mixed oxide; (ii) adding a rhodium nitrate solution to the slurry (i); (iii) adjusting the pH of the slurry (ii) to precipitate Rh onto the mixed oxide; (iv) adding milled 4% La2O3 doped alumina to the slurry (iii); (v) Thickening the washcoat with a rheology modifier.

[0146] The final composition of the bottom layer rear zone washcoat was a total of 1.5 g / in of ceria-zirconia composite. 3 , 4% La2O3 doped alumina 0.5g / in 3 , and Rh element 10g / ft 3 It contained:

[0147] The top layer front zone washcoat was prepared by: (i) grinding a ceria and zirconia mixed oxide; (ii) milling to produce a slurry containing 4% La2O3-doped alumina; (iii) blending the two slurries (ii) and (iii); (iv) adding palladium nitrate to the slurry (iii) and mixing; (v) adding gallic acid and mixing; (vi) adding and mixing barium sulfate powder; (vii) adjusting the pH to 7.0 or higher; (viii) thickening the washcoat (iv) with a rheology modifier;

[0148] The final composition of the top layer front zone washcoat was a ceria-zirconia composite at 0.4 g / in 3 , 4% La2O3 doped alumina 0.8g / in 3 , Ba element 150g / ft 3 , and Pd element 131 g / ft 3 It contained:

[0149] Washcoat coating on flow-through monolith substrate: (i) First, apply the bottom layer front zone dose to 75%-80% of the dose length using a precision coating method. Dry until 80% or more of the moisture has been removed. (ii) Calcination. (iii) Apply the bottom layer rear zone washcoat to a target dose length of 75% to 80%. Dry to a minimum of 80% moisture removal. (iv) Apply the top layer to the front zone by precision coating method targeting 30%-35% dose length. Dry to 80% moisture removal or more. (v) Calcining again.

[0150] Catalyst of the present invention 1-150 g / ft 3 Spray-dried BaSO4 on a mixed carrier with BaSO4 The bottom layer front zone and rear zone washcoat slurries were prepared in the same manner as Reference Catalyst 1.

[0151] The top layer front zone washcoat was prepared by: (i) blending 4% La2O3 doped alumina with ceria and zirconia mixed oxide slurry; (ii) adding water to adjust the solids content; (iii) adding taurine and Ba acetate crystals to the blended slurry and mixing; (iv) spray drying the slurry (iii) followed by calcination; (v) slurrying the spray-dried powder obtained in step (iv); (vi) adding palladium nitrate solution and mixing; (vii) adjusting the pH to 7 or higher; (viii) thickening the washcoat; The final composition of the top layer front zone washcoat was a ceria-zirconia composite at 0.4 g / in 3 , 4% La2O3 doped alumina 0.8g / in 3 , Ba element 150g / ft 3 , and Pd element 131 g / ft 3 It contained:

[0152] The application of the washcoat coating was also the same as for Reference Catalyst 1.

[0153] 2-300 g / ft of the catalyst of the present invention 3 Spray-dried BaSO4 on a mixed carrier with BaSO4 Correspondingly, bottom layer front zone and rear zone washcoat slurries were prepared in the same manner as Reference Catalyst 1.

[0154] The upper layer front zone washcoat was prepared in the same manner as inventive catalyst 1, with the only difference being that the amount of barium acetate in step (iii) of preparing the upper layer front zone washcoat was 300 g / ft 3 That is to be.

[0155] The final composition of the top layer front zone washcoat was a ceria-zirconia composite at 0.4 g / in 3 , 4% La2O3 doped alumina 0.8g / in 3 , Ba element 300g / ft 3 , and Pd element 131 g / ft 3 It contained:

[0156] The application of the washcoat coating was the same as for Reference Catalyst 1.

[0157] Example 1: XRD analysis of BA sulfate species The crystallite size of the Ba species in the spray-dried powders of Inventive Catalyst 1 and Inventive Catalyst 2 was analyzed by XRD, and the results are shown in Table 1. For comparison, the crystallite size of the BaSO compound used in Reference Catalyst 1 was also measured by the same technique and reported.

[0158] [Table 1]

[0159] Barite (BaSO4) was detected only in Reference Catalyst 1, Inventive Catalyst 1, and Inventive Catalyst 2. The estimated crystallite size of BaSO4 in Reference Catalyst 1 was approximately 170 nm with a standard deviation of 3 nm. In contrast, the barite (BaSO4) in the two inventive catalysts made by the spray drying process was much smaller, ranging from 7 to 12 nm.

[0160] Ba is a well-known Pd promoter in TWC technology. It can donate electrons to Pd, thereby promoting the Pd (II) This can improve Pd function because the electronic configuration of Pd becomes more similar to that of Rh. To maximize this promotion effect, intimate Ba-Pd contact is highly desirable. Typically, Pd species are highly dispersed (not measurable in this study) and are mostly located in the pores of the support material. Ba species with smaller particle sizes are preferred, especially because they are more likely to enter the pores of the support, bringing Ba into closer proximity with Pd. The two catalysts of the present invention yield fresh Ba species with sizes approximately 1 / 15 of those of the reference, and therefore, Pd-Ba interaction is expected to be improved.

[0161] Example 2: FE-EPMA analysis of the interaction between PD and BA Pearson correlation coefficients (product-moment correlation coefficients) were calculated based on the results of the FE-EPMA surface analysis and are shown in Table 2. Three different washcoat regions from each sample were analyzed (approximately 3,000 and 5,000 pixels in each extracted washcoat region), and the techniques and values ​​in Table 2 are averages. The Ba-Al and Ba-Ce interactions are nearly zero for Reference Catalyst 1 when using the BaSO4 compound. This is due to the micron-sized particles of the BaSO4 compound used. In contrast, positive Pearson correlation coefficients for Ba-Al and Ba-Ce were reported for the two spray-dried powders, suggesting that BaSO4 is dispersed on both support materials. Furthermore, the enhanced Pd-Ba interaction of the two inventive catalysts is confirmed by the higher Ba-Pd correlation coefficients. For comparison, Reference Catalyst 1 exhibits a slightly negative coefficient of -0.15, indicating that Ba and Pd are randomly arranged rather than physically close to each other.

[0162] [Table 2]

[0163] Example 3: Ignition performance test in engine test All catalysts were engine bench aged for 108 hours in a stoic / fuel-cut aging cycle targeting a peak catalyst bed temperature of 1000°C and then tested in a gasoline engine. Light-off performance was measured under typical conditions: gas volumetric space velocity of 95 K / hr, temperature gradient of 10°C / min, and air-fuel ratio (AFR) lambda of 14.55, perturbed with an amplitude of 0.5. THC, CO, and NO were measured. x The conversion was calculated by comparing the concentration of the feed gas with the concentration of the gas at the outlet of the catalyst.

[0164] HC, CO, and NO x T 50The light-off temperatures are shown in Table 3. The data clearly show that both Inventive Catalyst 1 and Inventive Catalyst 2 exhibited significantly improved light-off performance when compared to Reference Catalyst 1. Specifically, Inventive Catalyst 2 was more active than Inventive Catalyst 1, with a T 50 is about 15 to 20°C lower (T 50 is the temperature at which 50% conversion is reached).

[0165] [Table 3]

[0166] Example 4: Warm-up test in engine test All catalysts were engine bench aged for 108 hours in a stoic / fuel cut aging cycle targeting a peak catalyst bed temperature of 1000°C and then tested in a gasoline engine. Warm-up tests were typically conducted at a gas hourly space velocity of 95K. Pollutants from the engine out were preheated to 490°C and then directed onto the cold catalyst. Total hydrocarbons, carbon monoxide, and NO were measured. x The time to reach 50% conversion of T 50 H.C., T. 50 CO, and T 50 NO x THC, CO, and NO x The conversion was calculated by comparing the concentration of the feed gas with the concentration of the gas at the outlet of the catalyst.

[0167] The data in Table 4 clearly show that both Inventive Catalyst 1 and Inventive Catalyst 2 warm up faster than Reference Catalyst 1. Specifically, Inventive Catalyst 1 is more active than Inventive Catalyst 2, which exhibits the shortest time to reach a particular conversion level.

[0168] [Table 4]

[0169] Reference catalyst 2 The bottom layer washcoat slurry was prepared by: (i) grinding and separately preparing a slurry containing 4% La2O3-doped alumina; (ii) grinding the mixture to prepare a slurry containing ceria-zirconia mixed oxide; (iii) blending together the 4% La2O3 doped alumina slurry and the ceria zirconia mixed oxide slurry; (iv) adding the required amount of palladium nitrate; (v) adding barium nitrate; (vi) adding a binder; (vii) Thickening the washcoat slurry with a rheology modifier.

[0170] The final composition of the bottom layer washcoat was 0.4 g / in of 4% La2O3-doped alumina. 3 , ceria-zirconia composite 0.95 g / in 3 , Ba element 150g / ft 3 , and Pd element 18.2 g / ft 3 It contained:

[0171] The top layer rear zone washcoat slurry was prepared by: (i) grinding to produce a slurry containing ceria and zirconia mixed oxide; (ii) adding a rhodium nitrate solution to the slurry (i); (iii) adjusting the pH of the slurry (ii) to precipitate Rh onto the mixed oxide; (iv) adding milled 4% La2O3 doped alumina to the slurry (iii); (v) Thickening the washcoat with a rheology modifier.

[0172] The final composition of the top layer rear zone washcoat was a total of 1.5 g / in of ceria-zirconia composite. 3 , 4% La2O3 doped alumina 0.5g / in 3 , and Rh element 10.5g / ft 3 It contained:

[0173] The top layer front zone washcoat was prepared by: (i) grinding a ceria and zirconia mixed oxide; (ii) milling to produce a slurry containing 4% La2O3-doped alumina; (iii) blending the two slurries (ii) and (iii); (iv) adding palladium nitrate to the slurry (iii) and mixing; (v) adding gallic acid and mixing; (vi) adding and mixing barium sulfate powder; (vii) adjusting the pH to 7.0 or higher; (viii) thickening the washcoat (iv) with a rheology modifier;

[0174] The final composition of the top layer front zone washcoat was a ceria-zirconia composite at 0.4 g / in 3 , 4% La2O3 doped alumina 0.8g / in 3 , Ba element 150g / ft 3 , and Pd element 153g / ft 3 It contained:

[0175] Washcoat coating on flow-through monolith substrate: (i) First, apply a precision coating method to the bottom layer front zone, with the dose length set to 50%-55%. Dry until 80% or more of the moisture has been removed. (ii) Coat the bottom layer rear zone washcoat to a target dose length of 50% to 55%. Dry to 80% or more moisture removal, then calcinate. (iii) Apply the top layer to the rear zone by precision coating method targeting 65% to 75% dose length. Dry to 80% moisture removal or greater. (iv) Apply the top layer front zone washcoat to a target dose length of 35% to 25%. Dry to 80% or more moisture removal and then calcinate.

[0176] Catalyst of the present invention 3-150 g / ft 3 Spray-dried BaSO4 on 4% La2O3-doped alumina with BaSO4 The bottom layer washcoat slurry and the top layer rear zone washcoat slurry were prepared in the same manner as Reference Catalyst 2.

[0177] The top layer front zone washcoat was prepared by: (i) preparing a slurry containing 4% La2O3-doped alumina; (ii) adding taurine and Ba acetate crystals to the blended slurry and mixing; (iii) spray drying the slurry (ii) followed by calcination; (iv) slurrying the spray-dried powder obtained in step (iii); (v) grinding to separately prepare a slurry containing ceria-zirconia mixed oxide; (vi) adding a ceria-zirconia mixed oxide slurry to the slurry of step iv); (vii) adding palladium nitrate solution and mixing; (viii) thickening the washcoat; The final composition of the top layer front zone washcoat was a ceria-zirconia composite at 0.4 g / in 3 , 4% La2O3 doped alumina 0.8g / in 3 , Ba element 150g / ft 3 , and Pd element 153g / ft 3 It contained:

[0178] The application of the washcoat coating was also the same as for Reference Catalyst 2.

[0179] Example 5: Warm-up test in engine test All catalysts were engine bench aged for 108 hours in a stoic / fuel cut aging cycle targeting a peak catalyst bed temperature of 1000°C and then tested in a gasoline engine. Warm-up tests were typically conducted at a gas hourly space velocity of 95K. Pollutants from the engine out were preheated to 490°C and then directed onto the cold catalyst. Total hydrocarbons, carbon monoxide, and NO were measured. x The time to reach 50% conversion of T 50 H.C., T. 50 CO, and T 50 NO x THC, CO, and NO x The conversion was calculated by comparing the concentration of the feed gas with the concentration of the gas at the outlet of the catalyst.

[0180] The data in Table 5 clearly show that inventive catalyst 3 exhibits a shorter time to reach a particular conversion level.

[0181] [Table 5]

[0182] 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 for producing an alkaline earth metal sulfate-loaded support material, comprising: providing a first slurry comprising a support material, alkaline earth metal ions, and an organic compound, wherein the organic compound has a sulfo group (—SO ３ H), sulfonyl group (-S(=O) ２ -), and sulfinyl group (-S(=O)-); spray drying the first slurry to provide a spray-dried powder; and heating the spray-dried powder to form an alkaline earth metal sulfate-loaded support material.

2. The method of claim 1 , wherein the first slurry is substantially free of platinum group metals.

3. 3. The method of claim 1 or claim 2, wherein the first slurry consists essentially of, preferably consists of, the support material, the alkaline earth metal ions, the organic compound, and optionally counterions to the alkaline earth metal ions.

4. The method of any one of claims 1 to 3, wherein the first slurry is an aqueous slurry.

5. The method according to any one of claims 1 to 4, wherein the organic compound further comprises an amine functional group, preferably a primary amine functional group.

6. The method of any one of claims 1 to 5, wherein the organic compound comprises a sulfo group and a primary amine group.

7. The method according to any one of claims 1 to 6, wherein the organic compound comprises 1 to 6 carbon atoms, preferably 2 to 4 carbon atoms, more preferably 2 carbon atoms.

8. 5. The method of any one of claims 1 to 4, wherein the organic compound comprises one or more of aminomethanesulfonic acid, taurine, homotaurine, 4-aminobutane-1-sulfonic acid, 2-aminopropane-1-sulfonic acid, 2-methyltaurine, dimethyl sulfone, sulfonane, cysteic acid, dimethyl sulfoxide, and aminobenzenesulfonic acid, preferably taurine.

9. 9. The method of any one of claims 1 to 8, wherein the alkaline earth metal ions comprise one or more of calcium ions, strontium ions, and barium ions, preferably strontium and / or barium ions, more preferably barium ions.

10. The method of any one of claims 1 to 9, wherein the support material comprises an inorganic oxide.

11. The method of any one of claims 1 to 10, wherein the support material comprises one or more of alumina, silica, titania, ceria, zirconia, ceria-zirconia mixed oxide, vanadia, lanthana and zeolites.

12. The method according to any one of claims 1 to 11, wherein the support material comprises alumina and / or ceria-zirconia mixed oxide, preferably the support material comprises alumina and ceria-zirconia mixed oxide.

13. 13. The method of claim 12, wherein the alumina and / or ceria-zirconia mixed oxide is doped with a dopant.

14. 14. The method according to claim 13, wherein the alumina and / or ceria-zirconia mixed oxide is doped with a dopant comprising one or more of lanthanum, neodymium, yttrium, niobium, praseodymium, hafnium, molybdenum, titanium, vanadium, zinc, cadmium, manganese, iron, copper, calcium, barium, strontium, cesium, magnesium, potassium, and sodium, preferably one or more of lanthanum, neodymium, and yttrium.

15. 15. The method according to claim 13 or 14, wherein the dopant is present in the alumina and / or ceria-zirconia mixed oxide in an amount of 0.001% to 20% by weight, preferably 0.5% to 10% by weight, based on the total weight of the dopant and the alumina and / or ceria-zirconia mixed oxide.

16. The carrier material has a D of 0.1 to 30 μm, preferably 2 to 10 μm, as measured using dynamic light scattering. ５０ 16. The method of any one of claims 1 to 15, wherein the compound is in the form of a powder having a formula:

17. providing a first slurry comprising a support material, alkaline earth metal ions, and an organic compound; providing a solution containing alkaline earth metal ions and the organic compound, preferably the solution being an aqueous solution; Providing a carrier material; and contacting the solution with the support material to form the first slurry.

18. 18. The method of any one of claims 1 to 17, wherein heating the spray-dried powder comprises heating the spray-dried powder at a temperature of from 300 to 700°C for from 10 minutes to 5 hours.

19. The method of any one of claims 1 to 18, wherein heating the spray-dried powder comprises calcining the spray-dried powder.

20. The method according to any one of the preceding claims, wherein the first slurry comprises a solids content of 5 to 40%, preferably 10 to 30%.

21. 21. The method of any one of claims 1 to 20, further comprising stirring the first slurry prior to the step of spray drying the first slurry, preferably the first slurry is stirred for at least 10 minutes, more preferably at least 20 minutes, even more preferably at least 30 minutes.

22. An alkaline earth metal sulfate-loaded support material obtained or obtainable by a method according to any one of claims 1 to 21.

23. 23. The alkaline earth metal sulfate supported support material of claim 22, wherein the alkaline earth metal sulfate supported support material comprises 1 to 25 wt. %, preferably 2 to 20 wt. % or 5 to 20 wt. % alkaline earth metal sulfate, based on the total weight of the alkaline earth metal sulfate supported support material.

24. 24. The alkaline earth metal sulfate-supported support material according to claim 22 or claim 23, wherein the alkaline earth metal sulfate comprises nanoparticles of the alkaline earth metal sulfate having a crystallite size of 0.1 nm to 30 nm, preferably 5 to 25 nm or 5 to 20 nm.

25. 1. A method of making a catalyst article, said method comprising: Producing an alkaline earth metal sulfate-supported support material according to a method as claimed in any one of claims 1 to 21 or providing an alkaline earth metal sulfate-supported support material as claimed in any one of claims 22 to 24; providing a second slurry comprising the alkaline earth metal sulfate-bearing support material and platinum group metal ("PGM") ions; disposing the second slurry on a substrate; and heating the second slurry to form PGM nanoparticles on the alkaline earth metal sulfate-loaded support material.

26. 26. The method of claim 25, wherein the second slurry is an aqueous slurry.

27. Providing a second slurry comprises: providing an intermediate slurry comprising the alkaline earth metal sulfate-loaded support material; 27. A method according to claim 25 or claim 26, comprising contacting the intermediate slurry with a PGM salt, preferably with a solution comprising said PGM salt.

28. Providing an intermediate slurry is advantageous in that the alkaline earth metal sulfate-loaded support material has a D of about 5 to 15 μm, preferably about 4 to 6 μm. ５０ 28. The method of claim 27, comprising disintegrating the alkaline earth metal sulfate-loaded support material, preferably using a high shear mixer, so as to have:

29. 29. The method of any one of claims 25 to 28, further comprising stirring the second slurry prior to the step of disposing the second slurry on a substrate, preferably the second slurry is stirred for at least 10 minutes, more preferably at least 20 minutes, and even more preferably at least 30 minutes.

30. 30. The method of any one of claims 25 to 29, wherein the second slurry further comprises a binder and one or more of an acid or base, a thickener and / or a further inorganic oxide.

31. A method according to any one of claims 25 to 30, wherein the second slurry has a solids content of 10 to 40%, preferably 15 to 35%.

32. The method of any one of claims 25 to 31, wherein disposing the second slurry on a substrate comprises washcoating.

33. Disposing the second slurry on the substrate includes contacting the second slurry with the substrate, and optionally applying a vacuum and / or an air knife to the substrate; and / or The method of any one of claims 25 to 22, comprising drying the second slurry on the substrate.

34. heating the slurry to form PGM nanoparticles on the alkaline earth metal sulfate-loaded support material; at a temperature of 400°C to 700°C, preferably 400°C to 600°C, more preferably 450°C to 600°C, and / or 34. The method according to any one of claims 25 to 33, carried out for 10 to 360 minutes, preferably 35 to 120 minutes.

35. 35. The method of any one of claims 25 to 34, wherein heating the slurry to form PGM nanoparticles on the alkaline earth metal sulfate-loaded support material comprises calcining.

36. The method of any one of claims 25 to 35, wherein the substrate comprises cordierite.

37. The method of any one of claims 25 to 36, wherein the substrate is in the form of a flow-through monolith or a wall-flow filter.

38. A catalytic article obtained or obtainable by the method of any one of claims 25 to 37.

39. 39. The catalyst article of claim 38, wherein the alkaline earth metal sulfate-loaded support material comprises 1 to 25 wt. % of the alkaline earth metal sulfate, based on the total weight of the alkaline earth metal sulfate and the support material.

40. 40. The catalytic article of claim 38 or claim 39, wherein the alkaline earth metal sulfate comprises nanoparticles of the alkaline earth metal sulfate having a crystallite size of 0.1 nm to 30 nm, preferably 5 to 25 nm or 5 to 20 nm.

41. 41. The catalytic article of claim 40, wherein the alkaline earth metal sulfate supported support material is present in a first catalytic region and the alkaline earth metal sulfate nanoparticles are uniformly distributed within the first catalytic region.

42. 42. Catalytic article according to any one of claims 38 to 41, wherein the PGM nanoparticles have a crystallite size of 0.1 nm to 20 nm, preferably 5 to 15 nm.

43. 43. The catalytic article of any one of claims 40 to 42, wherein M = C ± 70%, preferably M = C ± 50%, more preferably M = C ± 30%, even more preferably M = C ± 20%, wherein M is the crystallite size of the PGM nanoparticles and C is the crystallite size of the alkaline earth metal sulfate nanoparticles.

44. The alkaline earth metal sulfate-supported carrier material is present in a first catalyst region, and when a cross section of the first catalyst region of the catalyst article is analyzed by FE-EPMA under conditions of a pixel (cross section) size of 0.34 μm×0.34 μm and a measurement pixel (cross section) number of 256×256, the characteristic X-ray intensity (α: cps) of the alkaline earth metal element (Ae) and the characteristic X-ray intensity (β: cps) of the palladium (Pd) are measured for each pixel, and the Pearson correlation coefficient calculated using the obtained α and β for each pixel is defined as R Ａｅ／Ｐｄ When specifying Ａｅ／Ｐｄ 44. The catalytic article of any one of claims 38 to 43, wherein the value of is at least 0.

1.

45. the alkaline earth metal sulfate-supported support material is present in a first catalyst zone, the support material comprising alumina and ceria-zirconia mixed oxide; When a cross section of the first catalyst region of the catalyst article is analyzed by FE-EPMA under the conditions of a pixel (cross section) size of 0.34 μm×0.34 μm and a measurement pixel (cross section) number of 256×256, the characteristic X-ray intensity (α: cps) of the alkaline earth metal element (Ae) and the characteristic X-ray intensity (γ: cps) of the aluminum (Al) are measured for each pixel, and the Pearson correlation coefficient calculated using the obtained α and γ at each pixel is defined as R Ａｅ／Ａｌ When specifying Ａｅ／Ａｌ is at least 0.1, When a cross section of the first catalyst region of the catalyst article is analyzed by FE-EPMA under the conditions of a pixel (cross section) size of 0.34 μm×0.34 μm and a measurement pixel (cross section) number of 256×256, the characteristic X-ray intensity (α: cps) of the alkaline earth metal element (Ae) and the characteristic X-ray intensity (δ: cps) of the cerium (Ce) are measured for each pixel, and the Pearson correlation coefficient calculated using the obtained α and δ for each pixel is defined as R Ａｅ／Ｃｅ When specifying Ａｅ／Ｃｅ 45. The catalytic article of any one of claims 38 to 44, wherein the value of is at least 0.

1.

46. a total loading of the alkaline earth metal sulfate supported support material having the PGM (e.g., Pd) nanoparticles formed thereon of 0.5 g / in ３ ~5g / in ３ The catalytic article according to any one of claims 38 to 45, wherein

47. 1. A catalytic article comprising: A substrate; a first catalytic region disposed on the substrate; the first catalytic region comprises a support material having PGM (such as Pd) nanoparticles and alkaline earth metal sulfate nanoparticles supported thereon; The catalytic article, wherein the alkaline earth metal sulfate nanoparticles are uniformly distributed within the first catalytic region.

48. 48. The catalytic article of claim 47, wherein the catalytic article is obtained or obtainable by a method according to any one of claims 25 to 37.

49. The catalytic article of any one of claims 38 to 48, wherein the catalytic article is for use in an emission treatment system, preferably the catalytic article is for three-way catalysis.

50. the alkaline earth metal sulfate-supported support material is present in a first catalytic region, and the catalytic article further comprises a second catalytic region; 50. The catalytic article of any one of claims 38 to 49, wherein the second catalytic region comprises palladium, platinum and / or rhodium.

51. 51. The catalytic article of claim 50, wherein the first catalytic region forms a first layer on the substrate, the second catalytic region forms a second layer on the substrate, the first layer extending from a first end of the substrate, and the second layer extending from a second end of the substrate, preferably the first catalytic region and the second catalytic region are each disposed directly on the substrate.

52. a third catalytic region, said second catalytic region comprising palladium / platinum, and optionally 52. The catalytic article of claim 50 or 51, wherein the third catalytic region comprises rhodium and is disposed on the first catalytic region and / or the second catalytic region such that the first catalytic region and / or the second catalytic region are each located between the third catalytic region and the substrate.

53. 10g / ft ３ ~200g / ft ３ of palladium, preferably 50 g / ft ３ ~150g / ft ３ 53. The catalytic article of any one of claims 38 to 52, comprising palladium of

54. An emissions treatment system comprising the catalytic article of any one of claims 38 to 53.

55. 55. The emission treatment system of claim 54 for a gasoline engine.

56. 56. The emission treatment system of claim 55, wherein the gasoline engine operates under stoichiometric conditions.

57. 1. A method for treating an exhaust gas, the method comprising: Providing a catalyst article according to any one of claims 38 to 53; contacting the catalytic article with an exhaust gas.

58. 58. The method of claim 57, wherein the exhaust gas is from a gasoline engine.

59. 59. The method of claim 58, wherein the gasoline engine is operated under stoichiometric conditions.

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