Improved sulfur-containing organic compound assisted metal nanoparticle synthesis for three-way catalytic applications

Abstract

The present invention provides a method of making an alkaline earth metal sulfate supported support material, the method comprising: providing a first slurry comprising a support material, an alkaline earth metal ion and an organic compound wherein the organic compound comprises a functional group selected from the group consisting of a sulfonic acid group (-SO3H), a sulfonyl group (-S (= O) 2-) 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 an alkaline earth metal sulfate loaded support material.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a carrier material loaded with alkaline earth metal sulfate, a carrier material loaded with alkaline earth metal sulfate, a method for manufacturing a catalyst article, a catalyst article, an emission treatment system, and a method for treating exhaust gas. Background Art

[0002] Three-way catalysts (TWCs) convert CO, HC, and NO from gasoline engine exhaust x to non-toxic compounds simultaneously at a stoichiometric air-fuel ratio (about 98%). Specifically, the oxidation of CO and HC to CO2 and steam (H2O) is mainly catalyzed by Pd, while NO x to N2 reduction is mainly catalyzed by Rh. Modern TWCs use supported platinum group metal (hereinafter referred to as "PGM") catalysts (Pd, Rh, Pt, etc.) deposited on a single layer, double layer, or multi-layer carrier, where the carrier material consists of metal oxides with a high specific surface area, mainly stable γ-alumina and ceria-containing oxygen storage materials. The supported catalyst carrier coating is applied to a ceramic monolithic substrate.

[0003] The conventional preparation of TWC carrier coating slurries generally involves using solutions of inorganic PGM precursors (such as nitrates, acetates, hydroxides, or chloride salts) to deposit PGM elements on the oxide carrier via an initial impregnation method or a wet impregnation method. Promoter salts are usually also added to the carrier coating formulation to obtain enhanced TWC performance. Once the monolithic substrate is coated with the slurry carrier coating thus prepared, drying and calcination steps are then used to decompose the inorganic salts and fix the PGM and promoter elements to the carrier material. Conventional TWCs prepared using the above methods generally only have limited control over the characteristics of the catalytically active substances (i.e., the average particle size of the PGM and the promoter, the affinity of these active components for the target carrier material, and the distribution of these active components within the same washcoat ("WC") for improving metal-carrier interaction). This is mainly due to migration and grain growth during the drying and high-temperature calcination processes.

[0004] Alkaline earth metals such as barium are well-known excellent promoters for Pd catalytic functions. Ba can donate electrons to Pd, making the electronic configuration of Pd (II) more like that of Rh, thus improving TWC activity [Non-Patent Document 1]. On Ba-promoted Pd catalysts, the adsorption strength of NO on Pd x and the adsorption strength of CO both decrease, resulting in NO xand an increase in CO conversion rate [Non-Patent Document 2; Non-Patent Document 3]. Ba also helps to stabilize PdO and inhibits sintering caused by high-temperature exposure during the service life of the three-way catalytic converter. Last but not least, Ba is a good stabilizer for alumina carrier materials, which helps to maintain a high dispersion of Pd species.

[0005] When using the Ba component as an additive, it is important to control the positions and sizes of both palladium and barium to optimize the synergistic interaction with the active Pd, Ba species, and carrier components. However, in catalysts obtained by known methods, since alkaline earth metal-containing species generally have larger particle sizes compared to Pd nanoparticles, the interaction may not be optimal. In addition, this interaction may deteriorate as the catalyst obtained by the known method ages. Therefore, a method for manufacturing a catalyst article is needed that can achieve a more optimized interaction between PGM (such as Pd) nanoparticles and alkaline earth metal-containing species in the resulting catalyst article, ideally with equivalent particle sizes and closely adjacent distributions, thereby achieving performance improvement and also reducing aging sensitivity.

[0006] Due to capillary effects, soluble alkaline earth metal species and Pd precursors tend to migrate toward the surface of the carrier coating during the drying step after coating. In this case, the Ba component and Pd species are not evenly distributed within the carrier coating, resulting in a non-optimal interaction between the Ba / Pd species and the metal oxide carrier material. During typical TWC aging, due to the high-temperature effect, significant grain growth occurs in the Pd and Ba species, which weakens the interaction between Pd-Ba and ultimately leads to the inactivation of the TWC catalyst. The non-optimal metal-carrier interaction accelerates this grain growth and further weakens the catalytic performance. Therefore, it is equally important to improve the uniformity of the distribution of Pd nanoparticles and alkaline earth metal-containing species in the carrier coating and ensure that both have similar small particle sizes. This optimization can better resist TWC aging due to the optimal metal-carrier interaction.

[0007] In the course of technological research and development, researchers have made a great deal of effort to reduce the particle size of barium species to promote closer contact with Pd species, and at the same time control the position of barium species within the carrier coating by using some insoluble barium compounds. Ball milling / bead milling of BaSO4 compounds is not very effective for preparing nanoscale barium sulfate species [Patent Document 1; Patent Document 6]. Sulfuric acid was added to the Pd carrier coating with acetic acid Ba or barium hydroxide as the precursor to generate barium sulfate species during the calcination step. Smaller BaSO4 particle sizes were obtained; however, they were still in the micron range and far from the nanoscale target [Patent Documents 2 to 5].

[0008] Citation List :

[0009] Patent Literature :

[0010] Patent Document 1: US8741799

[0011] Patent Document 2: US20120165185

[0012] Patent Document 3: US8545780

[0013] Patent Document 4: US8835346

[0014] Patent Document 5: 20140329669

[0015] Patent Document 6: WO2014156746

[0016] Non-Patent Literature :

[0017] Non - Patent Document 1: Applied Catalyst B, 30, 2001, 287

[0018] Non - Patent Document 2: Journal of Molecular Catalysis A: Chemical, 349, 2011, 94

[0019] Non - Patent Document 3: Applied Catalysis A: General403, 2011, 12 SUMMARY OF THE INVENTION

[0020] One aspect of the present disclosure relates to a method for manufacturing a carrier material loaded with alkaline earth metal sulfate, the method comprising: providing a first slurry comprising a carrier material, alkaline earth metal ions, and an organic compound, wherein the organic compound comprises a functional group selected from sulfonic acid group (-SO3H), 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 a carrier material loaded with alkaline earth metal sulfate.

[0021] Another aspect of the present disclosure relates to a carrier material loaded with alkaline earth metal sulfate obtainable or obtained by the method of the above - mentioned aspect.

[0022] Another aspect of the present disclosure relates to a method of manufacturing a catalyst article, the method comprising: manufacturing a support material loaded with an alkaline earth metal sulfate according to the method of the above aspect, or providing a support material loaded with an alkaline earth metal sulfate according to the above aspect; providing a second slurry that comprises the support material loaded with an alkaline earth metal sulfate and platinum group metal (“PGM”) ions; disposing the second slurry on a substrate; and heating the slurry to form PGM nanoparticles on the support material loaded with an alkaline earth metal sulfate.

[0023] Another aspect of the present disclosure relates to a catalyst article obtainable or obtainable by the method of the above aspect.

[0024] Another aspect of the present disclosure relates to a catalyst article comprising: a substrate; and a first catalytic region disposed on the substrate; wherein the first catalytic region comprises a support material on which PGM nanoparticles and alkaline earth metal sulfate nanoparticles are loaded; wherein the alkaline earth metal sulfate nanoparticles are uniformly distributed within the first catalytic region.

[0025] Another aspect of the present invention relates to an emissions treatment system comprising the catalyst article of the above aspect.

[0026] Another aspect of the present disclosure relates to a method of treating exhaust gas, the method comprising: providing the catalyst article of the above aspect; and contacting the catalyst article with the exhaust gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will now be described in conjunction with the following non-limiting drawings, wherein:

[0028] Figure 1 Shows an embodiment according to the present invention, which embodiment comprises a first catalytic region (single layer) that is 100% of the axial length L of the substrate.

[0029] Figure 2a Shows an embodiment according to the present invention, wherein the first catalytic region extends 100% of the axial length L as the bottom layer; the second catalytic region extends 100% of the axial length L as the top layer. Figure 2b Depicts Figure 2a a variant of

[0030] Figure 3a Shows an embodiment according to the present invention, wherein the first catalytic region extends less than 100% of the axial length L from the inlet end; the second catalytic region extends less than 100% of the axial length L from the outlet end. The total length of the second catalytic region and the first catalytic region is equal to or less than the axial length L. Figure 3b Depicts Figure 3a a variant of

[0031] Figure 3c Shows an embodiment according to the present invention, where the first catalytic region extends less than 100% of the axial length L from the inlet end; the second catalytic region extends less than 100% of the axial length L from the outlet end. The total length of the second catalytic region and the first catalytic region is greater than the axial length L. Figure 3d Depicts Figure 3c a variant of

[0032] Figure 4a Shows an embodiment according to the present invention, where the first catalytic region extends less than 100% of the axial length L from the inlet end; the second catalytic region extends less than 100% of the axial length L from the outlet end. The total length of the second catalytic region and the first catalytic region is less than or equal to the axial length L. The third catalytic region extends 100% of the axial length L and covers the first catalytic region and the second catalytic region as the top layer. Figure 4b Depicts Figure 4a a variant of

[0033] Figure 4c Shows an embodiment according to the present invention, where the third catalytic region extends 100% of the axial length L as the bottom layer. The first catalytic region extends less than 100% of the axial length L from the inlet end; the second catalytic region extends less than 100% of the axial length L from the outlet end. The total length of the second catalytic region and the first catalytic region is less than or equal to the axial length L. Figure 4d Depicts Figure 4c a variant of

[0034] Figure 5a Shows an embodiment according to the present invention, where the first catalytic region extends less than 100% of the axial length L from the inlet end; the second catalytic region extends less than 100% of the axial length L from the outlet end. The total length of the second catalytic region and the first catalytic region can be less than, equal to, or greater than the axial length L. The third catalytic region extends less than 100% of the axial length L from the inlet end; the fourth catalytic region extends less than 100% of the axial length L from the outlet end. The total length of the third catalytic region and the fourth catalytic region can be less than, equal to, or greater than the axial length L. The first catalytic region and the second catalytic region form the bottom layer; and the third catalytic region and the fourth catalytic region form the top layer. Figure 5b , Figure 5c and Figure 5d Depicts Figure 5a a variant of

[0035] Figure 6a Shows an embodiment according to the present invention, where the first catalytic region extends 100% of the axial length L as the bottom layer; the second catalytic region extends 100% of the axial length L as the intermediate layer; and the third catalytic region extends 100% of the axial length L as the top layer. Figure 6b andFigure 6c depicts Figure 6a a variant of

[0036] Figure 7a shows an embodiment according to the present invention, wherein the first catalytic region extends less than 100% of the axial length L from the inlet end; the second catalytic region extends less than 100% of the axial length L from the outlet end. The total length of the second catalytic region and the first catalytic region is greater than the axial length L. The third catalytic region extends 100% of the axial length L and covers the first catalytic region and the second catalytic region as a top layer. Figure 7b to Figure 7f depicts Figure 7a a variant of

[0037] Figure 7g shows an embodiment according to the present invention, wherein the first catalytic region extends less than 100% of the axial length L from the inlet end; the second catalytic region extends less than 100% of the axial length L from the outlet end. The total length of the second catalytic region and the first catalytic region may be less than, equal to, or greater than the axial length L. The third catalytic region extends less than 100% of the axial length L from the inlet end and at least partially covers the first catalytic region and / or the second catalytic region. Figure 7h and Figure 7i depicts Figure 7g a variant of Figure 7j shows an embodiment according to the present invention, wherein the first catalytic region extends less than 100% of the axial length L from the inlet end; the second catalytic region extends less than 100% of the axial length L from the outlet end. The total length of the second catalytic region and the first catalytic region may be less than, equal to, or greater than the axial length L. The third catalytic region extends less than 100% of the axial length L from the outlet end and at least partially covers the second catalytic region and / or the first catalytic region. Figure 7k and Figure 7l depict Figure 7j a variant of Detailed Description

[0038] The present invention attempts to solve at least some of the problems associated with the prior art or at least provide a commercially acceptable alternative solution thereto.

[0039] In a first aspect, the present invention provides a method for manufacturing a carrier material loaded with alkaline earth metal sulfate, the method comprising: providing a first slurry comprising a carrier material, alkaline earth metal ions, and an organic compound, wherein the organic compound comprises a functional group selected from a sulfonic acid group (-SO3H), a sulfonyl group (-S(=O)2-), 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 a carrier material loaded with alkaline earth metal sulfate.

[0040] Unless expressly indicated to the contrary, each aspect or embodiment as defined herein can be combined with any other aspect or embodiment. In particular, any feature indicated as preferred or advantageous can be combined with any other feature indicated as preferred or advantageous.

[0041] Surprisingly, when the carrier material loaded with alkaline earth metal sulfate produced by the method of the present invention is used as the PGM (such as Pd) carrier material in the catalytic zone (such as a washcoat) of a catalyst article, the catalyst article can provide desirable catalytic activity, particularly three-way catalytic activity, when used in an emission treatment system. For example, the catalyst article can exhibit favorable light-off performance during three-way catalytic reduction in a stoichiometric gasoline engine, particularly the conversion rates of NO, CO, and total hydrocarbons. Such favorable catalytic activity and light-off performance can be superior to those exhibited by conventional catalyst articles having the same / similar PGM species, loading, carrier, and configuration. The catalyst article can be more durable compared to conventional catalyst articles. In other words, such favorable catalytic activity can still be exhibited even after aging.

[0042] Advantageously, compared to conventional catalyst articles, such excellent performance can facilitate the use of a lower loading of PGM and / or promoter metals (such as alkaline earth metals) without compromising catalytic performance. Given the high cost of such metals (such as palladium), this can be beneficial. In addition, such excellent performance can facilitate the partial or complete replacement of high-cost PGM with lower-cost PGM or other transition metals without compromising catalytic performance.

[0043] As described herein, the PGM (including PGM nanoparticles) throughout the specification 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.

[0044] In addition, such a catalyst article can provide surprisingly efficient TWC performance under "cold start" conditions. This is because the promoter interaction between the alkaline earth metal (such as barium) and palladium (if present) can have a significant synergistic effect in such catalyst articles.

[0045] Without wishing to be bound by theory, it is speculated that this superior performance may stem from the nanoscale particle size advantage of alkaline earth metal sulfates. By the method of this aspect via the organic compound route, supported nanoparticles can be formed on the carrier material, thereby achieving this property. This may be because, it is believed that the presence of the organic compound during the calcination stage slows down the formation rate of the alkaline earth metal sulfate, thereby enabling it to form nanoparticles of nanoscale particle size. This small particle size may be beneficial for matching the size distribution of PGM (preferably palladium) particles that can be loaded onto the carrier material, and thus for use in catalyst articles. In the catalyst articles thus obtained, the PGM or palladium nanoparticles and the alkaline earth metal sulfate nanoparticles can also form a favorable synergistic distribution relative to each other, that is, the two exhibit a high degree of spatial correlation (in other words, especially through the small particle size and the characteristics of highly uniformly distributed nanoparticles, that is, by making the distribution of palladium nanoparticles and alkaline earth metal sulfate nanoparticles highly uniform, the number of palladium-alkaline earth metal interaction sites can be significantly increased).

[0046] Without wishing to be bound by theory, it is speculated that the method of the present invention (wherein the slurry provided in the method contains alkaline earth metal ions and the organic compound described herein, and wherein the slurry is subsequently spray-dried) can help to make the particle size of the alkaline earth metal sulfate supported on the carrier material smaller and the distribution more uniform.

[0047] Furthermore, without wishing to be bound by theory, it is speculated that this method can make the particle sizes of PGM (such as Pd) and alkaline earth metal sulfate reach a similar level after the PGM (such as Pd) is loaded onto the carrier material, that is, the particle sizes of the two are in the same order of magnitude. Generally, in conventional methods, the alkaline earth metal sulfate nanoparticles can be up to 5 times, 10 times or even 20 times that of the PGM (such as Pd) nanoparticles. In the method of the present invention, since it is possible to prepare small-sized alkaline earth metal sulfate nanoparticles, once the PGM (such as Pd) nanoparticles are added, the interaction and spatial correlation between the PGM (such as Pd) and the alkaline earth metal may be significantly enhanced. This is because the nanoparticles can thus be located closely adjacent to each other on the carrier material (for example, if uniformly distributed), and, for example, enter pores of the same size in the carrier material. Therefore, a highly uniform distribution of particles of similar size can be provided. By optimizing the possibility of interaction between the PGM (such as Pd) and the alkaline earth metal promoter substance, the above beneficial effects can be achieved.

[0048] Without wishing to be bound by theory, it is also believed that such a distribution of the resulting alkaline earth metal sulfate nanoparticles can contribute to achieving favorable aging properties, i.e., increasing the resistance to deactivation during aging (e.g., cold start emission control activity), especially once PGM or palladium nanoparticles can be loaded thereon. This may be because smaller nanoparticles with a more uniform distribution can be formed, i.e., having a relatively large number of direct interactions between PGM or palladium and the alkaline earth metal, and a relatively small number of direct PGM-PGM interactions and alkaline earth metal-alkaline earth metal direct interactions (i.e., between adjacent nanoparticles). During the aging process, such a catalyst article may be more resistant to the process of the same type of particles forming larger nanoparticles through sintering / coalescence, thereby avoiding catalyst deactivation caused thereby. For example, this may be due to the highly uniform distribution of the particles enabling nanoparticles of "other" substances to act as a physical barrier to the sintering / coalescence of nanoparticles of the same substance. Thus, advantageously, a catalyst article with a higher resistance to aging deactivation can be provided. In other words, this may be due to the alkaline earth metal sulfate nanoparticles provided by the method of this aspect of the invention possibly having a smaller size and being able to be uniformly distributed on the carrier material. Thereafter, once the PGM or palladium nanoparticles are loaded onto the carrier material, these PGM or palladium nanoparticles may exhibit particle size distribution characteristics similar to those of the alkaline earth metal nanoparticles and be able to achieve a uniform distribution among the alkaline earth metal nanoparticles of similar size.

[0049] Another advantage of the method may be that during the calcination stage, alkaline earth metal sulfates (such as BaSO4) can be formed in-situ in the pores of the carrier material (especially lanthanum-doped alumina), thereby restricting the crystal growth of the alkaline earth metal sulfate.

[0050] Perhaps most importantly, it has been surprisingly found that by first providing a carrier material loaded with alkaline earth metal sulfate by the method of the present invention and then using the carrier material loaded with alkaline earth metal sulfate for the preparation of the catalytic region (such as a washcoat) of a catalyst article - especially, for example, by loading PGM or specifically palladium thereon - a catalyst article can be prepared that can exhibit the above-mentioned beneficial effects and enable the alkaline earth metal sulfate (nanoparticles) to be uniformly distributed in the catalytic region or washcoat. Such a uniform distribution can also improve the catalytic performance of the catalyst article. In other words, when the carrier material loaded with alkaline earth metal sulfate of the present invention is used in the catalytic region of a catalyst article, the above-mentioned beneficial effects can be achieved due to the favorable particle size distribution of the alkaline earth metal sulfate, while ensuring that the alkaline earth metal sulfate remains uniformly distributed in the bulk of the catalytic region.

[0051] This is in sharp contrast to the conventional method for manufacturing catalyst articles, which, for example, directly coats a slurry containing a support material, alkaline earth metal ions (optionally containing an organic compound and optionally containing PGM or palladium ions) onto a substrate (i.e., without pre-preparing the support material loaded with alkaline earth metal sulfate via the method of the present invention), and then dries and / or heats and / or calcines the slurry by a conventional method. Without wishing to be bound by theory, this may stem from the characteristics of the drying step of the conventional preparation method: during the evaporation of the support coating solvent (usually water), due to the presence of alkaline earth metal ions, organic compounds, and / or their complexes in the solution, as the solvent evaporates, the solutes move towards the surface, and a relatively high proportion of the alkaline earth metal substances (nanoparticles) may subsequently form near the surface layer of the support coating rather than achieving a uniform or consistent distribution. This method can be regarded as a typical support coating preparation method for using such components. For organic compounds with relatively low water solubility such as taurine, this situation may be particularly obvious, because the solubility of such compounds in water is low, and thus a relatively large amount of solvent may need to be added, resulting in a low slurry concentration.

[0052] In contrast, when using the support material loaded with alkaline earth metal sulfate of the present invention in such a support coating, since the alkaline earth metal sulfate nanoparticles with an ideal particle size distribution are already loaded on the support material, and these alkaline earth metal sulfate nanoparticles are insoluble, this can prevent the movement and repositioning of the alkaline earth metal sulfate. In other words, it can prevent the capillary migration of the alkaline earth metal substances and at the same time achieve the beneficial effects brought about by the ideal particle size distribution of the alkaline earth metal sulfate by using the organic compounds described herein.

[0053] Advantageously, such a catalyst article can exhibit better light-off temperature characteristics and can reach the T of the catalyst faster during the heating process. 50 This is particularly significant for the TWC activity indicators (such as the emission reduction effects of total hydrocarbons (THC), CO, and NO). x T is the temperature at which the catalyst reaches 50% conversion for a specific pollutant species, which is a well-known definition to those skilled in the art. 50 As used herein, the term "loaded" (for example, in the context of "support material loaded with alkaline earth metal sulfate") can cover that the alkaline earth metal sulfate can be directly loaded on and / or in the support material. As used herein in the context of the present invention, the term "loaded on and / or in..." can cover that the alkaline earth metal sulfate (typically in the form of nanoparticles) is in direct contact with at least a part of the surface of the support material, and / or if the support material has a porous structure, is present in at least part of the pores of the support material.

[0054]

[0055] ​As used herein, the term "support material" can encompass any material capable of supporting at least an alkaline earth metal sulfate thereon or therein. The support material can take any form, but is typically in the form of a powder, more typically a high surface area powder. When using the method of the present invention to prepare a catalytic filter (such as a wall-flow filter or a flow-through filter), the support material will typically be in powder form, having a D 50 of, for example, from 0.1 μm to 30 μm, more typically from 2 μm to 10 μm as measured by dynamic light scattering, and even more typically from 4 μm to 6 μm. Such particle sizes can contribute to obtaining desirable rheological properties of the slurry used to coat the monolithic substrate, thereby reducing the increase in back pressure. Preferred support materials are described elsewhere herein.

[0056] Unless otherwise specified or implied, the use of terms such as "first", "second", etc. is only intended as a label and is not intended to indicate the relative position or orientation of a particular feature.

[0057] The term "slurry" as used herein can encompass a liquid containing an insoluble material (such as insoluble particles). The slurries described herein can comprise (1) a solvent; (2) soluble components, such as free PGM (such as Pd) ions, free alkaline earth metal ions, and free organic compounds (i.e., components present outside the support material); and (3) an insoluble content, support particles that may or may not interact with the solution components. Slurries are particularly effective in depositing materials onto a substrate, especially for maximizing gas diffusion and minimizing pressure drop during catalytic conversion.

[0058] The term "spray drying" as used herein and other derivatives of this term are taken in their conventional meaning in the art, which can involve, for example, rapidly drying a liquid or slurry with a hot gas. The specific method of spray drying is not particularly limited, and those skilled in the art will know suitable methods.

[0059] The step of heating the spray-dried powder can generally include forming nanoparticles of alkaline earth metal sulfate on the support material. Without wishing to be bound by theory, this is thought to be due to the presence of the organic compounds described herein.

[0060] Heating the slurry is typically carried out in an oven or furnace, more typically in a belt or static oven or furnace, usually in hot air with a specific flow from one direction. This heating may include calcination. During heating, any complexes that may have formed in the first slurry can be at least partially decomposed, substantially decomposed, or completely decomposed. In other words, the ligands of such complexes (e.g., organic compounds) are at least partially, substantially, or completely removed or separated from the alkaline earth metal and ultimately removed from the catalyst article. However, it is believed that the organic compounds containing the sulfur-containing functional groups described herein can decompose to provide alkaline earth metal sulfates. As a result of heating (calcination), the support material is typically substantially free of the organic compound, more typically completely free of the organic compound.

[0061] As used herein, the term "nanoparticle" can generally cover particles having a Rietveld crystallite size of 0.01 nm to 100 nm as measured by XRD. The nanoparticles can be of any shape, such as spherical, plate-shaped, cubic-shaped, cylindrical, hexagonal, or rod-shaped, but are typically spherical.

[0062] After the heating step, the support material is typically cooled, more typically cooled to room temperature. Cooling is typically carried out in air with or without a coolant / medium, usually without a coolant.

[0063] Preferably, the first slurry is substantially free of platinum group metals such as platinum, palladium, and / or rhodium. Due to the inherent limitations of the spray drying process, if PGMs are also present in the first slurry, part of the PGM yield may be lost during the process. This situation is undesirable, especially since PGMs are expensive and their loss / waste will directly violate the core design goal of PGM reduction in the present invention. If PGMs are to be loaded onto the support material for use in the catalyst article, then preferably the loading step is carried out after the spray drying process, more preferably after manufacturing the support material loaded with alkaline earth metal sulfate according to the method of the first aspect.

[0064] As used herein, the expression "substantially free of" with respect to a material, usually in the context of the content of a slurry, region, layer, or zone, means that the material is present in a minor amount based on the total weight of the material, such as ≤5 wt%, preferably ≤2 wt%, more preferably ≤1 wt%, even more preferably ≤0.5 wt%, still more preferably ≤0.1 wt%, still more preferably ≤0.01 wt%, still more preferably ≤0.005 wt%. The expression "substantially free of" encompasses the expression "not containing".

[0065] Preferably, the first slurry consists essentially of, more preferably consists of: a carrier material, alkaline earth metal ions, an organic compound, and optionally, a counterion of the alkaline earth metal ions. Suitable counterions of the alkaline earth metal ions are known to those skilled in the art. The counterions of the alkaline earth metal ions can include, for example, hydroxide ions, nitrate ions, and / or acetate ions, preferably acetate ions.

[0066] As used herein, the expression "consists essentially of" limits the scope of a feature to include the specified materials or steps, as well as any other materials or steps that do not materially affect the basic properties of the feature, such as trace impurities. The expression "consists essentially of" encompasses the expression "consists of".

[0067] Preferably, the first slurry contains water. In other words, the first slurry is preferably an aqueous slurry. This is consistent with typical carrier coating techniques in the art. Therefore, in order to carry out the method of the present invention, since similar components are used, it will be simple to modify the techniques and equipment used in conventional methods to carry out the method of the present invention. Therefore, the organic compound is preferably at least partially soluble in water.

[0068] The organic compound contains a functional group selected from a sulfo group (-SO3H), a sulfonyl group (-S(=O)2-), and a sulfinyl group (-S(=O)-). Without wishing to be bound by theory, it is believed that such sulfur-containing groups can interact and / or complex with the alkaline earth metal ions in the first slurry. Furthermore, it is precisely due to the presence of such sulfur-containing groups that the formation of alkaline earth metal sulfates (nanoparticles) is promoted.

[0069] The organic compound preferably further contains an amine functional group, preferably a primary amine functional group. In this regard, the organic compound preferably contains a sulfo group and a primary amino group.

[0070] The organic compound can contain 1 to 6 carbon atoms, preferably 2 to 4 carbon atoms, more preferably 2 carbon atoms. Such organic compounds can provide a good balance between solubility in solution, the ability to form complexes with metal substances, and the ability to decompose upon heating to form nanoparticles of a desired size.

[0071] In particular, the organic compound preferably includes one or more of methanesulfonic acid, taurine, hypotaurine, 4-aminobutane-1-sulfonic acid, 2-aminopropane-1-sulfonic acid, 2-methyltaurine, dimethyl sulfone, sulfolane, sulfopropylalanine, dimethyl sulfoxide, and aminobenzenesulfonic acid, more preferably taurine. In some embodiments, the molar ratio of the organic compound (such as taurine) to barium can 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 (such as taurine) to barium can be from 3:1 to 1:1, 2:1 to 1:1, or 1.5:1 to 1:1.

[0072] The water solubility of such preferred organic compounds may be relatively low, and thus the rapid drying characteristics caused by spray drying can help maintain the uniform distribution of the alkaline earth metal sulfate on the carrier material.

[0073] The alkaline earth metal ions preferably include one or more of calcium ions, strontium ions, and barium ions, more preferably strontium ions and / or barium ions, and even more preferably barium ions. It is known that barium in combination with palladium provides excellent promoter activity, for example, in TWC. Providing the first slurry generally can include contacting the carrier material and / or the organic compound with an alkaline earth metal salt (including a solution of the alkaline earth metal salt), preferably wherein the alkaline earth metal salt includes one or more of alkaline earth metal hydroxides, alkaline earth metal nitrates, and alkaline earth metal acetates, preferably alkaline earth metal acetates. Preferably, the alkaline earth metal salt includes barium acetate.

[0074] Preferably, the carrier material includes inorganic oxides, more preferably metal oxides, and even more preferably refractory metal oxides. The carrier material preferably includes one or more of alumina, silica, titanium dioxide, cerium dioxide, zirconium oxide, cerium dioxide-zirconium oxide mixed oxide, vanadium oxide, lanthanum oxide, and zeolite. The carrier material more preferably includes alumina and / or cerium dioxide-zirconium oxide mixed oxide, and the carrier material even more preferably includes alumina and cerium dioxide-zirconium oxide mixed oxide. The alumina is preferably γ-alumina. The cerium dioxide-zirconium oxide mixed oxide preferably has a cerium dioxide:zirconium oxide molar ratio of 10:90 to 90:10, more preferably 30:70 to 70:30, and even more preferably 40:60 to 60:40.

[0075] As used herein, the term "mixed oxide" generally refers to a mixture of oxides in a single-phase form, as is commonly known in the art. As used herein, the term "composite oxide" generally refers to a composition of oxides having more than one phase, as is commonly known in the art.

[0076] Particularly preferably, the carrier material comprises both alumina and a cerium-zirconium mixed oxide. For example, when an alkaline earth metal sulfate (preferably barium sulfate) is used in combination with a PGM such as Pd: (i) it can generally provide particularly good NO x conversion when supported on alumina, and (ii) it can generally provide particularly good CO / THC conversion when supported on the cerium-zirconium mixed oxide.

[0077] It has surprisingly been found that the method of the present invention can facilitate the simultaneous loading of an alkaline earth metal sulfate onto both alumina and a cerium-zirconium mixed oxide. In conventional preparation methods involving slower drying of a slurry comprising slurry components, the alkaline earth metal sulfate can generally be more readily loaded onto and / or into alumina than the cerium-zirconium mixed oxide. This is thought to be due to, for example, the relatively high surface area of alumina compared to the cerium-zirconium mixed oxide. However, the method of the present invention can facilitate a more uniform distribution of the alkaline earth metal sulfate between these two different carrier materials. Advantageously, this can provide the above beneficial effects by a single manufacturing method, i.e., without separately loading the alkaline earth metal sulfate onto each of the different carrier materials and then combining these carrier materials. In other words, the method of the present invention can obtain alumina loaded with an alkaline earth metal sulfate and a cerium-zirconium mixed oxide loaded with an alkaline earth metal sulfate in one method by simply including two different carrier materials in a first slurry and then spray-drying the first slurry comprising these two different carrier materials simultaneously. This is surprising.

[0078] The alumina and / or the cerium-zirconium mixed oxide is preferably doped with a dopant. The dopant preferably comprises 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 preferably is present in the alumina and / or the cerium-zirconium mixed oxide in an amount of 0.001 wt% to 20 wt%, preferably 0.5 wt% to 10 wt%, based on the total weight of the dopant and the alumina and / or the cerium-zirconium mixed oxide. Preferably, the carrier material comprises La-doped alumina and a cerium-zirconium mixed oxide.

[0079] Throughout this application, "wt%" in relation to a dopant is calculated, for example, based on its metal oxide. When doped, the carrier material is preferably a mixed oxide.

[0080] Preferably, the carrier material is in powder form, with a D 50 of 0.1 μm to 30 μm, preferably 2 μm to 10 μm, more preferably 4 μm to 6 μm. D 50It can be measured by dynamic light scattering technique. This feature refers to the D of the carrier material provided in the first slurry 50 , i.e., the D before the step of spray-drying the first slurry 50 .

[0081] Accordingly, in a preferred embodiment, there is provided a method of manufacturing a carrier material loaded with barium sulfate, the method comprising: providing a first slurry comprising a carrier material, barium ions, and an organic compound, wherein the organic compound comprises a functional group selected from a sulfonic acid group (-SO3H), a sulfonyl group (-S(=O)2-), and a sulfinyl group (-S(=O)-), and wherein the carrier material comprises alumina, preferably La-doped alumina, and a cerium dioxide-zirconium dioxide mixed oxide; spray-drying the first slurry to provide a spray-dried powder; and heating the spray-dried powder to form a carrier material loaded with barium sulfate, preferably wherein the organic compound comprises taurine.

[0082] The step of providing the first slurry generally may comprise contacting the carrier material, an alkaline earth metal ion (usually in the form of an alkaline earth metal salt), the organic compound with a solvent (preferably comprising water). The components of the slurry can be provided / contacted with each other in any order, either sequentially or simultaneously. However, preferably, providing the first slurry comprises: providing a solution comprising an alkaline earth metal ion and an organic compound, preferably wherein the solution is an aqueous solution; providing the carrier material; and contacting the solution with the carrier material to form the first slurry. Providing the solution generally may comprise contacting the alkaline earth metal ion (usually in the form of an alkaline earth metal salt), the organic compound with a solvent (preferably comprising water). Without wishing to be bound by theory, it is believed that by first providing a solution comprising an alkaline earth metal ion and an organic compound, it is speculated that during the calcination stage, due to the presence of the organic compound, the formation rate of alkaline earth metal sulfate is relatively slow, thereby obtaining alkaline earth metal sulfate with a nanoscale particle size. This small particle size may be beneficial for matching the size distribution of PGM (preferably palladium) particles that can be loaded onto the carrier material, and thus for use in catalyst articles.

[0083] Preferably, heating the spray-dried powder comprises heating the spray-dried powder at a temperature of from 300 °C to 700 °C for 10 minutes to 5 hours, more preferably heating at a temperature of from 400 °C to 600 °C for 30 minutes to 4 hours, even more preferably heating at a temperature of from 450 °C to 550 °C for 1 hour to 3 hours, still more preferably heating at a temperature of about 500 °C for about 2 hours.

[0084] Preferably, the heat-spray-dried powder comprises a calcined spray-dried powder. As used herein, the term "calcination" and related expressions can cover a heat treatment process for achieving thermal decomposition or thermally induced changes under conditions of absence of air or oxygen, or only limited supply of air or oxygen. However, generally, calcination in the context of the present invention involves heating in air in an oven. In some preferred embodiments, the calcination comprises heating (in air within the oven) at a temperature of 350 °C to 1100 °C, preferably 400 °C to 900 °C, more preferably 450 °C to 800 °C for 1 hour to 8 hours, preferably 2 hours to 5 hours.

[0085] Preferably, the first slurry has a solids content of 5% to 40%, more preferably 10% to 30%, even more preferably 10% to 20%, still more preferably about 15%. Such a solids content may be particularly suitable for the spray-drying process of the present invention.

[0086] The method preferably further comprises stirring the first slurry before the step of spray-drying the first slurry, preferably wherein the first slurry is stirred for at least 10 minutes, more preferably at least 20 minutes, even more preferably at least 30 minutes. Preferably, the first slurry is stirred for 10 minutes to 90 minutes, more preferably 20 minutes to 60 minutes, even more preferably 30 minutes to 40 minutes. Stirring can advantageously increase the uniformity of the slurry and thus increase the dispersion of the alkaline earth metal sulfate on the carrier material.

[0087] In an alternative aspect, the present invention provides a method for manufacturing a carrier material loaded with an alkaline earth metal sulfate, the method comprising: providing a first slurry comprising a carrier material, alkaline earth metal ions, and an organic compound, wherein the organic compound comprises a functional group selected from a sulfonic acid group (-SO3H), a sulfonyl group (-S(=O)2-), and a sulfinyl group (-S(=O)-); drying the first slurry to provide a dried powder; and heating the dried powder to form a carrier material loaded with an alkaline earth metal sulfate; wherein the first slurry is substantially free of platinum group metals.

[0088] The related preferred features and embodiments of the first aspect are equally applicable to this aspect. For at least similar reasons, the method of this alternative aspect can provide advantages similar to those of the first aspect. The drying is preferably carried out under the following conditions: at a temperature of 60 °C to 200 °C, more preferably 70 °C to 130 °C; and / or for 10 minutes to 360 minutes, preferably 15 minutes to 60 minutes.

[0089] In yet another aspect, the present invention provides a carrier material loaded with an alkaline earth metal sulfate obtainable by or capable of being obtained by the method of the above aspects.

[0090] The relevant preferred features and embodiments of the first aspect are equally applicable to this aspect. Additionally, for the avoidance of doubt, where appropriate, the following preferred features are equally applicable to the methods of the above aspects.

[0091] Preferably, the support material loaded with alkaline earth metal sulfate contains 1 wt% to 25 wt% of alkaline earth metal sulfate based on the total weight of the support material loaded with alkaline earth metal sulfate. More preferably, the support material loaded with alkaline earth metal sulfate contains 2 wt% to 20 wt% or 5 wt% to 20 wt% of alkaline earth metal sulfate based on the total weight of the support material loaded with alkaline earth metal sulfate. If there are two or more different types of support materials, the wt% is based on the total weight of all the support materials loaded with alkaline earth metal sulfate.

[0092] Preferably, the alkaline earth metal sulfate includes nanoparticles of alkaline earth metal sulfate. Preferably, the alkaline earth metal sulfate includes alkaline earth metal sulfate nanoparticles having a crystallite size of 0.1 nm to 30 nm, preferably 5 nm to 25 nm or 5 nm to 20 nm, more preferably 5 nm to 15 nm. Unless otherwise specified, the crystallite size is preferably the Rietveld crystallite size. The crystallite size can 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 achieve the advantageous properties discussed above, such as high activity and resistance to aging inactivation. In addition, the combination of the size of such nanoparticles with the particle size that is typically similar to that of PGM (such as Pd) nanoparticles can contribute to achieving the above-mentioned beneficial characteristics due to the particle size matching.

[0093] Unless otherwise described herein, any crystallite size described herein can be measured by XRD. Suitable techniques are known in the art. For example, such a technique can be described as follows. To obtain X-ray diffraction data, an X’Pert Pro MPD diffractometer can be used with BraggBrentano HDA mirror, a 1 / 4° divergent slit, a 20 mm mask, a sample spinner, and a PIXcel detector are used together. Three repeated scans can be performed in the range of 5° to 115° with a step size of 0.02°, and the total scan time is 50 minutes. HighScore Plus software can be used to analyze the data. The transitional alumina phase can be modeled using a partial or unknown crystal structure method (N.V.Y. SCARLETT and I.C. MADSEN, Quantification of phases with partial or not known crystal structure, Powder Diffraction (2006), 21(4), 278 - 284, which is incorporated herein by reference), and all other phases can be modeled using Rietveld. The crystallite size and strain can be measured based on the Pseudo-Voigt curve function and corrected for instrumental broadening. In the field of the present invention, the crystallite size measured by XRD is a common parameter for determining the nanoparticle size of such substances.

[0094] In yet another aspect, the present invention provides a method of manufacturing a catalyst article, the method comprising: manufacturing a support material loaded with an alkaline earth metal sulfate according to the method of the above aspect, or providing a support material loaded with an alkaline earth metal sulfate according to the above aspect; providing a second slurry comprising the support material loaded with an alkaline earth metal sulfate and PGM ions; disposing the second slurry on a substrate; and heating the second slurry to form PGM nanoparticles on the support material loaded with an alkaline earth metal sulfate.

[0095] As used herein, the term "catalyst article" can encompass an article on or in which a catalyst is loaded. The article can take the form of, for example, a flow-through monolith or a filter (such as a wall-flow filter). The catalyst article can be used in an emissions treatment system, particularly for gasoline engines, preferably a stoichiometric gasoline engine emissions treatment system. The catalyst article can be used in three-way catalysis.

[0096] As used herein, the term "substrate" can encompass, for example, a ceramic or metal honeycomb or a filter block (such as a wall-flow filter or a flow-through filter). The substrate can comprise a ceramic single substrate. The substrate can vary in its material composition, size and configuration, pore shape and density, and wall thickness. Suitable substrates are known in the art and can be a flow-through monolith or a wall-flow filter, preferably a flow-through monolith.

[0097] The step of providing the second slurry generally may include contacting a support material loaded with an alkaline earth metal sulfate, PGM ions (usually in the form of PGM salts such as PGM (such as Pd) nitrate and / or PGM (such as Pd) acetate) with a solvent (preferably including water).

[0098] Preferably, the second slurry contains water. In other words, the second slurry is preferably an aqueous slurry. This is consistent with typical support coating techniques in the art. Thus, to carry out the method of the present invention, since similar components are used, it will be straightforward to modify the techniques and equipment used in conventional methods to carry out the method of the present invention.

[0099] Preferably, providing the second slurry includes: providing an intermediate slurry that contains a support material loaded with an alkaline earth metal sulfate; and contacting the intermediate slurry with a PGM salt, preferably with a solution containing a PGM salt. The PGM salt preferably includes one or more of PGM nitrate and PGM acetate, more preferably PGM nitrate. The intermediate slurry contains a support material loaded with an alkaline earth metal sulfate and a solvent (preferably water). Preferably, the intermediate slurry consists essentially of a support material loaded with an alkaline earth metal sulfate and a solvent, and more preferably consists of a support material loaded with an alkaline earth metal sulfate and a solvent. The intermediate slurry is preferably provided by contacting a support material loaded with an alkaline earth metal sulfate with a solvent. Preferably, providing the intermediate slurry includes subjecting the support material loaded with an alkaline earth metal sulfate to a comminution treatment (such as by grinding and / or (intensive) mixing), preferably using a high-shear mixer, such that the D 50 is about 5 μm to 15 μm, more preferably about 4 μm to 6 μm. D 50 can be measured by dynamic light scattering techniques.

[0100] The method preferably further includes stirring the second slurry before the step of setting the second slurry on a substrate, preferably wherein the second slurry is stirred for at least 10 minutes, more preferably at least 20 minutes, even more preferably at least 30 minutes. Preferably, the second slurry is stirred for 10 minutes to 90 minutes, more preferably 20 minutes to 60 minutes, even more preferably 30 minutes to 40 minutes. Stirring can advantageously increase the uniformity of the slurry and thus can increase the distribution of PGM ions on the support material loaded with an alkaline earth metal sulfate.

[0101] Preferably, the second slurry further comprises one or more of the following components: a binder; an acid or a base; a thickener and / or another inorganic oxide. In other words, providing the second slurry preferably further comprises contacting the slurry comprising the carrier material loaded with alkaline earth metal sulfate and PGM ions with one or more of the following components: a binder; an acid or a base; a thickener and / or another inorganic oxide. The another inorganic oxide may be as described elsewhere herein, but does not necessarily contain the alkaline earth metal sulfate loaded thereon.

[0102] The binder may comprise, for example, an oxide material having a small particle size to bond together the individual insoluble particles in the carrier coating slurry. The use of a binder in the carrier coating is well known in the art. Typical binders may include alumina.

[0103] The thickener may comprise, for example, a natural polymer having functional hydroxyl groups that interact with the insoluble particles in the carrier coating slurry. It is used for the purpose of thickening the carrier coating slurry to improve the coating profile during coating the carrier coating onto the substrate. It is usually burned off during the calcination of the carrier coating. Examples of specific thickeners / rheology modifiers for the carrier coating include guar gum, gum arabic, xanthan gum, gellan gum, schizophyllan, scleroglucan, welan gum, diutan gum, hydroxyethyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, methyl hydroxyethyl cellulose, methyl hydroxypropyl cellulose, and ethyl hydroxyethyl cellulose. The thickener may include Natrasol.

[0104] Providing the second slurry may further comprise adjusting the pH of the second slurry to 6 or higher, preferably 7 or higher, such as with tetraethylammonium hydroxide (TEAOH). For example, such a pH may provide optimal conditions for coating the carrier coating.

[0105] Preferably, the second slurry has a solids content of 10% to 40%, preferably 15% to 35%. Such a solids content may render the slurry rheology suitable for setting the loaded carrier material onto the substrate. For example, if the substrate is a honeycomb monolith, such a solids content may enable a thin layer of the carrier coating to be deposited on the inner walls 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 may enable the slurry to enter the walls of the wall-flow filter.

[0106] The second slurry can be disposed on the substrate using techniques known in the art. Generally, the second slurry can be poured into the substrate inlet in a predetermined amount using a specific forming tool to dispose the supported carrier material (i.e., preferably also loaded with PGM ions at this time) on the substrate. As discussed in more detail below, subsequent vacuum and / or air knife and / or drying steps can be employed during this disposition step. When the substrate is a filter block, the supported carrier material can be disposed on the filter wall, inside the filter wall (if the filter wall is a porous structure), or both.

[0107] Heating the second slurry is typically carried out in an oven or furnace, more typically in a belt or static oven or furnace, and typically in a specific flow of hot air from one direction. This heating can include calcination. This heating can also include drying. The drying step and the calcination step can be continuous or sequential. For example, a separate carrier coating can be applied after the substrate has been coated with a previous carrier coating and dried. If the coating is complete, a single continuous heating program can also be used to dry and calcine the substrate with the applied carrier coating. During heating, the PGM ions can coalesce and / or sinter to form PGM nanoparticles on the carrier material. Such particles of PGM can also begin to form metal-metal bonds and metal-oxide bonds. Of course, heating the second slurry typically includes heating the second slurry and the substrate simultaneously. Of course, the step of heating the second slurry can thus typically include, for example, fixing the carrier material to the substrate via a binder.

[0108] After the heating step, the substrate is typically cooled, more typically to room temperature. Cooling is typically carried out in air with or without a coolant / medium, typically without a coolant.

[0109] Thus, the method of this aspect typically results in the formation of a carrier material loaded with PGM and alkaline earth metal sulfate. The carrier material loaded with PGM and alkaline earth metal sulfate is typically disposed on the substrate in the form of regions, zones, carrier coatings, or layers. In other words, the catalyst article typically includes a first catalytic region that includes a carrier material on which PGM nanoparticles and alkaline earth metal sulfate nanoparticles are loaded. The first catalytic region is typically disposed on the substrate.

[0110] As used herein, the term "disposed on" can cover a catalyst composition or catalytic zone being disposed directly on a substrate, i.e., without an intervening material, and / or indirectly on a substrate, i.e., with an intervening material. If the substrate is porous, the term "disposed on" can also cover having the catalyst composition or catalytic zone disposed therein, e.g., within the pores of the substrate, i.e., where the catalyst composition or catalytic zone (and its support material) is disposed on and / or within it. The term "washcoat" as used herein is well known in the art and refers to an adherent coating typically applied to a substrate during catalyst production.

[0111] Preferably, disposing the second slurry on the substrate includes applying a washcoat.

[0112] 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 supported carrier material that may be included in the slurry. Drying is preferably carried out at a temperature of 60 °C to 200 °C, more preferably 70 °C to 130 °C; and / or for 10 minutes to 360 minutes, preferably 15 minutes to 60 minutes.

[0113] Preferably, heating the slurry to form PGM (such as Pd) nanoparticles on the supported alkaline earth metal sulfate carrier material includes heating at the following parameters: 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 10 minutes to 360 minutes, preferably 35 minutes to 120 minutes.

[0114] Preferably, heating the slurry to form PGM nanoparticles on the supported alkaline earth metal sulfate carrier material includes calcination.

[0115] The substrate preferably includes cordierite. The substrate can be in the form of a honeycomb monolith, a wall flow filter, or a flow through filter. The substrate can be "blank", i.e., a substrate without a washcoat applied. Alternatively, the substrate can have one or more washcoats loaded thereon. In this case, the final catalyst article can contain multiple different washcoats.

[0116] In a further aspect, the present invention provides a catalyst article obtainable by or obtainable through the method of the above aspects.

[0117] The relevant preferred features and embodiments of the above aspects equally apply to this aspect. Additionally, for the avoidance of doubt, the following preferred features equally apply to the methods of the above aspects where appropriate.

[0118] Compared to conventional catalyst articles, such catalyst articles can exhibit favorable light-off performance, particularly for the light-off of NO, CO, and total hydrocarbons during three-way catalytic conversion for stoichiometric gasoline emission reduction. The catalyst article can also exhibit other favorable properties described herein, such as high resistance to deactivation upon aging, and high activity, such as under "cold start" conditions. In addition, such catalyst articles can exhibit a lower light-off temperature and a shorter time to reach T of such pollutants 50 for such pollutants.

[0119] Preferably, the support material loaded with alkaline earth metal sulfate contains 1 wt% to 25 wt% of alkaline earth metal sulfate based on the total weight of the alkaline earth metal sulfate and the support material. More preferably, the support material loaded with alkaline earth metal sulfate contains 2 wt% to 20 wt% or 5 wt% to 20 wt% of alkaline earth metal sulfate based on the total weight of the support material loaded with alkaline earth metal sulfate. If there are two or more different types of support materials, the wt% is based on the total weight of all the support materials loaded with alkaline earth metal sulfate. However, for the avoidance of doubt, the total weight used for this calculation basis does not include the weight of any PGM (such as Pd) present.

[0120] Preferably, the alkaline earth metal sulfate includes nanoparticles of alkaline earth metal sulfate. Preferably, the alkaline earth metal sulfate includes alkaline earth metal sulfate nanoparticles having a crystallite size of 0.1 nm to 30 nm, preferably 5 nm to 25 nm or 5 nm to 20 nm, more preferably 5 nm to 15 nm. Preferably, substantially all of the alkaline earth metal sulfate nanoparticles have such a crystallite size. Such particle size can advantageously achieve the favorable properties discussed above, such as high activity and resistance to deactivation upon aging. In addition, the combination of the size of such nanoparticles with the particle size that is typically similar to that of PGM nanoparticles can contribute to achieving the above-mentioned beneficial properties due to the matching of the particle sizes.

[0121] Preferably, the support material loaded with alkaline earth metal sulfate is present in the first catalytic zone, and the alkaline earth metal sulfate nanoparticles are uniformly distributed within the first catalytic zone. As used herein, the term "uniformly distributed" can encompass that the concentration of the alkaline earth metal sulfate particles is (substantially) uniform throughout the first catalytic zone. In other words, it is preferred that there are no local enrichment regions of the alkaline earth metal sulfate particles (i.e., regions with a higher concentration of alkaline earth metal sulfate particles compared to other regions) in the first catalytic zone, such as at the surface of the first catalytic zone (especially when the first catalytic zone is a support coating). The first catalytic zone should be understood to cover the entire area or volume in which the second slurry has been disposed (i.e., not a subset of that area or volume). For example, this property can be observed using SEM. This property can provide a catalyst article having the advantageous TWC conversion properties described herein. In addition, as described herein, compared to other methods that still involve alkaline earth metal ions in the substrate deposition step of the present method, the method of the present invention surprisingly promotes such uniform distribution because the alkaline earth metal sulfate particles have been loaded on and / or in the support material. Thus, this capillary migration phenomenon of the alkaline earth metal substance can be alleviated, which can provide a catalyst article with improved catalytic performance. However, since the alkaline earth metal sulfate particles are manufactured by the method described herein, their particle size distribution also exhibits better properties. Such a final product may be difficult to achieve an equally simple manufacturing process using other methods.

[0122] Preferably, the crystallite size of PGM (such as Pd) nanoparticles is from 0.1 nm to 20 nm, more preferably from 5 nm to 15 nm. Preferably, substantially all of the PGM (such as Pd) nanoparticles have such a crystallite size. The crystallite size is preferably the Rietveld crystallite size measured as described herein. Such a particle size can advantageously achieve the advantageous properties discussed above, such as high activity and resistance to aging deactivation.

[0123] Preferably M = C ± 70%, preferably M = C ± 50%, more preferably M = C ± 30%, even more preferably M = C ± 20%, where M is the (Rietveld) crystallite size of PGM (such as Pd) nanoparticles and C is the (Rietveld) crystallite size of the alkaline earth metal sulfate nanoparticles. In other words, for the reasons described above, 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., within the same order of magnitude range.

[0124] Preferably, the support material loaded with alkaline earth metal sulfate is present in the first catalytic zone, and the support material comprises alumina and cerium-zirconium mixed oxide; and when the cross-section of the first catalytic zone of the catalyst article is subjected to area analysis by FE-EPMA under the conditions of a pixel (cross-section) size of 0.34 μm × 0.34 μm and a measured number of pixels (cross-sections) 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 aluminum (Al) are measured for each pixel, and the Pearson correlation coefficient calculated using α and γ obtained for each pixel is designated as R Ae / Al , so R Ae / Al has a value of at least 0.1, preferably at least 0.2; and when the cross-section of the first catalytic zone of the catalyst article is subjected to area analysis by FE-EPMA under the conditions of a pixel (cross-section) size of 0.34 μm × 0.34 μm and a measured number of pixels (cross-sections) 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 cerium (Ce) are measured for each pixel, and the Pearson correlation coefficient calculated using α and δ obtained for each pixel is designated as R Ae / Ce , so R Ae / Ce has a value of at least 0.1, preferably at least 0.2. In other words, the alkaline earth metal sulfate is preferably loaded on both alumina and cerium-zirconium composite oxide in the catalyst article. For the reasons described herein, such an arrangement may be advantageous, and its simpler production method (i.e., including fewer steps) can be facilitated by the method of the present invention.

[0125] Preferably, the support material loaded with alkaline earth metal sulfate is present in the first catalytic zone, and when the cross-section of the first catalytic zone of the catalyst article is subjected to area analysis by FE-EPMA under the conditions of a pixel (cross-section) size of 0.34 μm × 0.34 μm and a measured number of pixels (cross-sections) 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 α and β obtained for each pixel is designated as R Ae / Pd , so R Ae / Pd has a value of at least 0.1, preferably at least 0.2, where 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 is determined by the following formula: R Ae / Pd= (Covariance) / (Standard Deviation of α × Standard Deviation of β), where in the area analysis by FE-EPMA, the first variable (α) is the characteristic X-ray intensity of the alkaline earth metal element (Ae), and the second variable (β) is the characteristic X-ray intensity of palladium (Pd). Such calculations are known to those skilled in the art. In other words, preferably, the alkaline earth metal element and palladium are highly correlated in such catalyst articles. That is, depending on the distribution of palladium on the substrate, the alkaline earth metal can exist in a highly dispersed state. Thus, the ability of the alkaline earth metal to act as a promoter substance 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. It may not be easy to achieve such a high degree of correlation using the larger alkaline earth metal sulfate nanoparticles of conventional catalyst articles (i.e., those having small palladium nanoparticles but much larger alkaline earth metal sulfate nanoparticles).

[0126] Preferably, the total loading of the carrier material loaded with PGM (such as Pd) nanoparticles and alkaline earth metal sulfate nanoparticles formed thereon is 0.5 g / in 3 to 5 g / in 3 .

[0127] In yet another aspect, the present invention provides a catalyst article comprising: a substrate; and a first catalytic region disposed on the substrate; wherein the first catalytic region comprises a carrier material on which PGM nanoparticles and alkaline earth metal sulfate nanoparticles are loaded; wherein these alkaline earth metal sulfate nanoparticles are uniformly distributed within the first catalytic region.

[0128] The related preferred features and embodiments of the above aspect are equally applicable to this aspect.

[0129] Compared to conventional catalyst articles, such catalyst articles can exhibit favorable light-off performance, particularly for the light-off of NO, CO, and total hydrocarbons during three-way catalytic conversion for stoichiometric gasoline emission reduction. The catalyst articles can also exhibit other favorable properties described herein, such as high resistance to deactivation upon aging, and high activity, such as a lower light-off temperature and a shorter time to reach T 50 of such pollutants.

[0130] Preferably, the catalyst article is obtained by or capable of being obtained by the method of the above aspect.

[0131] Preferably, the catalyst article is used in an emission treatment system, preferably wherein the catalyst article is used for three-way catalysis. Preferably, the catalyst article is used to treat exhaust gas from a gasoline engine.

[0132] Preferably, the support material loaded with alkaline earth metal sulfate is present in the first catalytic zone, and the catalyst article further comprises a second catalytic zone; and wherein the second catalytic zone comprises palladium, platinum, and / or rhodium. In certain embodiments, the first catalytic zone forms a first layer on the substrate and the second catalytic zone 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 zone forms a first layer (bottom layer) on the substrate and the first catalytic zone forms a second layer (top layer) on top of the second catalytic zone.

[0133] Preferably, the catalyst article further comprises a third catalytic zone, wherein the second catalytic zone comprises palladium and / or platinum, and optionally, wherein the third catalytic zone comprises rhodium, and is disposed on top of the first catalytic zone and / or the second catalytic zone such that the first catalytic zone and / or the second catalytic zone are each positioned between the third catalytic zone and the substrate.

[0134] In another preferred embodiment, the first catalytic zone forms a first layer on the substrate and the second catalytic zone forms a second layer on the substrate, the first layer being directly disposed on the substrate and the second layer being directly disposed on the first layer. In another preferred embodiment, the first catalytic zone forms a first layer on the substrate and the second catalytic zone forms a second layer on the substrate, the second layer being directly disposed on the substrate and the first layer being directly disposed on the first layer. In another preferred embodiment, the catalyst article further comprises a third catalytic zone, wherein the third catalytic zone is directly disposed on the first layer or the second layer, optionally wherein the second catalytic zone comprises platinum and the third catalytic zone comprises rhodium. In yet another preferred embodiment, the catalyst article further comprises a third catalytic zone, wherein the first catalytic zone is directly disposed on the second catalytic zone and / or the third catalytic zone, optionally wherein the second catalytic zone comprises palladium and the third catalytic zone comprises rhodium.

[0135] In other words, a catalyst article including a catalytic region formed by the method of the present invention may have such a catalyst layer, for example, as a top layer, an intermediate layer, or a bottom layer. As used herein, the term "bottom layer" may encompass a layer (e.g., a washcoat) that is closest to or in contact with the substrate (i.e., the substrate wall). As used herein, the term "top layer" may encompass a layer that is further away from the substrate (i.e., the substrate wall) than the bottom layer and may be located on top of the bottom layer (e.g., a washcoat). In such a layered catalyst article, the top layer and / or the bottom layer of the carrier material may have additional PGM, such as platinum, thereon. In such a layered catalyst article, the top layer and / or the bottom layer may comprise multiple PGMs, i.e., may be bimetallic (e.g., containing Pd-Rh or Pd-Pt) or trimetallic (e.g., Pd-Rh-Pt). The catalyst article may include two or more catalyst zones, such as an upstream zone and a downstream zone. These zones may differ from each other by having different PGMs (e.g., Rh upstream and Pd downstream, or vice versa), or by the amounts of different types of PGMs (e.g., monometallic, bimetallic, or trimetallic).

[0136] In any of the preferred embodiments of the above preferred embodiments, the first catalytic region, the second catalytic region, and / or the third catalytic region may be in the form of a zone that covers less than 100% of the substrate, such as 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.

[0137] The substrate may have a first end and a second end and have an axial length L.

[0138] The first catalytic region may extend 100% of the axial length L (e.g., see Figure 1 , Figure 2a , Figure 2b and Figure 6a to Figure 6c ). In some embodiments, the first catalytic region may extend 20% to 99%, 30% to 90%, or 40% to 80% of the axial length L. Alternatively, the first catalytic region may extend 30% to 70% of the axial length L. Preferably 40% to 60% of the axial length L, more preferably 45% to 55% of the axial length L (e.g., see Figure 3a to Figure 5d and Figure 7a to Figure 7l ).

[0139] The second catalytic region may extend 100% of the axial length L (e.g., see Figure 2a , Figure 2b and Figure 6a to Figure 6c ).

[0140] The second catalytic zone may extend from 30% to 70% of the axial length L. Preferably from 40% to 60% of the axial length L, more preferably from 45% to 55% of the axial length L, and most preferably, the total length of the second zone and the first zone is equal to or greater than the axial length L (e.g., see Figure 3a to Figure 5d and Figure 7a to Figure 7l ).

[0141] The second catalytic zone may overlap the first catalytic zone by up to 0.1% to 99% of the axial length L (e.g., see Figure 3c and Figure 3d , the first catalytic zone may cover the second catalytic zone or the second catalytic zone may cover the first catalytic zone). Alternatively, the total length of the second catalytic zone and the first catalytic zone may be equal to the axial length L (e.g., see Figure 3a and Figure 3b ). In yet another alternative, the total length of the second catalytic zone and the first catalytic zone may be less than the axial length L, e.g., not greater than 95%, 90%, 80% or 70% of the axial length L.

[0142] The third catalytic zone may extend 100% of the axial length L (e.g., see Figure 4a to Figure 4d and Figure 6a to Figure 6c ).

[0143] The third catalytic zone may be less than the axial length L, e.g., not greater than 95%, 90%, 80% or 70% of the axial length L (e.g., see Figure 5a to Figure 5d and Figure 7g to Figure 71).

[0144] The second catalytic zone may overlap the first catalytic zone by up to 0.1% to 99% of the axial length L (e.g., see Figure 7a to Figure 71), the first catalytic zone may cover the second catalytic zone or the second catalytic zone may cover the first catalytic zone). Alternatively, either the second zone or the first zone may extend from 30% to 70% of the axial length L. Preferably from 40% to 60% of the axial length L, more preferably from 45% to 55% of the axial length L, and most preferably, the total length of the second zone and the first zone is equal to or less than the axial length L (e.g., see Figure 4a to Figure 4d ).

[0145] The catalyst article preferably contains from 10 g / ft 3 to 200 g / ft 3 of palladium, preferably from 50 g / ft 3 to 150 g / ft 3 of palladium. Advantageously, such palladium levels may be lower than those of conventional catalyst articles without compromising catalytic activity.

[0146] In yet another aspect, the present invention provides an emissions treatment system comprising the catalyst article described herein.

[0147] The emissions treatment system is preferably for a gasoline engine.

[0148] The gasoline engine is preferably operated under stoichiometric conditions.

[0149] The present invention may also encompass a fuel combustion and emissions treatment system that includes an engine, preferably a gasoline engine, and the emissions treatment system of the above aspect.

[0150] In yet another aspect, the present invention provides a method for treating exhaust gas, the method comprising: providing the catalyst article described herein; and contacting the catalyst article with the exhaust gas.

[0151] The exhaust gas preferably comes from a gasoline engine. The catalyst article is particularly suitable for treating such exhaust gas. In addition, exhaust gas from a gasoline engine is generally more demanding than exhaust gas from a diesel engine. Therefore, the advantageous aging properties of the catalyst article described herein are particularly beneficial for it. The gasoline engine is preferably operated under stoichiometric conditions.

[0152] As used herein, the term "zone" refers to a region on a substrate, which is typically obtained by drying and / or calcining a washcoat. For example, a "zone" may be provided or carried on a substrate in the form of a "layer" or "region". Generally, the zones or arrangements on the substrate are controlled during the process of applying the washcoat to the substrate. A "zone" typically has distinct boundaries or edges (i.e., one zone can be distinguished from another using conventional analytical techniques).

[0153] Generally, a "zone" has a substantially uniform length. In this context, referring to a "substantially uniform length" means a length that does not deviate from its average value (e.g., the difference between the maximum length and the minimum length) by more than 10%, preferably by no more than 5%, and more preferably by no more than 1%.

[0154] Preferably each "zone" has a substantially uniform composition (i.e., when a part of a zone is compared with another part of that zone, there is no significant difference in the composition of the washcoat). In this context, a substantially uniform composition means a material (e.g., a zone) in which the difference in composition is 5% or less, typically 2.5% or less, and most typically 1% or less when a part of a zone is compared with another part of that zone.

[0155] As used herein, the term "region" refers to a zone having a length less than the total length of the substrate, such as ≤75% of the total length of the substrate. A "region" typically has a length of at least 5% (e.g., ≥5%) of the total length of the substrate (i.e., a substantially uniform length).

[0156] The total length of the substrate is the distance between its inlet end and its outlet end (e.g., opposite ends of the substrate).

[0157] As used herein, any reference to a "zone disposed at the inlet end of the substrate" refers to a zone disposed or carried on the substrate that is closer to the inlet end of the substrate compared to a zone closer to the outlet end of the substrate. Thus, the midpoint of this zone is closer to the inlet end of the substrate compared to the midpoint of the substrate (i.e., at its half-length) closer to the outlet end. Similarly, as used herein, any reference to a "zone disposed at the outlet end of the substrate" refers to a zone disposed or carried on the substrate that is closer to the outlet end of the substrate compared to a zone closer to the inlet end of the substrate. Thus, the midpoint of this zone is closer to the outlet end of the substrate compared to the midpoint of the substrate (i.e., at its half-length) closer to the inlet end.

[0158] The term "washcoat" is well known in the art and refers to an adherent coating that is typically applied to a substrate during catalyst production.

[0159] As used herein, the acronym "PGM" refers to "platinum group metals". The term "platinum group metals" generally refers to metals selected from Ru, Rh, Pd, Os, Ir, and Pt, preferably metals selected from Ru, Rh, Pd, Ir, and Pt. Generally speaking, the term "PGM" preferably refers to metals selected from Rh, Pt, and Pd.

[0160] As used herein, the term "loading" refers to a measurement in g / ft 3 per unit based on the weight of the metal.

[0161] When this specification refers to "a" or "an", this encompasses both the singular and plural forms.

[0162] The following non-limiting examples merely illustrate the invention. Those skilled in the art will recognize many variations within the spirit of the invention and the scope of the claims.

[0163] Reference Catalyst 1

[0164] The bottom front zone washcoat slurry is prepared by:[[]]

[0165] (i) Mixing a palladium nitrate solution with a diluted barium acetate solution,

[0166] (ii) Adding taurine to the above mixed solution (i) and maintaining the mixture,

[0167] (iii) Separately grinding and making a slurry containing alumina doped with 4% La2O3,

[0168] (iv) Add the pre-solution in step (ii) to the pre-ground alumina slurry doped with 4% La2O3 in step (iii) and mix them;

[0169] (v) Grind separately and prepare a slurry containing a mixed oxide of cerium dioxide and zirconium oxide,

[0170] (vi) Add the obtained cerium dioxide-zirconium oxide mixed oxide slurry in step (v) to the batch in step (iv),

[0171] (vii) Thickening the carrier coating slurry in (vi) using a rheology modifier.

[0172] The final composition of the front area carrier coating of the bottom layer contains: 0.4 g / in 3 of cerium dioxide-zirconium oxide complex, 0.8 g / in 3 of alumina doped with 4% La2O3, 150 g / ft 3 of Ba element and 9 g / ft 3 of Pd element.

[0173] The carrier coating slurry of the rear area of the bottom layer is prepared as follows:

[0174] (i) Grind and prepare a slurry containing a mixed oxide of cerium dioxide and zirconium oxide,

[0175] (ii) Add rhodium nitrate solution to the slurry in step (i),

[0176] (iii) Adjust the pH of the slurry in step (ii) to precipitate Rh onto the mixed oxide,

[0177] (iv) Add the ground alumina doped with 4% La2O3 to the slurry in step (iii),

[0178] (v) Thickening the carrier coating using a rheology modifier.

[0179] The final composition of the rear area carrier coating of the bottom layer contains: a total of 1.5 g / in 3 of cerium dioxide-zirconium oxide complex, 0.5 g / in 3 of alumina doped with 4% La2O3 and 10 g / ft 3 of Rh element.

[0180] The front area carrier coating of the top layer is prepared as follows:

[0181] (i) Grind the mixed oxide of cerium dioxide and zirconium oxide,

[0182] (ii) Grind and prepare a slurry containing alumina doped with 4% La2O3,

[0183] (iii) Blend the above two slurries (ii) and (iii).

[0184] (iv) Add palladium nitrate to the slurry (iii) for mixing.

[0185] (v) Add gallic acid and mix.

[0186] (vi) Add barium sulfate powder and mix.

[0187] (vii) Adjust the pH to 7.0 or higher.

[0188] (viii) Thicken the carrier coating (iv) using a rheology modifier.

[0189] The final composition of the front zone carrier coating of the top layer contains: 0.4 g / in 3 of cerium zirconium composite oxide, 0.8 g / in 3 of alumina doped with 4% La2O3, 150 g / ft 3 of Ba element and 131 g / ft 3 of Pd element.

[0190] Coat the carrier coating on the monolithic flow-through substrate:

[0191] (i) Using the precision coating method, first apply a dose of 75% to 80% of the application length to the front zone of the bottom layer. Dry to a moisture removal rate of 80% or higher.

[0192] (ii) Calcinate.

[0193] (iii) Coat the carrier coating of the rear zone of the bottom layer to reach the target value of 75% to 80% of the application length.

[0194] Dry to a moisture removal rate of 80% or higher.

[0195] (iv) Apply the front zone of the top layer through the precision coating method, with the target application length controlled at 30% to 35%. Dry to a moisture removal rate of 80% or higher.

[0196] (v) Calcinate again.

[0197] The catalyst 1 of the present invention - BaSO4 is spray-dried on a blended carrier, and the loading amount is 150 g / ft 3 BaSO4

[0198] Prepare the carrier coating slurries for the front and rear zones of the bottom layer in the same manner as that of the reference catalyst 1.

[0199] The carrier coating of the front zone of the top layer is prepared as follows:

[0200] (i) Blend the alumina doped with 4% La2O3 with the cerium and zirconium mixed oxide slurry.

[0201] (ii) Add water to adjust the solids content,

[0202] (iii) Add taurine and barium acetate crystals to the blended slurry and mix,

[0203] (iv) Spray-dry the slurry (iii), followed by calcination,

[0204] (v) Slurry the spray-dried powder obtained in step (iv),

[0205] (vi) Add palladium nitrate solution and mix,

[0206] (vii) Adjust the pH to 7 or higher,

[0207] (viii) Thicken the carrier coating;

[0208] The final composition of the front zone of the top layer carrier coating contains: 0.4 g / in 3 of cerium zirconia composite, 0.8 g / in 3 of alumina doped with 4% La2O3, 150 g / ft 3 of Ba element and 131 g / ft 3 of Pd element.

[0209] The carrier coating is also applied in the same manner as that of the reference catalyst 1.

[0210] The catalyst of the present invention 2 - BaSO4 is spray-dried onto the blended carrier, and the loading amount is 300 g / ft 3 BaSO4

[0211] Accordingly, the slurry of the front zone and the rear zone carrier coatings of the bottom layer is prepared in the same manner as that of the reference catalyst 1.

[0212] The front zone carrier coating of the top layer is prepared in the same method as that of the catalyst 1 of the present invention, and the only difference is that the amount of barium acetate in the preparation step (iii) of the front zone carrier coating of the top layer is 300 g / ft 3 .

[0213] The final composition of the front zone of the top layer carrier coating contains: 0.4 g / in 3 of cerium zirconia composite, 0.8 g / in 3 of alumina doped with 4% La2O3, 300 g / ft 3 of Ba element and 131 g / ft 3 of Pd element.

[0214] The application of the carrier coating is the same as that of the reference catalyst 1.

[0215] Example 1: XRD Analysis of Barium Sulfate Substance

[0216] The microcrystalline sizes of Ba species in the spray-dried powders of the catalyst 1 of the present invention and the catalyst 2 of the present invention were analyzed by XRD, and the results are shown in Table 1. For comparison, the microcrystalline size of the BaSO4 compound used in the reference catalyst 1 was also measured by the same technique and reported.

[0217] Table 1: XRD Results

[0218]

[0219] Barite (BaSO4) was detected only in the reference catalyst 1, the catalyst 1 of the present invention, and the catalyst 2 of the present invention. The estimated microcrystalline size of BaSO4 in the reference catalyst 1 was about 170 nm, with a standard deviation of 3 nm. In contrast, in these two catalysts of the present invention prepared by the spray-drying method, the size of barite (BaSO4) was 7 nm to 12 nm, significantly smaller than that of the conventional method.

[0220] Ba is a well-known Pd promoter in TWC technology. Ba can provide electrons to Pd, making the electronic configuration of Pd( II ) more like that of Rh, and thus can improve the Pd function. To maximize this promotion effect, close contact between Ba and Pd is highly desirable. Generally, Pd species are highly dispersed (not measurable in this study) and most are located in the pores of the support material. Smaller particle size of Ba species is beneficial because it is particularly more likely to enter the pores of the support, resulting in close proximity of Ba and Pd. These two catalysts of the present invention obtain fresh Ba species, whose size is approximately one-fifteenth of the Ba species in the reference catalyst, so an enhanced Pd-Ba interaction is expected.

[0221] Example 2: FE-EPMA Analysis of the Interaction between PD and BA

[0222] The Pearson correlation coefficient (product-moment correlation coefficient) is calculated based on the results of area analysis by FE-EPMA and is shown in Table 2. Using this technique, three different carrier coating regions from each sample were analyzed (each extracted carrier coating region contained approximately 3000 to 5000 pixels), and the values in Table 2 are the average of the measurement results for each region. When using the BaSO4 compound, the Ba-Al and Ba-Ce interactions of reference catalyst 1 were almost zero. This is because micron-sized BaSO4 compound particles were used. In contrast, for the two spray-dried powders, the Pearson correlation coefficients of Ba-Al and Ba-Ce were both positive, indicating that BaSO4 was effectively dispersed on both carrier materials. In addition, the Pd-Ba interaction enhancement characteristics of these two catalysts of the present invention were verified by the relatively high Ba-Pd correlation coefficients. For comparison, the correlation coefficient of reference catalyst 1 showed a slightly negative value of -0.15, indicating that Ba and Pd were randomly located and not physically close to each other.

[0223] Table 2: Pearson correlation coefficients obtained by EPMA

[0224]

[0225] Example 3: Ignition Performance Test in Engine Testing

[0226] All catalysts were aged on an engine bench for 108 hours using a stoichiometric / fuel cut-off aging cycle with a target catalyst bed peak temperature of 1000 °C and then tested on a gasoline engine. The light-off performance test was carried out under typical operating conditions: the gas hourly space velocity was 95 K / h, the temperature ramp was 10 °C / min, and the air-fuel ratio (AFR) λ value was perturbed periodically with an amplitude of ±0.5 around a reference point of 14.55. The conversions of THC, CO, and NO x were calculated by comparing the concentrations of the feed gas and the gas at the catalyst outlet.

[0227] T 50 The HC, CO, and NO at the light-off temperature x are shown in Table 3. The data clearly show that both catalyst 1 of the present invention and catalyst 2 of the present invention showed significantly improved light-off performance compared to reference catalyst 1. Specifically, the activity of catalyst 2 of the present invention was even higher than that of catalyst 1 of the present invention, with T 50 about 15 °C to 20 °C lower (T 50 is the temperature at which the conversion rate reaches 50%).

[0228] Table 3: Engine Bench Flameout Test Results

[0229]

[0230] Example 4: Temperature Rise Test in Engine Testing

[0231] All catalysts were aged on an engine bench for 108 hours using a stoichiometric / fuel cut-off aging cycle with a target catalyst bed peak temperature of 1000 °C and then tested on a gasoline engine. The temperature rise test was typically carried out at a gas hourly space velocity of 95 K. Pollutants from the engine were preheated to 490 °C and then directed to the cold catalyst. Total hydrocarbons, carbon monoxide, and NO x The time to reach 50% conversion was named T 50 HC, T 50 CO, and T 50 NO x . The conversions of THC, CO, and NO were calculated by comparing the concentrations of the feed gas and the gas at the catalyst outlet x .

[0232] The data in Table 4 clearly show that both Catalyst 1 and Catalyst 2 of the present invention heat up faster than Reference Catalyst 1. Specifically, Catalyst 1 of the present invention has even higher activity than Catalyst 2 of the present invention, showing the shortest time to reach a specific conversion level.

[0233] Table 4: Engine Bench Temperature Rise Test Results

[0234]

[0235] Reference Catalyst 2

[0236] The underlying support coating slurry was prepared by the following method:

[0237] (i) Grind and make a slurry containing alumina doped with 4% La2O3 separately,

[0238] (ii) Grind and make a slurry containing a cerium-zirconium mixed oxide separately,

[0239] (iii) Blend the alumina slurry doped with 4% La2O3 and the cerium-zirconium mixed oxide slurry together,

[0240] (iv) Add the required amount of palladium nitrate,

[0241] (v) Add barium nitrate,

[0242] (vi) Add a binder,

[0243] (vii) Thickened the support coating slurry using a rheology modifier.

[0244] The final composition of the underlying support coating contains 0.4 g / in 3Alumina doped with 4% La2O3, 0.95 g / in 3 Cerium zirconia composite, 150 g / ft 3 Element Ba, 18.2 g / ft 3 Element Pd.

[0245] The top rear zone carrier coating slurry is prepared as follows:

[0246] (i) Grind and make a slurry containing a mixed oxide of cerium oxide and zirconia,

[0247] (ii) Add a rhodium nitrate solution to the slurry (i),

[0248] (iii) Adjust the pH of the slurry (ii) so that Rh precipitates onto the mixed oxide,

[0249] (iv) Add the ground alumina doped with 4% La2O3 to the slurry (iii),

[0250] (v) Thicken the carrier coating using a rheology modifier.

[0251] The final composition of the top rear zone carrier coating contains: a total of 1.5 g / in 3 Cerium zirconia composite, 0.5 g / in 3 Alumina doped with 4% La2O3, and 10.5 g / ft 3 Element Rh.

[0252] The top front zone carrier coating is prepared as follows:

[0253] (i) Grind the mixed oxide of cerium oxide and zirconia,

[0254] (ii) Grind and make a slurry containing alumina doped with 4% La2O3,

[0255] (iii) Blend the above two slurries (ii) and (iii).

[0256] (iv) Add palladium nitrate to the slurry (iii) for mixing,

[0257] (v) Add gallic acid and mix,

[0258] (vi) Add barium sulfate powder and mix,

[0259] (vii) Adjust the pH to 7.0 or higher,

[0260] (viii) Thicken the carrier coating (iv) using a rheology modifier.

[0261] The final composition of the top front zone washcoat contains: 0.4 g / in 3 of cerium zirconium oxide composite, 0.8 g / in 3 of alumina doped with 4% La2O3, 150 g / ft 3 of Ba element and 153 g / ft 3 of Pd element.

[0262] Coat the washcoat on the monolithic flow-through substrate:

[0263] (i) Using the precision coating method, first apply a dose of 50% to 55% of the application length to the bottom front zone. Dry to a moisture removal rate of 80% or higher.

[0264] (ii) Coat the bottom rear zone washcoat to reach the target value of 50% to 55% of the application length. Dry to a moisture removal rate of 80% or higher, and then calcine.

[0265] (iii) Apply the top rear zone by the precision coating method, with the target application length controlled at 65% to 75%. Dry to a moisture removal rate of 80% or higher.

[0266] (iv) Coat the top front zone washcoat to reach the target value of 35% to 25% of the application length. Dry to a moisture removal rate of 80% or higher, and then calcine.

[0267] Catalyst 3 of the Present Invention - Spray-Drying BaSO4 on Alumina Doped with 4% La2O3, Loading Amount 150g / ft 3 BaSO4

[0268] Prepare the bottom washcoat slurry and the top rear zone washcoat slurry in the same manner as that of the reference catalyst 2.

[0269] The top front zone washcoat is prepared as follows:

[0270] (i) Make a slurry containing alumina doped with 4% La2O3,

[0271] (ii) Add taurine and barium acetate crystals to the blended slurry and mix,

[0272] (iii) Spray-dry the slurry (ii), and then calcine,

[0273] (iv) Slurry the spray-dried powder obtained in step (iii),

[0274] (v) Grind separately and make a slurry containing the cerium zirconium mixed oxide;

[0275] (vi) Add the cerium zirconium mixed oxide slurry to the slurry in step (iv),

[0276] (vii) Add palladium nitrate solution and mix.

[0277] (viii) Thicken the washcoat.

[0278] The final composition of the washcoat for the top front zone contains: 0.4 g / in 3 of cerium zirconium composite, 0.8 g / in 3 of alumina doped with 4% La2O3, 150 g / ft 3 of Ba element and 153 g / ft 3 of Pd element.

[0279] The washcoat is also applied in the same manner as that of the reference catalyst 2.

[0280] Example 5: Temperature Rise Test in Engine Testing

[0281] All the catalysts are aged on an engine bench for 108 hours using a stoichiometric / fuel cut-off aging cycle with a target catalyst bed peak temperature of 1000 °C, and then tested on a gasoline engine. The warm-up test is usually carried out at a gas hourly space velocity of 95 K. The pollutants from the engine are preheated to 490 °C and then directed to the cold catalyst. Record the time to reach 50% conversion for total hydrocarbons, carbon monoxide and NO x , named as T 50 HC, T 50 CO and T 50 NO x . Calculate the conversion rates of THC, CO and NO x by comparing the concentrations of the feed gas and the gas at the catalyst outlet.

[0282] The data in Table 5 clearly show that the catalyst 3 of the present invention exhibits a shorter time to reach a specific conversion level.

[0283] Table 5: Engine Bench Temperature Rise Test Results

[0284] Time (s) Reference Catalyst 2 Catalyst 3 of the Present Invention <![CDATA[T 50 HC]]> 10.4 9.4 <![CDATA[T 50 CO]]> 8.3 7.4 <![CDATA[T 50 NO x > 9.7 8.1

[0285] The above detailed description has been provided by way of illustration and example, and is not intended to limit the scope of the appended claims. Many variations of the presently preferred embodiments illustrated herein will be apparent to those of ordinary skill in the art and remain within the scope of the appended claims and their equivalents.

Claims

1. A method for manufacturing a support material loaded with alkaline earth metal sulfate, the method comprising: Providing a first slurry, the 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 sulfonic acid group (-SO3H), a sulfonyl group (-S(=O)2-), 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 a support material loaded with alkaline earth metal sulfate.

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

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

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

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

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

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

8. The method according to any one of claims 1 to 4, wherein the organic compound comprises one or more of methanesulfonic acid, taurine, hypotaurine, 4-aminobutane-1-sulfonic acid, 2-aminopropane-1-sulfonic acid, 2-methyltaurine, dimethyl sulfone, sulfan, sulfopropylalanine, dimethyl sulfoxide, and aminobenzenesulfonic acid, preferably taurine.

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

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

11. The method according to any one of the preceding claims, wherein the support material comprises one or more of alumina, silica, titanium dioxide, cerium dioxide, zirconium oxide, cerium dioxide-zirconium oxide mixed oxide, vanadium oxide, lanthanum oxide, and zeolite.

12. The method according to any one of the preceding claims, wherein the support material comprises alumina and / or cerium dioxide-zirconium oxide mixed oxide, preferably wherein the support material comprises alumina and cerium dioxide-zirconium oxide mixed oxide.

13. The method according to claim 12, wherein the alumina and / or cerium dioxide-zirconium oxide mixed oxide is doped with a dopant.

14. The method according to claim 13, wherein the alumina and / or cerium dioxide-zirconium oxide 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 a dopant comprising one or more of lanthanum, neodymium, and yttrium.

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

16. The method according to any one of the preceding claims, wherein the carrier material is in powder form and has a D 50 of from 0.1 μm to 30 μm, preferably from 2 μm to 10 μm, as measured by dynamic light scattering.

17. The method according to any one of the preceding claims, wherein providing the first slurry comprising a support material, alkaline earth metal ions and an organic compound comprises: providing a solution comprising the alkaline earth metal ions and the organic compound, preferably wherein the solution is an aqueous solution; providing a support material; and bringing the solution into contact with the support material to form the first slurry.

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

19. The method according to any one of the preceding claims, 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 has a solids content of 5% to 40%, preferably 10% to 30%.

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

22. A support material loaded with alkaline earth metal sulfate, the support material loaded with alkaline earth metal sulfate being obtainable or obtained by the method according to any one of the preceding claims.

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

24. The support material loaded with alkaline earth metal sulfate 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 nm to 25 nm or 5 nm to 20 nm.

25. A method of manufacturing a catalyst article, the method comprising: manufacturing a support material loaded with alkaline earth metal sulfate by the method according to any one of claims 1 to 21, or providing a support material loaded with alkaline earth metal sulfate according to any one of claims 22 to 24; providing a second slurry comprising the support material loaded with alkaline earth metal sulfate and platinum group metal ("PGM") ions; disposing the second slurry on a substrate; and heating the second slurry to form PGM nanoparticles on the support material loaded with alkaline earth metal sulfate.

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

27. The method according to claim 25 or claim 26, wherein providing the second slurry comprises: providing an intermediate slurry comprising the carrier material loaded with the alkaline earth metal sulfate; and contacting the intermediate slurry with a PGM salt, preferably with a solution comprising the PGM salt.

28. The method according to claim 27, wherein providing the intermediate slurry comprises subjecting the carrier material loaded with the alkaline earth metal sulfate to a crushing treatment, preferably using a high shear mixer, such that the D 50 is from about 5 μm to 15 μm, more preferably from about 4 μm to 6 μm.

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

30. The method according to any one of claims 25 to 29, wherein the second slurry further comprises one or more of the following components: a binder; an acid or a base; a thickening agent and / or another inorganic oxide.

31. The 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 according to any one of claims 25 to 31, wherein setting the second slurry on a substrate comprises applying a carrier coating.

33. The method according to any one of claims 25 to 22, wherein setting the second slurry on the substrate comprises 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.

34. The method according to any one of claims 25 to 33, wherein heating the slurry to form PGM nanoparticles on the carrier material loaded with the alkaline earth metal sulfate comprises heating according to the following parameters: 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 10 minutes to 360 minutes, preferably 35 minutes to 120 minutes.

35. The method according to any one of claims 25 to 34, wherein heating the slurry to form PGM nanoparticles on the carrier material loaded with the alkaline earth metal sulfate comprises calcination.

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

37. The method according to 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 catalyst article, the catalyst article being obtainable or obtained by the method according to any one of claims 25 to 37.

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

40. The catalyst article according to 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 nm to 25 nm or 5 nm to 20 nm.

41. The catalyst article according to claim 40, wherein the carrier material loaded with the alkaline earth metal sulfate is present in a first catalytic zone, and wherein the nanoparticles of the alkaline earth metal sulfate are uniformly distributed within the first catalytic zone.

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

43. The catalyst article according to 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%, where M is the crystallite size of the PGM nanoparticles and C is the crystallite size of the nanoparticles of the alkaline earth metal sulfate.

44. A catalyst article according to any one of claims 38 to 43, wherein the support material loaded with alkaline earth metal sulfate is present in the first catalytic region, and wherein when the cross-section of the first catalytic region of the catalyst article is subjected to area analysis by FE-EPMA under the conditions of a pixel (cross-section) size of 0.34 μm × 0.34 μm and a measured number of pixels (cross-section) 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 α and β obtained for each pixel is designated as R Ae / Pd , and thus R Ae / Pd has a value of at least 0.

1.

45. The catalyst article according to any one of claims 38 to 44, wherein the carrier material loaded with the alkaline earth metal sulfate is present in a first catalytic zone, and the carrier material comprises alumina and a cerium-zirconium mixed oxide; and When area analysis of the cross-section of the first catalytic region of the catalyst article is performed by FE-EPMA under the conditions that the pixel (cross-section) size is 0.34 μm × 0.34 μm and the number of measured pixels (cross-sections) is 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 aluminum (A1) are measured for each pixel, and the Pearson correlation coefficient calculated using α and γ obtained for each pixel is designated as R Ae / Al , then R Ae / A1 has a value of at least 0.1; and When the cross-section of the first catalytic region of the catalyst article is subjected to area analysis by FE-EPMA under the conditions that the pixel (cross-section) size is 0.34 μm × 0.34 μm and the number of measured pixels (cross-sections) is 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 cerium (Ce) are measured for each pixel, and the Pearson correlation coefficient calculated using α and δ obtained for each pixel is designated as R Ae / Ce , and then R Ae / Ce has a value of at least 0.

1.

46. The catalyst article according to any one of claims 38 to 45, wherein the total loading of the supported alkaline earth metal sulfate carrier material on which the PGM (such as Pd) nanoparticles are formed is 0.5 g / in 3 to 5 g / in 3 .

47. A catalyst article comprising: a substrate; and a first catalytic zone disposed on the substrate; wherein the first catalytic zone comprises a carrier material on which PGM (such as Pd) nanoparticles and nanoparticles of an alkaline earth metal sulfate are loaded; wherein the nanoparticles of the alkaline earth metal sulfate are uniformly distributed within the first catalytic zone.

48. The catalyst article according to claim 47, the catalyst article being obtained or capable of being obtained by the method according to any one of claims 25 to 37.

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

50. The catalyst article according to any one of claims 38 to 49, wherein the carrier material loaded with the alkaline earth metal sulfate is present in a first catalytic zone, and the catalyst article further comprises a second catalytic zone; and wherein the second catalytic zone contains palladium, platinum, and / or rhodium.

51. The catalyst article according to claim 50, wherein the first catalytic zone forms a first layer on the substrate, and the second catalytic zone 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 wherein the first catalytic zone and the second catalytic zone are each directly disposed on the substrate.

52. The catalyst article according to claim 50 or claim 51, further comprising a third catalytic zone, wherein the second catalytic zone contains palladium and / or platinum; and optionally Wherein the third catalytic region contains rhodium and is disposed on top of the first catalytic region and / or the second catalytic region such that the first catalytic region and / or the second catalytic region is each located between the third catalytic region and the substrate.

53. The catalyst article according to any one of claims 38 to 52, which contains from 10 g / ft 3 to 200 g / ft 3 of palladium, preferably from 50 g / ft 3 to 150 g / ft 3 of palladium.

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

55. The emissions treatment system according to claim 54, which is for a gasoline engine.

56. The emissions treatment system according to claim 55, wherein the gasoline engine operates under stoichiometric conditions.

57. A method of treating exhaust gas, the method comprising: providing the catalyst article of any one of claims 38 to 53; and contacting the catalyst article with the exhaust gas.

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

59. The method according to claim 58, wherein the gasoline engine operates under stoichiometric conditions.

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