Diesel oxidation catalyst with improved hydrocarbon light-off properties

Abstract

The present disclosure relates to an oxidation catalyst composition for use in close-coupled diesel oxidation catalyst (ccDOC) applications, where the ccDOC can function as a heat generator under high space velocity conditions. The oxidation catalyst composition includes a high surface area support material doped with at least one metal oxide and a platinum group metal (PGM) supported on the doped high surface area support material.

Description

[Technical Field]

[0001] This application claims priority to U.S. Provisional Application No. 63 / 092,574, filed on 16 October 2020, the contents of which are incorporated herein by reference in their entirety.

[0002] This disclosure relates to catalyst compositions suitable for processing the exhaust gas flow of an internal combustion engine, such as a diesel engine, and catalyst articles and systems incorporating such compositions, and methods for using them. [Background technology]

[0003] Environmental regulations concerning emissions from internal combustion engines are becoming increasingly stringent worldwide. Lean combustion engines, such as diesel engines, offer users excellent fuel efficiency due to their high air-fuel ratio operation under lean fuel conditions. However, diesel engines emit particulate matter (PM), unburned hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx). x It also emits exhaust gases containing NO x This refers to various chemical species of nitrogen oxides, particularly nitric oxide and nitrogen dioxide. The two components of exhaust particulate matter are the soluble organic fraction (SOF) and the insoluble carbonaceous soot fraction. SOF condenses in layers on the soot and originates from unburned diesel fuel and lubricating oil. Depending on the exhaust gas temperature, SOF exists in diesel exhaust as vapor or aerosol (i.e., fine droplets of liquid condensate). Soot is composed of carbon particles.

[0004] Oxidation catalysts containing noble metals, such as one or more platinum group metals (PGMs), dispersed on a refractory metal oxide support such as alumina, are used in the exhaust treatment of diesel engines to convert both hydrocarbon and carbon monoxide gaseous pollutants into carbon dioxide and water by catalyzing the oxidation of these pollutants. Such catalysts are contained in a unit called a diesel oxidation catalyst (DOC), which is placed in the exhaust passage from the diesel engine to treat the exhaust before releasing it into the atmosphere. Diesel oxidation catalysts may be formed on a ceramic or metallic substrate on which one or more catalyst coating compositions are deposited. In addition to the conversion of gaseous HC and CO emissions and particulate matter (SOF portion), oxidation catalysts containing one or more PGMs promote the oxidation of NO to NO2. The catalyst is defined, for example, at its light-off temperature or the temperature at which 50% conversion is achieved (T 50 Characterized by (also known as)

[0005] As regulations on vehicle emissions become stricter, controlling emissions during the cold start period is becoming increasingly important. NOx emission regulations for large diesel vehicles in 2024 require tailpipe NOx to be below 0.1 g / HP-Hr. Catalysts used to treat internal combustion engine exhaust are less effective at relatively low temperatures, such as during the initial cold start period of engine operation, because the engine exhaust is not hot enough (e.g., below 200°C) for effective catalytic conversion of toxic components in the exhaust. At low temperatures, exhaust gas treatment systems are less effective at handling hydrocarbons (HC) and nitrogen oxides (NOx). x ) and / or do not exhibit sufficient catalytic activity to effectively treat carbon monoxide (CO) emissions. For example, catalytic components such as selective catalytic reduction (SCR) catalyst components do not exhibit sufficient catalytic activity at temperatures above 200°C. xWhile effective in converting to N2, it does not exhibit sufficient activity at lower temperature ranges (<200°C), such as during cold starts or prolonged low-speed city driving. During initial engine startup, for example, during the first 400 seconds of operation, the exhaust temperature at the SCR inlet may be below 170°C, at which temperature the SCR may not yet be fully functional. As a result, nearly 70% of the system outlet NOx may be emitted during the first 500 seconds of engine operation.

[0006] Currently, DOC performance and SCR performance during cold start (i.e., NO before SCR functions) x A gap exists between DOC and SCR performance because DOC operates at lower temperatures than SCR. One way to improve DOC+SCR system performance is to accelerate SCR performance at the low-temperature end of the spectrum by rapidly heating the gas entering the SCR before the total NOx emissions exceed the regulation limit. Achieving this result without relying on impractical electric heating is difficult. Therefore, there is a need in the art for a system that improves the performance of DOC+SCR systems during low-temperature operation. [Overview of the project] [Problems that the invention aims to solve]

[0007] This disclosure provides oxidation catalyst compositions for use in applications of close-coupled diesel oxidation catalysts (ccDOCs), where the ccDOC functions as a heat generator. Typical oxidation catalyst compositions (e.g., DOC compositions) may not be suitable for use in such ccDOC applications. Applications of close-coupled diesel oxidation catalysts require formulations that function for low-temperature HC light-off in the presence of nitric oxide (NO) to suppress HC light-off. In some embodiments of this disclosure, it has been found that certain weakly acidic, porous, high-surface-area support materials supporting platinum group metals (PGMs) can be used to minimize NO interference in HC light-off. Furthermore, in some embodiments, the catalyst compositions disclosed herein are suitable for use under high space velocity conditions, and are suitable for applications in ccDOCs, for example. [Means for solving the problem]

[0008] Therefore, in some embodiments, oxidation catalyst compositions for use in a closely coupled diesel oxidation catalyst (ccDOC) are provided, the oxidation catalyst composition comprising a high surface area alumina support material doped with at least one metal oxide, and a platinum group metal (PGM) supported on the doped alumina support material, wherein the ccDOC is 100,000 h -1 The doped high-surface-area alumina support material functions at the above space velocity and lights off hydrocarbons at temperatures below approximately 250°C in the presence of nitric oxide (NO), and the doped high-surface-area alumina support material is a large-pore material having an average pore opening size of at least approximately 15 nm, and the doped high-surface-area alumina support material has a total acidity greater than 300 μmol per gram, or both.

[0009] In some embodiments, the doped high-surface-area alumina-supported material has a Brønsted acidity greater than 1 μmol per gram.

[0010] In some embodiments, at least one metal oxide is an oxide of titanium, silicon, manganese, iron, nickel, zinc, zirconium, tin, or any combination thereof. In some embodiments, at least one metal oxide is selected from titanium oxide, silicon oxide, manganese oxide, iron oxide, nickel oxide, zinc oxide, zirconium oxide, tin oxide, and combinations thereof. In some embodiments, at least one metal oxide is selected from silica, titania, manganese oxide, and combinations thereof. In some embodiments, at least one metal oxide is titania.

[0011] In some embodiments, the oxidation catalyst composition comprises from about 1 wt% to about 20 wt% of at least one metal oxide, based on the total mass of the oxidation catalyst composition.

[0012] In some embodiments, the oxidation catalyst composition comprises from about 1 wt% to about 10 wt% of PGM, based on the total mass of the oxidation catalyst composition. In some embodiments, the PGM is platinum or a mixture of platinum and palladium. In some embodiments, the PGM is a mixture of platinum and palladium having a mass ratio of platinum to palladium of from about 1 to about 10.

[0013] In some embodiments, the oxidation catalyst composition effectively oxidizes HC in an exhaust gas stream containing hydrocarbons (HC) and nitrogen oxides (NOx), where the exhaust gas stream has a ratio of CO to HC of 100 or greater. In some embodiments, the oxidation catalyst composition effectively oxidizes HC in an exhaust gas stream containing hydrocarbons (HC) and nitrogen oxides (NOx), where the exhaust gas stream has a ratio of CO to HC in the range of 100 to 10,000.

[0014] In some embodiments, the high surface area alumina support material has a surface area of at least about 90 m 2 / g. In some embodiments, the high surface area alumina support material has a surface area of from about 90 m 2 / g to about 150 m 2 / g.

[0015] In some embodiments, the high-surface-area alumina support material is a large-pore material having an average pore opening size of at least about 15 nm. In some embodiments, the high-surface-area alumina support material is a large-pore material having an average pore opening size of about 15 nm to about 200 nm, or about 20 nm to about 50 nm.

[0016] In some embodiments, the high-surface-area alumina support material is doped with about 1% to about 20% titania, based on the mass of the doped high-surface-area alumina support material. In some embodiments, the high-surface-area alumina support material is doped with about 1% to about 10% titania, or about 3% to about 7% titania, based on the mass of the doped high-surface-area alumina support material.

[0017] In some embodiments, the oxidation catalyst composition further comprises manganese oxide.

[0018] In some embodiments, the oxidation catalyst composition comprises about 1% to about 5% by mass of platinum, palladium, or a mixture thereof, based on the total mass of the oxidation catalyst composition, where the high surface area alumina support material is doped with about 5% to about 10% by mass of titania, based on the mass of the doped high surface area alumina support material, and the high surface area alumina support material is about 90 m 2 / g ~ approx. 150m 2 It has a surface area per g and an average pore opening size of approximately 15 nm to approximately 200 nm, or both.

[0019] In some embodiments, hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NO) are used. xA system is provided for processing exhaust gas flows from an internal combustion engine containing ), the system comprising: a close-coupled diesel oxidation catalyst (ccDOC) article located downstream of the internal combustion engine, comprising a substrate and an oxidation catalyst composition disclosed herein disposed on at least a portion of the substrate; a diesel oxidation catalyst (DOC) article located downstream of the engine and adapted for the oxidation of HC, CO and NOx; and a system located downstream of the DOC article and adapted for the oxidation of nitrogen oxides (NOx). x The system includes selective catalytic reduction (SCR) articles adapted for the reduction of ) and any catalyst articles in fluid communication with the exhaust gas flow. In some embodiments, the system including the engine and the close-coupled diesel oxidation catalyst has fewer than five catalyst articles in fluid communication between the engine and the close-coupled diesel oxidation catalyst. In some embodiments, the system including the engine and the close-coupled diesel oxidation catalyst has fewer than four catalyst articles in fluid communication between the engine and the close-coupled diesel oxidation catalyst. In some embodiments, the system including the engine and the close-coupled diesel oxidation catalyst has fewer than three catalyst articles in fluid communication between the engine and the close-coupled diesel oxidation catalyst. In some embodiments, the system including the engine and the close-coupled diesel oxidation catalyst has fewer than two catalyst articles in fluid communication between the engine and the close-coupled diesel oxidation catalyst. In some embodiments, the system including the engine and the close-coupled diesel oxidation catalyst has no catalyst articles in fluid communication between the engine and the close-coupled diesel oxidation catalyst.

[0020] In some embodiments, the disclosure relates to HC and NO present in the exhaust gas stream from an internal combustion engine. xThe present invention provides a method for reducing NO2, the method comprising: an introduction step of introducing a quantity of HC into the exhaust flow to form an HC-rich exhaust gas flow; a contact step of contacting the HC-rich exhaust gas flow with an oxidation catalyst composition disclosed herein to generate heat through the combustion of HC, thereby forming a heated first effluent, where the oxidation catalyst composition is placed on a substrate and is located in close proximity downstream of the internal combustion engine; a contact step of contacting the heated first effluent with a diesel oxidation catalyst adapted for the oxidation of HC and NO, thereby forming a second effluent in which the level of HC is reduced and the level of NO2 is increased; an injection step of injecting a reducing agent into the second effluent that has exited the diesel oxidation catalyst to obtain a third effluent; and a third effluent being treated with NO2. x By contacting it with an SCR catalyst suitable for reduction, HC and NO are produced. x The process includes a contact step, which forms a treated exhaust gas flow with a reduced level.

[0021] These and other features, aspects, and advantages in this disclosure will become apparent from reading the following detailed description in conjunction with the accompanying drawings briefly described below. This disclosure includes any combination of two, three, four or more of the embodiments described above, and any combination of two, three, four or more features or elements described herein, whether or not such features or elements are expressly combined in any particular embodiment described herein. This disclosure is intended to be read holistically so that any distinguishable feature or element of the disclosure is intended to be combinable in any of its various aspects and embodiments, unless the context clearly indicates otherwise. Other aspects and advantages of this disclosure will become apparent below. [Brief explanation of the drawing]

[0022] To provide an understanding of the embodiments of this disclosure, accompanying drawings are referenced, with reference numbers indicating components of exemplary embodiments. The drawings are illustrative and should not be construed as limiting this disclosure. The disclosures described herein are shown as examples, not limitations, in the accompanying drawings. For simplicity and clarity, the features shown in the drawings are not necessarily drawn to scale. For example, the dimensions of some features may be exaggerated in comparison to others for clarity. Furthermore, where appropriate, reference numerals are repeated between the drawings to indicate corresponding or similar elements. [Figure 1] Figure 1A is a perspective view of an exemplary honeycomb substrate containing the oxidation catalyst composition according to the present disclosure. Figure 1B is an enlarged partial cross-sectional view of Figure 1A, which is along a plane parallel to the end face of the substrate in Figure 1A in an embodiment in which the substrate is a flow-through substrate, and shows an enlarged view of the multiple gas flow passages shown in Figure 1A. [Figure 2] Figure 2 is a cross-sectional view of an exemplary wall-flow filter. [Figure 3] Figures 3A, 3B, and 3C are non-limiting illustrations of exemplary coating configurations. [Figure 4] Figure 4 is a schematic diagram showing one embodiment of an exhaust treatment system in which the ccDOC catalyst article of this disclosure is used. [Figure 5] Figure 5 is a schematic diagram showing one embodiment of an exhaust treatment system in which the ccDOC catalyst article of this disclosure is used. [Figure 6] Figure 6 is a graph of CO2 generation amount versus temperature according to one embodiment of the present disclosure. [Figure 7] Figure 7 is a graph of CO2 generation amount versus temperature according to one embodiment of the present disclosure. [Figure 8] Figure 8 is a graph of CO2 generation amount versus temperature according to one embodiment of the present disclosure. [Figure 9] Figure 9 is a graph of CO2 generation amount versus temperature according to an embodiment of the present disclosure. [Figure 10] Figure 10 is a graph of CO2 generation amount versus temperature according to one embodiment of the present disclosure. [Figure 11] Figure 11 is a graph of CO2 generation amount versus temperature according to one embodiment of the present disclosure. [Figure 12] Figure 12 is a graph of CO2 generation amount versus temperature according to an embodiment of the present disclosure. [Figure 13] Figure 13 is a graph showing the amount of N2O and CO2 generated versus temperature according to one embodiment of the present disclosure. [Figure 14] Figure 14 is a graph of CO2 generation amount versus temperature according to one embodiment of the present disclosure. [Figure 15] Figure 15 is a graph of CO2 generation amount versus temperature according to one embodiment of the present disclosure. [Figure 16] Figure 16 is a graph showing the amount of NO2, N2O, and CO2 generated versus temperature according to one embodiment of the present disclosure. [Figure 17] Figure 17 is a graph showing the amount of NO2, N2O, and CO2 generated versus temperature according to one embodiment of the present disclosure. [Figure 18] Figure 18 shows an infrared absorption spectrum according to an embodiment of the present disclosure. [Figure 19] Figure 19 shows an infrared absorption spectrum according to an embodiment of the present disclosure. [Figure 20] Figure 20 is a bar graph of DOC outlet temperature versus inlet temperature according to an embodiment of the present disclosure (fresh). [Figure 21] Figure 21 is a bar graph of DOC outlet temperature versus inlet temperature according to an embodiment of the present disclosure (fresh). [Figure 22] Figure 22 is a bar graph of DOC outlet temperature versus inlet temperature according to an embodiment of the present disclosure (aging). [Figure 23] Figure 23 is a line graph of DOC outlet temperature versus inlet temperature for an embodiment of the present disclosure with 0.6 volume% diesel fuel injection. [Figure 24] Figure 24 is a line graph of DOC outlet temperature versus inlet temperature in an embodiment of the present disclosure with 1 volume% diesel fuel injection. [Modes for carrying out the invention]

[0023] In some embodiments, the disclosure provides oxidation catalyst compositions for use in applications of closely coupled diesel oxidation catalysts (ccDOCs), where the ccDOC can function as a heat generator by oxidizing (i.e., burning) hydrocarbons (HC) obtained from rich HC injection in the cylinder or diesel fuel injection in the exhaust. In some embodiments, this HC combustion rapidly heats the exhaust gas flow leaving the ccDOC, resulting in the exhaust flow entering downstream catalyst articles, such as selective catalytic reduction (SCR) catalyst articles, having an elevated temperature, thereby promoting the cold-start NOx conversion performance of the SCR catalyst.

[0024] In some embodiments, the presence of nitric oxide (NO) in the exhaust gas stream suppresses HC combustion (elevated light-off temperature) within oxidation catalyst articles, such as DOC articles. In some embodiments, fuel combustion within oxidation catalyst articles under these exhaust diesel fuel injection ("in-pipe" fuel injection) conditions occurs at the approximate temperature at which the fuel is injected and at high space velocities. Typical oxidation catalyst (e.g., DOC) compositions may not be suitable for use under such conditions, and therefore, close-coupling applications may require oxidation catalysts with different formulations. In some embodiments of this disclosure, it has been found that certain weakly acidic, porous, high-surface-area support materials supporting platinum group metals (PGMs) can minimize NO interference in HC light-off. Furthermore, as disclosed herein, in some embodiments, catalyst compositions comprising such weakly acidic, porous, high-surface-area support materials supporting PGMs are suitable for use under high space velocity conditions and are suitable for applications in ccDOC.

[0025] The disclosure is described in more detail below. However, the disclosure may be embodied in many different forms and should not be construed as being limited to the embodiments described herein.

[0026] definition In this specification, the articles "a" and "an" refer to one or more grammatical objects (i.e., at least one). Any range referred to in this specification is inclusive. The term "about" used throughout is used to describe and explain small variations. For example, "about" means that there may be a modification of ±5%, ±4%, ±3%, ±2%, ±1%, ±0.5%, ±0.4%, ±0.3%, ±0.2%, ±0.1%, or ±0.05%. Any number, whether explicitly stated or not, is modified by the term "about". Numbers modified by the term "about" include a specific value. For example, "about 5.0" includes 5.0.

[0027] "Reduction" means a decrease in quantity caused by any means.

[0028] The term “related” means, for example, “equipped with,” “connected,” or “communicated,” for example, “electrically connected,” or “fluidally connected,” or otherwise connected in order to perform a function. The term “related” means, for example, directly or indirectly related through one or more other articles or elements.

[0029] "Average particle size" is D 50 This is synonymous with meaning that half of the particle population has a particle size greater than this point, and the other half has a particle size less than this point. Particle size refers to primary particles. Particle size is measured using laser light scattering techniques with a dispersion or dry powder, for example, in accordance with ASTM method D4464. 90 The particle size distribution, measured using a scanning electron microscope (SEM) or transmission electron microscope (TEM) for submicron-sized particles and a particle size analyzer for support-containing particles (micron size), shows that 90% (by number) of the particles have a Ferret diameter smaller than a certain size.

[0030] A "catalyst" is a substance that accelerates a chemical reaction. A catalyst includes a "catalytically active species" and a "carrier" that supports or holds the active species.

[0031] "Functional article" means an article comprising a substrate having a functional coating composition, particularly a catalyst and / or adsorbent coating composition, placed on top of it.

[0032] In this disclosure, the term "catalyst article" means an article comprising a substrate having a catalyst coating composition.

[0033] "CSF" refers to a catalytic soot filter that is a wall-flow monolith. The wall-flow filter consists of alternating inlet and outlet channels, where the inlet channel is blocked at the outlet end and the outlet channel is blocked at the inlet end. The exhaust gas flow carrying soot entering the inlet channel is forced to pass through the filter wall before exiting the outlet channel. In addition to soot filtration and regeneration, the CSF carries an oxidation catalyst, oxidizing CO and HC to CO2 and H2O, or NO to NO2, thereby promoting downstream SCR catalytic action or facilitating the oxidation of soot particles at lower temperatures. When placed behind the LNT catalyst, the CSF can have an H2S oxidation function to suppress H2S emissions during the LNT desulfurization process. In some embodiments, the SCR catalyst can also be directly coated onto the wall-flow filter, called SCRoF.

[0034] "DOC" refers to a diesel oxidation catalyst that converts hydrocarbons and carbon monoxide in the exhaust gas of a diesel engine. Typically, a DOC comprises one or more platinum group metals, such as palladium and / or platinum, a supporting material, such as alumina, HC storage zeolite, and optionally an accelerator and / or stabilizer.

[0035] "LNT" refers to platinum group metals, ceria, and the lean condition between NO x Lean NO is a catalyst containing an alkaline earth trapping material (e.g., BaO or MgO) suitable for adsorbing. x It refers to a trap. Under rich conditions, NO x It is released and reduced to nitrogen.

[0036] The term "catalytic system" used here refers to a combination of two or more catalysts, for example, the main oxidation catalyst and another catalyst, for example, lean NO x This refers to a combination of a trap (LNT), a catalytic soot filter (CSF), or a selective catalytic reduction (SCR) catalyst. Alternatively, the catalytic system may be in the form of a washcoat, where two or more catalysts are mixed together or coated in separate layers.

[0037] As used herein and in the claims, the term “composed of” is intended to be non-exclusive, like the terms “include” or “contain.” The term “composed of” does not mean to exclude other possible articles or elements. The term “composed of” may also be equivalent to “applicable.”

[0038] Generally, the term "effective" means that, with respect to the defined catalytic activity or storage / release activity, it is effective by mass or mole, for example, about 35% to 100%, about 40%, about 45%, about 50%, or about 55% to about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, or about 95%.

[0039] "Essentially absent" means "almost none" or "not intentionally added," and present only in trace and / or inadvertently present amounts. For example, in a particular embodiment, "essentially absent" means less than 2 wt%, less than 1.5 wt%, less than 1.0 wt%, less than 0.5 wt%, less than 0.25 wt%, or less than 0.01 wt%, based on the mass of the total composition shown.

[0040] The term "exhaust flow" or "exhaust gas flow" refers to any combination of flowing gases containing solid or liquid particulate matter. The flow contains gaseous components, such as the exhaust from a lean combustion engine, which contains certain non-gaseous components such as droplets and solid particulate matter. Typically, the exhaust gas flow from a combustion engine contains combustion products (CO2 and H2O), incomplete combustion products (carbon monoxide (CO) and hydrocarbons (HC)), and nitrogen oxides (NOx). x), further comprising flammable and / or carbonaceous particulate matter (soot), and unreacted oxygen and nitrogen. The terms “upstream” and “downstream” as used herein refer to the relative directions corresponding to the flow of engine exhaust gases from the engine to the tailpipe, with the engine located upstream and the tailpipe and any pollution reduction items, such as filters and catalysts, located downstream of the engine. The inlet end of the substrate is synonymous with the “upstream” end or “front” end. The outlet end is synonymous with the “downstream” end or “rear” end. The upstream area is upstream of the downstream area. The upstream area may be closer to the engine or manifold, and the downstream area may be further away from the engine or manifold.

[0041] The term "fluid-connected" is used to refer to articles located in the same exhaust line, i.e., articles through which a common exhaust flow passes. Fluid-connected articles may be adjacent to each other in the exhaust line, or they may be separated by one or more articles, also referred to as a "wash-coated monolith."

[0042] The term used here is "nitrogen oxide" or "NO x " specifies nitrogen oxides such as NO or NO2.

[0043] In this context, "impregnated" or "penetrated" refers to the process of allowing the catalyst material to penetrate the pore structure of the support material.

[0044] The terms "support" or "supporting material" used herein refer to any high-surface-area material to which the catalytic noble metal is applied, such as a metal oxide material. The term "on the support" means "dispersed on top of," "integrated into," "impregnated," "on top of," "inside," "deposited on top of," or other related terms.

[0045] The term "selective catalytic reduction" (SCR) used here refers to a catalytic process that reduces nitrogen oxides to dinitrogen (N2) using a nitrogen-based reducing agent.

[0046] As used herein, the term “substrate” refers to a monolithic material on which a catalyst composition, i.e., a catalyst coating, is typically arranged in the form of a wash coat. In some embodiments, the substrate is a flow-through monolith and a monolithic wall-flow filter. Flow-through and wall-flow substrates are also taught, for example, in International Patent Application Publication 2016 / 070090, which is incorporated herein by reference in its entirety. A wash coat is formed by preparing a slurry containing a predetermined solid content (e.g., 30–90% by mass) of catalyst in a liquid, then coating this onto the substrate and drying to provide a wash coat layer. The reference to “monolithic substrate” means a single, homogeneous and continuous structure from inlet to outlet. A wash coat is formed by preparing a slurry containing a specific solid content (e.g., 20%–90% by mass) of particles in a liquid medium, then coating this onto the substrate and drying to provide a wash coat layer.

[0047] The terms “on” and “over” in relation to coating layers are used synonymously. The term “directly on” means in direct contact. In certain embodiments of the disclosed articles, one coating layer is referred to as “on” a second coating layer, and such language is intended to encompass embodiments having an intervening layer where direct contact between coating layers is not required (i.e., “on” is not synonymous with “directly on”).

[0048] As used herein, “washcoat” has the common sense in the art and is a thin, adhered coating of a catalyst or other material applied to a substrate material, such as a honeycomb-type carrier member that is sufficiently porous for the gas flow to be treated to pass through. The metal-promoting molecular sieve-containing washcoat of this disclosure may optionally contain a binder selected from silica, alumina, titania, zirconia, ceria, or a combination thereof. The amount of binder supported is about 0.1 to 10 wt% based on the mass of the washcoat. As used herein and as described in Heck, Ronald and Farrauto, Robert, Catalytic Air Pollution Control, New York: Wiley-Interscience, 2002, pp. 18-19, the washcoat layer includes a washcoat layer constitutively distinct from, or underlying, a layer of material placed on the surface of a monolithic substrate. The substrate may contain one or more wash coat layers, each wash coat layer may differ in some way (for example, its physical properties, such as particle size or crystalline phase), and / or its chemical catalytic function may differ.

[0049] The term "vehicle" means any vehicle equipped with an internal combustion engine, including, but not limited to, passenger cars, sports utility vehicles, minivans, vans, trucks, buses, garbage trucks, freight trucks, construction vehicles, heavy machinery, military vehicles, and agricultural vehicles.

[0050] Unless otherwise specified, all parts and percentages are by mass. "Mass percentage (wt%)" is based on the entire composition excluding any volatiles, i.e., on the dry solids content, unless otherwise specified.

[0051] Any method described herein may be carried out in any preferred order, unless otherwise specified herein or unless it is clearly inconsistent with the context. Any examples or illustrative language provided herein (e.g., "etc.") are intended solely to better illustrate the materials and methods and do not limit their scope unless specifically claimed. Language in the specification should not be construed as indicating elements not claimed as essential to the carrying out of the disclosed materials and methods.

[0052] All U.S. patent applications, published patent applications, and patents referenced herein are incorporated herein by reference.

[0053] Non-exclusive exemplary embodiments Without limiting them, some embodiments of this disclosure include: 1. An oxidation catalyst composition for use in a closely coupled diesel oxidation catalyst (ccDOC), High surface area alumina support material doped with at least one metal oxide, and Platinum group metals (PGMs) supported on doped alumina support material, Including, here, ccDOC, 100,000h -1 It operates at the above space velocity to light off hydrocarbons at temperatures below approximately 250°C in the presence of nitric oxide (NO), and The doped high-surface-area alumina support material is a large-pore material having an average pore opening size of at least about 15 nm, and / or A doped high-surface-area alumina support material has a total acidity greater than 300 μmoles per gram. Oxidation catalyst composition.

[0054] 2. The oxidation catalyst composition of Embodiment 1, wherein the doped high-surface-area alumina support material has a Brønsted acidity greater than 1 μmol per gram.

[0055] 3. The oxidation catalyst composition of Embodiment 1, wherein at least one metal oxide is an oxide of titanium, silicon, manganese, iron, nickel, zinc, zirconium, tin, or any combination thereof.

[0056] 4. An oxidation catalyst composition of Embodiment 1, wherein at least one metal oxide is selected from silica, titania, manganese oxide, and combinations thereof.

[0057] 5. The oxidation catalyst composition of Embodiment 1, wherein at least one metal oxide is titania.

[0058] 6. The oxidation catalyst composition of Embodiment 1, wherein the oxidation catalyst composition contains at least one metal oxide in an amount of about 1% by mass to about 20% by mass, based on the total mass of the oxidation catalyst composition.

[0059] 7. The oxidation catalyst composition of Embodiment 1, wherein the oxidation catalyst composition contains about 1% by mass to about 10% by mass of PGM based on the total mass of the oxidation catalyst composition.

[0060] 8. The oxidation catalyst composition of Embodiment 1, wherein PGM is platinum or a mixture of platinum and palladium.

[0061] 9. The oxidation catalyst composition of Embodiment 1, wherein PGM is a mixture of platinum and palladium in which the mass ratio of platinum to palladium is about 1 to about 10.

[0062] 10. The oxidation catalyst composition of Embodiment 1, wherein the oxidation catalyst composition effectively oxidizes hydrocarbons (HC) and nitrogen oxides (NOx) in an exhaust gas stream, and the exhaust gas stream has a CO-to-HC ratio of 100 or more.

[0063] 11. High surface area alumina support material, at least about 90 m 2 The oxidation catalyst composition of Embodiment 1 having a surface area of ​​ / g.

[0064] 12. High surface area alumina support material, approximately 90 m 2 / g ~ approx. 150m2 The oxidation catalyst composition of Embodiment 1 having a surface area in the range of / g.

[0065] 13. The oxidation catalyst composition of Embodiment 1, wherein the high surface area alumina support material is a large-pore material having an average pore opening size of at least about 15 nm.

[0066] 14. The oxidation catalyst composition of Embodiment 1, wherein the high surface area alumina support material is a large-pore material having an average pore opening size in the range of about 15 nm to about 200 nm, or about 20 nm to about 50 nm.

[0067] 15. The oxidation catalyst composition of Embodiment 1, wherein a high-surface-area alumina support material is doped with about 1% to about 20% by mass of titania, based on the mass of the doped high-surface-area alumina support material.

[0068] 16. The oxidation catalyst composition of Embodiment 1, wherein the high surface area alumina support material is doped with about 1% to about 10% by mass of titania, or about 3% to about 7% by mass of titania, based on the mass of the doped high surface area alumina support material.

[0069] 17. The oxidation catalyst composition according to embodiment 15, further comprising manganese oxide.

[0070] 18. The oxidation catalyst composition contains approximately 1% to 5% by mass of platinum, palladium, or a mixture thereof, based on the total mass of the oxidation catalyst composition. The high-surface-area alumina support material is doped with approximately 5% to 10% titania, based on the mass of the doped high-surface-area alumina support material, and High surface area alumina support material, approximately 90m 2 / g ~ approx. 150m 2 An oxidation catalyst composition of Embodiment 1 having a surface area in the range of / g, an average pore opening size of about 15 nm to about 200 nm, or both.

[0071] 19. Hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx)x A system for processing exhaust gas flow from an internal combustion engine containing ), wherein the system: A close-coupled diesel oxidation catalyst (ccDOC) article located downstream of an internal combustion engine, comprising a substrate and an oxidation catalyst composition according to any one of claims 1 to 17 disposed on at least a portion of the substrate, A diesel oxidation catalyst (DOC) article located downstream of the engine and suitable for the oxidation of HC, CO, and NOx, Located downstream of DOC articles, nitrogen oxides (NOx) x Selective catalytic reduction (SCR) articles suitable for the reduction of ) Includes, A system in which all catalytic components are in fluid communication with the exhaust gas flow.

[0072] 20. HC and NO present in exhaust gases from internal combustion engines x A method of reducing, A process of introducing a certain amount of HC into the exhaust gas flow to form an exhaust gas flow rich in HC, A step of bringing an exhaust gas flow rich in HC into contact with an oxidation catalyst composition according to any one of claims 1 to 18, thereby generating heat through the combustion of HC, and thereby forming a heated first effluent, wherein the oxidation catalyst composition is placed on a substrate and is located in close proximity downstream of the internal combustion engine, A step of bringing a heated first effluent into contact with a diesel oxidation catalyst suitable for the oxidation of HC and NO, thereby forming a second effluent in which the level of HC is reduced and the level of NO2 is increased, A process in which a reducing agent is injected into the second effluent that has exited the diesel oxidation catalyst to obtain a third effluent, The third spill is NO x By contacting it with an SCR catalyst suitable for reduction, HC and NO are produced. x A method comprising the step of forming a treated exhaust gas flow with a reduced level.

[0073] Oxidation catalyst (DOC) composition In some embodiments, the Disclosure provides oxidation catalyst compositions for use in closely coupled diesel oxidation catalysts (ccDOCs), the compositions comprising a high-surface-area, large-pore-opening support material doped with at least one metal oxide, and a platinum group metal (PGM) supported on the doped, high-surface-area, large-pore-opening support material. Exemplary components of the compositions are further described below herein.

[0074] supporting material In some embodiments, the oxidation catalyst compositions described herein include a high-surface-area support material doped with at least one metal oxide. The term “support material” as used herein refers to a high-surface-area opening material on which a catalyst species (e.g., a platinum group metal) is supported, such as by precipitation, association, dispersion, impregnation, or other preferred methods.

[0075] "High surface area" is generally defined as 60 m². 2 exceeding / g, and in many cases up to approximately 200m 2 / g or more, for example, up to approximately 350m 2 This refers to a support material exhibiting a BET surface area of ​​1 / g. "BET surface area" has its usual meaning, referring to the Brunauer-Emmett-Teller method, which measures surface area by N2 adsorption measurement. Unless otherwise indicated, "surface area" refers to BET surface area. In some embodiments, high surface area opening support materials are at least about 90 m². 2 / g, for example, about 90ml 2 / g~about 200m 2 / g, or approximately 90m 2 / g ~ approx. 150m 2 It has a surface area of ​​ / g.

[0076] In some embodiments, the high-surface-area support material is a large-pore-aperture material. "Large-pore-aperture" means that the support particles have an average pore aperture size of at least about 15 nm, for example, about 15 nm to about 200 nm. In some embodiments, more than about 80% of the pores have a diameter greater than 20 nm. In some embodiments, the pore diameter is about 20 nm to about 50 nm. The pore diameter can be measured using BET-type N2 adsorption or desorption experiments.

[0077] In some embodiments, the support material includes a refractory metal oxide that exhibits chemical and physical stability at high temperatures, such as those associated with gasoline or diesel engine exhaust. Exemplary refractory metal oxides include alumina, silica, zirconia, titania, and other physical mixtures or chemical combinations thereof (e.g., atomically doped combinations, and activated compounds such as activated alumina). In some embodiments, the high-surface-area, large-pore-opening support material is selected from silica, alumina, titania, and combinations thereof. Useful commercially available aluminas used as starting materials in exemplary processes include activated alumina, e.g., high-bulk-density gamma alumina, low- or medium-bulk-density large-pore gamma alumina, and low-bulk-density large-pore boehmite and gamma alumina. In some embodiments, the high-surface-area, large-pore-opening support material includes alumina.

[0078] In some embodiments, the high surface area, large pore opening support material useful in the catalyst compositions disclosed herein is doped with at least one metal oxide. In some embodiments, the high surface area, large pore opening support material contains about 1% to about 20% by mass of at least one metal oxide, for example, about 1% to about 15% by mass, about 1% to about 10% by mass, or about 3% to about 7% by mass, based on the mass of the doped high surface area, large pore opening support material. In some embodiments, the high surface area, large pore opening support material contains at least one metal oxide in about 1% by mass, about 2% by mass, about 3% by mass, about 4% by mass, about 5% by mass, about 6% by mass, about 7% by mass, about 8% by mass, about 9% by mass, or about 10% to about 11% by mass, about 12% by mass, about 13% by mass, about 14% by mass, about 15% by mass, about 16% by mass, about 17% by mass, about 18% by mass, about 19% by mass, or about 20% by mass, based on the mass of the doped, high surface area, large pore opening support material.

[0079] Suitable metal oxides include titanium, silicon, manganese, iron, nickel, zinc, zirconium, tin, and combinations thereof. In some embodiments, at least one metal oxide is an oxide of titanium, silicon, manganese, iron, nickel, zinc, zirconium, tin, or any combination thereof. In some embodiments, at least one metal oxide is selected from silica, titania, and combinations thereof. In some embodiments, at least one metal oxide is titania.

[0080] In some embodiments, the support material for high surface area and large pore opening is silica doped with titania, manganese oxide, iron oxide, nickel oxide, zinc oxide, zirconia, tin oxide, or any combination thereof.

[0081] In some embodiments, the support material for high surface area and large pore openings is alumina doped with titania, silica, manganese oxide, iron oxide, nickel oxide, zinc oxide, zirconia, tin oxide, or any combination thereof. In some embodiments, the support material for high surface area and large pore openings is alumina doped with titania.

[0082] In some embodiments, the support material for high surface area and large pore opening is titania doped with alumina, silica, manganese oxide, iron oxide, nickel oxide, zinc oxide, zirconia, tin oxide, or any combination thereof.

[0083] In some embodiments, the high surface area, large pore opening support material is alumina doped with titania in amounts of about 1% to about 20% by mass, about 1% to about 10% by mass, or about 3% to about 7% by mass, based on the mass of the doped high surface area, large pore opening support material. In some embodiments, the titania-doped alumina is further doped with silica. In some embodiments, the high surface area, large pore opening support material is alumina doped with about 5% by mass or about 10% by mass, based on the mass of the doped high surface area, large pore opening support material.

[0084] In some embodiments, the dopant metal oxide(s) can be introduced, for example, by using an induced wetting impregnation technique or through the use of colloidal mixed oxide particles. In some embodiments, at least one metal oxide is present in the form of a mixed oxide in the doped, high-surface-area, large-pore-opening support material, meaning that the metal oxides are covalently bonded to each other via shared oxygen atoms.

[0085] Platinum group metals (PGM) In some embodiments, the ccDOC compositions described herein include platinum group metals (PGMs) supported on a doped, high-surface-area, large-pore-opening support material. PGMs include platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rh), osmium (Os), iridium (Ir), gold (Au), and mixtures thereof. PGMs may include PGMs in any valence state. The term “PGM” as used herein refers to both the catalytically active form of each PGM and the corresponding PGM compound, complex, etc., which decomposes upon calcination or use of the catalyst, or otherwise converts to the catalytically active form, typically a metal or metal oxide. PGMs may be in a metallic form with zero valence ("PGM(0)"), or PGMs may be in an oxide form (including, but not limited to, platinum or its oxides). The amount of PGM(0) present can be measured using ultrafiltration, followed by inductively coupled plasma / emission spectroscopy (ICP-OES) or X-ray photoelectron spectroscopy (XPS).

[0086] In some embodiments, PGM includes platinum, palladium, ruthenium, gold, or a combination thereof. In some embodiments, PGM includes platinum, palladium, or a combination thereof. In some embodiments, PGM is a combination of platinum and palladium. Exemplary mass ratios of Pt / Pd combinations include Pt:Pd mass ratios of about 30 to about 1, for example, about 30:1, about 25:1, about 20:1, about 15:1, about 10:1, about 5:1, about 4:1, about 3:1, about 2:1, or about 1:1. In some embodiments, the Pt / Pd mass ratio is about 30:1. In some embodiments, the Pt / Pd mass ratio is about 20:1. In some embodiments, the Pt / Pd mass ratio is about 10:1. In some embodiments, the Pt / Pd mass ratio is about 10:1 to about 1:1. In each case, the mass ratio is element (metal) based.

[0087] In some embodiments, the PGM may be present in an amount ranging from about 0.01% to about 20% by mass on a metal basis, based on the total mass of the doped, high-surface-area, large-porous-opening support material, including the supported PGM. In some embodiments, the ccDOC composition may contain, for example, Pt or Pt / Pd in ​​amounts ranging from about 0.1 wt%, about 0.5 wt%, about 1.0 wt%, about 1.5 wt%, or about 2.0 wt% to about 3 wt%, about 5 wt%, about 7 wt%, about 9 wt%, about 10 wt%, about 12 wt%, about 15 wt%, about 16 wt%, about 17 wt%, about 18 wt%, about 19 wt%, or about 20 wt%, based on the total mass of the doped, high-surface-area, large-porous-opening support material, including the supported PGM.

[0088] While the foregoing description provides several preferred ranges or amounts for the PGM and dopants of the oxidation catalyst composition, it should be noted that each disclosed range or amount for one of these components may be combined with the disclosed ranges or amounts for other components to form new ranges or subranges. Such embodiments are also expressly contemplated by this disclosure.

[0089] Preparation of oxidation catalyst compositions In some embodiments, the PGM and / or dopant metal oxide may be supported on a doped, high-surface-area, large-pore-opening support material, for example, by dispersing a soluble precursor of the PGM and / or dopant metal oxide thereon (e.g., by dispersion or impregnation). In some embodiments, the preparation of the oxidation catalyst compositions described herein involves treating (e.g., impregnating) a high-surface-area, large-pore-opening support material in particulate form with a solution containing the PGM precursor (e.g., platinum and / or palladium salt) and the dopant metal oxide precursor individually or as a mixture. In some embodiments, the doped, high-surface-area, large-pore-opening support material may be prepared separately or commercially available before impregnation with the PGM. The PGM is introduced into or onto the support material by any suitable means, e.g., spontaneous wetting, coprecipitation, or other methods known in the art. In some embodiments, a preferred method for impregnating a support material with PGM or arranging PGM on top of a support material is to prepare a mixture of solutions of the desired PGM precursor (e.g., platinum compounds and / or palladium compounds) to produce a slurry. Non-limiting examples of suitable PGM precursors include palladium nitrate, tetraamminepalladium nitrate, tetraammineplatinum acetate, and platinum nitrate. In some embodiments, during the calcination process and / or during the initial stages of use of the composition, such compounds are converted to a catalytically active form of the metal or its compound. In some embodiments, the slurry is acidic, for example, having a pH of about 2 to less than about 7. The pH of the slurry may be lowered by adding an appropriate amount of inorganic or organic acid to the slurry. In some embodiments, a combination of both can be used, taking into account the compatibility of the acid with the raw materials. Inorganic acids include, but are not limited to, nitric acid. Organic acids include, but are not limited to, acetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, glutamic acid, adipic acid, maleic acid, fumaric acid, phthalic acid, tartaric acid, and citric acid. In some embodiments, the slurry is dried and calcined to provide an oxidation catalyst composition.In some embodiments, the PGM is described as being dispersed in, impregnated in, placed on, or contained within a support material.

[0090] The disclosed oxidation catalyst compositions may, in some embodiments, be prepared via an induced wetting impregnation method. In some embodiments, induced wetting impregnation, also known as capillary impregnation or dry impregnation, is used for the synthesis of heterogeneous materials, i.e., catalysts. In some embodiments, a metal precursor (e.g., the PGM precursor or dopant disclosed herein, or both) is dissolved in an aqueous or organic solution, and then the metal-containing solution is added to a material to be impregnated (e.g., a support material with a high surface area and large pore openings) that contains the same pore volume as the volume of the added solution. In some embodiments, the solution is drawn into the pores of the support material by capillary action. In some embodiments, if the solution is added beyond the pore volume of the support material, the transport of the solution changes from a capillary process to a much slower diffusion process. In some embodiments, the impregnated material can then be dried and calcined to remove volatile components in the solution and deposit the active species (e.g., PGM) on the surface of the material. In some embodiments, the maximum load capacity is limited by the solubility of the precursor in the solution. In some embodiments, the concentration profile of the impregnated support material depends on the mass transfer conditions within the pores during impregnation and drying.

[0091] In some embodiments, the PGM is provided in particulate form in the oxidation catalyst composition, for example, as fine particles with a diameter of 1 to 15 nanometers or less, as opposed to being dispersed on or impregnated into a support.

[0092] catalyst article In some embodiments, the closely coupled diesel oxidation catalyst (ccDOC) article comprises the oxidation catalyst composition disclosed herein. In some embodiments, the article comprises a substrate on which the oxidation catalyst composition disclosed herein is disposed in at least a portion thereof. Preferred and exemplary substrates are described below herein.

[0093] Base material In some embodiments, the oxidation catalyst composition is placed on a substrate to form a catalyst article. In some embodiments, the catalyst article, including the substrate, is used as part of an exhaust gas treatment system (for example, a catalyst article including, but not limited to, an article containing the oxidation catalyst composition disclosed herein). In some embodiments, the useful substrate is three-dimensional and, similar to a cylinder, has length, diameter, and volume. The shape does not necessarily have to conform to a cylinder. The length is the axial length defined by the inlet and outlet ends.

[0094] In some embodiments, the substrate for the disclosed composition(s) may consist of any material commonly used in the preparation of automotive catalysts and may include a metal or ceramic honeycomb structure. In some embodiments, the substrate typically provides a plurality of walls to which a washcoat composition is applied and adhered, thereby acting as a substrate for the catalyst composition.

[0095] In some embodiments, the ceramic substrate may be made of any suitable refractory material, such as cordierite, cordierite-α-alumina, aluminum titanate, silicon titanate, silicon carbide, silicon nitride, zircon mullite, spodumene, alumina-silica-magnesia, zircon silicate, sillimanite, magnesium silicate, zircon, petalite, α-alumina, aluminosilicate, etc.

[0096] In some embodiments, the substrate may be metallic, comprising one or more metals or metal alloys. In some embodiments, the metallic substrate may include any metallic substrate, for example, one having openings or “die-cut portions” in the channel wall. In some embodiments, the metallic substrate may be used in various forms, such as pellets, corrugated sheets, or monolithic foams. Examples of metallic substrates may include heat-resistant base metal alloys, for example, one in which iron is substantial or the main component. In some embodiments, the alloy may contain one or more of nickel, chromium, and aluminum, and the total of these metals may, advantageously in each case, based on the mass of the substrate, contain at least about 15 wt% (mass percent) of the alloy, for example, about 10 to about 25 wt% of chromium, about 1 to about 8 wt% of aluminum, and 0 to about 20 wt% of nickel. Examples of metallic substrates include those having linear channels, those having protruding blades along axial channels to obstruct gas flow and initiate communication of gas flow between channels, and those having blades and holes to improve gas transport between channels and enable radial gas transport throughout the monolith. In some embodiments, the metallic substrate may be used in close-coupling positions, allowing for rapid heating of the substrate and, correspondingly, rapid heating of the catalyst composition (e.g., oxidation catalyst composition) coated thereon.

[0097] Any suitable substrate for the catalyst articles disclosed herein may be used, for example, a monolithic substrate of the type in which fine, parallel gas flow passages extend from an inlet or outlet surface of the substrate and the passages are open to the fluid flow passing through them ("flow-through substrate"). In some embodiments, a suitable substrate is of the type having a plurality of fine, substantially parallel gas flow passages extending along the longitudinal axis of the substrate, typically each passage being blocked at one end of the substrate body, with alternating passages being blocked at opposite end faces ("wall flow filter"). Flow-through substrates and wall flow substrates are also taught, for example, in International Patent Application Publication WO2016 / 070090, which is incorporated herein by reference in its entirety.

[0098] In some embodiments, the catalyst substrate includes a honeycomb substrate in the form of a wall-flow filter or a flow-through substrate. In some embodiments, the substrate is a wall-flow filter. Exemplary flow-through substrates and wall-flow filters are described further below.

[0099] Flow-through substrate In some embodiments, the substrate is a flow-through substrate (e.g., a monolithic substrate including a flow-through honeycomb monolith substrate). In some embodiments, the flow-through substrate has fine, parallel gas flow passages extending from the inlet end to the outlet end of the substrate, and the passages are open to the fluid flow. In some embodiments, the passages are essentially straight lines from their fluid inlet to their fluid outlet and are defined by walls on which a catalytic coating is arranged so that the gas flowing through the passages comes into contact with the catalytic material. In some embodiments, the flow paths of the flow-through substrate are thin-walled channels, which can be any preferred cross-sectional shape and size, such as trapezoidal, rectangular, square, sinusoidal, hexagonal, elliptical, or circular. In some embodiments, the flow-through substrate is made of ceramic or metal as described above.

[0100] Flow-through substrates, for example, have a volume of approximately 50 in. 3 ~About 1200in 3The cell density (inlet opening) is approximately 60 cells (cpsi) to approximately 500 cpsi or up to approximately 900 cpsi per square inch, for example, approximately 200 cpsi to approximately 400 cpsi, and the wall thickness is approximately 50 microns to approximately 200 microns or approximately 400 microns. Figures 1A and 1B illustrate an exemplary substrate 2, which is a flow-through substrate coated with the catalyst composition described herein. Referring to Figure 1A, the exemplary substrate 2 has a cylindrical shape and a cylindrical outer surface 4, an upstream end face 6, and a corresponding downstream end face 8 identical to the end face 6. The exemplary substrate 2 has a plurality of fine, parallel gas flow channels 10 formed inside. As can be seen in Figure 1B, the channels 10 are formed by walls 12 and extend through the carrier 2 from the upstream end face 6 to the downstream end face 8, and the channels 10 are unobstructed so that a fluid flow, such as a gas flow, can pass through the carrier 2 in the longitudinal direction through its gas flow channels 10. As is more readily apparent in Figure 1B, the wall 12 is sized and constructed such that the gas passage 10 has a substantially regular polygonal shape. As shown in the illustration, the catalyst composition can be applied to multiple distinctly different layers if desired. In the illustrated embodiment, the catalyst composition consists of both a separate bottom layer 14 attached to the wall 12 of the carrier member and a second separate top layer 16 coated on the bottom layer 14. The disclosure includes, for example, one or more (e.g., two, three, or four or more) catalyst composition layers and is not limited to the two-layer embodiment shown in Figure 1B. Further exemplary coating configurations are disclosed below.

[0101] Wall flow filter substrate In some embodiments, the substrate is a wall flow filter having multiple fine, substantially parallel gas flow passages extending along the longitudinal axis of the substrate. In some embodiments, each passage is blocked at one end of the substrate body, and alternating passages are blocked at the opposite end face. Such exemplary monolithic wall flow filter substrates may contain up to about 900 or more flow passages (or “cells”) per square inch of cross-section, but may contain far fewer. For example, the substrate may have about 7 to 600, more typically about 100 to 400, cells (“cpsi”) per square inch. The cells may have rectangular, square, circular, elliptical, triangular, hexagonal, or other polygonal cross-sections.

[0102] Figure 2 shows a cross-sectional view of an exemplary monolithic wall flow filter substrate. Alternating blocked and open passages (cells) are shown. The blocked or closed ends 100 are staggered with the open passages 101, with each opposite end being either open or blocked. The filter has an inlet end 102 and an outlet end 103. Arrows crossing the porous cell walls 104 represent exhaust gas flow entering the open cell end, diffusing through the porous cell walls 104, and exiting the open outlet cell end. The blocked ends 100 obstruct the gas flow and promote diffusion through the cell walls. Each cell wall has an inlet side 104a and an outlet side 104b. The passages are surrounded by cell walls.

[0103] In some embodiments, the wall flow filter article substrate is, for example, about 50 cm 3 , about 100cm 3 , about 200cm 3 , about 300cm 3 , about 400cm 3 , about 500cm 3 , about 600cm 3 , about 700cm 3 , about 800cm 3 , about 900cm 3 Or approximately 1000cm 3 From approximately 1500cm 3 , about 2000cm 3 , about 2500cm 3, about 3000cm 3 , about 3500cm 3 , about 4000cm 3 , about 4500cm 3 Or approximately 5000cm 3 The volume may be such that the wall flow filter substrate typically has a wall thickness of about 50 microns to about 2000 microns, for example, about 50 microns to about 450 microns, or about 150 microns to about 400 microns.

[0104] In some embodiments, the walls of the wall flow filter are porous, having at least about 50% or at least about 60% wall porosity, and their average pore size is at least about 5 microns before the placement of the functional coating. For example, the wall flow filter article substrate in some embodiments has a porosity of ≥50%, ≥60%, ≥65%, or ≥70%. For example, the wall flow filter article substrate in some embodiments has a wall porosity of about 50%, about 60%, about 65%, or about 70% to about 75%, about 80%, or about 85%, and an average pore size of about 5 microns, about 10 microns, about 20 microns, about 30 microns, about 40 microns, or about 50 to about 60 microns, about 70 microns, about 80 microns, about 90 microns, or about 100 microns before the placement of the catalyst coating. The terms “wall porosity” and “substrate porosity” mean the same thing and are synonymous. Porosity is the ratio of void volume to the total volume of the substrate. Pore size may be measured according to the ISO 15901-2 (static volume) procedure for nitrogen pore size analysis. Nitrogen pore size may also be measured using a TRISTAR 3000 series micrometer. Nitrogen pore size may also be measured using the BJH (Barrett-Joyner-Halenda) calculation and 33 desorption points. Useful wall-flow filters have high porosity, allowing for high loading of catalyst compositions without excessive back pressure during operation.

[0105] Coating composition and composition In some embodiments, to produce the catalyst articles of the Disclosure, a substrate described herein is brought into contact with the catalyst composition disclosed herein to provide a coating (for example, by depositing a slurry containing particles of the catalyst composition onto the substrate). The coating of the oxidation catalyst composition is referred herein, for example, to “catalyst coating composition” or “catalyst coating.” The terms “catalyst composition” and “catalyst coating composition” are synonymous.

[0106] In some embodiments, the oxidation catalyst compositions disclosed herein may be prepared using a binder, for example, a ZrO2 binder derived from a suitable precursor, such as zirconyl acetate, or any other suitable zirconium precursor, such as zirconyl nitride. In some embodiments, the zirconyl acetate binder provides a homogeneous and intact coating after thermal aging, for example, when the catalyst is exposed to high temperatures of at least about 600°C, for example, about 800°C, and a higher water vapor environment of about 5% or more. In some embodiments, the binder includes, but is not limited to, alumina and silica. Alumina binders include, for example, aluminum oxide, aluminum hydroxide, and aluminum oxyhydroxyd. Colloidal forms of aluminum salts and alumina may also be used. Silica binders include various forms of SiO2, including silicates and colloidal silica. In some embodiments, the binder composition includes any combination of zirconia, alumina, and silica. In some embodiments, the binder includes boehmite, gamma-alumina, or delta / theta-alumina, and silica sol. In some embodiments, if present, the binder is used in an amount of about 1 to about 5 wt% of the total wash coat load. In some embodiments, the binder can be zirconia-based or silica-based, for example, zirconium acetate, zirconia sol, or silica sol. In some embodiments, if present, the alumina binder is about 0.05 g / in 3 ~Approx. 1g / in 3 It is used in such quantities. In some embodiments, the binder is alumina.

[0107] In some embodiments, the catalyst coating may comprise one or more coating layers, where at least one layer comprises an oxidation catalyst composition disclosed herein. In some embodiments, the catalyst coating may comprise a single layer or a plurality of coating layers. In some embodiments, the catalyst coating comprises one or more thin, adhered coating layers positioned and attached to at least a portion of the substrate. In some embodiments, the entire coating comprises individual "coating layers".

[0108] In some embodiments, the catalyst article may include the use of one or more catalyst layers and combinations of one or more catalyst layers. In some embodiments, the catalyst material may be present only on the inlet side of the substrate wall, only on the outlet side, on both the inlet and outlet sides, or the wall itself may consist of all or part of the catalyst material. In some embodiments, the catalyst coating may be on the surface of the substrate wall and / or within the pores of the substrate wall, i.e., it may be "inside" and / or "on top of" the substrate wall. Thus, the expression "catalyst coating placed on the substrate" means on any surface, for example, on the wall surface and / or on the pore surface.

[0109] In some embodiments, the catalyst composition may be applied in the form of a wash coat containing a support material having catalytically active species on top. In some embodiments, the wash coat is formed by preparing a slurry containing a predetermined solid content (e.g., about 10% to about 60% by mass) of the support in a liquid solvent, which is applied to the substrate, dried, and calcined to provide a coating layer. In some embodiments, if multiple coating layers are applied, the substrate is dried and calcined after each layer is applied and / or after a desired number of layers have been applied. In some embodiments, the catalyst material(s) are applied to the substrate as a wash coat. In some embodiments, a binder may be used as described above.

[0110] In some embodiments, a catalyst composition(s) is independently mixed with water to form a slurry for coating a catalyst substrate, such as a honeycomb substrate. In some embodiments, in addition to catalyst particles, the slurry may optionally contain a binder (e.g., alumina, silica), a water-soluble or water-dispersible stabilizer, an accelerator, an associative thickener, and / or a surfactant (including anionic, cationic, nonionic, or amphoteric surfactants). In some embodiments, the pH range of the slurry is approximately 3 to approximately 6. Addition of acidic or basic species to the slurry can be carried out to adjust the pH as appropriate. For example, in some embodiments, the pH of the slurry is adjusted by adding ammonium hydroxide or aqueous nitric acid.

[0111] In some embodiments, the slurry can be pulverized to improve particle mixing and the formation of a homogeneous material. In some embodiments, pulverization is performed using a ball mill, continuous mill, or other similar apparatus, and the solid content of the slurry may be, for example, about 20 wt% to about 60 wt%, more specifically about 20 wt% to about 40 wt%. In some embodiments, the slurry after pulverization has particles of about 10 to about 40 microns, for example, about 10 to about 30 microns, for example, about 10 to about 15 microns. 90 Characterized by particle size.

[0112] Next, the slurry is coated onto the catalyst substrate using any wash-coat technique known in the art. In some embodiments, the catalyst substrate is immersed in the slurry one or more times, or otherwise coated with the slurry. Subsequently, in some embodiments, the coated substrate is dried at a high temperature (e.g., 100°C to 150°C) for a certain period of time (e.g., 10 minutes to about 3 hours), and then calcined by heating at, for example, 400°C to 600°C for about 10 minutes to about 3 hours in some embodiments. Following drying and calcination, the final wash-coat coating layer can be considered to be essentially solvent-free.

[0113] In some embodiments, after calcination, the amount of catalyst supported by the wash-coat technique described above can be determined by calculating the difference between the coated mass and the uncoated mass of the substrate. As will be apparent to those skilled in the art, the amount of catalyst supported can be modified in some embodiments by changing the slurry rheology. In some embodiments, the coating / drying / calcination process that produces the wash-coat can be repeated as needed to build up the coating to a desired level of support or thickness, meaning that multiple wash-coats are applicable.

[0114] In some embodiments, the wash coat(s) may be applied so that various coating layers are in direct contact with the substrate. In some embodiments, one or more “undercoats” may be present so that the catalyst or adsorbent coating layer or at least a portion of the coating layer is not in direct contact with the substrate (rather, it is in contact with the undercoat). In some embodiments, one or more “overcoats” may be present so that at least a portion or layer of the coating layer is not directly exposed to a gaseous flow or atmosphere (rather, it is in contact with the overcoat). In some embodiments, the catalyst composition may be present in the bottom layer on top of the substrate.

[0115] In some embodiments, the catalyst composition may be in the upper coating layer above the bottom coating layer. In some embodiments, the catalyst composition may be present in both the upper and bottom layers. In some embodiments, any one layer extends along the entire axial length of the substrate, for example, the bottom layer extends along the entire axial length of the substrate, and the upper layer also extends over the bottom layer along the entire axial length of the substrate. In some embodiments, each of the upper and bottom layers may extend from either the inlet or outlet end.

[0116] For example, both the bottom and top coating layers may extend from the same substrate end, the top layer may partially or completely overlap the bottom layer, the bottom layer may extend along a portion or the entire length of the substrate, and the top layer may extend along a portion or the entire length of the substrate. In some embodiments, the top layer may overlap a portion of the bottom layer. For example, the bottom layer may extend along the entire length of the substrate, and the top layer may extend from either the inlet or outlet end to about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of the length of the substrate.

[0117] In some embodiments, the bottom layer extends from either the inlet or outlet end for about 10%, 15%, 25%, 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 95% of the length of the substrate, and the top layer may extend from either the inlet or outlet end for about 10%, 15%, 25%, 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 95% of the length of the substrate, with at least a portion of the top layer overlapping the bottom layer. This "overlapping" area may extend over, for example, about 5% to 80% of the length of the substrate, for example, about 5%, 10%, 20%, 30%, 40%, 50%, 60%, or 70% of the length of the substrate.

[0118] In some embodiments, the top and / or bottom coating layers may be in direct contact with the substrate. In some embodiments, one or more “undercoats” may be present so that at least a portion of the top and / or bottom coating layers are not in direct contact with the substrate (rather, they are in contact with the undercoat). In some embodiments, one or more “overcoats” may be present so that at least a portion of the top and / or bottom coating layers are not directly exposed to a gaseous flow or atmosphere (rather, they are in contact with the overcoat). In some embodiments, the undercoat is an “under” layer of the coating layers, the overcoat is an “over” layer of the coating layers, and the interlayer is an “intermediate” layer between the two coating layers.

[0119] In some embodiments, the upper and lower coating layers may be in direct contact with each other without any intermediate layer. In some embodiments, the different coating layers may not be in direct contact, and there may be a “gap” between the two areas. In some embodiments, if present, an intermediate layer may prevent direct contact between the upper and lower layers. In some embodiments, the intermediate layer partially prevents direct contact between the upper and lower layers, thereby allowing partial direct contact between the upper and lower layers. In some embodiments, the intermediate layer(s), undercoat(s), and overcoat(s) may contain one or more catalysts, or may not contain catalysts. In some embodiments, the catalyst coating may include multiple identical layers, for example, multiple layers containing the same catalyst composition.

[0120] In some embodiments, the catalyst coating may be advantageously "regionalized," including a regionized catalyst layer, i.e., the catalyst coating contains various compositions over the axial length of the substrate. This is also described as "laterally regionized." For example, the layer may extend from the inlet end to the outlet end for about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of the length of the substrate. In some embodiments, the different coating layers may be adjacent to each other but not overlap. In some embodiments, the different layers may overlap in portions of each other to provide a third "intermediate" region. The intermediate region may extend, for example, over about 5% to about 80% of the length of the substrate, for example, about 5%, 10%, 20%, 30%, 40%, 50%, 60%, or 70% of the length of the substrate.

[0121] In some embodiments, each different layer may extend over the entire length of the substrate, or over a portion of the substrate, and may overlap each other, either on top of or underneath, or partially or completely. In some embodiments, each different layer may extend from either the inlet or outlet end. In some embodiments, different catalyst compositions may be present in separate coating layers. In some embodiments, the catalyst coating may comprise multiple identical layers.

[0122] The area of ​​this disclosure is defined by the relationship between the coating layers. With respect to various coating layers, there are several possible zoning configurations. For example, there may be an upstream area and a downstream area, an upstream area, an intermediate area, and a downstream area, or four different areas. If the two layers are adjacent and do not overlap, there are upstream and downstream areas. If the two layers overlap to some extent, there are upstream, downstream, and intermediate areas. For example, if one coating layer extends over the entire length of the substrate, and another coating layer extends from the exit end to a certain length and overlaps with a portion of the first coating layer, there are upstream and downstream areas.

[0123] In some embodiments, the first and second coating layers may be superimposed, with the first layer on top of the second, or the second layer on top of the first (i.e., top / bottom), for example, when the first coating layer extends from the inlet end to the outlet end, and the second coating layer extends from the outlet end to the inlet end. In this case, the catalyst coating includes an upstream region, an intermediate (overlapping) region, and a downstream region. The first and / or second coating layers are synonymous with the top and / or bottom layers described above.

[0124] In some embodiments, the first coating layer may extend from the inlet end to the outlet end, and the second coating layer may extend from the outlet end to the inlet end, in which case the layers do not overlap with each other, for example, the layers are adjacent.

[0125] Figures 3A, 3B, and 3C show several possible coating layer configurations having two coating layers, at least one of which contains a catalyst composition disclosed herein. The illustration shows a substrate wall 200 on which coating layers 201 (upper coat) and 202 (bottom coat) are positioned. These are simplified exemplary illustrations, and in the case of a porous wall flow filter substrate, coatings adhering to pores and pore walls are not shown, nor are blocked ends shown. In Figure 3A, coating layers 201 and 202 each extend over the entire length of the substrate, with the upper layer 201 overlapping the bottom layer 202. The substrate in Figure 3A does not contain a regioned coating configuration. In Figure 3B, the bottom coating layer 202 extends about 50% of the length of the substrate from the outlet, and the upper coating layer 201 extends beyond 50% of the length from the inlet, overlapping a portion of layer 202 to provide an upstream region 203, an intermediate overlapping region 205, and a downstream region 204. In Figure 3C, coating layer 202 extends approximately 50% of the substrate length from the outlet, coating layer 201 extends beyond 50% of the length from the inlet, and overlaps with a portion of layer 202, providing an upstream region 203, an intermediate overlapping region 205, and a downstream region 204. Figures 3A, 3B, and 3C are useful for illustrating coating compositions on wall-through or flow-through substrates.

[0126] In some embodiments, the oxidation catalyst coating, and any area, layer, or section of the coating, is based on the volume of the substrate, for example, about 0.3 g / in. 3 ~Approximately 6.0g / in 3 , or approximately 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0 g / in 3 ~Approximately 1.5g / in 3 Approximately 2.0g / in 3 Approximately 2.5g / in 3 Approximately 3.0g / in 3 Approximately 3.5g / in 3 Approximately 4.0g / in 3 Approximately 4.5g / in 3 Approximately 5.0g / in 3 Or approximately 5.5g / in3 It is present on the substrate at a loading (concentration) which refers to the dry solid mass per volume of the substrate, for example, the dry solid mass per volume of the honeycomb monolith. The concentration is based on the cross-section or the whole of the substrate. In some embodiments, the upper coating layer is present at a lower loading than the bottom coating layer.

[0127] In some embodiments, the PGM loading of the oxidation catalyst composition on the disclosed substrate is, based on the volume of the substrate, about 2 g / ft 3 , about 5 g / ft 3 or about 10 g / ft 3 to about 250 g / ft 3 , for example, about 20 g / ft 3 , about 30 g / ft 3 , about 40 g / ft 3 , about 50 g / ft 3 or about 60 g / ft 3 to about 100 g / ft 3 , about 150 g / ft 3 or about 200 g / ft 3 , about 210 g / ft 3 , about 220 g / ft 3 , about 230 g / ft 3 , about 240 g / ft 3 or about 250 g / ft 3 may be. In some embodiments, the PGM is present, for example, in the catalyst layer at about 0.1 wt%, about 0.5 wt%, about 1.0 wt%, about 1.5 wt% or about 2.0 wt% to about 3 wt%, about 5 wt%, about 7 wt%, about 9 wt%, about 10 wt%, about 12 wt% or about 15 wt% based on the mass of the layer.

[0128] Exhaust gas treatment system Some embodiments relate to hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NO xThis is a system for processing exhaust gas flow from an internal combustion engine containing ). In some embodiments, the system includes a close-coupled diesel oxidation catalyst (ccDOC) article located downstream of the internal combustion engine, the ccDOC article comprising a substrate as described herein and an oxidation catalyst composition as described herein disposed on at least a portion of the substrate. In some embodiments, the ccDOC article is configured for use in a close-coupled position, meaning that the article is located in close proximity downstream of the engine that generates the exhaust flow and is in fluid communication with the exhaust flow. In some embodiments, the ccDOC article has a lifespan of 150,000 h -1 It operates at a space velocity above, lightly turning off HC at temperatures below approximately 200°C and rapidly raising the temperature of the exhaust gases that emit ccDOC material.

[0129] In some embodiments, the system further includes one or more catalytic articles located downstream of the ccDOC and in fluid communication with the exhaust gas flow exiting the ccDOC. In some embodiments, the relative arrangement of the various catalytic components present in the emissions treatment system may be varied. In some embodiments, the engine may be a diesel engine operating in a combustion state with more air than is required for stoichiometric combustion, i.e., a lean state. In some embodiments, the engine may be an engine associated with a stationary supply source (e.g., a generator or pump station). In some embodiments, as referenced above, the use of ccDOC is particularly advantageous in combination with a downstream SCR catalyst. In some embodiments, the ccDOC plays a role in enhancing SCR performance at the low-temperature end of the spectrum by rapidly heating the exhaust gas entering the SCR to activate the SCR before the total NOx emissions exceed the permissible limits under current regulations.

[0130] In some embodiments of exhaust gas treatment systems and methods, the exhaust gas flow is received by an article(s) or treatment system by entering at an upstream end and exiting at a downstream end. In some embodiments, the inlet end of the substrate or article is synonymous with the “upstream” end or “front” end. In some embodiments, the outlet end is synonymous with the “downstream” end or “rear” end. The treatment system is generally located downstream of the internal combustion engine and is in fluid communication with the internal combustion engine.

[0131] In some embodiments, the system includes one or more articles, for example, a diesel oxidation catalyst (DOC), and one or more articles containing a reducing agent injector, a selective catalytic reduction catalyst (SCR), a soot filter, an ammonia oxidation catalyst (AMOx), or a lean NOx trap (LNT). In some embodiments, the article containing the reducing agent injector is a reducing article. In some embodiments, the reduction system includes a reducing agent injector and / or a pump and / or a reservoir, etc.

[0132] In some embodiments, the treatment system may further include a selective catalytic reduction catalyst and / or a soot filter and / or an ammonia oxidation catalyst. In some embodiments, the soot filter may not be catalytic, or it may be catalytic (CSF). For example, the treatment system may include, from upstream to downstream, articles containing the ccDOC article, DOC, CSF, urea injector, SCR article, and AMOx disclosed herein. A lean NOx trap (LNT) may also be included. In some embodiments, such articles may be on separate substrates, or they may be layered or regioned on a single substrate in various combinations. In some embodiments, one or more of DOC, CSF, SCR, LNT, and AMOx may be combined in a single article, or they may exist as separate articles.

[0133] In some embodiments, the system further includes a second diesel oxidation catalyst (DOC) article located downstream of the engine and downstream of the ccDOC, and adapted for the oxidation of HC, CO, and NOx. In some embodiments, a DOC suitable for use in an exhaust treatment system can effectively catalyze the oxidation of CO and HC to carbon dioxide (CO2). In some embodiments, the DOC can convert at least 50% of the CO or HC components present in the exhaust gas. In some embodiments, the DOC typically does not include oxidation catalyst compositions uniquely provided herein. Rather, conventional DOC catalyst compositions comprising one or more platinum group metals (e.g., palladium and / or platinum), a support material such as alumina, a zeolite for HC storage, and optionally an accelerator and / or stabilizer can be advantageously used. In some embodiments, suitable DOC catalyst compositions are described, for example, in U.S. Patent No. 10,335,776 and U.S. Patent Application Publication No. 16 / 170,406, which are incorporated herein by reference in their entirety.

[0134] In addition to treating exhaust gas emissions using DOC, the emissions treatment system may use a soot filter for the removal of particulate matter. The soot filter may be located upstream or downstream of the DOC, but typically it is located downstream of the DOC. In some embodiments, the soot filter is a catalytic soot filter (CSF). In some embodiments, the CSF may include a substrate coated with washcoat particles containing one or more catalysts for burning the captured soot and / or oxidizing the emissions in the exhaust gas stream. In some embodiments, the soot combustion catalyst can be any known catalyst for soot combustion. For example, the CSF may be coated with one or more high-surface-area refractory oxides (e.g., aluminum oxide or ceria-zirconia) for the combustion of CO and unburned hydrocarbons and some particulate matter. In some embodiments, the soot combustion catalyst may be an oxidation catalyst containing one or more precious metal catalysts (e.g., platinum and / or palladium).

[0135] In some embodiments, the system uses nitrogen oxides (NOx). x The system further includes selective catalytic reduction (SCR) articles adapted for the reduction of NO, where each catalyst article is in fluid communication with the exhaust gas flow. In some embodiments, the SCR catalyst article may be located upstream or downstream of the DOC and / or soot filter. In some embodiments, a suitable SCR catalyst article for use in an exhaust treatment system is NO at a high temperature of 650°C. x The reduction of exhaust components can be effectively catalyzed. In some embodiments, the SCR catalyst component is able to reduce NO even under conditions of low loading, which are typically associated with lower exhaust temperatures. x It is active in the reduction of NO. In some embodiments, the SCR catalyst article is active in the reduction of NO depending on the amount of reducing agent added to the system. x It is possible to convert at least 50% of the (for example, NO) component to N2. In some embodiments, preferred SCR catalysts are described, for example, U.S. Patent Nos. 4,961,917 and 5,516,497, which are incorporated herein by reference in their entirety.

[0136] An exemplary emissions treatment system is illustrated in Figure 4. Figure 4 shows a schematic diagram of emissions treatment system 20. As shown, the emissions treatment system may include several catalytic components in series downstream of an engine 22, such as a lean combustion engine. At least one of the catalytic components includes an oxidation catalyst composition (e.g., ccDOC) as disclosed herein. Figure 4 shows five catalytic components in series, 24, 26, 28, 30, and 32, but the total number of catalytic components can vary, and the five components are merely examples.

[0137] Table 1 presents various exhaust gas treatment system configurations for one or more embodiments, though not limited to these. Note that each catalyst is connected to the next catalyst via an exhaust conduit, with the engine being upstream of catalyst A, A upstream of catalyst B, B upstream of catalyst C, C upstream of catalyst D, and D upstream of catalyst E (if present). References to components A-E in the table can be cross-referenced using the same symbols in Figure 4.

[0138] The LNT catalysts listed in Table 1 are NO x Any conventionally used catalyst can be used as a trap, and typically includes base metal oxides (BaO, MgO, CeO2, etc.) and platinum group metals (e.g., Pt and / or Rh) for the oxidation and reduction of NO by the catalyst. x Contains an adsorbent composition.

[0139] References to SCR in the table refer to SCR catalysts. References to SCRoF (or SCR on a filter) refer to particulate or soot filters (e.g., wall-flow filters) that may contain an SCR catalyst composition. In an uncatalyzed form, such particulate filters are called diesel particulate filters (DPFs).

[0140] References to AMOx in the table refer to an ammonia oxidation catalyst, which is provided downstream of the catalyst in some embodiments of this disclosure and can remove any slipped ammonia from the exhaust gas treatment system. AMOx is used synonymously with ammonia slip catalyst (ASC). In some embodiments, the AMOx catalyst may contain PGM components. In some embodiments, the AMOx catalyst may include a bottom coat containing one or more PGMs and a top coat having SCR functionality.

[0141] As will be recognized by those skilled in the art, in the configurations listed in Table 1, any one or more of components A, B, C, D, or E may be placed on a particulate filter such as a wall-flow filter, or on a flow-through honeycomb substrate. In some embodiments, the engine exhaust system includes one or more catalytic compositions mounted near the engine (proximity position, CC) with additional catalytic compositions located below the vehicle body (underbody position, UF). In some embodiments, the exhaust gas treatment system may further include urea injection components (typically upstream of the SCR component).

[0142] [Table 1]

[0143] In some embodiments, the system comprises a close-coupled diesel oxidation catalyst (ccDOC) article located downstream of an internal combustion engine, comprising a substrate and an oxidation catalyst composition disclosed herein disposed on at least a portion of the substrate; a diesel oxidation catalyst (DOC) article located downstream of the engine and downstream of the ccDOC, adapted for the oxidation of HC, CO, and NOx; and a diesel oxidation catalyst (DOC) article located downstream of the DOC article, adapted for the oxidation of nitrogen oxides (NOx). x The system includes a selective catalytic reduction (SCR) article adapted for the reduction of ccDOC, where all catalyst articles are in fluid communication with the exhaust gas flow. In some embodiments, the system further includes a soot filter which may or may not be catalytic, and AMOx. In some embodiments, the system includes the ccDOC described herein, a DOC article located downstream of the ccDOC, a diesel particulate filter located downstream of the DOC, a mixer configured to introduce and mix ammonia or an ammonia precursor with the exhaust gas flow, an SCR catalyst including an upstream iron-enhanced zeolite and a downstream copper-enhanced zeolite, and AMOx located downstream of the SCR, where all catalyst articles are in fluid communication with the exhaust gas flow. An illustration of such a system is shown in Figure 5.

[0144] Exhaust gas flow treatment method Some embodiments are methods for treating lean combustion engine exhaust gas streams, which include bringing the exhaust gas stream into contact with an emissions treatment system of the Disclosure. In some embodiments, hydrocarbons (HC) and carbon monoxide (CO) present in the exhaust gas stream of any engine can be converted to carbon dioxide and water in ccDOC, DOC, or both. In some embodiments, higher hydrocarbons (greater than C6) can also be detected, but hydrocarbons present in the engine exhaust gas stream include C1-C6 hydrocarbons (i.e., lower hydrocarbons) such as methane.

[0145] Some embodiments describe the presence of HC, CO, and NO in the exhaust gas flow from an internal combustion engine. xThe method for reducing HC is as follows: an introduction step, in which an amount of HC is introduced into the exhaust flow to form an HC-rich exhaust gas flow; a contact step, in which the HC-rich exhaust gas flow is brought into contact with an oxidation catalyst composition disclosed herein, thereby generating heat through the combustion of HC and thereby forming a heated first effluent, where the oxidation catalyst composition is placed on a substrate and is located in close proximity downstream of the internal combustion engine; a contact step, in which the heated first effluent is brought into contact with a diesel oxidation catalyst suitable for the oxidation of HC, CO and NO, thereby forming a second effluent in which the levels of HC and CO are reduced and the level of NO2 is increased; an injection step, in which a reducing agent is injected into the second effluent that has exited the diesel oxidation catalyst to obtain a third effluent; and the third effluent is treated with NO2 x By contacting it with an SCR catalyst suitable for reduction, the HC, CO, and NO are reduced. x The process includes a contact step, which forms a treated exhaust gas flow with a reduced level.

[0146] In some embodiments, the catalyst compositions, articles, systems, and methods disclosed herein are suitable for treating exhaust gas flows from internal combustion engines, such as gasoline engines, light diesel engines, and heavy diesel engines. In some embodiments, the catalyst compositions are also suitable for treating emissions from stationary industrial processes. In some embodiments, the internal combustion engine is a diesel engine. In some embodiments, the internal combustion engine is a light or heavy diesel engine.

[0147] It will be readily apparent to those skilled in the art that appropriate modifications and applications to the compositions, methods, and applications described herein can be made without departing from the scope of any embodiment or aspect thereof. The compositions and methods provided are illustrative and are not intended to limit the embodiments within the claims. All of the various embodiments, aspects, and options disclosed herein can be combined in any modification. The scope of the compositions, formulations, methods, and processes described herein includes all actual or potential combinations of the embodiments, aspects, options, examples, and preferences herein. Any patents and publications referenced herein are incorporated herein by reference with respect to their specific teachings as described herein, unless otherwise specifically provided. [Examples]

[0148] The present disclosure will be further illustrated by the following examples, which are provided for illustrative purposes only and should not be construed as limiting the present invention. Unless otherwise specified, all parts and percentages are by mass, and all mass percentages are expressed on a dry basis, meaning excluding water content, unless otherwise specified.

[0149] Example 1: 2% Pt on an alumina support (reference example) A reference sample (2% Pt on alumina) was prepared. High surface area (surface area 150 m²) 2 A refractory alumina support with small pores (average pore opening less than approximately 15 nm) was added to a Pt compound solution (prepared according to the method disclosed in US2017 / 0304805, incorporated herein by reference) to prepare a slurry with a solid concentration of approximately 30%. This slurry was then used to prepare a Pt compound solution. 90 The material was ground for 10 minutes until it was less than 20 microns in size. The ground powder was then dried and calcined at 590°C. The resulting dried powder was divided into two parts. The first part was used as is ("fresh"), and the second part was aged for 20 hours at 650°C in air containing 10% water vapor ("aged").

[0150] Example 2: 2% Pt on silica-alumina support (reference example) A reference sample (2% Pt on alumina) was prepared. High surface area (surface area 150 m²) 2 A silica-doped refractory alumina support with small pores (average pore opening less than approximately 15 nm) was added to a Pt compound solution (prepared according to the method disclosed in US2017 / 0304805, incorporated herein by reference) to prepare a slurry with a solid concentration of approximately 30%. This slurry was then processed into a D 90 The material was ground for 10 minutes until it was less than 20 microns in size. The ground powder was then dried and calcined at 590°C. The resulting dried powder was divided into two parts. The first part was used as is ("fresh"), and the second part was aged for 20 hours at 650°C in air containing 10% water vapor ("aged").

[0151] Example 3: 2% Pt on a 5% titania-alumina support (Example of the invention) The sample of the invention (5% titania-alumina with 2% Pt) was prepared by the method of Example 1, but instead of alumina, a high surface area (surface area 150 m²) was used. 2 A refractory alumina support doped with 5% titania, having small pores (average pore opening of approximately 15 nm or less), was used.

[0152] Example 4: 2% Pt on a 10% titania-alumina support (Example of the invention) The sample for the inventive example (10% titania-alumina with 2% Pt) was prepared by the method of Example 1, but instead of alumina, a low surface area (surface area ~80m²) was used. 2 A refractory alumina support with large pores (average pore opening of approximately 25 nm) and doped with 10% titania was used.

[0153] Example 5: 2% Pt on a 4% lantana-alumina support (reference example) A sample for the reference example (4% lantana-alumina with 2% Pt) was prepared using the method of Example 1, but instead of alumina, a low surface area (surface area ~80m²) was used. 2A refractory alumina support with large pores (average pore opening of approximately 50 nm) and 4% lantana doped was used.

[0154] Example 6: 2% Pt on a 4% zirconia-alumina support (Example of the invention) A sample for the reference example (4% zirconium-alumina with 2% Pt) was prepared using the method of Example 1, but instead of alumina, a high surface area (surface area 150 m²) was used. 2 A refractory alumina support doped with 4% zirconia (average pore size less than approximately 15 nm) was used.

[0155] Example 7: 2% Pt on a 5% manganese-alumina support (Example of the invention) The sample for the reference example (5% manganese-alumina with 2% Pt) was prepared using the method of Example 1, but instead of alumina, a high surface area (surface area approximately 150 m²) was used. 2 A refractory alumina support doped with 5% manganese oxide and having large pores (average pore opening of approximately 23 nm) was used.

[0156] Example 8: 2% Pt on a large-pore alumina support (Example of the invention) The sample of the invention (2% Pt on large-pore alumina) was prepared by the method of Example 1, but instead of the alumina in Example 1, a sample with an average pore opening of 40 nm and a surface area of ​​90 m² was used. 2 Large-pore alumina ( / g) was used.

[0157] Example 9: Reactor test light-off experiment The hydrocarbon light-off in the reactor was evaluated for the powder samples of Examples 1-8 under steady-state and continuous heating conditions, with and without nitric oxide (NO) in the feed. The catalyst was first dehydrated under an argon atmosphere at 400°C for 1 hour at a flow rate of 100 ml / min. The gas supply was 500 ppm propylene (C3H8) and 10% oxygen (O2) with and without NO (500 ppm when NO was present). Continuous light-off was monitored with a ramp of 10°C / min from 120°C to 250°C. Steady-state light-off was measured by stepwise immersion for 5 minutes at five different temperatures (150°C, 180°C, 200°C, 220°C, 250°C).

[0158] The light-off reaction of propylene was investigated using an operando spectroscopy unit. The operando unit consisted of a Linkam CCR1000 powder bed flow-through reactor equipped with a calcium fluoride (CaF2) window, enabling infrared spectroscopy of the catalyst under operating conditions. The gaseous components of the operando reactor exhaust were monitored using a Hiden Analytical Mass Spectrometer (MS) and an FT-IR gas cell analyzer-MKS MultiGas.

[0159] When measuring the performance of ccDOC, the effluent gas temperature from the ccDOC is an important factor. Since the effluent temperature is determined by the heat generated by the combustion of hydrocarbons (HC), the CO2 formation rate is a better indicator of catalyst performance than the HC conversion rate. Specifically, the feed HC gas (e.g., propylene) may form polymeric substances (such as graphite-based coke), which can contribute to HC conversion that is not useful in ccDOC applications. Therefore, HC light-off was evaluated using the CO2 formation rate as a performance criterion.

[0160] Example 10. Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) Experiment Powder samples from Examples 1-8 were evaluated by DRIFTS experiments during operando reactions. DRIFTS experiments were performed using an Agilent CARY680 FTIR spectrometer equipped with a Linkam CCR1000 high-temperature environment chamber featuring a mercury-cadmium telluride (MCT-HgCdTe) detector and a calcium fluoride (CaF2) window. The sample powders were dehydrated in flowing Ar at 40°C for 1 hour at a flow rate of 100 ml / min. DRIFTS were collected during operando reactions at various temperatures. The absorbance spectra of the DRIFTS were extracted for analysis after subtracting the background spectrum.

[0161] Example 11. Results The operand results showed that the continuous heating experiment yielded similar results to the steady-state experiments of the two reference example articles (Examples 1 and 2; Figures 6 and 7, respectively). The results shown in Figure 8 showed that the light-off performance of Example 3 of the present invention was faster than that of both reference example articles (Examples 1 and 2).

[0162] To further illustrate the benefits of adding Ti to an alumina support, a comparison of Reference Example 1 and Invention Example 4 was plotted (Figure 9), clearly showing the rapid light-off phenomenon (sharper temperature rise gradient) caused by the addition of Ti to the alumina support.

[0163] Figures 10 and 11 illustrate the uniqueness of the Ti additive compared to other additives, such as La (Example 5; Figure 10) and Mn (Example 7; Figure 11). Adding La or Mn to the alumina support reduced the light-off performance. However, when the Mn-containing sample reached the light-off temperature, HC was added more effectively, and runs with NO in the feed produced more CO2 than runs without NO in the feed. While not theoretically bound, this suggests that NO2 formation from the Mn-containing catalyst may aid in the combustion of absorbed HC, resulting in more CO2 and more heat generation. To further investigate this NO2 formation from the Mn-containing catalyst, experiments were conducted with various additives (approximately 5% by mass) added to the alumina without using PGM (platinum group metals; i.e., Pt). The results shown in Figures 12 and 13 demonstrate that the Mn-containing support improves NO2 formation at low temperatures. A characteristic of this NO2 formation, as shown in Figure 11, is that when light-off occurs, it leads to an improvement in the HC conversion rate of the Pt sample on the Mn-containing support (Example 7; Figure 13).

[0164] The operand results for Example 8 (Figure 14) showed that an alumina support with a large pore opening (40 nm) performed better than one with a narrow pore opening (e.g., compared to Examples 1 and 2; 10 nm pore opening). Although not bound by theory, the formation of polymeric materials (graphite, coke, etc.) can inactivate the catalyst by masking the active site, so it is thought that supports with large pore openings reduce masking compared to supports with small pore openings.

[0165] Figure 15 shows the benefits of the Zr additive (Example 6). Its light-off temperature was not as low as in Examples 1 and 2 when NO was not present in the feed gas, but its resistance to NO inhibition was relatively strong (Figure 15). When NO was present in the feed, the CO2 formation rate was comparable to that of Invention Example 3 and better than Reference Examples 1 and 2. However, Example 6 tended to form polymer material over time, as shown in steady-state measurements (5 minutes at each temperature).

[0166] Since manufacturers must meet exhaust gas regulations throughout the vehicle's service life, the performance of the exhaust catalyst must be durable throughout the vehicle's useful life. Given this constraint, aged catalysts were evaluated for durability. Reference Examples 1 and 2 were evaluated after aging for 20 hours at 650°C in air containing 10% water vapor, using the same operand settings. Reference Example 1 clearly outperformed Reference Example 2 in CO2 and N2O formation, but was inferior in NO2 formation (Figures 16 and 17). Depending on the selection of the downstream catalyst used following the catalyst composition disclosed herein in the form of a ccDOC, Reference Example 1 or 2 may be useful in the ccDOC. For example, the composition of Example 1 can be used when only exothermic generation is required, or the composition of Example 2 can be used when an SCR catalyst is located following the ccDOC.

[0167] Since manufacturers prefer that ccDOC light-off be as fast as possible to reduce the time required for subsequent catalysts to function downstream, the temperature rise rate of the catalyst composition and its effluent is an important factor in evaluating the performance of the catalyst composition. Therefore, embodiments of this disclosure were evaluated in this respect. The results of measuring the CO2 production rate gradient for aged samples of Examples 1 to 3 are shown in Tables 2 and 3.

[0168] [Table 2]

[0169] Even without NO in the feed, Example 3 surpassed both Reference Examples 1 and 2 in both HC conversion rate and CO2 generation rate, demonstrating that Invention Example 3 achieved faster light-off and higher exothermic generation. When NO was added to the feed gas, Invention Example 3 still surpassed both Reference Examples 1 and 2 in both HC conversion rate and CO2 generation rate, as shown in Table 3.

[0170] [Table 3]

[0171] Although not constrained by theory, the fact that the initiation of CO2 formation and the generation of N2O coincide suggests that the obstruction of NO during HC light-off is due to the NO molecule blocking the O2 dissociation site. Rapid conversion of NO to N2O makes it easier to remove NO, thus accelerating HC light-off. This is supported by the FT-IR spectrum shown in Figure 18. Similar results were observed in Examples 4 and 8, as shown in Table 4 and Figure 19.

[0172] [Table 4]

[0173] The results for the powder showed that both Ti doping and large pore opening properties contributed to the HC light-off temperature, regardless of the presence or absence of NO in the feed, indicating some synergistic effect between Pt and Ti, as well as the benefit of improved Knudsen diffusion coefficient due to the large pore opening support. Ti doping altered the NO adsorption properties, and the large pore opening of the support promoted diffusion, allowing HC molecules to move rapidly within the catalyst powder, thereby resulting in a fast HC light-off (Examples 5-8; Figure 19).

[0174] Preparation of core samples In Examples 2, 3, and 4, catalyst compositions prepared from the support materials described above were used to achieve a PGM loading of 200 g / ft 3 Monolithic coated articles with a Pt:Pd mass ratio of 10:1 were prepared according to the preparation method described below. Unless otherwise specified, all parts and percentages are by mass, and all mass percentages and ratios are expressed on a dry basis, meaning excluding moisture, unless otherwise specified.

[0175] Example 12. Reference item A catalyst composition was prepared by impregnating the support material (5% silica-alumina) of Example 2 with an aqueous solution of tetraamine platinum complex by dropwise addition while mixing onto a dry powder. Subsequently, a solution of palladium nitrate was added to the Pt / support wet powder under continuous planetary motion until a completely homogeneous mixture of PGM was obtained on the support material. Deionized water was added to this semi-wet powder to prepare a slurry with a solid content of 45% and a pH of approximately 4.5 adjusted with acetic acid. Then, the well-dispersed mixture was loaded into a mill, and the solid particle size was measured D 90 The particle size was reduced to approximately 5.3 microns. The pulverized slurry was then washed and coated onto a ceramic monolith substrate (1 inch D x 3 inch L) with a drying gain of 1.92 g / in. 3 The coated parts were then placed in an oven and dried at 120°C for 2 hours, and then baked at 590°C for 1 hour.

[0176] Example 13. Example Article of the Invention Example 13 was prepared using the method of Example 12, but instead of silica-alumina, the support material of Example 4 (10% titania-alumina) was used.

[0177] Example 14. Example Article of the Invention Example 14 was prepared using the method of Example 12, but instead of silica-alumina, the support material of Example 3 (5% titania-alumina) was used.

[0178] result The cores of the coated catalyst samples from Examples 12-14 were tested for catalytic activity in hydrocarbon oxidation at a space velocity of ~100 K / hour in a laboratory reactor using a synthesis gas mixture containing 1000 ppm (C1)HC derived from diesel fuel, 8% oxygen, 350 ppm NO, 5% H2O, and the remainder nitrogen. Each sample was tested both fresh and aged. The outlet temperatures for three DOC inlet temperatures (190, 200, and 225°C) 10 minutes after simulated diesel fuel injection are shown in Figures 20 and 21.

[0179] As a result, the results for the powder (operando) were confirmed (i.e., the Ti-containing alumina supports of Examples 13 and 14 improved the diesel fuel light-off temperature compared to Reference Example 12, even when NO was present in the feed). After hydrothermal aging at 600°C for 35 hours, each sample was tested again. The results (Figure 22) confirmed the observations from fresh samples and the corresponding operando results (i.e., the Ti-containing supports improved the diesel fuel light-off temperature even when NO was present in the feed).

[0180] Example 15. Preparation and testing of a full-size article A full-size reference catalyst article (Example 15A) was prepared according to Example 12, and a full-size inventive catalyst article (Example 15B) was prepared according to Example 13. Both full-size samples were 200 g / ft. 3 They had the same PGM load with a Pt / Pd ratio of 10:1. The substrate dimensions for both articles were 9 inches D x 3 inches L, at 400 cpsi.

[0181] The items of Examples 15A and 15B were tested on a commercially available engine dynamometer (Cummins ISX engine) at a steady-state temperature for 15 minutes, during which the exhaust inlet temperature was gradually decreased from 235°C to 180°C in increments of approximately 10°C, while performing cylinder fuel injection.

[0182] Results averaged over 5 minutes, starting 4 minutes after injection, are shown in Figures 23 and 24 (6,000 and 10,000 ppm diesel fuel injections, respectively). Example 15B clearly demonstrated improved activity at temperatures below 200°C, as evidenced by the relatively high DOC outlet temperature. These data validated laboratory-scale test results.

[0183] Example 16. Acidity measurement The acidity sites of the Brønsted (proton donor) and Lewis (electron acceptor) regions were evaluated using pyridine adsorption measured by diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) for samples of compositions from Examples 1 (Reference Example) and 4. A sample of the catalyst composition (approximately 40 mg) was ground into a fine powder using an agate mortar and transferred to an aluminum sample cup. Before acidity measurement, the sample was dehydrated at 450°C for 1 hour while flowing dry N2. The sample was heated to 180°C and 400°C under flowing N2 for 50 minutes, then cooled, and the DRIFT spectrum was collected using a Thermo Scientific iS50 FTIR spectrometer equipped with an MCT detector and a Spectra-Tech diffuse reflectance high-temperature chamber with a KBr window, while passing a constant N2 gas through it. The data are reported in Table 5.

[0184] [Table 5]

[0185] The results (Table 5) show that high concentrations of acidic sites (both Brønsted and Lewis sites, particularly Brønsted sites) at temperatures within the hydrocarbon light-off region (e.g., approximately 180°C) are associated with the good hydrocarbon light-off performance in the presence of nitric oxide in Example 4. While not bound by theory, high concentrations of acidic sites, particularly Brønsted sites, combined with the large pore size of the support material in Invention Example 4, are considered beneficial in minimizing nitric oxide inhibition of hydrocarbon light-off.

Claims

1. An oxidation catalyst composition for use in a close-coupled diesel oxidation catalyst (ccDOC), A high-surface-area alumina support material doped with at least one metal oxide, and Platinum group metals (PGMs) supported on doped alumina support material, Includes, The aforementioned ccDOC is 100,000h －１ It operates at the above space velocity to light off hydrocarbons at temperatures below approximately 250°C in the presence of nitric oxide (NO), and The doped high-surface-area alumina support material is a large-pore material having an average pore opening size of at least about 15 nm, as measured using a BET-type N2 adsorption or desorption experiment, and The doped high-surface-area alumina support material has a total acidity greater than 300 μmoles per gram, and The aforementioned high surface area alumina support material has at least about 90 m ２ It has a surface area of ​​ / g, and An oxidation catalyst composition having an exhaust gas flow with a CO-to-HC ratio of 100 or more.

2. The oxidation catalyst composition according to claim 1, wherein the doped high-surface-area alumina support material is a large-pore material having an average pore opening size of at least about 20 nm.

3. The oxidation catalyst composition according to claim 1, wherein the doped high-surface-area alumina support material has a Brønsted acidity greater than 1 μmol per gram.

4. The oxidation catalyst composition according to claim 1, wherein the at least one metal oxide is an oxide of titanium, silicon, manganese, iron, nickel, zinc, zirconium, tin, or any combination thereof.

5. The oxidation catalyst composition according to claim 1, wherein the at least one metal oxide is selected from silica, titania, manganese oxide, and combinations thereof.

6. The oxidation catalyst composition according to claim 1, wherein the at least one metal oxide is titania.

7. The oxidation catalyst composition according to claim 1, wherein the oxidation catalyst composition contains at least one metal oxide in an amount of about 1% by mass to about 20% by mass, based on the total mass of the oxidation catalyst composition.

8. The oxidation catalyst composition according to claim 1, wherein the oxidation catalyst composition contains about 1% by mass to about 10% by mass of the PGM based on the total mass of the oxidation catalyst composition.

9. The oxidation catalyst composition according to claim 1, wherein the PGM is platinum or a mixture of platinum and palladium.

10. The oxidation catalyst composition according to claim 1, wherein the PGM is a mixture of platinum and palladium in which the mass ratio of platinum to palladium is about 1 to about 10.

11. The high surface area alumina support material has a surface area in the range of about 90 m ２ / g to about 150 m ２ / g, the oxidation catalyst composition of claim 1.

12. The oxidation catalyst composition according to claim 1, wherein the high surface area alumina support material is a large-pore material having an average pore opening size in the range of about 15 nm to about 200 nm, or about 20 nm to about 50 nm.

13. The oxidation catalyst composition according to claim 1, wherein the high surface area alumina support material is doped with about 1% by mass to about 20% by mass of titania, based on the mass of the doped high surface area alumina support material.

14. The oxidation catalyst composition according to claim 1, wherein the high surface area alumina support material is doped with about 1% to about 10% by mass of titania, or about 3% to about 7% by mass of titania, based on the mass of the doped high surface area alumina support material.

15. The oxidation catalyst composition according to claim 13, further comprising manganese oxide.

16. The oxidation catalyst composition contains, based on the total mass of the oxidation catalyst composition, about 1% to about 5% by mass of platinum, palladium, or a mixture thereof. The high-surface-area alumina support material is doped with approximately 5% to 10% by mass of titania, based on the mass of the doped high-surface-area alumina support material, and The aforementioned high surface area alumina support material is approximately 90 m ２ / g ~ approx. 150m ２ The oxidation catalyst composition according to claim 1, having a surface area in the range of / g, an average pore opening size of about 15 nm to about 200 nm, or both.

17. Hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NO) ｘ A system for processing exhaust gas flow from an internal combustion engine containing ), wherein the system is: A close-coupled diesel oxidation catalyst (ccDOC) article located downstream of an internal combustion engine, comprising a substrate and an oxidation catalyst composition according to any one of claims 1 to 15 disposed on at least a portion of the substrate, A diesel oxidation catalyst (DOC) article located downstream of the engine and suitable for the oxidation of HC, CO, and NOx, Located downstream of the aforementioned DOC article, nitrogen oxides (NO ｘ Selective catalytic reduction (SCR) articles suitable for the reduction of ) Includes, A system in which all catalytic components are in fluid communication with the exhaust gas flow.

18. HC and NO present in the exhaust gas flow from an internal combustion engine ｘ A method for reducing A process of introducing a certain amount of HC into the exhaust gas flow to form an exhaust gas flow rich in HC, A step of bringing an exhaust gas flow rich in HC into contact with an oxidation catalyst composition according to any one of claims 1 to 16, thereby generating heat through the combustion of HC, and thereby forming a heated first effluent, wherein the oxidation catalyst composition is placed on a substrate and is located in close proximity downstream of the internal combustion engine, The heated first effluent is brought into contact with a diesel oxidation catalyst suitable for the oxidation of HC and NO, thereby reducing the level of HC and NO. ２ A process in which a second spill is formed with an increased level, A step of injecting a reducing agent into the second effluent that has come out of the diesel oxidation catalyst to obtain a third effluent, The third outflow mentioned above is NO ｘ It is brought into contact with an SCR catalyst suitable for reduction, thereby reducing HC and NO ｘ A method comprising the step of forming a treated exhaust gas flow with a reduced level.

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