Post-treatment of alcohol fuel instead of diesel engine using selective catalytic reactor with oxidation function

Abstract

An internal combustion engine system is described herein. The system uses a selective catalytic reactor (SCR) with an oxidation function to treat NOx emissions and a second exhaust gas component in the exhaust gas of an internal combustion engine. The SCR with oxidation function includes at least two stages: a NOx reduction stage having a NOx reduction matrix configured to react with and reduce the amount of NO2 and / or NO in the exhaust gas of an internal combustion engine, and a NOx reduction stage having a NOx reduction matrix configured to react with and reduce the amount of NO2 and / or NO in the exhaust gas of the internal combustion engine; and an oxidation stage having an oxidation catalyst configured to oxidize at least a portion of the second exhaust gas component. The oxidation stage may be applied to the NOx reduction substrate, or may replace portions of the NOx reduction substrate.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an exhaust aftertreatment system for treating exhaust gas from an internal combustion engine, and more particularly, to a system and method that utilizes an oxidation selective catalytic reactor to oxidize unburned hydrocarbons and formaldehyde to a desired level. BACKGROUND

[0002] Internal combustion engines are widely used in various industries. Internal combustion engines can operate on a variety of different liquid fuels, gaseous fuels, and various blends. Spark-ignition engines employ an electric spark to initiate combustion of fuel and air, while compression-ignition engines typically compress the gases in the cylinder to the auto-ignition threshold, such that ignition of the fuel begins without the need for a spark. In an effort to reduce greenhouse gases (GHG), there have been efforts to change the first fuel used in combustion engines from fuels such as diesel to alcohol fuels such as ethanol and methanol or combinations of these fuels. Alcohol fuels can be introduced into the combustion chamber in various ways. For example, methanol can be introduced into the inlet air stream through the intake manifold of the engine. This type of injection is sometimes referred to as “port fuel injection.” Direct fuel injection (DFI) systems use injectors to inject alcohol directly into the combustion chamber. While sometimes more complex than port fuel injection systems, when properly configured, direct fuel injection systems can burn the fuel more cleanly, sometimes producing exhaust products similar to non-alcohol systems such as diesel-only systems.

[0003] In some combustion engines, the exhaust gas often contains various ratios of nitrogen dioxide (NO2) to nitric oxide (NO). The amount of nitrogen dioxide (NO2) can increase significantly when alcohol-based fuels or other oxygenated fuels are used with diesel fuel. NO2 can be considered a pollutant due to its effects on humans. In addition, NO2 also promotes the formation and modification of other pollutants such as ozone, particulate matter, and acid rain. There have been efforts to reduce the amount of NO2 produced in diesel engines using alcohol fuels such as methanol. For example, U.S. Patent No. 11,143,078 to Moore et al. (“the ‘078 patent”) describes one such effort. The ‘078 patent describes the use of a close-coupled SCR catalyst and a first SCR catalyst. The close-coupled SCR catalyst is used during low load operating conditions, while the first SCR catalyst is used during high load operating conditions. However, the system (and process) described in the ‘078 patent has some shortcomings. For example, the system of the ‘078 patent uses a second SCR catalyst (close-coupled SCR catalyst), thus requiring additional components. In addition, the close-coupled SCR catalyst and the first SCR catalyst are used to reduce NOx in the exhaust gas. The remaining unburned alcohol fuel can not be treated and can be at least partially released into the atmosphere.

[0004] Some examples of the present disclosure are directed to overcoming these and other deficiencies of such systems. SUMMARY

[0005] In one aspect of the present disclosure, an internal combustion engine system includes an internal combustion engine configured to combust diesel fuel and a second fuel using direct fuel injectors to inject the diesel fuel and the second fuel into cylinders of the internal combustion engine, wherein a portion of exhaust gas of the internal combustion engine includes nitrogen dioxide (NO2), nitrogen monoxide (NO), and a second exhaust component, wherein at least a portion of the second exhaust component includes unburned second fuel; a selective catalytic reactor (SCR) having an oxidation function including a NOx reduction stage and an oxidation stage, the NOx reduction stage including a NOx reduction substrate configured to react with and reduce an amount of NO and NO2 in the exhaust gas of the internal combustion engine, the oxidation stage including an oxidation catalyst configured to oxidize and reduce at least a portion of the second exhaust component in the exhaust gas to generate a treated exhaust gas.

[0006] In another aspect of the present disclosure, a selective catalytic reactor (SCR) having an oxidation function for treating exhaust gas of an internal combustion engine that uses direct fuel injectors to inject a first fuel and a second fuel into cylinders of the internal combustion engine includes a NOx reduction stage and an oxidation stage, the NOx reduction stage including a NOx reduction substrate configured to react with and reduce an amount of NO2 and NO in the exhaust gas of the internal combustion engine, the oxidation stage including an oxidation catalyst configured to oxidize and reduce at least a portion of the second exhaust component in the exhaust gas to generate a treated exhaust gas.

[0007] In still another aspect of the present disclosure, a method of controlling emissions in exhaust gas of an internal combustion engine using direct fuel injectors includes directing at least a portion of the exhaust gas to a NOx reduction stage of a selective catalytic reactor (SCR) having an oxidation function, the NOx reduction stage including a NOx reduction substrate configured to react with and reduce an amount of NO2 or NO in the exhaust gas of the internal combustion engine, and directing at least a portion of the exhaust gas to an oxidation stage of the SCR having an oxidation function, the oxidation stage including an oxidation catalyst configured to oxidize and reduce at least a portion of a second exhaust component in the at least a portion of the exhaust gas to generate a treated exhaust gas. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1An internal combustion engine system configured to control emissions using a selective catalytic reactor with oxidation functionality is illustrated in accordance with various embodiments of the presently disclosed subject matter.

[0009] Figure 2 A direct fuel injector usable in a combustion engine system configured to control emissions is illustrated in accordance with various embodiments of the presently disclosed subject matter.

[0010] Figure 3 A side view cross-sectional view of a selective catalytic reactor with oxidation functionality having a catalyst tube with an oxidation layer for oxidizing a second exhaust component in accordance with various examples of the presently disclosed subject matter.

[0011] Figure 4 A cross-sectional view of a catalyst tube having an oxidation layer for oxidizing a second exhaust component in accordance with various examples of the presently disclosed subject matter.

[0012] Figure 5 A method of using a selective catalytic reactor with oxidation functionality having a catalyst tube with an oxidation stage for oxidizing a second exhaust component in accordance with various examples of the presently disclosed subject matter. DETAILED DESCRIPTION

[0013] In all of the drawings, like reference numerals will be used to denote identical or similar components among the drawings. Figure 1 An internal combustion engine system 100 configured to control emissions is illustrated in accordance with various embodiments of the presently disclosed subject matter. The internal combustion engine system 100 includes an internal combustion engine 102 having a plurality of combustion cylinders (not shown). The internal combustion engine 102 can have any number of combustion cylinders. It should be understood that the combustion cylinders are associated with pistons (not shown) that can move between top dead center and bottom dead center positions in generally conventional fashion, typically in a four-stroke engine cycle, although other combustion cycles can be used and are considered to be within the scope of the presently disclosed subject matter. The pistons will be coupled with a crankshaft (not shown) that can rotate to provide torque for vehicle propulsion, to operate a generator to generate electrical energy, or in still other applications such as operating a compressor, a pump, or various other types of equipment.

[0014] The internal combustion engine 102 is fueled by a first fuel 104 stored in a first fuel tank 106 and a second fuel 108 stored in a second fuel tank 110. The first fuel 104 can include a higher cetane / lower octane liquid fuel, and the second fuel 108 can include a lower cetane / higher octane liquid fuel. In this context, the terms “higher” and “lower” can be understood as relative terms with respect to one another. Thus, the first fuel 104 can have a higher cetane number and a lower octane number than the cetane number and octane number of the second fuel 108. The first fuel 104 can include diesel distillate fuel, dimethyl ether, biodiesel, hydrotreated vegetable oil (HVO), gas-to-liquid (GTL) renewable diesel, any of a variety of liquid fuels with a cetane enhancer, or another fuel type. The second fuel 108 can include an alcohol fuel such as, for example, methanol or ethanol, or yet other fuel types such as, but not limited to, isopropanol, n-propanol, and tert-butyl alcohol. For purposes of this disclosure, the first fuel 104 is described as a diesel fuel and the second fuel 108 is described as methanol, but as noted above, the presently disclosed subject matter can be used with other fuel types. Figure 1

[0015] The first fuel 104 can be delivered to the engine 102 by a first fuel pump 112 in fluid communication with the first fuel tank 106. The second fuel 108 can be delivered to the engine 102 by a second fuel pump 114 in fluid communication with the second fuel tank 110. Air 117 for combustion can be received through an intake manifold 119. Using the first fuel pump 112 and the second fuel pump 114, the first fuel 104 and the second fuel 108 can be provided to a direct fuel injector 116 of the engine 102. The direct fuel injector 116 receives the first fuel 104 and / or the second fuel 108 and injects the delivered fuel into a combustion chamber of the engine 102 as described in Figure 2

[0016] Figure 2 A direct fuel injector 202 that can be used in a combustion engine system configured to control emissions in accordance with various embodiments of the presently disclosed subject matter is illustrated. It should be noted that the injector 202 as illustrated in Figure 2 is used to illustrate an example fluid flow using a direct fuel injector, as the injector 202 and other components illustrated herein can have additional features, components, or structures that are not illustrated in the present figure and other figures but can additionally be used. Moreover, the injector 202 is one example of a type of direct fuel injector that can be used, as other configurations and designs can be used such as separate fuel injectors for the first fuel and the second fuel and are considered to be within the scope of the present disclosure. Returning to Figure 2 ​​The fuel injector 202 injects the fuel charge 204 into a cylinder 208 of the engine 102 through an injector port 206 for combustion. It is noted that although one fuel injector 202 is illustrated, the presently disclosed subject matter can be used with other types of injectors, including injectors having separate ports for the first and second fuels, and are considered to be within the scope of the presently disclosed subject matter.

[0017] The fuel charge 204 includes a first fuel portion 210 that includes the first fuel 104 and a second fuel portion 212 that includes the second fuel 108. The first fuel 104 is injected first to start the combustion process in the cylinder 208, thereby acting as a pilot fuel. The injector 202 includes a first fuel inlet 214 for receiving the first fuel 104 from a first fuel input line 215. The injector 202 also includes a second fuel inlet 218 for receiving the second fuel 108 from a second fuel input line 217. To produce the fuel charge 204, the injector 202 includes a piston 222. The piston 222 is configured to create a vacuum in a first action to draw the first fuel 104 and the second fuel 108 into an injection chamber 224 of the injector 202. The piston 222 then creates pressure in a second action to push the first fuel 104 and the second fuel 108 in the injection chamber 224 into the cylinder 208. In the example injector 202 illustrated in Figure 2 In the example injector 202 illustrated in

[0018] Returning to Figure 1which further describes the treatment of combustion products in the exhaust 118. In a diesel fuel engine, the "fuel NOx" in the exhaust 118 is formed from the oxidation of nitrogen in the air in the combustion cylinder at elevated combustion temperatures during the combustion process. To reduce the amount of NOx in the emissions from a diesel fuel engine, the internal combustion engine system 100 also includes a selective catalytic reactor (SCR) 120 with oxidation functionality to provide a treated exhaust 122. The SCR 120 with oxidation functionality is made from various porous ceramic materials used as a support, such as titanium oxide, and the active catalytic component is typically oxides of base metals (such as vanadium, molybdenum, and tungsten), zeolites, or various noble metals. A reductant, such as but not limited to anhydrous ammonia (NH3), aqueous ammonia (NH4OH), or urea (CO(NH2)2) solution, is added to the stream of flue gas or exhaust and reacts on the catalyst. As the reaction proceeds toward completion, nitrogen gas (N2) and carbon dioxide (CO2) are produced in the case of urea. The reduction reaction in the SCR 120 with oxidation functionality proceeds variously based on the compounds entering the SCR 120 with oxidation functionality and their respective stoichiometric ratios. Equation #1 below represents the slow rate of the reduction reaction when the entering reactants are at the stoichiometric ratios indicated in Equation #1. Equation #2 below represents the standard rate of the reduction reaction when the entering reactants are at the stoichiometric ratios indicated in Equation #2. Equation #3 below represents the fast rate of the reduction (fast SCR) reaction when the entering reactants are at the stoichiometric ratios indicated in Equation #3.

[0019]

[0020] Due to the rate of the reduction reaction, in some examples, it can be preferable to allow the stoichiometry of Equation #3. The optimal stoichiometry for Equation #3 is when the stoichiometric ratio of NO to NO2 is 50 / 50, allowing the SCR 120 with oxidation functionality to continue the fast SCR reaction. This "fast SCR" reaction functions at 180-300°C to improve de-NOx performance. When diesel is replaced by methanol (or another alcohol fuel) in a lean-burn internal combustion engine, most of the NOx in the emissions can be in the form of NO2. However, in some examples, including when using direct fuel injectors, the exhaust 118 can contain both combustion products (i.e., NO / NOx) and a second exhaust component, such as unburned second fuel 108 and other compounds such as formaldehyde, carbon monoxide, and hydrocarbons.

[0021] To treat both NO / NOx and the second exhaust component in exhaust 118, the oxidation- functioned SCR 120 includes a NOx reduction stage 124 and an oxidation stage 126. Although oxidation stage 126 is shown downstream of NOx reduction stage 124, it can be positioned partially or entirely at one or more locations along the flow path of exhaust 118 within oxidation- functioned SCR 120. The NOx reduction stage includes the above-described oxidation- functioned SCR catalysts that effect NOx reduction via Equations 1-3. Oxidation stage 126 uses an oxidation catalyst such as, but not limited to, a metal zeolite (e.g., a copper zeolite) to oxidize the second exhaust component. In some examples, the oxidation catalyst can be coated with one or more components such as a noble metal as a washcoat. In some examples, oxidation- functioned SCR 120 includes a first portion that is an extruded matrix, e.g., vanadium with an ammonia slip catalyst, and a second portion that is a region coated with a noble metal oxidation catalyst. Some oxidation catalysts include, but are not limited to, platinum, palladium, rhodium, or a monolithic honeycomb substrate coated with a platinum group metal catalyst. Thus, the NOx component of exhaust 118 is treated in oxidation- functioned SCR 120 using a NOx reduction catalyst, while the second exhaust component is treated in oxidation- functioned SCR 120 using a noble metal oxidation catalyst. In some examples, depending on the materials selected, a portion of the NOx component of exhaust 118 can also be treated in oxidation stage 126. One example oxidation- functioned SCR 120 having NOx reduction stage 124 and oxidation stage 126 is described below in Figure 3 FIG. 1.

[0022] Figure 3 FIG. 2 is a side cross-sectional view of an oxidation- functioned SCR 120 having catalyst tubes for oxidizing a second exhaust component according to various examples of the presently disclosed subject matter. Figure 3 FIG. 3 is a side cross-sectional view of oxidation- functioned SCR 120 including a closure 302 that encloses a reaction volume 304 within oxidation- functioned SCR 120. Catalyst tubes 306 are disposed within reaction volume 304 of oxidation- functioned SCR 120 (the side walls 308 of closure 302 are partially removed to show at least a portion of catalyst tubes 306). Exhaust 118 enters closure 302 of oxidation- functioned SCR 120 and flows through catalyst tubes 306, whereby NOx in exhaust 118 is treated in NOx reduction stage 124 and the second exhaust component is oxidized in oxidation stage 126. It is noted that in some examples, oxidation stage 126 can be at the inlet of one or more of catalyst tubes 306, along the length of one or more of catalyst tubes 306, and / or proximate to the outlet of one or more of catalyst tubes 306, or various combinations thereof. One example catalyst tube 306 is described below in Figure 4 FIG. 4.

[0023] Figure 4 is a cross-sectional view of a catalyst tube 306 having an oxidation stage 126 for oxidizing a second exhaust component according to various examples of the presently disclosed subject matter. The NOx reduction stage 124 includes a first uncoated region 403 that includes a NOx reduction substrate 402. The NOx reduction substrate 402 is comprised of a catalyst for reducing NOx within the exhaust 118. The exhaust 118 flows through the NOx reduction substrate 402. The catalyst tube 306 also includes a second region 405 that includes the oxidation stage 126. In some examples, the second region 405 can also include portions of the NOx reduction substrate 402. The oxidation stage 126 includes one or more portions of the SCR 120 having an oxidation function, where the NOx reduction substrate 402 is coated with an oxidation catalyst and / or where the NOx reduction substrate 402 is replaced with an oxidation catalyst. For example, the oxidation stage 126 includes stage sections 404 and 406. The stage sections 404 and 406 can be sections where the NOx reduction substrate 402 has an oxidation catalyst applied to a portion of the surface of the NOx reduction substrate 402. In these regions, i.e., where the oxidation coating is applied to a portion of the surface of the NOx reduction substrate 402, the exhaust 118 can treat NOx in the stage sections 404 and 406 as the exhaust 118 travels into the portions of the NOx reduction substrate 402, and treat the second exhaust component as the exhaust 118 travels into the portions of the oxidation catalyst.

[0024] As described above, portions of the NOx reduction substrate 402 can be replaced with an oxidation catalyst instead of the NOx reduction substrate 402 being coated. For example, the stage section 408 can not include the NOx reduction substrate 402. In the volume filled by the stage section 408, the NOx reduction substrate 402 can have been removed, or the stage section 408 can have been added to the NOx reduction substrate 402. In the stage section 408, because the catalyst is an oxidation catalyst, the primary treatment can be oxidation of the second exhaust component. However, in some examples, some oxidation catalysts can also reduce the level of NOx in the exhaust 118, and thus can be used for both second exhaust product oxidation and NOx reduction. Using one or more of the various examples described herein, the exhaust 118 exits the SCR 120 having an oxidation function as the treated exhaust 122.

[0025] Figure 5 is a method 500 using an SCR 120 having an oxidation function with a catalyst tube 306 having an oxidation stage 126 for oxidizing a second exhaust component according to various examples of the presently disclosed subject matter. The order of described operations is not intended to be construed as a limitation, and any number of the described operations can be combined in any order and / or in parallel to implement a process.

[0026] Method 500 begins at step 502, where engine 102 is started. Engine 102 can be various types of internal combustion engines. In one example, engine 102 is a diesel fuel engine that uses an alcohol, such as methanol, as a second fuel. When the second fuel is used, diesel fuel can be used as a first fuel and / or as a pilot fuel.

[0027] At step 504, first fuel 104 and second fuel 108 are injected into engine 102 by a fuel injector, such as direct fuel injector 202. Figure 2 In some examples, the first fuel is used as a pilot fuel. As shown in FIG. 2, fuel load 204 can include a first injection of fuel including first fuel portion 210, followed by a second injection of fuel including second fuel portion 212. First fuel 104 is injected first to start the combustion process in cylinder 208, acting as a pilot fuel. Figure 2

[0028] At step 506, the first and second fuels, including fuel load 204, are combusted in cylinder 208 of engine 102. The result of the combustion process is exhaust 118. Exhaust 118 can include compounds and components, such as NO and NOx, as well as second exhaust components, such as uncombusted second fuel.

[0029] At step 508, exhaust 118 is directed to SCR 120 having an oxidation function. SCR 120 having an oxidation function is used to treat exhaust 118 to reduce or remove various components of exhaust 118 for eventual introduction into the environment surrounding engine system 100.

[0030] At step 510, exhaust 118 is treated in NOx reduction stage 124. NOx reduction stage 124 includes first uncoated region 403 including NOx reduction substrate 402. NOx reduction substrate 402 is comprised of a catalyst for reducing NOx within exhaust 118.

[0031] At step 512, second exhaust components of exhaust 118 are oxidized in oxidation stage 126 of SCR 120 having an oxidation function. Oxidation stage 126 uses an oxidation catalyst, such as but not limited to a metal zeolite (e.g., copper zeolite) to oxidize the second exhaust components. In some examples, SCR 120 having an oxidation function includes a first portion that is an extruded substrate, for example, vanadium with an ammonia slip catalyst, and a second portion that is a region coated with a noble metal oxidation catalyst. Some oxidation catalysts include, but are not limited to, platinum, palladium, and rhodium. In other examples, the first portion is an SCR containing extruded vanadium, metal zeolite, or other material. In other examples, the SCR includes a coated material. It is noted that, as discussed above, the oxidation stage 126 can be a portion of the SCR 120 having an oxidation function. Figure 4 ​As described herein, depending on the location of the oxidation stage 126 in the NOx reduction matrix 402, step 510 for multiple portions of exhaust gas 118 may occur before, after, or simultaneously with step 512. It should also be noted that in some instances, the oxidation stage may help reduce the amount of NO and NO2 moving through exhaust gas 118 via an SCR 120 with oxidation functionality.

[0032] Industrial applicability

[0033] This disclosure generally relates to emission control of internal combustion engines, primarily diesel engines that use fuels such as methanol as a substitute for all or part of diesel fuel. The use of methanol (or other similar fuels) in diesel engines (including those using direct fuel injectors) can result in NO / NO2 (NOx) and second exhaust products (e.g., unburned methanol) in the exhaust. Aspects of this disclosure use an SCR 120 with an oxidation function. The SCR 120 with an oxidation function employs a two-stage treatment process within itself. In one stage—NOx reduction stage 124—NOx combustion products in exhaust gas 118 are reduced. In another stage within the SCR 120 with an oxidation function—oxidation stage 126—second exhaust components are reduced. In some instances, oxidation stage 126 consists of multiple sections of NOx reduction stage 124 coated with an oxidation catalyst. In other instances, multiple sections of NOx reduction stage 124 have been replaced (e.g., removed or replaced) by the oxidation catalyst used in oxidation stage 126.

[0034] Unless explicitly excluded, using the singular to describe a component, structure, or operation does not preclude the use of multiple such components, structures, or operations or their equivalents. As used herein, the word "or" refers to any possible permutation of a set of items. For example, the phrase "A, B, or C" refers to at least one of A, B, C, or any combination thereof, such as any of the following: A; B; C; A and B; A and C; B and C; A, B, and C; or multiple items such as A and A; B, B, and C; A, A, B, C, and C, etc.

[0035] While various aspects of this disclosure have been specifically shown and described with reference to the foregoing embodiments, those skilled in the art will understand that various other embodiments can be contemplated through modifications to the disclosed machinery, systems, and methods without departing from the spirit and scope of the disclosure. Such embodiments should be understood to fall within the scope of this disclosure as defined by the claims and any equivalents.

Claims

1. An internal combustion engine system, the internal combustion engine system comprising: An internal combustion engine configured to use a direct fuel injector to inject diesel fuel and a second fuel into its cylinder to burn the diesel fuel and the second fuel, wherein a portion of the exhaust of the internal combustion engine contains nitrogen dioxide (NO2), nitric oxide (NO), and a second exhaust component, wherein at least a portion of the second exhaust component contains unburned second fuel. A selective catalytic reactor (SCR) with oxidation function, the SCR comprising: NOx reduction stage, the NOx reduction stage comprising a NOx reduction matrix configured to react with the NO2 or NO in the exhaust of the internal combustion engine and reduce the amount of the NO2 or NO; and An oxidation stage comprising an oxidation catalyst configured to oxidize and reduce at least a portion of the second exhaust component in the exhaust gas to generate treated exhaust gas.

2. The internal combustion engine system according to claim 1, wherein the second fuel comprises methanol, ethanol, n-propanol, isopropanol or tert-butanol.

3. The internal combustion engine system according to claim 1, wherein the oxidation catalyst comprises a metal zeolite, platinum, palladium, rhodium, or an integral honeycomb substrate coated with a platinum group metal catalyst.

4. The internal combustion engine system of claim 1, wherein the oxidation stage comprises an oxidation catalyst coated on at least a portion of the NOx reduction matrix.

5. The internal combustion engine system of claim 1, wherein a plurality of portions of the NOx reduction matrix are replaced by the oxidation catalyst.

6. A selective catalytic converter (SCR) with oxidation function for treating exhaust gas from an internal combustion engine, said internal combustion engine using direct fuel injectors to inject a first fuel and a second fuel into its cylinders, said SCR with oxidation function comprising: NOx reduction stage, the NOx reduction stage comprising a NOx reduction matrix configured to react with NO2 or NO in the exhaust of the internal combustion engine and reduce the amount of NO2 or NO; and An oxidation stage comprising an oxidation catalyst configured to oxidize and reduce at least a portion of a second exhaust component in the exhaust gas to produce treated exhaust gas.

7. The SCR with oxidation function according to claim 6, wherein the second fuel comprises methanol, ethanol, n-propanol, isopropanol or tert-butanol.

8. The SCR with oxidation function according to claim 6, wherein the oxidation catalyst comprises a metal zeolite, platinum, palladium, rhodium or an integral honeycomb substrate coated with a platinum group metal catalyst.

9. The SCR with oxidation function according to claim 6, wherein at least a portion of the NO2 is treated in a plurality of portions of the NOx reduction matrix coated with the oxidation catalyst.

10. The SCR with oxidation function according to claim 6, wherein the SCR further comprises a plurality of oxidation stages.

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