METHOD AND SYSTEMS FOR A DIESEL OXIDATION CATALYTIC CONVERTER

Abstract

A method comprising: generating NO2 in a catalyst (70) comprising a washcoat with zirconium, one or more base metal oxides and a palladium oxide, wherein an exhaust gas flow rate is between the lower and upper threshold flow rates; and facilitating regeneration of a particulate filter (72) located downstream of the catalyst (70) via NO2 when an exhaust gas temperature is greater than a threshold temperature; wherein the palladium oxide is contained in an upstream section (70A) of the catalyst (70) in relation to a direction of the exhaust gas flow; and the at least one base metal oxide is contained in a downstream section (70B) of the catalyst (70) in relation to the direction of the exhaust gas flow.

Description

Area The present description generally concerns processes and systems for a diesel oxidation catalyst (DOC) with a combination of precious metal and base metal compounds. General state of the art / Summary A diesel oxidation catalyst (DOC) can rapidly oxidize NO to NO₂ for treatment in an SCR system or to promote the regeneration of a particulate filter. One or more platinum group metals (e.g., Pt, Pd, Rh, etc.) are coupled to a substrate of the DOC and promote NO₂ formation, while also providing the added characteristic of low start-up temperatures. However, DOCs containing large amounts of platinum group metals can degrade after a certain number of vehicle miles, thus limiting their NO₂ production capabilities. Other attempts to address NO2 generation involve DOCs with a composition that includes a combination of one or more metals or platinum group metals with one or more base metal oxides. An exemplary approach is shown by Cooper et al. in US 4,902,487 A. In this approach, a precious metal (e.g., a platinum group metal), such as platinum, is coated onto a ceramic honeycomb substrate. The catalyst is configured to catalyze NO to NO2 in the presence of O2. A particulate filter, comprising one or more base metal oxides and / or La / Cs / V2O5, is located downstream of the catalyst. Thus, the particulate filter can achieve lower regeneration temperatures in the presence of NO2 generated by the catalyst. Furthermore, patent EP 2 927 445 A1 describes a motor-driven vehicle with an oxidation catalyst in the exhaust manifold and a particulate filter downstream of the oxidation catalyst, wherein the exhaust gas temperature is increased above a threshold temperature to regenerate the particulate filter. Furthermore, patent US 2002 / 0131914 A1 describes an oxidation catalyst with a zirconium oxide support containing base metal oxides and palladium oxide located on different parts of the zirconium oxide support. However, the inventors of the present invention have recognized potential problems associated with such systems. For example, the NO2-generating catalyst can be bypassed if sulfate formation becomes a problem. Consequently, regeneration options for the particulate filter, which uses NO2, are reduced. To mitigate the problem described, the present invention proposes a method according to claim 1 and a system according to claim 8. Preferred embodiments of the invention are the subject of the dependent claims. The problem described above can therefore be addressed by a method for generating NO2 in a catalyst comprising a washcoat with zirconium, one or more base metal oxides and palladium oxide, which does not oxidize sulfur, wherein the palladium oxide is contained in an upstream section of the catalyst in relation to a direction of the exhaust gas flow, and wherein the at least one base metal oxide is contained in a downstream section of the catalyst in relation to the direction of the exhaust gas flow, and wherein an exhaust gas flow is between lower and upper threshold flow rates, and facilitating the regeneration of a particulate filter located downstream of the catalyst via NO2 when an exhaust gas temperature is greater than a threshold temperature.In this way, an NO2 production rate is calculated based on values ​​stored in a lookup table that correspond to the exhaust gas flow rate and exhaust gas temperature to determine whether particulate filter regeneration can be facilitated by NO2. As an example, the particulate filter can be regenerated actively or passively. When the particulate filter is above a threshold temperature for oxygen-facilitated regeneration, the filter is hot enough to regenerate in the presence of oxygen (e.g., to burn off deposited particles). However, the threshold temperature for oxygen-facilitated regeneration is relatively high (e.g., 450–700 °C) compared to a threshold temperature for NO₂-facilitated regeneration (e.g., 300–450 °C). The threshold temperature for NO₂-facilitated regeneration corresponds to regeneration in the presence of a quantity of NO₂ greater than a threshold quantity for NO₂ particulate filter regeneration. The production of NO₂ by the aftertreatment system relies on at least one exhaust gas flow rate.If the detected exhaust gas flow rate is higher than a lower threshold flow rate, NO2 produced by the aftertreatment system can promote regeneration of the particulate filter. In this way, lower exhaust gas temperatures, which may correspond to driving at low to medium load, can be used to regenerate the particulate filter in conjunction with the NO2 production from the aftertreatment system, which is configured to maintain its reactivity and durability in a diesel exhaust environment. It is understood that the foregoing summary is provided to present, in simplified form, a selection of concepts that are described in more detail in the detailed description. It is not intended to identify important or essential features of the claimed subject matter, the scope of which is defined solely by the claims following the detailed description. Furthermore, the claimed subject matter is not limited to implementations that address the disadvantages mentioned above or in any part of this disclosure. Brief description of the drawings Fig. 1 shows a single cylinder of an engine. Fig. 2 shows a diagram illustrating NO2 production by the aftertreatment device. Fig. 3 shows a comparison of soot oxidation rates at a particulate filter in the presence of NO2 and oxygen. Fig. 4 shows a method for regenerating a particulate filter. Fig. 5 shows a graph illustrating engine operating parameters based on the method from Fig. 4. Fig. 6 shows a graph illustrating specific active controls for regenerating the particulate filter. Detailed description The following description concerns systems and methods for a diesel oxidation catalyst (DOC) comprising one or more catalysts with platinum group metal (PGM) oxides mixed with one or more base metal oxides (BMOs). In one example, the PGM is Pd, which allows the DOC to exclude Pt, which can be prone to degradation due to its reactivity with sulfur dioxide, whereas Pd is unreactive with sulfur dioxide. The composition of the mixture can be tailored based on one or more downstream emission control device configurations (e.g., a particulate filter) and the exhaust system environment of an engine, such as the one shown in Fig. 1. Particulate filters can be regenerated passively or actively.Passive regeneration occurs when exhaust gas temperatures are sufficiently high, without adjusting engine operating parameters beyond driver demand. Active regeneration occurs when engine operating parameters are adjusted to raise exhaust gas temperatures to a sufficiently high level. Thus, active regeneration may reduce the vehicle's fuel efficiency to increase the exhaust gas temperature. The DOC, which comprises a mixture of PGM and BMO catalysts, is configured to produce NO₂ to promote particulate filter regeneration and / or NOx treatment in a selective catalytic reduction (SCR) device. The DOC can produce a varying amount of NO₂ based on minimum exhaust gas temperatures, as illustrated by a graph in Fig. 2. As described above, NO₂ can promote particulate filter regeneration. In the example in Fig.3. NO2 reduces particulate filter regeneration temperatures compared to oxygen particulate filter regeneration temperatures. In other words, particulate filter regenerations facilitated by oxygen occur at higher temperatures than particulate filter regenerations facilitated by NO2. A method for managing the regeneration activation and states of a particulate filter is shown in Fig. 4. The method takes into account the exhaust gas flow rate, the exhaust gas temperature, the NO2 production from the DOC, and the particulate filter load. A curve illustrating an operating sequence of the engine executing the method is shown in Fig. 5. A curve illustrating an operating sequence of the engine performing active controls to regenerate the particulate filter is shown in Fig. 6. Figure 1 shows a schematic representation of a cylinder of a multi-cylinder engine 10 in an engine system 100, which may be included in a vehicle's drive system. The engine 10 can be controlled, at least partially, by a control system comprising a controller 12 and by input from a driver 132 via an input device 130. In this example, the input device 130 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal. A combustion chamber 30 of the engine 10 can contain a cylinder formed by cylinder walls 32, with a piston 36 positioned therein. The piston 36 can be coupled to a crankshaft 40, so that an alternating motion of the piston is translated into a rotational motion of the crankshaft. The crankshaft 40 can be coupled to at least one drive wheel of a vehicle via an intermediate gear system.Furthermore, a starter can be coupled to the crankshaft 40 via a flywheel to enable a starting process of the engine 10. The combustion chamber 30 can draw in intake air from an intake manifold 44 via an intake port 42 and expel combustion gases via an exhaust port 48. The intake manifold 44 and the exhaust port 48 can be selectively connected to the combustion chamber 30 via an intake valve 52 and an exhaust valve 54, respectively. In some examples, the combustion chamber 30 can include two or more intake valves and / or two or more exhaust valves. Engine 10 can be a turbocharged engine, comprising a compressor mechanically coupled to a turbine. Alternatively, engine 10 can be supercharged, with a compressor powered by an electric motor (e.g., a battery). A turbine blade can rotate as exhaust gas flows through the turbine, which in turn drives the compressor. Engine power can be increased by compressing (e.g., increasing the density of) the intake air flowing through the compressor to the engine. In some examples, an intercooler may be located between the compressor and the engine. The intercooler can cool the compressed intake air, further increasing the density of the intake air and thus increasing engine power. In this example, the inlet valve 52 and the exhaust valve 54 can be controlled by cam actuation via the cam actuation system 51 and 53, respectively. The cam actuation systems 51 and 53 can each include one or more cams and use one or more of the following systems: cam profile switching (CPS), variable cam timing (VCT), variable valve timing (VVT), and / or variable valve lift (VVL), which can be operated by the controller 12 to vary the valve operation. The position of the inlet valve 52 and the exhaust valve 54 can be determined by the valve position sensors 55 and 57, respectively. In alternative examples, the inlet valve 52 and / or the exhaust valve 54 can be controlled by electric valve actuation.For example, cylinder 30 may alternatively include an inlet valve controlled by electric valve actuation and an exhaust valve controlled by cam actuation, including CPS and / or VCT systems. In the illustration, a fuel injection device 69 is directly coupled to the combustion chamber 30 to inject fuel directly into it, proportional to the pulse width of a signal received by the control unit 12. In this way, the fuel injection device 69 provides so-called direct injection of fuel into the combustion chamber 30. The fuel injection device can be mounted, for example, in the side or top of the combustion chamber. The fuel can be supplied to the fuel injection device 69 by a fuel system (not shown) that includes a fuel tank, a fuel pump, and a fuel distributor.In some examples, the combustion chamber 30 may alternatively or additionally include a fuel injection device arranged in the intake manifold 44 in a configuration that provides so-called port fuel injection into the intake manifold upstream of the combustion chamber 30. The intake duct 42 can include a throttle 62, which has a throttle valve 64. In this specific example, the position of the throttle valve 64 can be varied by the control unit 12 via a signal provided to an electric motor or actuator contained within the throttle 62, a configuration commonly referred to as electronic throttle control (ETC). In this way, the throttle 62 can be operated to vary the intake air supplied to the combustion chamber 30, along with other engine cylinders. The position of the throttle valve 64 can be provided to the control unit 12 by a throttle position signal. The intake duct 42 can include an air mass flow sensor 120 and a manifold pressure sensor 122 for sensing the amount of air entering the engine 10. An exhaust gas sensor 126 is coupled to the exhaust gas channel 48, which is arranged upstream of an aftertreatment device 70 in one direction of the exhaust gas flow. The sensor 126 can be any sensor for providing an indication of an air-fuel ratio of the exhaust gas, such as a linear lambda probe or UEGO probe (wideband or wide-range lambda probe), a dual-state lambda probe or EGO probe, a HEGO probe (heated EGO probe), or a NOx, HC, or CO sensor. In one example, the upstream exhaust gas sensor 126 is a UEGO configured to provide an output, such as a voltage signal, that is proportional to the amount of oxygen contained in the exhaust gas. The controller 12 converts the lambda probe output into an air-fuel ratio of the exhaust gas via a lambda probe transfer function. The aftertreatment device 70 is coupled along the exhaust duct 48 upstream of an emission control device 72, as shown in the illustration. In one example, the aftertreatment device 70 is a diesel oxidation catalyst (DOC). The aftertreatment device 70 is physically coupled to the exhaust duct, so that exhaust gas from the engine flows through the device before flowing through any remaining portion of the exhaust duct 48 (e.g., before flowing into the emission control device 72). In other words, the catalyst is hermetically sealed along its outer circumference to an exhaust pipe of an exhaust duct. Thus, the catalyst receives exhaust gas through the exhaust duct upstream of the emission control device 72. The aftertreatment device 70 can include a substrate with integrated flow channels through which exhaust gas can flow. In one example, the substrate is a honeycomb made of cordierite. A washcoat with a support and one or more base metals can be applied to the substrate. In one example, the support is zirconium oxide (ZrO2). The base metals can include Co, Cu, Ce, Mn, Ni, Fe, Mn, MO, and W. For example, the washcoat contains a dosage level of 15 to 75 wt% of one or more of the base metal oxides (BMOs). For instance, a washcoat can contain Mn, Cu, and Ce at 20, 7.5, and 15 wt%, respectively. The base metal oxides are selected based on the vehicle's exhaust environment. Thus, the type and quantity of BMOs are adjusted in response to the vehicle's exhaust environment.For example, Co and Cu are the least sensitive to sulfur and are least inhibited by hydrocarbons (HCs) of the listed base metal oxides. Wo, Mo, and Ce produce NO₂ at lower temperatures compared to the other listed base metal oxides, thus enabling passive NO₂ regeneration for the particulate filter at a lower temperature (e.g., 200 °C). Mn exhibits the greatest NO oxidation potential to produce NO₂. The exhaust environment can depend on at least one environmental factor and driver behavior. For example, if a driver typically drives in a cold environment (e.g., Detroit, Michigan), a dealership might sell the driver a vehicle that includes the aftertreatment system 70 with a larger amount of woad, molybdenum, or ce compared to a vehicle that drives in a warm environment (e.g., Los Angeles, California).If a driver moves from a warm climate to a cold climate, the original aftertreatment system can alternatively be replaced with a new aftertreatment system incorporating a different composition of base metal oxides configured for colder exhaust temperatures due to the colder climate. For example, the exhaust environment might be lean, and the base metal oxides used could include one or more of Mn₂O₃, CuO, and CeO₂. Alternatively, blends of BMO designs can be used to compensate for operation across a wide range of environmental conditions that may affect the vehicle's nominal operating conditions. The washcoat may further comprise a Pd washcoat applied to it. Thus, the substrate includes multiple catalytic materials, which contain one or more base metal oxides and Pd. In one example, a Pd section of the catalyst is located upstream of a BMO section in a forward axial zone, such as the upstream section 70A. Alternatively, the Pd section may be located on an upper section of the device 70. In other words, the upstream section 70A may contain a larger amount of Pd catalyst (e.g., PdO) compared to a downstream section 70B. This allows hydrocarbons to be oxidized before they reach the downstream section 70B, where NO oxidation can occur on the BMO. One wt.% of the Pd catalyst may be in the range of 0.5 to 3. In one example, the wt.% of Pd in ​​the washcoat is exactly 2. Furthermore, the wt.-% of BMOs in the washcoat exactly 50. The emission control device 72 is arranged along the exhaust duct 48 downstream of the exhaust gas sensor 126 and the aftertreatment device 70, as shown in the illustration. The device 72 can be a three-way catalyst (TWC), a NOx trap, a diesel oxidation catalyst, a selective catalytic reduction device, a particulate filter (PF), various other emission control devices, or combinations thereof. In some examples, the emission control device 72 can be periodically reset by operating at least one cylinder of the engine within a specific air-fuel ratio during engine operation 10. In this example, the emission control device 72 is a particulate filter. NO2 can promote particulate filter regeneration and / or selective catalytic reduction of nitrogen oxide (NOx) emissions. For example, particulate filter regeneration can occur at low exhaust gas temperatures during low- to medium-load driving conditions in the presence of high NO2 concentrations. For instance, exhaust gas temperatures of 300 to 400 °C may be sufficient to initiate particulate filter regeneration in the presence of an NO2 concentration greater than the NO2-facilitated regeneration threshold. If regeneration occurs when the NO2 concentration is lower than the NO2-facilitated threshold, oxygen-facilitated regeneration is used, and exhaust gas temperatures can exceed 600 °C to initiate oxygen-facilitated regeneration. A selective catalytic reduction (SCR) device 74 is located downstream of the particulate filter 72, as shown in the illustration. Exhaust gas thus flows through the particulate filter 72 before passing through the SCR device 74. The SCR device 74 can reduce NO2 and other compounds via a reducing agent that coats the surfaces of the SCR device 74. An injection device (not shown) can be located between the particulate filter 72 and the SCR device 74 and is configured to introduce reducing agent into the exhaust gas channel upstream of the SCR device 74. Those skilled in the art will understand that other combinations of the DOC 70, the particulate filter 72, and the SCR 74 can be implemented without deviating from the scope of this disclosure.For example, a combination might include a first DOC upstream of an SCR device, with the SCR device being upstream of a second DOC, and the second DOC being upstream of a particulate filter. The first and second DOCs can be essentially identical. Alternatively, the first and second DOCs can comprise different combinations and / or amounts of BMOs. Furthermore, the positioning of the SCR and particulate filter can be reversed, with the particulate filter located upstream of the SCR. An exhaust gas recirculation (EGR) system 140 can direct a desired portion of the exhaust gas from the exhaust gas channel 48 into the intake manifold 44 via an EGR channel 152, which branches off from the exhaust gas channel 48 at a point between the exhaust gas sensor 126 and the aftertreatment device 70. The amount of EGR supplied to the intake manifold 44 can be varied by the control unit 12 via an EGR valve 144. Under certain conditions, the EGR system 140 can be used to regulate the temperature of the air-fuel mixture within the combustion chamber, thus providing a method for controlling the ignition timing during some combustion modes. The controller 12 is represented as a microcomputer, which includes a microprocessor unit 102, input / output ports 104, an electronic storage medium for executable programs and calibration values, which in this specific example is represented as a read-only memory 106 (e.g. a non-volatile memory), a direct access memory 108, a keep-alive memory 110 and a data bus.In addition to the signals discussed previously, the control unit 12 can receive various signals from sensors coupled to the engine 10, including the mass airflow (MAF) measurement from the mass airflow sensor 120; the engine coolant temperature (ECT) from a temperature sensor 112 coupled to a cooling sleeve 114; an engine position signal from a Hall-effect sensor 118 (or other type) detecting the position of the crankshaft 40; the throttle position from a throttle position sensor 65; and a manifold absolute pressure (MAP) signal from sensor 122. An engine speed signal can be generated by the control unit 12 from the crankshaft position sensor 118. The manifold pressure signal also provides an indication of the vacuum or pressure in the intake manifold 44.It should be noted that various combinations of the aforementioned sensors can be used, such as a MAF sensor without a MAP sensor and vice versa. During engine operation, the engine torque can be derived from the output of the MAP sensor 122 and the engine speed. Furthermore, this sensor, together with the detected engine speed, can provide a basis for estimating the charge (including air) introduced into the cylinder. In one example, the crankshaft position sensor 118, which can also be used as an engine speed sensor, can produce a predetermined number of evenly spaced pulses per revolution of the crankshaft. Computer-readable data can be programmed on the read-only memory 106 of a storage medium, representing instructions that can be executed by the processor 102 to carry out the procedures described below, as well as other variants that are anticipated but not explicitly listed. The controller 12 receives signals from the various sensors shown in Fig. 1 and uses the various actuators shown in Fig. 1 to adjust the engine operation based on the received signals and instructions stored in the controller's memory. For example, the exhaust gas sensor 126 can detect one or more exhaust back pressure and exhaust gas temperature readings. The controller 12 can determine the load on the particulate filter 72 based on the detected exhaust back pressure and determine whether regeneration is required. If the exhaust gas temperature is not high enough for passive regeneration, the controller 12 can initiate active heating controls to increase the exhaust gas temperature. For example, increasing the exhaust gas temperature might involve adjusting an actuator of the fuel injection device 69 to modify the amount of fuel injected after combustion to raise the exhaust gas temperature.Additionally or alternatively, the EGR valve 144 can be moved to a more closed position to reduce the amount of EGR flowing through cylinder 30, thereby increasing exhaust gas temperatures. In some examples, a fuel injection device, such as the fuel injection device 69 or another fuel injection device located downstream of cylinder 30 in the exhaust duct 48, can additionally or alternatively inject fuel to provide exothermic heat above the aftertreatment device 70 to actively heat the PF 72. The person skilled in the art understands that the specific routines described below in the flowcharts can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. Accordingly, various illustrated actions or functions can be performed in the illustrated sequence or in parallel, or in some cases, omitted. Likewise, the processing sequence is not necessarily required to achieve the features and benefits but is intended to facilitate illustration and description. Although not explicitly illustrated, one or more of the illustrated actions or functions can be performed repeatedly, depending on the specific strategy employed.Furthermore, these figures graphically represent code that is programmed onto the computer-readable storage medium in the controller 12 and is executed by the controller in combination with the motor hardware, as illustrated in Fig. 1. Thus, a system can comprise a catalyst located in an exhaust duct of an engine-driven vehicle, wherein the catalyst comprises a washcoat with a zirconium oxide support, several base metal oxides, and palladium oxide, wherein the palladium oxide is contained in an upstream section of the catalyst relative to a direction of exhaust flow, and wherein the base metal oxides are contained in a downstream section of the catalyst relative to the direction of exhaust flow, and wherein said base metal oxides Mn, Cu, and Ce are present in a weight percent ratio of 20:7.5:15, and a particulate filter located in a position in the exhaust duct downstream of the catalyst relative to a direction of exhaust flow, and a controller with computer-readable instructions stored thereon that enable the controller to operate the particulate filter via active controls configured to do so.The regeneration process includes actively increasing the exhaust gas temperature to a temperature greater than a threshold temperature and adjusting the exhaust gas flow rate to a rate between the upper and lower threshold exhaust gas flow rates. In one example, the threshold temperature is a threshold temperature for NO2-facilitated regeneration, and the threshold temperature for NO2-facilitated regeneration is lower than a threshold temperature for oxygen-facilitated regeneration. The threshold temperature for NO2-facilitated regeneration is based on a particulate filter regeneration temperature in the presence of NO2 that is greater than a threshold amount of NO2, while the threshold temperature for oxygen-facilitated regeneration is based on a particulate filter regeneration temperature in the presence of an amount of NO2 that is less than the threshold amount of NO2. The catalyst is physically coupled to the exhaust duct.and wherein exhaust gas from the engine flows through the catalyst before flowing into the particulate filter. A device for selective catalytic reduction is located downstream of the particulate filter. Referring to Fig. 2, this figure shows a diagram 200 illustrating the NO₂ output of a post-treatment device (e.g., post-treatment device 70 from Fig. 1) as a function of temperature. As described above, the post-treatment device 70 is a DOC with a substrate coated with Pd and one or more base metal oxides. Thus, diagram 200 illustrates the NO₂ output of a specific DOC. In one example, the DOC comprises a washcoat with a zirconium oxide (e.g., ZrO₂), a palladium oxide (e.g., PdO), and a group of base metal oxides, including manganese oxides (e.g., Mn₂O₃), cerium oxides (e.g., CeO₂), and copper oxides (e.g., CuO). The wt.% of the base metal oxides contained in the washcoat is in the range of 1 to 30, and the wt.% of the PdO in the washcoat is in the range of 0.5 to 3. In one example, the DCO 70 comprises a honeycomb substrate consisting of cordierite treated with a washcoat. ZrO2, PdO, CuO, CeO2, and Mn2O3 are also included in the washcoat. In another example, the base metal oxides and the PdO are applied in different washcoats. For instance, the washcoat containing the base metal oxides is applied first, followed by the washcoat containing PdO, or vice versa. This can layer the catalyst and provide the DOC with increased reactivity based on exhaust system conditions. In this way, the DOC is essentially unreactive to sulfur dioxide (SO2). For example, the PdO can oxidize CO and hydrocarbons, and the base metal oxides can oxidize NO, but neither catalyst can oxidize SO2, thus extending the DOC's lifespan. The temperature increases from left to right in the figure. In one example, the temperature corresponds to an exhaust gas temperature. Alternatively, the temperature corresponds to the temperature of the aftertreatment device. Additionally, the NO2 output of the aftertreatment device is shown as a percentage of the total NO2 output of the vehicle, where the total NO2 output is the sum of the NO2 output of the engine and the NO2 output of the aftertreatment device. For example, if the NO2 output of the aftertreatment device is essentially equal to 60%, then the NO2 output of the engine is essentially equal to 40%. In this way, a reduction in the NO2 output of the aftertreatment device corresponds to no less than the total NO2 production in the aftertreatment device.This means that the total NO2 output is a ratio, and as the temperature increases, so does the engine combustion temperature, leading to increased NO2 output from both the engine and the aftertreatment system. However, the engine's NO2 output can increase faster than the aftertreatment system's NO2 output as the temperature rises. Although not shown in Diagram 200, the NO2 production of the aftertreatment system also depends on the exhaust gas flow rate. Specifically, the aftertreatment system produces higher amounts of NO2 when the exhaust gas flow rate is within a range between the lower and upper threshold flow rates. Thus, exhaust gas flow rates below the lower threshold flow rate are too slow and may correspond to an exhaust gas temperature that is too low (e.g., 150 °C). Alternatively, low exhaust gas flow rates and low exhaust gas temperatures may correspond to low NOx output from the engine, which limits NO2 production at the aftertreatment system. Additionally, exhaust gas flow rates above the upper threshold flow rate are too fast and may correspond to an exhaust gas temperature that is too high (e.g., 600 °C). At these extreme ends of the exhaust gas temperature range shown, the NO2 output of the aftertreatment system is reduced.High exhaust gas temperatures above a thermodynamic limit (e.g. above 600 °C) and high exhaust gas flow rates reduce the efficiency of the aftertreatment device to produce NO2. The NO2 output 210 of the aftertreatment device begins to increase from a relatively low level before reaching 200 °C. For example, before 180 °C, the NO2 output of the aftertreatment device is less than 10% of the total output. This may correspond to an amount of NO2 that is too low to initiate the regeneration of a particulate filter (e.g., the particulate filter 72 from Fig. 1). As exhaust gas temperatures increase above 200 °C, the NO2 output 210 of the aftertreatment device produces a larger proportion of the total NO2 output. Similarly, between 260 °C and 360 °C, the NO2 output 210 of the aftertreatment device is substantially equal to or greater than 50%. This means that the aftertreatment device produces at least half of the total NO2 output from 260 to 360 °C.When the temperature increases from 360 °C, the NO2 output from the aftertreatment device is less than 50%, meaning that the aftertreatment device begins to produce less than half of the total NO2 output. However, as described above, the actual amount of NO2 output from the aftertreatment device can continue to increase. In one example, the actual amount of NO2 produced by the aftertreatment device is highest at 400 °C. The NO2 output from the aftertreatment device can correspond to a soot oxidation rate and / or particulate filter regeneration rate, as described below. Referring to Fig. 3, diagram 300 shows a soot oxidation rate based on regenerations facilitated by NO2 or oxygen. In one example, a regeneration initiated by NO2 involves an amount of NO2 in the exhaust gas that is greater than a threshold for NO2-facilitated regeneration. For example, the threshold is a ratio of NO2 output to carbon. Hydrocarbons are first oxidized to CO and then by NO2 to CO2. Thus, at least two moles (e.g., equivalents) of NO2 are consumed for each mole of hydrocarbon (e.g., HC). This can be seen in equations 1 and 2: NO2 + C → NO + CO (1) NO2 + CO → NO + CO2 (2) Thus, oxygen-facilitated regeneration includes the amount of NO2 in the exhaust gas that is lower than the threshold for NO2-facilitated regeneration. As described below with reference to Diagram 300, NO2 can promote the oxidation of soot on the particulate filter, so that the temperatures required to oxidize soot deposited on the particulate filter are significantly reduced in the presence of an amount of NO2 greater than the threshold for NO2-facilitated regeneration. Diagram 300 includes the NO2 oxidation rate curve 310 and the oxygen oxidation rate curve 320. The NO2 oxidation rate curve 310 represents the rate of soot oxidation on the particulate filter based on regeneration initiated by an amount of NO2 greater than the threshold for NO2-facilitated regeneration. The oxygen oxidation rate curve 320 represents the rate of soot oxidation on the particulate filter based on regeneration initiated by oxygen. As shown, regeneration exposed to a larger amount of NO2 (e.g., an amount of NO2 greater than the threshold for NO2-facilitated regeneration) can begin at lower temperatures than regeneration exposed to a smaller amount of NO2 (e.g., an amount of NO2 less than the threshold for NO2-facilitated regeneration). Specifically, the NO2 oxidation rate increases above zero at 200 °C, and the oxygen oxidation rate increases above zero at 340 °C. The NO2 oxidation rate reaches a peak of 32, or similar, at 400 °C. The oxygen oxidation rate reaches a peak of 35, or similar, at 570 °C. Thus, NO2-facilitated regenerations exhibit a soot oxidation rate similar to oxygen-facilitated regenerations, despite the oxidation taking place at lower exhaust gas temperatures. Thus, the diagram illustrates 300 particulate filter regenerations facilitated by NO2 and oxygen. Due to the lower temperatures of NO2-facilitated regeneration, active particulate filter regenerations can consume less fuel than oxygen-facilitated regeneration. Consequently, adjustments made to increase exhaust temperatures for active regeneration are less costly and consume less fuel when facilitated by NO2 rather than oxygen, as described below. The catalyst described above can be used herein with a process which is stored on a controller with computer-readable instructions which, when listed, enable the controller to carry out the process.The process comprises generating NO2 in a catalyst comprising a washcoat with zirconium, one or more base metal oxides, and palladium oxide, wherein the palladium oxide is located in an upstream section of the catalyst relative to a direction of exhaust gas flow, and wherein the at least one base metal oxide is located in a downstream section of the catalyst relative to the direction of exhaust gas flow, and wherein an exhaust gas flow is between lower and upper threshold flow rates, and facilitating the regeneration of a particulate filter located downstream of the catalyst via NO2 when an exhaust gas temperature exceeds a threshold temperature. The generation of NO2 involves exhaust gas flows through the catalyst, wherein the exhaust gas flows at an exhaust gas flow rate between upper and lower exhaust gas thresholds, and wherein the exhaust gas temperature is greater than 200 °C.The threshold temperature is a threshold temperature for NO2-facilitated regeneration, and this threshold temperature is based on the particulate filter being exposed to an amount of NO2 capable of facilitating regeneration. Regeneration is facilitated by NO2 when the amount of NO2 produced by the engine and catalyst exceeds a threshold amount for NO2 regeneration. It can be determined that the particulate filter requests regeneration when the particulate filter load exceeds a threshold load. However, if the exhaust gas temperature is lower than the threshold temperature, regeneration involves initiating active controls to adjust engine operating parameters in order to increase the exhaust gas temperature. These active controls include one or more of the following: reducing the EGR flow rate, increasing the fuel injection pressure, increasing the fuel injection volume, reducing the air-fuel ratio, increasing the manifold pressure, and delaying fuel injection. With reference to Fig. 4, this document shows a method 400 for regenerating the particulate filter 72 from Fig. 1. Instructions for carrying out the method 400 can be executed by a controller based on instructions stored in a memory of the controller and in conjunction with signals received from sensors of the engine system, such as those described above with reference to Fig. 1. The controller can use motor actuators of the engine system to adjust the engine operation according to the methods described below. Procedure 402 includes determining, estimating, and / or measuring current engine operating parameters. Current engine operating parameters may include engine temperature, engine speed, manifold pressure, ambient humidity, throttle position, engine load, EGR flow rate, exhaust gas temperature, and air-fuel ratio. In document 404, the procedure involves estimating a particulate filter load. In one example, the particulate filter load is estimated based on one or more exhaust backpressures, which can be detected by the exhaust gas sensor 126 shown in Fig. 1. Alternatively, a difference in exhaust pressure directly upstream and downstream of the particulate filter can correspond to the particulate filter load. As the backpressure and / or the difference increases, the estimated particulate filter load increases. Thus, as the filter becomes increasingly loaded with soot, the exhaust flow through the filter is impaired, thereby increasing the exhaust backpressure. In another example, the particulate filter load can be estimated based on an estimated quantity of particles released from the engine since a previous regeneration.Thus, the previous regeneration establishes a baseline load, and the estimated amount of particles is added to this baseline to provide the particulate filter load. The estimated amount of particles is based on values ​​stored in a lookup table with multiple inputs corresponding to an engine particle output. The inputs can include engine load, engine temperature, throttle position, vehicle speed, ambient humidity, and air-fuel ratio. For example, an estimated engine particle output increases as the engine load increases, the throttle position increases, the vehicle speed increases, the ambient humidity increases, and the air-fuel ratio decreases. Alternatively, the particulate filter load can be estimated based on the number of miles driven since a previous regeneration, where a number of miles can directly correspond to a particle load. It is understood that a prior regeneration can be either complete or partial. Complete regeneration resets the particulate filter to a load where essentially zero particles are deposited on the filter. Partial regeneration reduces the particulate filter load to a load greater than zero, but less than the load before regeneration. A regeneration can be partial if it is terminated before completion because the regeneration conditions are no longer met. At any given rate, regeneration restores the particulate filter load to a lower level. Procedure 406 includes determining whether the particulate filter load is less than a threshold load. For example, if a pressure (e.g., back pressure) measured directly upstream of the particulate filter (e.g., exhaust back pressure) is greater than a threshold pressure, it is determined that the particulate filter load is greater than the threshold load. In other words, if the particulate filter load is greater than the threshold load, the exhaust flow through the filter is restricted, and the exhaust back pressure increases to a pressure greater than the threshold pressure. If the particulate filter load is less than the threshold load, procedure 400 proceeds to 408 to maintain current engine operating parameters and does not regenerate the particulate filter. In this way, exhaust gas flows through the filter at a sufficient rate and does not increase the exhaust back pressure to a level capable of restricting engine performance. In some examples, Procedure 400 can regenerate the particulate filter in response to the PF load being lower than the threshold load, provided the exhaust gas temperatures are sufficiently hot for passive regeneration, as described below. Additionally or alternatively, the procedure can actively regenerate the particulate filter as described below, with the duration of active regeneration based on the estimated particulate filter load. Thus, as the estimated particulate filter load increases, the duration of active regeneration also increases. In some examples, the determination that the PF load is lower than the threshold load may not prevent the particulate filter from regenerating, and the procedure can continue. If the PF load is not less than the threshold load, the procedure proceeds to 410 to estimate a PF temperature. For example, the exhaust gas temperature determined in 402 can be used to determine the PF temperature. Alternatively, a temperature sensor can be integrated into the particulate filter to directly measure its temperature. In procedure 412, procedure 400 involves determining whether the particulate filter (PF) temperature is greater than an oxygen-facilitated regeneration threshold temperature. The oxygen-facilitated regeneration threshold temperature is based on a particulate filter temperature capable of burning off particles deposited on it in the presence of oxygen and an amount of NO2 less than an NO2-facilitated regeneration threshold, as described above. In an example, the regeneration threshold temperature is 550 °C. Therefore, if the PF temperature is greater than the oxygen-facilitated regeneration threshold temperature, procedure 400 proceeds to 414 to passively regenerate the particulate filter and does not adjust the engine operating parameters.Thus, current engine operating parameters that meet driver requirements are sufficient to meet conditions for passive regeneration, and the particles on the particulate filter can burn in the presence of hot exhaust gas and oxygen. If the PF temperature is not greater than the threshold regeneration temperature, procedure 400 to 416 proceeds to measure an exhaust gas flow rate. In one example, the exhaust gas sensor 126 from Fig. 1 is configured to measure an exhaust gas flow rate. Thus, an exhaust gas flow rate flowing to the aftertreatment device 70 and the particulate filter 72 is essentially equal to the difference between the exhaust gas flow rate and an EGR flow rate. Alternatively, an exhaust gas flow rate sensor can be located downstream of the intersection between the exhaust duct 48 and the EGR duct 152. Thus, the exhaust gas flow rate sensor directly detects an exhaust gas flow rate flowing to the aftertreatment device 70 and the particulate filter 72. In another example, the exhaust gas flow rate can be calculated based on one or more engine operating conditions. For instance, an exhaust gas volume flow rate is calculated using volumetric efficiency, intake manifold air, an estimated EGR rate, fuel supply conditions, exhaust gas composition, and temperature. The exhaust gas volume flow rate is divided by a cross-section of the exhaust duct to determine the exhaust gas flow rate. The exhaust gas flow rate increases as the temperature increases. Additionally, the exhaust gas flow rate increases when the exhaust gas composition contains a greater amount of compounds with higher molar mass. In procedure 418, procedure 400 involves determining whether the exhaust gas flow rate is less than a lower threshold flow rate. The lower threshold flow rate corresponds to one or more engine operating parameters (e.g., engine load) that can produce a sufficient amount of NO to be oxidized at the aftertreatment device to produce a sufficient amount of NO₂ for particulate filter regeneration. This can be referred to herein as a threshold for NO₂-facilitated regeneration. As described above with respect to equations 1 and 2, the sufficient amount of NO₂ for particulate filter regeneration is essentially equal to two stoichiometric equivalents of NO₂ for each stoichiometric equivalent of C. If the exhaust gas flow rate is less than the lower threshold flow rate, procedure 400 proceeds to 420 to initiate active controls to increase the exhaust gas flow.This can include increasing engine revolutions per minute (rpm), reducing the EGR flow rate, increasing intake air, increasing fuel supply, reducing in-cylinder cooling, etc. In-cylinder cooling can include at least water injection into the cylinder. Increased fuel supply can include increasing primary and / or post-injection, with primary injection occurring before combustion and post-injection occurring after combustion and before exhaust. Procedure 400 further monitors the exhaust gas flow rate until the flow rate is no longer less than the lower threshold flow rate. If the exhaust gas flow rate is not less than the lower threshold flow rate, procedure 400 proceeds to 422 to determine whether the exhaust gas flow rate is greater than an upper threshold flow rate. In one example, the upper threshold flow rate is essentially the highest exhaust gas flow rate, where the exhaust gas is given sufficient time in the aftertreatment device to produce a desired amount of NO2 for particulate filter regeneration. Thus, if the exhaust gas flow rate is greater than the upper threshold flow rate, the exhaust gas is flowing too quickly, and procedure 400 proceeds to 424 to actively regenerate the particulate filter. Active regeneration of the particulate filter involves intrusively adjusting the engine operating parameters to increase the exhaust gas temperature in order to heat the particulate filter to a temperature higher than the threshold regeneration temperature.In one example, adjustments could include increasing fuel injection either through delayed fuel injection or an increased fuel injection volume. This sufficiently raises exhaust gas temperatures and allows oxygen to facilitate the regeneration of the particulate filter. If the exhaust gas flow rate is lower than the lower threshold flow rate, the exhaust gas flow rate is between the lower and upper threshold flow rates, and Procedure 400 transitions to 426 to initiate active heating controls to promote regeneration in the presence of NO2. The active heating controls may be essentially the same as the adjustments made during the active regeneration described in 424. However, the active heating controls may be more efficient than the adjustments corresponding to active regeneration when regeneration is facilitated by oxygen. For example, a temperature range for regenerating the particulate filter in the presence of high levels of NO2 (e.g., an amount of NO2 greater than a threshold amount for NO2-facilitated regeneration) is essentially 300–450 °C. This temperature range may also be referred to as the threshold temperature for NO2-facilitated regeneration.While operating in this temperature range, the aftertreatment system can produce 25-65% of the vehicle's total NO2 output. A temperature range for regenerating the particulate filter via O2 is essentially 500-600 °C. Therefore, adjustments made during active regeneration in the presence of low NO2 (e.g., an amount of NO2 below the threshold for NO2-facilitated regeneration) consume more fuel than adjustments made during active regeneration in the presence of high NO2. In procedure 428, procedure 400 involves determining whether conditions for particulate filter regeneration are still met. For example, if the exhaust gas flow rate falls below the lower threshold flow rate or rises above the upper threshold flow rate, the regeneration conditions for NO2 regeneration are no longer met. Additionally, if the particulate filter is completely regenerated (e.g., substantially all of the soot deposited on the filter has been burned), the regeneration conditions are no longer met. Additionally, or alternatively, conditions are no longer met if an engine component reaches a threshold temperature and requests cooler engine operating temperatures. Thus, one or more adaptations may be disabled to minimize deterioration of the engine component. This may terminate regeneration if the exhaust gas temperatures reach a certain temperature (e.g.,less than 300 °C), which is too low to continue regeneration. If the conditions for particulate filter regeneration are still met, procedure 400 transitions to 430 to continue regeneration with active controls. The regeneration process continues to monitor the regeneration conditions until they are no longer met. When the regeneration conditions are no longer met, procedure 400 transitions to 432 to deactivate the active heating controls and terminates the regeneration. In this way, the regeneration can be a full regeneration or a partial regeneration, where conditions cease to be met during the regeneration process, forcing its termination. Thus, a method for an engine-driven vehicle comprises regenerating a particulate filter without adjusting the engine operating parameters during a first mode, facilitating particulate filter regeneration with oxygen by adjusting the engine operating parameters to a first size during a second mode, and facilitating the particulate filter with NO2 by adjusting the engine operating parameters to a second size during a third mode, wherein the NO2 is produced by at least one diesel oxidation catalyst located upstream of the particulate filter, the diesel oxidation catalyst comprising a washcoat with a zirconium oxide support, the washcoat further comprising at least manganese oxide and a palladium catalyst; wherein the first size is greater than the second size. Regeneration is passively facilitated by oxygen if the exhaust gas temperature is higher than the threshold temperature for oxygen-facilitated regeneration, the amount of NO2 in the filter is lower than the threshold regeneration amount, and the exhaust gas flow rate is outside a range between the upper and lower threshold flow rates during the first mode. Alternatively, regeneration is passively facilitated by NO2 if the exhaust gas temperature is higher than the threshold temperature for NO2-facilitated regeneration, the amount of NO2 in the filter is higher than the threshold for NO2 regeneration, and the exhaust gas flow rate is within a range between the upper and lower threshold flow rates during the first mode. The particulate filter regeneration during the second mode involves initiating active controls configured to adjust engine operating parameters by the first parameter, where the first parameter corresponds to raising an exhaust gas temperature to a temperature greater than a threshold temperature for oxygen-facilitated regeneration, where the threshold temperature for oxygen-facilitated regeneration is 600 °C, and where the amount of NO2 at the particulate filter is less than a threshold amount for NO2 regeneration. Particulate filter regeneration during the third mode involves initiating active controls configured to adjust engine operating parameters through a second parameter. This second parameter corresponds to raising the exhaust gas temperature to a temperature greater than a threshold temperature for NO2-facilitated regeneration. The threshold temperature for NO2-facilitated regeneration is 450 °C, and the amount of NO2 at the particulate filter is greater than a threshold amount for NO2 regeneration. The threshold amount for NO2 regeneration corresponds to an amount of NO2 sufficient to promote the combustion of soot deposited on the particulate filter. The catalytic converter is hermetically sealed along its outer circumference to an exhaust pipe of an exhaust duct. Thus, the catalytic converter receives exhaust gas through the exhaust duct before the particulate filter. Referring to Fig. 5, it shows a curve 500 for controlling active regeneration of a particulate filter located downstream of a DOC with nitrogen oxide-releasing capabilities (e.g., the aftertreatment device 70 from Fig. 1). In one example, the operating sequence is based on the operation of the method 400 from Fig. 4, including the components from the engine system 100 in Fig. 1. However, for the sake of brevity, the curve 500 does not include conditions for passive regeneration. The curve 500 includes an exhaust gas temperature (line 510), a threshold temperature for NO2-facilitated regeneration (dashed line 512), and a threshold temperature for oxygen-facilitated regeneration (dashed line 514).The curve 500 further includes an exhaust gas flow rate (line 520), a lower threshold exhaust gas flow rate (dashed line 522), an upper threshold exhaust gas flow rate (dashed line 524), active controls (line 530), a quantity of released NO2 (line 540), a threshold quantity of NO2 regeneration (dashed line 542), a particulate filter load (line 550), and a threshold particulate load (dashed line 552). In one example, the PF load represents a PF load on the PF 72 from Fig. 1. Likewise, the released NO2 represents a quantity of NO2 released by the aftertreatment device 70. Time increases from one side of the figure to the right. Before t1, the exhaust gas temperature is relatively low (shown by line 510) and lower than the threshold temperature for NO2-facilitated regeneration (shown by dashed line 512). As shown and described above, the threshold temperature for NO2-facilitated regeneration is lower than the threshold temperature for oxygen-facilitated regeneration (shown by dashed line 514). The exhaust gas flow rate (shown by line 520) is lower than the lower threshold flow rate (shown by dashed line 522), which is lower than the upper threshold flow rate (shown by dashed line 524). The active controls are off (shown by line 530).In the examples shown, the active controls are a binary function, represented as on or off, as explained above and described in more detail below. These active controls can provide varying degrees of regeneration, thus promoting adaptation. Since the exhaust gas flow rate is lower than the lower threshold flow rate, the released NO2 is relatively low and below the threshold amount for NO2. The particulate filter load increases towards the threshold (shown by line 550 and dashed line 552, respectively). Consequently, due to the exhaust gas temperatures and therefore the particulate filter temperatures being too low, no regeneration occurs before t1. At t1, the particulate filter load exceeds the threshold PF load, indicating a need for regeneration. In response, the active controls are activated. Since the released NO2 is less than the threshold for NO2 regeneration, the active controls adjust the engine operating conditions to raise exhaust gas temperatures to the threshold temperature for oxygen-facilitated regeneration. Thus, the exhaust gas temperature begins to rise. Additionally, the exhaust gas flow rate also begins to increase due to the rising exhaust gas temperatures. After t1 and before t2, the active controls remain active. In one example, the active controls include increasing a post-injection quantity (e.g., a fuel injection after combustion and before the exhaust). The exhaust gas temperature increases above the threshold temperatures for NO2 and oxygen-facilitated regeneration. The exhaust gas flow rate remains below the lower threshold flow rate. The released NO2 remains relatively low and below the threshold amount for NO2 regeneration. At t2s, the active controls are engaged and the exhaust gas temperature is higher than the threshold temperature for oxygen-assisted regeneration. This initiates particulate filter regeneration, and the particulate filter load begins to decrease towards the threshold PF load. The released NO2 and the exhaust gas flow rate remain relatively low. After t2 and before t3, regeneration continues. The particulate filter load decreases further towards the threshold particulate filter load. The exhaust gas temperature remains higher than the threshold temperature for oxygen-facilitated regeneration because the active controls remain on. The exhaust gas flow rate and the released NO2 remain relatively low. At t3, the PF load falls below the threshold PF load, and consequently, the active controls are deactivated shortly after t3, as soon as the PF load falls below a sufficiently low level. The double arrow 532 indicates a duration during which the active controls were used for oxygen-facilitated regeneration. The exhaust gas temperature begins to decrease. The exhaust gas flow and the released NO2 remain relatively low. After t3 and before t4, the exhaust gas temperature drops to a level below the threshold temperatures for oxygen- and NO2-facilitated regeneration. However, the particulate filter (PF) load continues to decrease. This can occur due to "self-combustion," where the soot on the filter has already been ignited and continues to burn in the absence of high exhaust gas temperatures. Thus, the PF load decreases further to a relatively low level. The active controls remain deactivated, as regeneration is not requested. The exhaust gas flow rate begins to increase slightly towards the lower threshold flow rate. The released NO2 remains relatively low. At t4, the exhaust gas temperature is relatively low and essentially the same as before t1. The exhaust gas flow rate increases above the lower threshold flow rate while remaining below the upper threshold flow rate. Consequently, the released NO2 begins to increase. The particulate filter load begins to increase towards the threshold particulate filter load. The active controls remain off, as there is no regeneration requirement. After t4 and before t5, the exhaust gas flow rate continues to increase, while remaining between the lower and upper threshold flow rates. Thus, the released NO2 continues to increase towards the threshold for NO2 regeneration. The particulate filter load continues to increase towards the threshold particulate filter load. The active controls remain off, and the exhaust gas temperature remains essentially low. At t5, the PF load increases to a level greater than the threshold PF load. Fortunately, the NO2 released by the aftertreatment system exceeds the threshold for NO2 regeneration. Additionally, the exhaust gas flow rate remains between the lower and upper threshold flow rates. Therefore, the active controls are activated to raise the exhaust gas temperature from a relatively low temperature to the threshold temperature for NO2-facilitated regeneration. After t5 and before t6, the exhaust gas temperature increases towards the threshold temperature for NO2-facilitated regeneration. Therefore, NO2-facilitated regeneration does not yet occur, even though the exhaust gas flow is between the lower and upper threshold exhaust gas rates and the released NO2 is greater than the threshold amount for NO2 regeneration. The particulate filter load continues to increase. At t6, the exhaust gas temperature exceeds the threshold temperature for NO2-facilitated regeneration. This, in combination with the released NO2, which is greater than the threshold amount for NO2 regeneration, initiates particulate filter (PF) regeneration. Consequently, the PF load decreases towards the threshold PF load. The exhaust gas flow remains between the lower and upper threshold flow rates, and the active controls remain on. In some examples, active controls during NO2-facilitated regeneration also include adjusting exhaust gas flow rates. For instance, if the exhaust gas flow rate is lower than the lower threshold flow rate, active control involves increasing the engine revolutions per minute to increase the exhaust gas flow. Alternatively, if the exhaust gas flow rate is higher than the upper threshold flow rate, active control involves reducing the engine revolutions per minute and / or increasing the EGR. It is understood that active controls may also include adjusting other engine operating parameters to achieve the desired exhaust gas flow rate between the lower and upper threshold flow rates. After t6 and before t7, the PF load continues to decrease towards the threshold PF load. The released NO2 remains above the threshold for NO2-facilitated regeneration. The exhaust gas temperature remains above the threshold temperature for NO2-facilitated regeneration. The exhaust gas flow rate remains between the lower and upper threshold flow rates. The active controls remain active to ensure that the exhaust gas temperature remains above the threshold temperature for NO2-facilitated regeneration. At t7, the PF load decreases to a level lower than the threshold PF load, and in response, the active controls are deactivated shortly after t7 once the PF load falls to a sufficiently low level. Double arrow 534 indicates a duration during which the active controls were used for NO2-facilitated regeneration. As shown, double arrow 534 is shorter than double arrow 532. In this way, the active controls consume less fuel during NO2-facilitated regeneration than the active controls during oxygen-facilitated regeneration. This can be due to the lower threshold temperature of NO2-facilitated regeneration compared to oxygen-facilitated regeneration. The released NO2 remains above the threshold amount for NO2-facilitated regeneration. The exhaust flow remains between the upper and lower threshold flow rates.The exhaust gas temperature begins to decrease towards the threshold temperature for NO2-facilitated regeneration. After t7, the exhaust gas temperature decreases to a temperature lower than the threshold temperature for NO2-facilitated regeneration. The exhaust gas flow rate remains between the lower and upper threshold flow rates. The active controls are off. The released NO2 remains higher than the threshold for NO2-facilitated regeneration. The soot on the particulate filter continues to burn, and the PF load decreases towards a relatively low level. Referring to Fig. 6, it shows a curve 600 for controlling active regeneration of a particulate filter located downstream of a DOC with nitrogen oxide-releasing capabilities (e.g., the aftertreatment device 70 from Fig. 1). In one example, the operating sequence is based on the operation of the method 400 from Fig. 4, including the components from the engine system 100 in Fig. 1. However, for the sake of brevity, the curve 600 does not include conditions for passive regeneration. The curve 600 includes an exhaust gas temperature (line 610), a threshold temperature for NO2-facilitated regeneration (dashed line 612), and a threshold temperature for oxygen-facilitated regeneration (dashed line 614).The curve 600 further includes an amount of released NO2 (line 620), a threshold amount for NO2 regeneration (dashed line 622), a particulate filter load (line 630), a threshold particulate load (dashed line 632), the total fuel supply (line 640), and the fuel supply requested by the driver (dashed line 642). In an example, the PF load represents a PF load on the PF 72 from Fig. 1. The total fuel supply represents an amount of fuel supply based on a combination of driver demand and active controls. Thus, the total fuel supply and the fuel supply requested by the driver are essentially the same when the active controls are off. Time increases from one side of the figure to the right. The threshold regeneration quantity 622 is represented as a dynamic value in curve 600, whereas the threshold regeneration quantity 542 from curve 500 in Fig. 5 is static. Curve 500 does not represent a specific amount of fuel supplied; therefore, for the sake of simplicity, the threshold regeneration quantity 542 is shown as a fixed value. However, the threshold quantity 622 for NO2 regeneration represents a threshold quantity for NO2 regeneration based on a stoichiometric equivalence of carbon-containing compounds released into the exhaust duct (e.g. exhaust duct 48 from Fig. 1). Before t1, the exhaust gas temperature is relatively low. Specifically, the exhaust gas temperature (line 610) is lower than the threshold temperature for NO2-facilitated regeneration (line 612), which is lower than the threshold temperature for oxygen-facilitated regeneration (line 614). The released NO2 (line 620) is lower than the threshold amount for NO2 regeneration. The particulate matter load (line 630) increases towards the threshold particulate matter load (line 632). The total fuel supply (line 640) is essentially equal to the fuel supply requested by the driver (line 642). Thus, the fuel supply is based on a throttle position that is determined by an accelerator pedal position (e.g., driver demand). Therefore, the active controls are off. At t1, the particulate filter load is greater than the threshold particulate load. Thus, any back pressure measured upstream of the particulate filter is greater than a threshold back pressure, which may be based on a pressure capable of reducing engine output. However, the exhaust gas temperature remains lower than the threshold temperatures for NO₂ and oxygen-facilitated regenerations. Since the released NO₂ is less than the threshold for NO₂ regeneration, the initiated active controls are configured to increase the fuel supply to raise the exhaust gas temperature to a temperature higher than the threshold temperature for oxygen-facilitated regeneration. This increases the total fuel supply to a level greater than the driver's requirements. This may involve rich running (e.g., an air-fuel ratio less than 1).Alternatively, the active controls can activate a fuel injection device located in an exhaust duct downstream of the engine and upstream of the aftertreatment device, as described above. The fuel supply from the fuel injection device can be based on a difference between a current exhaust gas temperature and a desired exhaust gas temperature, with the fuel supply increasing as the difference increases. After t1 and before t2, the total fuel supply increases, causing the NO2 regeneration threshold to rise accordingly and the exhaust gas temperature to a level higher than the oxygen-facilitated regeneration threshold. At t2, regeneration is initiated and the particulate filter load decreases. The active controls remain on, and the total fuel supply is greater than the fuel supply requested by the driver. After t2 and before t3, regeneration continues, and the particulate filter load decreases to a level lower than the threshold particulate load. Therefore, the back pressure measured upstream of the particulate filter is lower than the threshold back pressure. At t3, the active controls are deactivated, and the total fuel supply decreases back towards the level requested by the driver. The threshold quantity for NO2 regeneration decreases in proportion to the amount of NO2 released. The particulate filter load continues to decrease due to self-combustion. After t3 and before t4, the particulate matter load is lower than the threshold particulate matter load and is relatively low. The released NO2 is lower than the threshold amount for NO2 regeneration. The exhaust gas temperature is relatively low and lower than the threshold temperatures for NO2 and oxygen regeneration. The total fuel supply decreases and is essentially equal to the fuel supply requested by the driver. Thus, the active controls are deactivated. At t4, the particulate filter load is no longer self-burning. Therefore, the particulate filter load begins to increase towards the particulate filter load threshold. After t4 and before t5, the particulate filter load continues to increase. The exhaust gas temperature remains relatively low. The released NO2 increases to a level greater than the threshold for NO2 regeneration. In one example, the released NO2 increases due to a reduction in the EGR flowing to the engine. The total fuel supply is essentially the same as the fuel supply requested by the driver. At t5, the particulate filter load is greater than the threshold particulate filter load. Therefore, regeneration is requested. However, the exhaust gas temperature is lower than the threshold temperatures for NO2- and oxygen-facilitated regenerations. Thus, the active controls are activated. However, the initiated active controls are less intrusive because the released NO2 is greater than the threshold for NO2 regeneration. Therefore, the temperature increase required to initiate regeneration is smaller than that at t1. After t5 and before t6, the total fuel supply increases. However, the magnitude of this increase is smaller than the increase between t1 and t2. Therefore, initiating active particulate filter regeneration when the released NO2 is greater than the threshold consumes more fuel than active regeneration when the released NO2 is less than the threshold.The exhaust gas temperature increases and is higher than the threshold temperature for NO2 regeneration and lower than the threshold temperature for oxygen regeneration. At t6, regeneration begins and the particulate filter load starts to decrease. The total fuel supply remains above the fuel supply requested by the driver. The exhaust gas temperature remains hot enough to allow regeneration in the presence of an amount of NO2 greater than the threshold for NO2-facilitated regeneration. After t6 and before t7, the particulate filter load decreases to a level below the threshold particulate load. Active controls are then deactivated, and the total fuel supply decreases towards the fuel supply requested by the driver. The released NO2 remains relatively high and greater than the threshold for NO2-facilitated regeneration. The exhaust gas temperature remains above the threshold temperature for NO2 regeneration. After t7, the exhaust gas temperature decreases as the total fuel supply decreases. The particulate filter load continues to decrease. The released NO2 remains above the threshold for NO2-facilitated regeneration. After t7, the exhaust gas temperature is lower than the threshold temperature for NO2 regeneration. However, the particulate filter load continues to decrease due to self-combustion. The total fuel supply decreases to be essentially equal to the fuel supply requested by the driver. Likewise, the threshold for NO2-facilitated regeneration decreases. In this way, an aftertreatment device is configured to reduce the regeneration temperatures for a particulate filter, thereby reducing fuel consumption when active controls are desired. The device comprises a washcoat with a zirconium oxide support, palladium oxide, and several base metals. The palladium oxide and base metals enable the device to maintain reactivity despite exposure to sulfur dioxide, while increasing NO oxidation efficiency. The engineering benefit of combining base metals and palladium oxide is to increase the device's durability while also improving its reactivity. This reduces regeneration temperatures in the presence of sufficient NO₂, which can increase fuel efficiency and provide cost savings for the driver. One example of a process involves generating NO2 in a catalyst comprising a washcoat with zirconium, one or more base metal oxides, and palladium oxide, wherein an exhaust gas flow is between lower and upper threshold flow rates, and facilitating the regeneration of a particulate filter located downstream of the catalyst via NO2 when an exhaust gas temperature exceeds a threshold temperature. A first example of the process further involves the threshold temperature being a threshold temperature for NO2-facilitated regeneration, and the threshold temperature for NO2-facilitated regeneration being based on the particulate filter being exposed to an amount of NO2 capable of facilitating particulate filter regeneration.A second example of the procedure, which optionally includes the first example, further involves regenerating the particulate filter in response to the exhaust gas temperature being lower than the threshold temperature. This includes initiating active controls to adjust engine operating parameters in order to increase the exhaust gas temperature. A third example of the procedure, which optionally includes the first and / or second example, further involves the active controls including one or more of the following: reducing the EGR flow rate, increasing the fuel injection pressure, increasing the fuel injection volume, reducing the air-fuel ratio, increasing the manifold pressure, and delaying the fuel injection.A fourth example of the process, which optionally includes one or more of the first three examples, further includes that regeneration by NO2 is facilitated when the amount of NO2 produced by the engine and the catalyst exceeds a threshold for NO2 regeneration. A fifth example of the process, which optionally includes one or more of the first four examples, further includes that the base metal oxides are in the range of 30 to 70 percent by weight of the washcoat. A sixth example of the process, which optionally includes one or more of the first five examples, further includes that NO2 streams are generated from the exhaust gas by the catalyst, and that the exhaust gas flows at an exhaust gas flow rate between the upper and lower exhaust gas thresholds, and where the exhaust gas temperature is greater than 200 °C. An exemplary system comprises a catalyst located in an exhaust duct of an engine-driven vehicle, wherein the catalyst comprises a washcoat with a zirconium oxide support, several base metal oxides and palladium oxide, a particulate filter located in a position in the exhaust duct downstream of the catalyst relative to a direction of exhaust flow, and a controller with computer-readable instructions stored thereon that enable the controller to actively regenerate the particulate filter by adjusting actuators to raise an exhaust temperature to a temperature greater than a threshold temperature and to adjust an exhaust flow rate to a rate between upper and lower threshold exhaust flow rates.A first example of the system further includes the threshold temperature being a threshold temperature for NO2-facilitated regeneration, and the threshold temperature for NO2-facilitated regeneration being lower than a threshold temperature for oxygen-facilitated regeneration. A second example of the system, which optionally includes the first example, further includes the threshold temperature for NO2-facilitated regeneration being determined based on a particulate filter regeneration temperature in the presence of NO2 that exceeds a threshold amount of NO2, and the threshold temperature for oxygen-facilitated regeneration being based on a particulate filter regeneration temperature in the presence of an amount of NO2 that is lower than the threshold amount of NO2.A third example of the system, which optionally includes the first and / or second example, further includes the catalyst being physically coupled to the exhaust manifold and exhaust gas from the engine flowing through the catalyst before entering the particulate filter. A fourth example of the system, which optionally includes one or more of the first to third examples, further includes a selective catalytic reduction device located downstream of the particulate filter. An example of a method for an engine-driven vehicle comprises regenerating a particulate filter without adjusting the engine operating parameters during a first mode, facilitating particulate filter regeneration with oxygen by adjusting the engine operating parameters to a first size during a second mode, and facilitating the particulate filter with NO2 by adjusting the engine operating parameters to a second size during a third mode, wherein the NO2 is produced by at least one diesel oxidation catalyst located upstream of the particulate filter, the diesel oxidation catalyst comprising a washcoat with a zirconium oxide substrate and at least one manganese oxide and a palladium catalyst; wherein the first size is greater than the second size.A first example of the procedure further includes passive oxygen-facilitated regeneration when the exhaust gas temperature is greater than a threshold temperature for oxygen-facilitated regeneration, the amount of NO2 at the filter is less than a threshold regeneration amount, and the exhaust gas flow rate is outside a range between upper and lower threshold flow rates during the first mode. A second example of the procedure, which optionally includes the first example, further includes passive NO2-facilitated regeneration when the exhaust gas temperature is greater than a threshold temperature for NO2-facilitated regeneration, the amount of NO2 at the filter is greater than a threshold amount for NO2 regeneration, and the exhaust gas flow rate is within a range between upper and lower threshold flow rates during the first mode.A third example of the procedure, which optionally includes the first and / or second example, further includes that the particulate filter regeneration during the second mode involves initiating active controls configured to adjust engine operating parameters by the first parameter, where the first parameter corresponds to raising an exhaust gas temperature to a temperature greater than a threshold temperature for oxygen-facilitated regeneration, and where the threshold temperature for oxygen-facilitated regeneration is equal to 600 °C, and where the amount of NO2 at the particulate filter is less than a threshold amount for NO2 regeneration.A fourth example of the procedure, which optionally includes one or more of the first to third examples, further includes that the particulate filter regeneration during the third mode involves initiating active controls configured to adjust engine operating parameters by the second quantity, where the second quantity corresponds to raising an exhaust gas temperature to a temperature greater than a threshold temperature for NO2-facilitated regeneration, and where the threshold temperature for NO2-facilitated regeneration is 350 °C, and where an amount of NO2 at the particulate filter is greater than a threshold amount for NO2 regeneration.A fifth example of the method, which optionally includes one or more of the first four examples, further includes that the threshold quantity for NO2 regeneration corresponds to an amount of NO2 sufficient to promote the combustion of soot deposited on the particulate filter. A sixth example of the method, which optionally includes one or more of the first five examples, further includes that the catalyst is hermetically sealed along its outer circumference to an exhaust pipe of an exhaust duct. A seventh example of the method, which optionally includes one or more of the first six examples, further includes that the catalyst receives exhaust gas through the exhaust duct upstream of the particulate filter. An example of a process for treating emissions from diesel combustion comprises passing diesel combustion exhaust gas over a diesel oxidation catalyst with a washcoat comprising zirconium oxide, palladium oxide, and at least one base metal oxide, wherein the washcoat is coated on the surface of a substrate and wherein the palladium oxide constitutes 0.5–3 wt.% of the washcoat. A first example of the process further includes that the zirconium oxide is ZrO₂. A second example of the process, which optionally includes the first example, further includes that the palladium oxide is PdO. A third example of the process, which optionally includes the first and / or second example, further includes that at least one base metal oxide comprises one or more of Mn₂O₃, CeO₂, and CuO.A fourth example of the process, which optionally includes one or more of the first three examples, further includes that the percentage weight of the at least one base metal oxide in the washcoat is 15 to 75. A fifth example of the process, which optionally includes one or more of the first four examples, further includes that the diesel oxidation catalyst is located upstream of a particulate filter relative to one direction of the exhaust gas flow. A sixth example of the process, which optionally includes one or more of the first five examples, further includes that the particulate filter is located upstream of a selective catalytic reduction device.A seventh example of the process, which optionally includes one or more of the first to sixth examples, further includes that the diesel oxidation catalyst is a first diesel oxidation catalyst upstream of a second diesel oxidation catalyst relative to a direction of the exhaust gas flow, and that the selective catalytic reduction device is located between the first and second diesel oxidation catalysts, and that a particulate filter is located downstream of the second diesel oxidation catalyst. An eighth example of the process, which optionally includes one or more of the first to seventh examples, further includes that the first and second diesel oxidation catalysts are identical.A ninth example of the process, which optionally includes one or more of the first to eighth examples, further includes the fact that the first diesel oxidation catalyst comprises different types of base metal oxides than the second diesel oxidation catalyst. An example of a diesel oxidation catalyst comprises a cordierite substrate with a honeycomb structure, a washcoat containing ZrO₂, PdO, and one or more base metal oxides applied to the substrate, wherein a PdO section is coated upstream of the base metal oxides relative to one direction of the exhaust gas flow, the base metal oxides comprising Mn₂O₃, CeO₂, and CuO, with a weight percent of the base metal oxides ranging from 15% to 75%. A first example of the catalyst further includes a washcoat containing exactly 2% PdO by weight and exactly 50% Mn₂O₃, CeO₂, and CuO by weight. An example of a diesel engine comprises an exhaust duct that accommodates a diesel oxidation catalyst upstream of a particulate filter and a selective catalytic reduction device. The diesel oxidation catalyst comprises a substrate coated with a washcoat containing ZrO₂, PdO, and a plurality of base metal oxides. The PdO is applied to an upstream portion of the substrate, and the plurality of base metal oxides is applied to a downstream portion of the substrate relative to one direction of the exhaust flow. A first example of the diesel engine further includes the upstream portion being configured to oxidize carbon-containing compounds, and the downstream portion being configured to oxidize nitrogen oxides.A second example of the diesel engine, which optionally includes the first example, further includes that the diesel oxidation catalyst is fixed in the exhaust manifold. A third example of the diesel engine, which optionally includes the first and / or second example, further includes that the diesel oxidation catalyst is located upstream of a particulate filter, so that exhaust gas flows through the diesel oxidation catalyst before reaching the particulate filter. A fourth example of the diesel engine, which optionally includes one or more of the first to third examples, further includes that the multitude of base metal oxides includes oxides of Co, Cu, Ce, Mn, Ni, Fe, Mo, and W. A fifth example of the diesel engine, which optionally includes one or more of the first to fourth examples, further includes that the multitude of base metal oxides includes exactly three base metal oxides, namely Mn₂O₃, CeO₂, and CuO.A sixth example of the diesel engine, which optionally includes one or more of the first five examples, further includes the diesel oxidation catalyst being located downstream of an EGR channel. A seventh example of the diesel engine, which optionally includes one or more of the first six examples, further includes the upstream and downstream sections of the diesel oxidation catalyst being in end-to-end contact. It should be noted that the exemplary control and estimation routines included herein can be used in conjunction with various engine and / or vehicle system configurations. The control methods and routines disclosed herein can be stored as executable instructions in non-volatile memory and executed by the control system, which comprises the control unit in combination with the various sensors, actuators, and other engine hardware. The specific routines described herein can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. Thus, various actions, operations, and / or functions shown can be performed in the sequence shown, in parallel, or, in some cases, omitted.Similarly, the processing sequence is not strictly necessary to achieve the features and benefits of the embodiments described here, but is provided for the sake of clarity and description. One or more of the illustrated actions, operations, and / or functions can be performed repeatedly, depending on the specific strategy employed. Furthermore, the described actions, operations, and / or functions can graphically represent code to be programmed in non-volatile memory of the computer-readable storage medium in the engine control system, with the described actions being carried out by executing the instructions in a system that includes the various engine hardware components in combination with the electronic control unit. It is understood that the configurations and routines disclosed herein are exemplary and that these specific embodiments are not to be interpreted in a limiting sense, as numerous variations are possible. For example, the foregoing technology can be applied to V-8, V-6, I-4, I-6, V-12, 4-cylinder boxer, and other engine types. The subject matter of this disclosure includes all novel and non-obvious combinations and sub-combinations of the different systems and configurations, and other features, functions, and / or properties disclosed herein. The following claims, in particular, describe certain combinations and subcombinations that are considered novel and not obvious. These claims may refer to "one" element, "a first" element, or the equivalent thereof. Such claims are to be understood as including one or more such elements and neither requiring nor excluding two or more such elements. Further combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amending the present claims or by filing new claims in this or a related application. Such claims, regardless of whether they have a broader, narrower, identical, or different scope compared to the original claims, are also considered to be included in the subject matter of the present disclosure.

Claims

A method comprising: generating NO2 in a catalyst (70) comprising a washcoat with zirconium, one or more base metal oxides and a palladium oxide, wherein an exhaust gas flow rate is between the lower and upper threshold flow rates; and facilitating regeneration of a particulate filter (72) located downstream of the catalyst (70) via NO2 when an exhaust gas temperature is greater than a threshold temperature; wherein the palladium oxide is contained in an upstream section (70A) of the catalyst (70) in relation to a direction of the exhaust gas flow; and the at least one base metal oxide is contained in a downstream section (70B) of the catalyst (70) in relation to the direction of the exhaust gas flow. The method of claim 1, wherein the threshold temperature is a threshold temperature for NO2-facilitated regeneration, and wherein the threshold temperature for NO2-facilitated regeneration is based on the regeneration which occurs in the presence of an amount of NO2 which is above the threshold amount for NO2 regeneration. The method of claim 1, further comprising regenerating the particulate filter (72) in response to the fact that the exhaust gas temperature is lower than the threshold temperature, by initiating active controls to adjust engine operating parameters to increase the exhaust gas temperature. Method according to claim 3, wherein the active controls comprise one or more of reducing an EGR flow rate, increasing a fuel injection pressure, increasing a fuel injection volume, reducing an air-fuel ratio, increasing a manifold pressure and delaying a fuel injection. Method according to claim 1, wherein regeneration is facilitated by NO2 when an amount of NO2 produced by a motor (10) and the catalyst (70) is greater than a threshold amount for NO2 regeneration. Method according to claim 1, wherein the at least one base metal oxide is in a range of 15 to 75 percent by weight of the washcoat. The method of claim 1, wherein it involves generating NO2 streams from exhaust gas through the catalyst (70) and wherein the exhaust gas flows at an exhaust gas flow rate between upper and lower exhaust gas thresholds and wherein the exhaust gas temperature is greater than 200 °C. System comprising: a catalyst (70) in an exhaust duct (48) of a vehicle powered by an engine (10), wherein the catalyst (70) comprises a washcoat with a zirconium oxide support, several base metal oxides and a palladium oxide, the palladium oxide being contained in an upstream section (70A) of the catalyst (70) relative to a direction of exhaust flow, and the base metal oxides being contained in a downstream section (70B) of the catalyst (70) relative to the direction of exhaust flow; wherein said base metal oxides Mn, Cu and Ce are present in a weight percent ratio of 20 to 7.5 to 15; a particulate filter (72) being located in a position of the exhaust duct (48) downstream of the catalyst (70) relative to a direction of exhaust flow;and a controller with computer-readable instructions stored thereon, enabling the controller (12) to perform the following: active regeneration of the particulate filter (72) by adjusting actuators to increase an exhaust gas temperature to a temperature greater than a threshold temperature and to adjust an exhaust gas flow rate to a rate between the upper and lower threshold exhaust gas flow rate. System according to claim 8, wherein the threshold temperature is a threshold temperature for NO2-facilitated regeneration and wherein the threshold temperature for NO2-facilitated regeneration is based on the regeneration which occurs in the presence of an amount of NO2 which is above the threshold amount for NO2 regeneration. System according to claim 9, wherein the threshold temperature for NO2-facilitated regeneration is determined on the basis of a regeneration temperature of the particle filter (72) in the presence of NO2 which is greater than a threshold amount of NO2, and wherein the threshold temperature for oxygen-facilitated regeneration is based on a regeneration temperature of the particle filter (72) in the presence of an amount of NO2 which is less than the threshold amount of NO2. System according to claim 8, wherein the catalyst (70) is physically coupled to the exhaust duct (48), and wherein exhaust gas from the engine (10) flows through the catalyst (70) before flowing into the particulate filter (72). System according to claim 8, further comprising a device for selective catalytic reduction located downstream of the particle filter (72). System according to claim 8, wherein the control (12) further comprises instructions to regenerate the particulate filter (72) without adjusting engine operating parameters during a first mode, to facilitate particulate filter regeneration with oxygen by adjusting engine operating parameters to a first size during a second mode, and to facilitate the particulate filter (72) with NO2 by adjusting engine operating parameters to a second size during a third mode, wherein the NO2 is produced by at least one catalyst (70) located upstream of the particulate filter (72), the catalyst (70) comprising a washcoat with a zirconium oxide substrate and at least one manganese oxide and a palladium catalyst; wherein the first size is larger than the second size. System according to claim 13, wherein the catalyst (70) receives exhaust gas through the exhaust channel (48) upstream of the particulate filter (72). System according to claim 13, wherein the catalyst (70) is hermetically sealed along its outer circumference on an exhaust pipe of an exhaust duct (48).

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