Abstract: A method for detecting an opening time of a valve, includes receiving a valve current profile of the valve and processing the valve current profile using at least a slope reflection detector to determine a status of the valve based on an output of the slope reflection detector.

Abstract: An exhaust treatment system includes a selective catalyst reduction filter (SCRF) device, a reductant delivery system, and a reductant storage module. The SCRF device includes a filter portion having a washcoat disposed thereon that defines a washcoat thickness (WCT). The reductant delivery system is configured to inject a reductant that reacts with the washcoat. The reductant storage module is in electrical communication with the reductant delivery system to determine a reductant setpoint that controls the amount of reductant injected from the reductant delivery system. The exhaust treatment system further includes a WCT compensation module configured to electrically communicate a WCT compensation value to the reductant storage module. The reductant storage module adjusts the setpoint according to the WCT compensation value such that the amount of ammonia that slips from the SCRF device is reduced as compared to the first setpoint.

Abstract: Systems, apparatus, and methods for selectively, preferentially, and/or actively removing or trapping SO3 from un-oxidized sulfur constituents in an exhaust gas effluent produced by an internal combustion engine are disclosed. Also disclosed are embodiments for regenerating an SO3 trap.

Abstract: An exhaust aftertreatment system includes an oxidation catalyst and a selective catalytic reduction (SCR) catalyst disposed in an exhaust stream of an internal combustion engine. A stay warm thermal management strategy is employed after warm-up of the aftertreatment system is complete to maintain the aftertreatment system above a temperature providing a desired performance threshold of one or more components of the aftertreatment system, such as the oxidation catalyst or the SCR catalyst.

Abstract: The present disclosure relates to a controller apparatus for regenerating a particulate matter sensor. The controller apparatus includes a sensing module configured to detect a soot loading on a particulate matter sensor and generate a regeneration request indicating a desired regeneration temperature and a heating module configured to receive the regeneration request and send a heating command signal to a heating element based on the regeneration request. The controller apparatus further includes an electrical resistance module configured to detect an electrical resistance in the heating element and determine an actual temperature of the heating element and a temperature feedback module configured to modify the heating command signal according to the difference between the desired regeneration temperature and the actual temperature. The present disclosure also includes a related method and system.

Abstract: A system and a method for operating a catalyst of a vehicle may include a catalyst configured to purify an exhaust gas of a vehicle engine, and a controller configured to perform a detection of internal temperature of the catalyst, wherein the controller detects the internal temperature of the catalyst by applying a change of precious metal loading of the catalyst to an internal temperature model of the catalyst.

Abstract: A method for metering reducing agent to an exhaust gas treatment device having a feed point and an SCR catalytic converter converting nitrogen oxide compounds in the exhaust gas, includes at least: a) calculating the following target conversion rates indicating what fraction of the nitrogen oxide compounds in the exhaust gas can be converted by the catalytic converter: a first rate determined from the power output of an internal combustion engine; a second rate determined from the mass flow of nitrogen oxide compounds in purified exhaust gas; and a third rate determined from a ratio of quantities of nitrogen oxide compounds upstream and downstream of the catalytic converter; b) selecting the lowest rate; c) determining the dosing quantity of reducing agent for the selected rate; and d) dosing the determined dosing quantity into the exhaust gas treatment device. An exhaust-gas treatment device and a motor vehicle are also provided.

Abstract: A self-diagnosing method for diagnosing a selective catalytic reduction (SCR) system of a vehicle that includes an internal combustion engine. An SCR system is arranged downstream of the engine, and the SCR system includes at least one exhaust gas sensor that is sensitive to nitrogen oxides (NOx) gas. The method includes a first diagnosing sequence (S1) of ensuring that the vehicle is in a stationary state, controlling the engine to operate in a high NOx output engine operating state and in a low NOx output engine operating state, registering an output signal of the at least one exhaust gas sensor when the engine operates in each of the high NOx output engine operating state and low NOx output engine operating state, and diagnosing NOx measurement performance of the at least one exhaust gas sensor on the basis of the registered sensor output.

Abstract: A method for reducing the pollutant emissions in the exhaust gas in a start/catalytic converter heating phase of an internal combustion engine featuring externally supplied ignition and having at least one catalytic converter in an exhaust gas tract of the internal combustion engine, and for adapting a catalytic converter heating strategy to suitable state variables of the internal combustion engine and the catalytic converter as well as to the fuel quantity, the aging state and ambient conditions. The internal combustion engine is operated in a first phase of the start/catalytic converter heating phase using a lean air-fuel mixture in a range between a lambda value of 1.05 and at a lean misfire limit of the internal combustion engine that lies at a higher lambda value, and/or in a second phase of the start/catalytic converter heating phase, initially using a rich air-fuel mixture.

Abstract: A method for feeding reducing agent to an exhaust gas mass flow in an exhaust gas treatment device provides a reducing agent feed port, a storage catalytic converter storing reducing agent and an SCR catalytic converter for selective catalytic reduction of nitrogen oxygen compounds in exhaust gas. A first dosing strategy is followed, loading of the storage catalytic converter with reducing agent is monitored and a first target conversion rate is determined based on current loading. Reducing agent is fed according to the first target conversion rate. A current conversion rate obtained with the SCR catalytic converter is determined. The current conversion rate is compared to the first target conversion rate and any deviation is registered. A further dosing strategy, not considering the loading of the storage catalytic converter, is used if the deviation exceeds a first threshold value. A motor vehicle and a stationary installation are also provided.

Abstract: A method, comprising purging a storage catalytic converter of stored NOx by diverting only a portion of incoming exhaust flow around the catalytic device while increasing injection of reductant to the storage catalytic converter; and responsive to the diverting, adjusting injection of an ammonia-containing fluid into recombined exhaust flow upstream of an SCR catalytic converter. Bypass of the storage catalytic converter reduces available oxygen and air flow through the storage catalytic converter, providing a more advantageous environment for reduction of NOx in the storage catalytic converter.

Abstract: Described are SCR catalyst systems comprising a first SCR catalyst composition and a second SCR catalyst composition arranged in the system, the first SCR catalyst composition promoting higher N2 formation and lower N2O formation than the second SCR catalyst composition, and the second SCR catalyst composition having a different composition than the first SCR catalyst composition, the second SCR catalyst composition promoting lower N2 formation and higher N2O formation than the first SCR catalyst composition. The SCR catalyst systems are useful in methods and systems to catalyze the reduction of nitrogen oxides in the presence of a reductant.

Abstract: A method for monitoring an exhaust after-treatment system that doses an exhaust treatment fluid held from a tank into an exhaust stream. The method includes determining a first temperature of the exhaust treatment fluid in the tank using a temperature sensor. If the first temperature of the exhaust treatment fluid is less than a predetermined temperature, a heater is activated to increase the first temperature of the exhaust treatment fluid. The increasing first temperature is then monitored relative to the predetermined temperature. Then, a second temperature when a phase change of the exhaust treatment fluid occurs is detected. The detected second temperature is then compared to the predetermined temperature to determine whether the exhaust treatment fluid is of sufficient quality, or to determine whether the temperature sensor is rational.

Abstract: A method is provided for operating an internal combustion engine of a motor vehicle. The method includes, but is not limited to storing exhaust gas while the engine is working, and supplying the stored exhaust gas into at least an engine cylinder during a subsequent start phase of the engine.

Abstract: The present invention is directed to a pollutant abatement system for vehicles propelled by a gasoline combustion engine, in particular a gasoline direct injection engine (GDI). In addition, this invention is concerned with a process of mitigating noxious compounds in the exhaust of such an engine efficiently by applying the inventive abatement system to fulfill future legislative exhaust regulations.

Abstract: In a method for enriching the exhaust gases of a combustion engine with unburnt hydrocarbon engine operating conditions are monitored and in-cylinder post injection of unburnt hydrocarbon into one predetermined cylinder of at least two cylinders connected to an exhaust manifold is performed when the monitored engine operating conditions equal predetermined engine operating conditions. The predetermined engine operating conditions are set for resulting in a substantially zero flow of the post-injected hydrocarbon to an EGR circuit for the specific design of the engine in operation.

Abstract: An internal combustion engine system of the present application includes a spark-ignited internal combustion engine that is powered by a gaseous fuel. The engine system also includes an exhaust system that is in exhaust gas receiving communication with the internal combustion engine. The exhaust system includes an exhaust treatment component. Additionally, the exhaust system includes a liquid fuel injection system in liquid fuel injecting communication with the exhaust system to inject liquid fuel into exhaust gas upstream of the exhaust treatment component.

Abstract: In a method for regeneration of nitrogen oxide storage catalytic converters in the exhaust gas tract of a gasoline engine assigned an exhaust aftertreatment system in the form of a Y system including two three-way catalytic converters, two downstream nitrogen oxide storage catalytic converters, one shared catalytic converter for selective catalytic reduction, and a rear nitrogen oxide storage catalytic converter, a first part of the exhaust gas in the first exhaust bank is set to rich and a second part of the exhaust gas in the second exhaust bank is set to lean in a first regeneration phase and subsequently, the second part of the exhaust gas in the second exhaust bank is set to rich and the first part of the exhaust gas in the first exhaust bank is set to lean in a second regeneration phase.

Abstract: The invention relates to a method for treating a gas containing nitrogen oxides (NOx), in which an NOx-reduction reaction is carried out using a nitrogen-containing reducing agent, which invention is characterized in that the catalyst used for the reduction reaction is a catalytic system containing a composition comprising zirconium, cerium and niobium in the following percentages by weight, expressed in terms of the weight of oxide: 10-50% of cerium, 5-20% of niobium and the remainder consisting of zirconium.

Abstract: An exhaust treatment system including an exhaust passage in communication with an engine that produces an exhaust. An exhaust canister is coupled to the exhaust passage, and the exhaust canister supports a plurality of exhaust treatment components therein for treating the exhaust, wherein exhaust canister is removable from the exhaust passage, and the exhaust treatment components are removable from the exhaust canister.

Abstract: Described is a selective catalytic reduction catalyst comprising an iron-promoted 8-ring small pore molecular sieve. Systems and methods for using these iron-promoted 8-ring small molecular sieves as catalysts in a variety of processes such as abating pollutants in exhaust gases and conversion processes are also described.

Abstract: Various systems and method for detecting exhaust NOx sensor degradation are disclosed. In one example, degradation of the NOx sensor is indicated responsive to reductant injection in an exhaust passage under engine off conditions. For example, degradation of the NOx sensor is indicated when an actual NOx sensor output differs from an expected NOx sensor output by more than a threshold amount.

Abstract: A method is provided for controlling a urea injection amount of a vehicle that controls urea injection in consideration of a difference between an internal temperature change rate and a regeneration temperature of an SCR integral diesel particulate filter.

Abstract: Exhaust gas apparatus for the cleaning of exhaust gas where the exhaust gas apparatus comprises an exhaust conduit section which is formed with at least two separate flow paths. Each flow path is provided with a particle filter for the removal of particulate matter from the exhaust gas, an NOx trap for the removal of NOx from the exhaust gas. The exhaust gas apparatus further comprises at least one cold flame vaporizer in which fuel is partially oxidized in preheated air to form a cold flame gas where the cold flame vaporizer is arranged in fluid communication with each of the flow paths in the exhaust conduit section such that the cold flame gas can flow through the particle filter and the NOx trap, and valve means for controlling the flow of cold flame gas from the cold flame vaporizer to each flow path in the exhaust conduit section. Thereby, both the particle filter and the NOx trap in at least one of the flow paths can be regenerated in a single operation.

Abstract: An O2 purge control method for two type catalysts may include, performing, by a WCC O2 purge of a warm up catalytic converter (WCC), a sensor based WCC O2 purge logic to which a voltage of a WCC O2 sensor is applied immediately after a fuel-cut; and when the sensor based WCC O2 purge logic is completed, applying an O2ucc learning history and an O2uccReset of an O2ucc (oxygen quantity adsorbed into UCC) for an under floor catalytic converter (UCC) and performing, by any one of a factor based UCC O2 purge logic to which an engine RPM and an Fpurge of a purge oxygen suction quantity [mg] are applied and a sensor based UCC O2 purge logic to which a voltage value of an UCC O2 rear sensor is applied, an UCC O2 purge of the UCC.

Abstract: An exhaust mixer provided may be used for mixing an additive, such as urea, in exhaust fluid flow. The exhaust mixer may be useful in reducing or preventing build-up of solid additive deposits by increasing efficiency of mixing of the additive. The exhaust mixer may be located at least partially within a mixing conduit and includes plurality of elongate mixing blades held in spaced configuration by a support. Each mixing blade may have a longitudinal axis extending along a longitudinal axis of the mixing conduit, wherein an injector module may be located upstream of the inlet of the mixing conduit.

Abstract: The invention relates to a method and an arrangement for operating an internal combustion engine. In the method a first distribution of values for at least one variable is used, the variable describing a physical property of the internal combustion engine, and over a second time period values for this variable are recorded and classified, such that a second distribution is determined. The first distribution is then compared with the second distribution such that the behavior of the internal combustion engine can be adapted on the basis thereof.

Abstract: Embodiments of the invention include a method for performing diagnostics of a selective catalytic reduction (“SCR”) device in an exhaust gas treatment system of an internal combustion engine. The method includes monitoring an amount of sulfur in the SCR device of the exhaust treatment system and monitoring, by an SCR diagnostics module, an efficiency of the SCR device and indicating when the efficiency of the SCR device falls below an efficiency diagnostics threshold. Based on determining that the amount of sulfur in the SCR device is above a first threshold, the method includes disabling an operation of the SCR diagnostics module.

Abstract: One form of the present application is an apparatus including an internal combustion engine structured to produce an exhaust flow, an exhaust system structured to receive the exhaust flow, and a reductant injector structured to inject reductant into a primary passage of the exhaust system upstream of a catalyst. The apparatus further includes an injector passage structured to receive a portion of exhaust upstream of the injector and further structured to flow the exhaust into the primary passage around the injector in a manner such that deposit formation is reduced.

Abstract: A method to produce a NOx trap composition, and its use in a NOx trap and in an exhaust system for internal combustion engines, is disclosed. The NOx trap composition is produced by heating an iron-containing zeolite in the presence of an inert gas and an organic compound to produce a reductively calcined iron/zeolite. A palladium compound is then added to the reductively calcined iron/zeolite, and the resulting Pd—Fe/zeolite is then calcined at 400 to 600° C. in the presence of an oxygen-containing gas to produce the NOx trap composition. The NOx trap composition shows low temperature NO capacity below 200° C., as well as an additional NO storage temperature window in the 200 to 250° C. range.

Abstract: An exhaust gas control apparatus for an internal combustion engine includes: a NOx purification catalyst arranged in an exhaust passage of the internal combustion engine; a degradation degree estimating unit estimating a degradation degree of the NOx purification catalyst; and an air-fuel ratio control unit adjusting an air-fuel ratio of exhaust gas flowing into the NOx purification catalyst, wherein, until the estimated degradation degree of the NOx purification catalyst reaches a predetermined degradation degree, the air-fuel ratio control unit adjusts the air-fuel ratio of the exhaust gas to a rich air-fuel ratio, and, when the estimated degradation degree of the NOx purification catalyst exceeds the predetermined degradation degree, the air-fuel ratio control unit changes the air-fuel ratio of the exhaust gas from the rich air-fuel ratio to a lean air-fuel ratio so that the NOx purification catalyst is regenerated.

Abstract: A method for metering fuel from a high pressure system, comprising at least one high pressure pump, one pressure accumulator and one high pressure injection valve, into an exhaust gas duct of an internal combustion engine in order to regenerate a nitrogen oxide storage catalyst (NSC) disposed in the exhaust gas duct, wherein a higher pressure of the fuel is generated by the electrically actuated high pressure pump, which discretely delivers fuel and has a constant stroke volume, wherein the fuel is supplied to the pressure accumulator comprising a pressure measuring device for determining the fuel pressure and wherein the fuel is injected into the exhaust gas duct via the downstream, electrically actuated high pressure injection valve.

Abstract: Various systems and methods are described for an engine system with an exhaust gas treatment system including a particulate filter. In one example method, accumulated hydrocarbons are removed from the exhaust gas treatment system by increasing an exhaust gas temperature to a first temperature responsive to a particulate filter regeneration request during extended cold idle operation. After a predetermined duration, the exhaust gas temperature is increased to a second, higher temperature to regenerate the particulate filter.

Abstract: A dosing control system for an exhaust system includes: a reductant fluid tank operable to contain a reductant solution comprising urea; an injector disposed in operable communication between a reductant tank and an SCR apparatus, the injector being operable to inject the reductant solution from the reductant tank into a flow of exhaust upstream of the SCR apparatus; a urea quality sensor (UQS) configured and disposed to sense a concentration of the urea in the reductant solution; and, a control module disposed in signal communication with the UQS and in operable communication with the injector, the control module being operable to adjust a dosing of the reductant solution injected by the injector based on a concentration of the urea in the reductant solution.

Abstract: A vehicle and method of updating aging of a selective catalytic reduction filter (SCRF) of an exhaust treatment system of the vehicle are disclosed. The method includes determining a desorption rate estimate of a catalyst of the SCRF and determining an ash volume estimate representative of an amount of ash collected inside the SCRF. The method also includes determining an ash correction factor from the ash volume estimate and calculating, via a controller, a corrected desorption rate value by multiplying the ash correction factor with the desorption rate estimate to update the aging of the SCRF.

Abstract: Methods and systems for regenerating an after treatment device are disclosed. In one example, the possibility of introducing fuel to oil during after treatment device regeneration is reduced. The methods and systems may reduce engine degradation and improve engine emissions.

Abstract: The invention provides an exhaust gas cleaning oxidation catalyst and in particular to an oxidation catalyst for cleaning the exhaust gas discharged from internal combustion engines of compression ignition type (particularly diesel engines). The invention further relates to a catalysed substrate monolith comprising an oxidising catalyst on a substrate monolith for use in treating exhaust gas emitted from a lean-burn internal combustion engine. In particular, the invention relates to a catalysed substrate monolith comprising a first washcoat coating and a second washcoat coating, wherein the second washcoat coating is disposed in a layer above the first washcoat coating.

Abstract: Components in an exhaust after treatment system (EATS) for a diesel engine are monitored by measuring heat released (QDOC) across a diesel oxidation catalyst (DOC) and heat released (QEATS) across the DOC and a diesel particulate filter (DPF) during an A Hi injection event, by calculating heat input from AHI fuel (QAHI) during performance of the AH I injection event with a fully functioning AHI nozzle, and by measuring NOX conversion efficiency (nSCR) from NOX to N2 by a selective catalytic reduction system (SCR) at a condition where a SCR is sensitive to feeding gas compositions while AHI is not in use. Malfunctioning components are identified using these measurements and calculations.

Abstract: A machine includes an engine having a coolant system, an electrical system, and an exhaust system. A diesel exhaust fluid (DEF) injector provides DEF into the exhaust system. The DEF injector includes a housing that forms a coolant passage therethrough. The coolant passage is adapted to accommodate a flow of coolant through the coolant passage for cooling the DEF injector. A DEF pump is arranged to provide DEF to the DEF injector from a reservoir during operation of the engine. A power management module is associated with the electrical system, the DEF injector and the DEF pump. An auxiliary power unit is associated with the power management module and is configured to remain active after the engine electrical system has been deactivated. The power management module is configured to cause a purge of the DEF from the DEF injector when the engine is shut down.

Abstract: The invention provides a method for purification of exhaust gas from a diesel engine in a system, which comprises a device for selective catalytic reduction and a diesel particulate filter preferably at least partially covered by a catalytic layer installed downstream of the device for selective catalytic reduction. A device for catalytic oxidation is installed upstream of the device for selective catalytic reduction and/or between the device for selective catalytic reduction and the diesel particulate filter. A device for injection of a controlled amount of reductant is installed inlet of the device for selective catalytic reduction, and a device for injection of a controlled amount of hydrocarbon is installed inlet of the catalytic oxidation.

Abstract: A mixing element positioned at an exhaust outlet of a Selective Catalytic Reduction (SCR) module is provided. The mixing element includes a base plate having an upper surface and a lower surface. The base plate is configured to deflect a portion of a flow of a fluid around the upper surface thereof. The mixing element also includes a plurality of vanes attached to the lower surface of the base plate in a spaced apart arrangement. The plurality of vanes is configured to induce a swirling effect in a flow of the fluid received therebetween.

Abstract: The present invention provides a diesel engine capable of preventing a PM accumulation amount from increasing excessively. If DOC inlet exhaust gas temperature (“IEGT”) does not reach a predetermined value T0, a control unit carries out air intake amount feedback control (“AIAFC”), and a target value of intake throttling is set to a predetermined air intake amount. If the DPF regenerating processing is not started even if elapsed time reaches a predetermined value t after AIAFC is started in a state where the DOC IEGT does not reach the predetermined value T0, the control unit changes AIAFC to exhaust gas temperature feedback control (“EGTFC”). In EGTFC, the control unit changes a target value of intake throttling to a predetermined DOC IEGT T0. If application of a load exceeding a predetermined amount is detected before the DOC IEGT reaches the predetermined value T0, the control unit returns EGTFC to AIAFC.

Abstract: An exhaust gas processing system includes a cylindrical tube through which an exhaust gas of an engine passes, a sensor configured to detect information regarding the exhaust gas discharged from the engine, a coil antenna provided on an outer periphery of the cylindrical tube and connected to a high-frequency power supply, and a control unit configured to control output power of the high-frequency power supply. The control unit controls output power of the high-frequency power supply based on the information detected by the sensor.

Abstract: An exhaust system for an engine is provided herein. The exhaust system includes an emission control device and an exhaust manifold having a plurality of runners merging at a confluence section positioned upstream of the emission control device. The exhaust system further includes a mixer plate positioned in the confluence section, the mixer plate including a central opening and a plurality of louvered vents positioned axially around the central opening, the louvered vents having angled openings facing a common rotational direction.

Abstract: A method and system for treating emissions includes charging particles in an exhaust stream, producing one or more radicals, and oxidizing at least a portion of the charged particles with at least a portion of the produced radicals. At least a portion of the charged particles in the exhaust stream are then attracted on at least one attraction surface which is one of oppositely charged from the charged particles and grounded. The attracted particles are oxidized with another portion of the one or more produced radicals to self regenerate the at least one attraction surface. Downstream from where the attracted particles are oxidized, at least a portion of one or more first compounds in the exhaust stream are converted to one or more second compounds downstream from the attracting. Additionally, at least a portion of any remaining charged particles are oxidized into one or more gases.

Abstract: A treatment device configured to receive a flow of exhaust from a power source is disclosed. The treatment device may have a first layer, a second layer, and a substrate layer. The first layer may include a selective catalytic reduction layer, and the second layer may be disposed downstream of the first layer and include an oxidation catalyst support. The substrate layer may be disposed adjacent to the second layer. Additionally, an additive may be disposed downstream of the first layer. The additive may be operative to substantially prohibit migration of a component of the second layer to the first layer upon treatment of the flow of exhaust by the oxidation catalyst support.

Abstract: A vehicle and a method of determining a reductant storage capacity set point of a selective catalytic reduction filter (SCRF) of an exhaust treatment system of a vehicle are disclosed. The method includes determining a storage estimate of a reductant inside the SCRF and determining a particulate estimate in the SCRF representative of an amount of particulate matter collected inside the SCRF. The method also includes determining a particulate correction factor from the particulate estimate and calculating, via a controller, a set point value of the reductant in the SCRF by computing together the particulate correction factor and the storage estimate to determine the reductant storage capacity set point of the SCRF.

Abstract: A process which solves the problem of supplying NO2 in accordance with requirements by means of temperature control of the precatalyst which is decoupled from the operating state of the engine. In an associated apparatus, a precatalyst which contains at least one oxidation component and whose temperature can be controlled independently of the operating state of the engine and an active SCR stage comprising an SCR catalyst with upstream metering facility for a reducing agent from an external source are arranged in series. A particle filter can be arranged between precatalyst and metering facility. The precatalyst preferably additionally contains a nitrogen oxide storage material.

Abstract: A system for detecting a leakage/failure in in an intake line of an internal combustion engine comprising an intake line (IL) and an exhaust line (EL), means (HFM) for measuring or for estimating a quantity of fresh air ({dot over (m)}HFM) entering said intake line (IL), means for measuring or for estimating a quantity of fuel ({dot over (m)}FUEL) injected in the engine (E), measurement or estimation means (? and/or NOx), on the exhaust line, adapted to provide a first value (?measured) of an air/fuel ratio introduced in the internal combustion engine (E), the system comprising processing means (ECU) adapted to calculate a second value (?exp) of said air/fuel ratio, calculated on the basis of the measured and estimated quantities of fresh air ({dot over (m)}HFM) and fuel ({dot over (m)}FUEL) to calculate an error (?err) between the first and the second value (?measured??exp) and to detect a condition of leakage/failure if said error is outside a predefined interval [?err?, ?err+] containing the value zero.

Abstract: Embodiments of the invention provide an engine aftertreatment apparatus comprising first and second diesel particulate filters (DPFs), the first DPF being provided upstream of the second DPF, the second DPF being provided with a coating of a second DPF catalyst, the second DPF catalyst being arranged to promote reduction of NOx.