Abstract: An aftertreatment system utilizes chemical reactions to treat an exhaust gas flow. A system for aftertreatment of the exhaust gas flow includes a NOx sensor configured to monitor within the exhaust gas flow one of a lambda value and a NOx concentration value and a computerized processor device configured to calibrate the monitored value for presence of one of NH3, H2, and hydrocarbons. In one embodiment, the system further includes a pair of NOx sensors, each monitoring both a lambda value and a NOx concentration value. In another embodiment, the system controls the aftertreatment based upon the calibrated values.

Abstract: A system according to the principles of the present disclosure includes an air/fuel ratio determination module and an emission level determination module. The air/fuel ratio determination module determines an air/fuel ratio based on input from an air/fuel ratio sensor positioned downstream from a three-way catalyst that is positioned upstream from a selective catalytic reduction (SCR) catalyst. The emission level determination module selects one of a predetermined value and an input based on the air/fuel ratio. The input is received from a nitrogen oxide sensor positioned downstream from the three-way catalyst. The emission level determination module determines an ammonia level based on the one of the predetermined value and the input received from the nitrogen oxide sensor.

Abstract: A system according to the principles of the present disclosure includes a storage estimation module and an air/fuel ratio control module. The storage estimation module estimates a first amount of ammonia stored in a first selective catalytic reduction (SCR) catalyst and estimates a second amount of ammonia stored in a second SCR catalyst. The air/fuel ratio control module controls an air/fuel ratio of an engine based on the first amount, the second amount, and a temperature of a substrate disposed in the second SCR catalyst.

Abstract: A method and system for operating an ammonia generation cycle in an internal combustion engine and a connected aftertreatment system includes monitoring a parameter of engine operation, comparing the parameter of engine operation to a threshold delineating operation of the engine in one of a stoichiometric operation and rich operation, and operating the ammonia generation cycle based upon the comparing indicating the parameter of engine operation exceeding the threshold.

Abstract: A system according to the principles of the present disclosure includes a rate determination module, a storage level determination module, and an air/fuel ratio control module. The rate determination module determines an ammonia generation rate in a three-way catalyst based on a reaction efficiency and a reactant level. The storage level determination module determines an ammonia storage level in a selective catalytic reduction (SCR) catalyst positioned downstream from the three-way catalyst based on the ammonia generation rate. The air/fuel ratio control module controls an air/fuel ratio of an engine based on the ammonia storage level.

Abstract: A powertrain includes an internal combustion engine having a combustion chamber and an aftertreatment system. A method for reducing NOx emissions in the powertrain includes monitoring an actual exhaust gas feedstream ratio of NO2 to NO, monitoring a desired exhaust gas feedstream ratio of NO2 to NO, comparing the actual and the desired exhaust gas feedstream ratios of NO2 to NO, and selectively initiating a NO2 generation cycle based upon the comparison of the actual and the desired exhaust gas feedstream ratios of NO2 to NO comprising injecting fuel mass into the combustion chamber after a primary combustion event.

Abstract: A system according to the principles of the present disclosure includes a storage estimation module and an air/fuel ratio control module. The storage estimation module estimates a first amount of ammonia stored in a first selective catalytic reduction (SCR) catalyst and estimates a second amount of ammonia stored in a second SCR catalyst. The air/fuel ratio control module controls an air/fuel ratio of an engine based on the first amount, the second amount, and a temperature of a substrate disposed in the second SCR catalyst.

Abstract: An exhaust aftertreatment system that receives an exhaust flow from a lean-burn engine and a method for treating the exhaust flow are described. The exhaust aftertreatment system may include a three-way-catalyst, an oxidation catalyst, and a NH3—SCR catalyst. The three-way-catalyst passively generates NH3 from native NOX contained in the exhaust flow when an A/F mixture supplied to the engine is cycled from lean to rich. The generated NH3 is then stored in the NH3—SCR catalyst to facilitate NOX reduction when the A/F mixture supplied to the engine is cycled back to lean. The oxidation catalyst is located upstream of the NH3—SCR catalyst and operates to lower the NO to NO2 molar ratio of the NOX fed to the NH3—SCR catalyst. The oxidation catalyst comprises perovskite oxide particles.

Abstract: Operation of a spark ignition, direct injection engine having an aftertreatment system including an oxidation catalyst and a selective catalyst reduction device is described. The method includes controlling to a stoichiometric air/fuel ratio and retarding spark ignition timing. Engine fueling is then controlled to a lean air/fuel ratio and spark is retarded. The engine is then operated to generate ammonia reductant. Engine operation then comprises operating at a preferred air/fuel ratio and controlling spark ignition timing to a preferred timing.

Abstract: A method for operating an internal combustion engine includes controlling the engine to a preferred air/fuel ratio to generate an engine-out exhaust gas feedstream including preferred concentrations of nitric oxide, carbon monoxide, and hydrogen, converting the nitric oxide, carbon monoxide, and hydrogen to ammonia across a first catalytic device; and storing the ammonia on an ammonia-selective catalytic reduction device fluidly serially connected downstream of the first catalytic device.

Abstract: Engine exhaust gas feedstream NOx emissions aftertreatment includes a catalytic device connected upstream of an ammonia-selective catalytic reduction device including a base metal. Engine operation can be modulated to generate an engine-out exhaust gas feedstream that converts to ammonia on the catalytic device. The ammonia is stored on the ammonia-selective catalytic reduction device, and used to reduce NOx emissions in the exhaust gas feedstream.

Abstract: A system according to the principles of the present disclosure includes an air/fuel ratio determination module and an emission level determination module. The air/fuel ratio determination module determines an air/fuel ratio based on input from an air/fuel ratio sensor positioned downstream from a three-way catalyst that is positioned upstream from a selective catalytic reduction (SCR) catalyst. The emission level determination module selects one of a predetermined value and an input based on the air/fuel ratio. The input is received from a nitrogen oxide sensor positioned downstream from the three-way catalyst. The emission level determination module determines an ammonia level based on the one of the predetermined value and the input received from the nitrogen oxide sensor.

Abstract: A system according to the principles of the present disclosure includes a rate determination module, a storage level determination module, and an air/fuel ratio control module. The rate determination module determines an ammonia generation rate in a three-way catalyst based on a reaction efficiency and a reactant level. The storage level determination module determines an ammonia storage level in a selective catalytic reduction (SCR) catalyst positioned downstream from the three-way catalyst based on the ammonia generation rate. The air/fuel ratio control module controls an air/fuel ratio of an engine based on the ammonia storage level.

Abstract: Engine exhaust gas feedstream NOx emissions aftertreatment includes a catalytic device and first and second ammonia selective catalytic reduction devices. The first and second ammonia-selective catalytic reduction devices each includes a base metal. Engine operation can be modulated to generate an engine-out exhaust gas feedstream that converts to ammonia. The ammonia is stored on the first and second ammonia selective catalytic reduction devices and used to reduce NOx emissions in the exhaust gas feedstream.

Abstract: Exhaust emissions from a spark-ignition direct-injection engine connected to an oxidation catalytic device and a selective catalyst reduction device having a capacity to store ammonia reductant are controlled. The engine operates in a first combustion mode to generate ammonia reductant, stored on the second aftertreatment device. The engine operates lean of stoichiometry and nitrides of oxygen in the exhaust gas feedstream are reduced on the second aftertreatment device.

Abstract: A method for supplying reductant into an exhaust gas feedstream for an internal combustion engine includes storing a fuel/reductant blend in the fuel storage and delivery system, separating the reductant from the fuel/reductant blend, storing the reductant in a reductant storage tank, and injecting the reductant into the exhaust gas feedstream upstream of the aftertreatment device.

Abstract: An exhaust gas aftertreatment system for treating an engine-out exhaust gas feedstream of a spark-ignition direct-injection engine includes a multi-stage catalytic converter comprising a converter inlet, a converter outlet, and a substrate having a first end associated with the converter inlet and a second end associated with the converter outlet. The substrate further includes a multiplicity of flow passages between the first and second ends of the substrate, a first surface location corresponding to the first end of the substrate, and a second surface location corresponding to the second end of the substrate. The first and second washcoat stages include washcoats formulated to generate hydrogen and ammonia from the engine-out exhaust gas feedstream. An ammonia-selective catalytic reduction device is downstream of the first and second washcoat stages.

Abstract: An exhaust aftertreatment system that receives an exhaust flow from a lean-burn engine and a method for treating the exhaust flow are described. The exhaust aftertreatment system may include a three-way-catalyst, an oxidation catalyst, and a NH3—SCR catalyst. The three-way-catalyst passively generates NH3 from native NOX contained in the exhaust flow when an A/F mixture supplied to the engine is cycled from lean to rich. The generated NH3 is then stored in the NH3—SCR catalyst to facilitate NOX reduction when the A/F mixture supplied to the engine is cycled back to lean. The oxidation catalyst is located upstream of the NH3—SCR catalyst and operates to lower the NO to NO2 molar ratio of the NOX fed to the NH3—SCR catalyst. The oxidation catalyst comprises perovskite oxide particles.

Abstract: A powertrain includes an internal combustion engine having a combustion chamber and an aftertreatment system. A method for reducing NOx emissions in the powertrain includes monitoring an actual exhaust gas feedstream ratio of NO2 to NO, monitoring a desired exhaust gas feedstream ratio of NO2 to NO, comparing the actual and the desired exhaust gas feedstream ratios of NO2 to NO, and selectively initiating a NO2 generation cycle based upon the comparison of the actual and the desired exhaust gas feedstream ratios of NO2 to NO comprising injecting fuel mass into the combustion chamber after a primary combustion event.

Abstract: A method for controlling hydrocarbon delivery to a hydrocarbon selective catalytic reduction device configured to receive an exhaust gas flow from an internal combustion engine includes monitoring measurable variable terms including factors affecting a conversion efficiency in the hydrocarbon selective catalytic reduction device, determining classifications of the measurable variable terms based upon measurable variable ranges, determining a desired hydrocarbon delivery value range based upon the classifications; and utilizing the desired hydrocarbon delivery value range to control the hydrocarbon delivery to the hydrocarbon selective catalytic reduction device.