An after treatment system is disclosed. The after treatment system may include an exhaust pipe through which an exhaust gas flows; a three-way catalyst (TWC) mounted on the exhaust pipe and purifying HC, CO, and NOx contained in the exhaust gas, an ammonia production catalyst (APC) mounted on the exhaust pipe at a downstream of the TWC, storing NOx at a lean air/fuel ratio, and generating H.sub.2, releasing the stored NOx, and generating NH.sub.3 using the released NOx and the generated H.sub.2 at a rich air/fuel ratio, and a selective catalytic reduction (SCR) catalyst mounted on the exhaust pipe at a downstream of the APC, storing the NH.sub.3 generated in the TWC and the APC, and reducing the NOx contained in the exhaust gas using the stored NH.sub.3.

An after treatment method for a lean-burn engine is disclosed. The after treatment method is configured to control an after treatment system sequentially equipped with an ammonia production catalyst module, a selective catalytic reduction (SCR) catalyst, and a CO clean-up catalyst (CUC) on an exhaust pipe through which an exhaust gas flows and which is connected to a lean-burn engine. NH.sub.3 generation in the ammonia production catalyst module is changed according to a temperature and a temperature change rate of the SCR catalyst.

An after treatment method for a lean-burn engine is disclosed. The after treatment method is configured to control an after treatment system sequentially equipped with an ammonia production catalyst module, a selective catalytic reduction (SCR) catalyst, and a CO clean-up catalyst (CUC) on an exhaust pipe through which an exhaust gas flows and which is connected to a lean-burn engine. In the after treatment method, a rich air/fuel ratio (AFR) is controlled in multiple phases in response to detecting that conversion to the rich AFR is desired.

An after treatment system for a lean-burn engine is disclosed. The after treatment system is sequentially equipped with an ammonia production catalyst module, a selective catalytic reduction (SCR) catalyst, and a CO clean-up catalyst (CUC) on an exhaust pipe through which an exhaust gas flows and which is connected to a lean-burn engine. An exhaust flow changer is disposed between the ammonia production catalyst module and the SCR catalyst. The exhaust flow changer changes flow of an exhaust gas discharged from the ammonia production catalyst module according to a temperature of the SCR catalyst.

A process of causing an engine (10) to perform high-temperature exhaust driving (D1) after urea water from an urea water injection valve (33) is not supplied to an SCR catalyst (34), and a process of causing the engine (10) to perform high-flow-rate exhaust driving (D2) after a flow rate of exhaust gas from a cylinder interior (13) is not reduced are performed on an ECU (40). A process of determining deterioration or malfunction of upstream and downstream NOx sensors (47 and 48) based on detected values (Ca and Cb) acquired when the engine speed (Na) reaches a determination speed (Nx) is performed on a vehicle external computer (52).

An exhaust system for a work vehicle includes a mixer that includes a nozzle configured to receive a first exhaust flow along a lateral axis through a plurality of openings in a peripheral wall of the nozzle. The nozzle also receives a diesel exhaust fluid along a longitudinal axis through a longitudinal inlet. Further, the nozzle is configured to mix the first exhaust flow and the diesel exhaust fluid to form an exhaust solution. In addition, the mixer includes a conduit configured to receive the exhaust solution along the longitudinal axis. Moreover, the conduit has an opening configured to receive a portion of the nozzle, and the conduit is configured to receive a second exhaust flow through a gap formed between the nozzle and the conduit at the opening, and the opening is positioned downstream of the plurality of openings.

An exhaust gas treatment system for an internal combustion engine includes an exhaust gas pathway configured to receive exhaust gas from the internal combustion engine, a temperature sensor configured to sense a temperature of the exhaust gas, a first injector configured to inject a first reductant into the exhaust gas pathway at a first location when the sensed temperature is below a threshold temperature, and a first treatment element positioned downstream of the first location. A second injector is configured to inject a second reductant of a different composition than the first reductant into the exhaust gas pathway at a second location downstream of the first treatment element when the sensed temperature is above the threshold temperature. The system further includes a second treatment element positioned downstream of the second location.

Methods and systems are provided for adjusting a regeneration scheme in response to ageing of a first catalyst and a second catalyst. In one example, a method may include determining a first ageing of the first catalyst and a second ageing of the second catalyst and updating factors of the regeneration scheme based on the first ageing and the second ageing.

An after treatment method for a lean-burn engine is disclosed. The after treatment method is configured to control an after treatment system sequentially equipped with an ammonia production catalyst module, a selective catalytic reduction catalyst, and a CO clean-up catalyst on an exhaust pipe through which an exhaust gas flows. In the after treatment method, the engine is operated sequentially at a stoichiometric air/fuel ratio (AFR) and a lean AFR prior to entering a rich AFR.

An arrangement of an internal combustion engine with at least one first and one second nitrogen oxide storage catalytic converter is provided, wherein the first nitrogen oxide storage catalytic converter is arranged within a low-pressure exhaust gas recirculation circuit. A method for operating the arrangement is furthermore provided, wherein the nitrogen oxide storage catalytic converters can be used for the production of ammonia under operating conditions with a high load by providing rich exhaust gas conditions.