The present disclosure provides SCR catalyst compositions capable of reducing nitrogen oxide (NO.sub.x) emissions in engine exhaust. The catalyst compositions include a reducible metal oxide support containing ceria, one or more transition metal oxides as a redox promotor; and an oxide of niobium, tungsten, silicon, molybdenum, or a combination thereof as an acidic promotor. The redox promotor and the acid promotor are both supported on the reducible metal oxide support. Further provided are SCR catalyst articles coated with such compositions, processes for preparing such catalyst compositions and articles, an exhaust gas treatment system including such catalyst articles, and methods for reducing NO.sub.x in an exhaust gas stream using such catalyst articles and systems.

A method for ascertaining an exhaust gas composition of an exhaust gas of an internal combustion engine with regard to an ammonia fraction and a nitrogen oxides fraction in an exhaust gas system including an SCR catalytic converter. The method includes detecting, using a sensor, a first signal whose magnitude is a function of the nitrogen oxides fraction of the exhaust gas upstream from the SCR catalytic converter, detecting using a sensor a second signal whose magnitude is a function of the ammonia fraction and the nitrogen oxides fraction of the exhaust gas downstream from the SCR catalytic converter, storing the two signals over an observation period, and ascertaining the ammonia fraction and optionally the nitrogen oxides fraction of the exhaust gas downstream from the at least one SCR catalytic converter using a calculation rule that uses the two signals during the observation period as input variables.

A method, flow device and system for method of guiding a flow of exhaust gas for aftertreatment, including receiving exhaust gas into a mixing chamber; supporting a mixing tube mostly in the mixing chamber obliquely to and extending through a peripheral wall of the mixing chamber; supporting by a reactant doser mount a reactant doser that doses reactant to the mixing tube; receiving, by a peripheral exhaust gas entry in the mixing tube, exhaust gas at reactant stream arriving from the doser; and forming by a swirl arrangement, a rotating flow around a mixing tube output and enhancing exhaust gas flow through the mixing tube by forming some pressure around the mixing tube downstream from the peripheral exhaust gas entry.

A method for checking operability of a first metering unit includes sending a control signal to a second metering unit to dispense a second quantity; comparing the quantity dispensed with the second quantity; sending a control signal to a second metering unit to introduce a third quantity; detecting the pressure drop caused by the introduction of the third quantity; sending a control signal to the first metering unit to introduce a first quantity; detecting the pressure drop caused by executing the control signal to introduce the first quantity; and ascertaining that the first metering unit is not functioning correctly if a difference between the pressure drop detected as a result of the execution of the control signal to introduce the first quantity and the pressure drop detected as a result of the execution of the control signal to introduce the third quantity is above a threshold.

An exhaust aftertreatment system for an internal combustion engine includes an outer casing having an exhaust gas inlet and an exhaust gas outlet between which a fluid flow path for exhaust gases is provided, a selective catalytic reduction unit provided in the fluid flow path for reducing nitrogen oxides, a reductant dosing device for adding reductant to the exhaust flow upstream of the selective catalytic reduction unit, and a rotatable mixer device for mixing the reductant with exhaust gases upstream of the selective catalytic reduction unit, an air inlet valve provided upstream of the mixer device for introducing air into the fluid flow path, and an electric motor arranged for rotating the mixer device to create a suction of air into the fluid flow path via the air inlet valve.

An exhaust gas aftertreatment system includes a housing assembly and a reductant delivery system. The housing assembly includes an upstream housing, a first inlet tube, a second inlet tube, and a mixing housing. The first inlet tube is coupled to the upstream housing and configured to receive a first portion of exhaust gas from the upstream housing. The second inlet tube is coupled to the upstream housing and configured to receive a second portion of the exhaust gas from the upstream housing. The mixing housing is coupled to the first inlet tube and the second inlet tube. The mixing housing is configured to receive the first portion of the exhaust gas from the first inlet tube and receive the second portion of the exhaust gas from the second inlet tube. The mixing housing is separated from the upstream housing by the first inlet tube and the second inlet tube.

A decomposition chamber for an exhaust aftertreatment system includes an inlet conduit centered on an inlet conduit axis and configured to receive exhaust, a decomposition conduit coupled to the inlet conduit, an endcap coupled to the decomposition conduit, and an injector coupled to the endcap and configured to provide reductant into the decomposition conduit along an injection axis. The decomposition chamber includes a guide swirl mixer coupled to at least one of the inlet conduit or the endcap. The guide swirl mixer includes a first portion disposed within the inlet conduit, and a second portion disposed within the decomposition conduit such that the inlet conduit axis extends through the second portion. The second portion extends at least partially around the injection axis.

A multi-stage mixer includes a multi-stage mixer inlet, a multi-stage mixer outlet, a first flow device, and a second flow device. The multi-stage mixer inlet is configured to receive exhaust gas. The multi-stage mixer outlet is configured to provide the exhaust gas to a catalyst. The first flow device is configured to receive the exhaust gas from the multi-stage mixer inlet and to receive reductant such that the reductant is partially mixed with the exhaust gas within the first flow device. The first flow device includes a plurality of main vanes and a plurality of main vane apertures. The plurality of main vane apertures is interspaced between the plurality of main vanes. The plurality of main vane apertures is configured to receive the exhaust gas and to cooperate with the plurality of main vanes to provide the exhaust gas from the first flow device with a swirl flow.

Systems and methods for controlling a regeneration process of catalyst(s) are disclosed. The method includes receiving, via Kalman filter, initial estimation from a previous instance of time. The initial estimation includes one or more first estimated inside temperature(s) and/or first estimated outlet temperature of A/T catalyst. An output from a simulation model may be generated to calculate a mean and covariance. Sensor measurement covariance may be compared against the mean and covariance of the output to update Kalman filter gain and process covariance. A weighted average may be calculated between sensor measurements and mean of the output to generate a second estimation for the next instance of time, wherein weight is based on Kalman filter gain. The second estimation includes one or more second estimated inside temperature(s) and/or second estimated outlet temperature of A/T catalyst to control the mass flow rate in diesel engine via a closed loop control system.

A nozzle including a first end and a second end. The first end includes at least a first inlet and a second inlet and the second end includes a plurality of outlets. An exterior surface extends from the first end to the second end of the nozzle. A plurality of vanes are disposed on the exterior surface and extend from the first end to the second end of the nozzle. A plurality of channels form along the exterior surface of the nozzle.