An automotive exhaust aftertreatment system for reducing effluents, such as nitrous oxides (NOx), in exhaust gasses passing through the system. The automotive exhaust aftertreatment system includes a dosing unit configured to inject primary and secondary reductant fluids into exhaust gasses based on various strategies to optimize operation of the system.

An automotive exhaust aftertreatment system includes an onboard ammonium carbamate reactor. The onboard ammonium carbamate reactor is coupled to a diesel emission fluid reservoir also included in the system and is configured to generate aqueous ammonium carbamate solution from diesel emission fluid. A doser configured to inject the generated aqueous ammonium carbamate solution has integrated heating.

An automotive exhaust aftertreatment system includes an onboard ammonium carbamate reactor. The onboard ammonium carbamate reactor is coupled to a diesel emission fluid reservoir also included in the system and is configured to generate aqueous ammonium carbamate solution from diesel emission fluid. A hybrid heating system for use with the ammonium carbamate reactor is provided in this disclosure.

A method for operating a feed module of an SCR catalytic converter system which has a feed pump, a feedback pump and a hydraulic interface channel. The feed module is operated in a test state in which a feed operation of the feed pump takes place and a feed operation of the feedback pump does not take place. Owing to a time profile of an MSP current (I.sub.MSP) of the feed pump it is decided in the test state whether the feed module is to change into a thawing state.

Systems and methods described herein relate to generating ammonia from engine exhaust instead of or in addition to using on-board storage tank(s) and/or doser(s) to provide the necessary chemical reagents for purification of the exhaust stream. Systems and methods for generating ammonia and/or hydrogen from engine exhaust in exhaust aftertreatment systems under ambient conditions comprise at least one water-gas shift (WGS) catalyst and at least one ammonia synthesis catalyst (AMS catalyst) positioned downstream of the WGS catalyst. The WGS catalyst is configured, using the engine exhaust gas as an input, to generate hydrogen used by the AMS catalyst as inputs to generate ammonia and/or hydrogen. The ammonia and/or hydrogen thus generated are used downstream in ammonia- and/or hydrogen-based selective catalytic reduction catalysts (SCR).

An exhaust aftertreatment system may include a reductant tank, a gaseous ammonia source, an injector, first conduit and a second conduit. The injector may receive the liquid reductant from the reductant tank and the gaseous ammonia from the gaseous ammonia source and inject the liquid reductant into a stream of exhaust gas in a first mode, inject the gaseous ammonia into the stream of exhaust gas in a second mode, and both the liquid reductant and the gaseous ammonia into the stream of exhaust gas in a third mode. The first conduit may communicate liquid reductant from the reductant tank to the injector. The second conduit may communicate gaseous ammonia from the gaseous ammonia source to the injector.

An extruded honeycomb catalyst for nitrogen oxide reduction according to the selective catalytic reduction (SCR) method in exhaust gases from motor vehicles includes an extruded active carrier in honeycomb form having a first SCR catalytically active component and with a plurality of channels through which the exhaust gas flows during operation, and a washcoat coating having a second SCR catalytically active component being applied to the extruded body, wherein the first SCR catalytically active component and the second SCR catalytically active component are each independently one of: (i) vanadium catalyst with vanadium as catalytically active component; (ii) mixed-oxide catalyst with one or more oxides, in particular those of transition metals or lanthanides as catalytically active component; and (iii) an Fe- or a Cu-zeolite catalyst.

An exhaust emission control system of an engine, including an NO.sub.x catalyst disposed in an exhaust passage for storing NO.sub.x within exhaust gas when an air-fuel ratio of the exhaust gas is lean, and reducing the stored NO.sub.x when the air-fuel ratio is approximately stoichiometric or rich, is provided. The system includes an SCR catalyst disposed in the exhaust passage downstream of the NO.sub.x catalyst and for purifying NO.sub.x within exhaust gas by causing a reaction with ammonia, a controller executing a NO.sub.x reduction controlling module for executing a control in which the air-fuel ratio is controlled to a target air-fuel ratio so that the stored NO.sub.x is reduced, and an ammonia adsorption amount acquiring module for acquiring an ammonia adsorption amount of the SCR catalyst by detection or estimation. The NO.sub.x reduction controlling module controls the target air-fuel ratio to be leaner as the ammonia adsorption amount increases.

An automotive exhaust aftertreatment system for a combustion engine in an automobile includes an ammonia gas distribution system for delivering gaseous ammonia to an exhaust stream. The ammonia gas distribution system is configured to mix the ammonia and the exhaust stream together before the exhaust gas and ammonia are exposed to a catalyst in the SCR.

Unenhanced DEF and anhydrous solid reductant capable of forming ammonia are mixed to create enhanced DEF which is injected into an engine exhaust aftertreatment system which performs selective catalytic reduction (SCR) of engine-out exhaust.