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 system for an internal combustion engine, comprising an exhaust gas recirculation (EGR) circuit for connecting an exhaust stream to an intake of the engine, wherein the EGR circuit comprises a heat exchanger and the heat exchanger includes a surface comprising a urea hydrolysis catalyst; and a urea injector for providing urea to the surface of the heat exchanger coated with the urea hydrolysis catalyst, and means for introducing resulting ammonia to the exhaust stream.

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.

Methods and systems are provided for an exhaust gas aftertreatment device. In one example, a method may include adjusting one or more engine operating parameters to produce ammonia in an ammonia generating device in response to an ammonia demand.

A module for use on-board a vehicle. The module includes a heater and at least a first and a second storage compartment. The first compartment at least partially surrounds the heater, and the second compartment at least partially surrounds the first compartment. The first compartment is configured to perform a first function in a first temperature range, and the second compartment is configured to perform a second function in a second temperature range, the second temperature range being lower than the first temperature range. The first compartment is in fluid communication with the second compartment. One function of the first and second function is receiving an ammonia precursor, and decomposing the ammonia precursor using a catalyst to generate an ammonia solution.

Described are exhaust gas treatment systems for treatment of a gasoline engine exhaust gas stream. The exhaust gas treatment systems comprise an ammonia generating catalyst and an ammonia selective catalytic reduction (SCR) catalyst downstream of the ammonia generating catalyst. The ammonia generating catalyst comprises a NO.sub.x storage component, a refractory metal oxide support, a platinum component, and a palladium component. The ammonia generating catalyst is substantially free of ceria. The platinum and palladium components are present in a platinum to palladium ratio of greater than about 1 to 1.

The production efficiency of ammonia is more raised while avoiding the necessity for a user to supply water for himself/herself in order to produce the ammonia. An exhaust gas purification apparatus comprises a catalyst which purifies an exhaust gas of an internal combustion engine by using ammonia; and an ammonia supplier which supplies the ammonia to the catalyst; wherein the ammonia supplier includes an ammonia producer which produces the ammonia from nitrogen and water; a nitrogen supplier which separates the nitrogen from air and which supplies the nitrogen to the ammonia producer; and a water supplier which separates the water from the exhaust gas of the internal combustion engine and which supplies the water to the ammonia producer.

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 ammonia gas generator for producing ammonia from a solution of an ammonia precursor substance, comprising a catalyst unit that comprises a catalyst for the decomposition and/or hydrolysis of ammonia precursor substances into ammonia and a mixing chamber provided upstream of the catalyst; an injection device for injecting the solution of the ammonia precursor substance into the mixing chamber; at least one inlet for the carrier gas; and an outlet for the formed ammonia gas, said ammonia gas generator also comprising a perforated disc.

An exhaust gas purification apparatus includes: an oxidation reduction catalytic converter; a selective reduction catalytic converter disposed downstream of the oxidation reduction catalytic converter; and a controller configured to perform a first control or a second control based on mixing ratios when a temperature is higher than a predetermined temperature. The first control is performed when the mixing ratio downstream of the selective reduction catalytic converter is greater than the mixing ratio upstream of the selective reduction catalytic converter so that the mixing ratio upstream of the selective reduction catalytic converter is changed from stoichiometric ratio to lean mixture ratio. The second control is performed when the mixing ratio downstream of the selective reduction catalytic converter is smaller than the mixing ratio upstream of the selective reduction catalytic converter so that the mixing ratio downstream of the selective reduction catalytic converter is changed from stoichiometric ratio to lean mixture ratio.