Disclosed are a method and system for controlling urea injection for selective catalyst reduction (SCR), capable of improving NOx purification efficiency by predicting an operating situation in which an amount of NOx production is rapidly increased using engine behavior and pre-occluding ammonia in advance. An opening state of an EGR valve may be detected at the time of rapid acceleration of a vehicle; a pressure condition in an intake manifold or an EGR valve pressure condition may be diagnosed according to the opening state of the EGR valve; and urea may be injected when the pressure condition meets an NOx excess production condition of rapidly increasing the amount of NOx production.

A catalyst article for treating a flow of a combustion exhaust gas comprises: a catalytically active substrate comprising one or more channels extending along an axial length thereof through which, in use, a combustion exhaust gas flows, the one or more channels having a first surface for contacting a flow of combustion exhaust gas; wherein the substrate is formed of an extruded vanadium-containing SCR catalyst material, wherein a first layer is disposed on at least a portion of the first surface, wherein the first layer comprises a washcoat of an ammonia slip catalyst composition comprising one or more platinum group metals supported on a particulate metal oxide support material, and wherein a layer comprising a washcoat of SCR catalyst composition is disposed on a surface in the one or more channels, wherein at least the portion of the first surface on which the first layer is disposed comprises a compound of copper, iron, cerium or zirconium or a mixture of any two or more thereof.

A method for operating an exhaust system of an internal combustion engine of a motor vehicle, in which exhaust gas from the internal combustion engine flows through a first SCR catalytic converter, which is followed by an ammonia barrier catalytic converter, and flows through a second SCR catalytic converter which is disposed downstream of the ammonia barrier catalyst, includes introducing a reducing agent introduced into the exhaust gas by a first metering device upstream of the first SCR catalytic converter and by a second metering device upstream of the second SCR catalytic converter. When a predetermined threshold value of a temperature of a region of the exhaust system is exceeded, a quantity of reducing agent introduced into the exhaust gas by the first metering device is increased.

A method of controlling a catalytic exhaust system having a first catalytic unit located upstream of a second catalytic unit includes i) providing a relationship between the temperature of the first catalytic unit, an amount of NH3 stored in the second catalytic unit, and a corresponding limit value of the amount of NH3 permitted in the first catalytic unit; ii) measuring or estimating the amount of NH3 in the second catalytic unit; iii) measuring or estimating the temperature of the first catalytic unit; iv) using the relationship and measured/estimated parameters of steps ii and iii to provide the limit value for the amount of NH3 to be stored in the first catalytic unit; and v) using the parameter from iv in the control of the catalytic exhaust system.

An exhaust control system includes: a temperature control module configured to, in response to a shutdown of an engine, turn on an air pump that, when on, pumps air into an exhaust system of the engine upstream of a selective catalytic reduction (SCR) catalyst; a target module configured to, while the air pump is on and the engine is off in response to the shutdown, selectively determine a target rate of injection of a diesel exhaust fluid (DEF) by a DEF injector based on increasing a present amount of ammonia stored by the SCR catalyst to at least a predetermined amount of ammonia; and a DEF control module configured to, while the air pump is on and the engine is off in response to the shutdown, control injection of the DEF by the DEF injector upstream of the SCR catalyst based on the target rate.

This mixing member, which, in an exhaust pipe, mixes exhaust gas and a reducing agent supplied in a supply direction that is inclined with respect to the emission direction of exhaust gas flow, has a main body comprising a gas inlet, a gas outlet, and a gas flow path which connects the gas inlet and the gas outlet and inside of which the exhaust gas and the reducing agent are mixed. When arranged inside the exhaust pipe, the gas inlet is provided in the end surface of the main body part that is positioned on the upstream side in the emission direction. The end surface is arranged inclined relative to the emission direction so as to face upstream in the supply direction of the reducing agent. The gas flow path is inclined relative to the supply direction and extends in parallel with the emission direction.

An exhaust system for the treatment of an exhaust gas comprising a species to be treated, the system comprising: a first gas inlet for providing a flow of exhaust gas; a second gas inlet for providing a flow of heated gas; a plurality of sorbent beds for releasably storing the species; one or more catalysts for decomposing the species; first and second exhaust gas outlets; and a valve system configured to establish independently for each sorbent bed fluid communication in a first or second configuration, wherein: i) in the first configuration the flow of the exhaust gas from the first gas inlet contacts a sorbent bed for storing the species and then passes to the first gas outlet; and ii) in the second configuration the flow of heated gas from the second gas inlet contacts a sorbent bed for releasing the species, passes to one of the one or more catalysts and then passes to the second exhaust gas outlet; wherein the valve system is configured to ensure that at least one sorbent bed is in the first configuration and, preferably at least one other sorbent bed is in the second configuration.

The invention provides an emission control system for treatment of an exhaust gas stream that includes an oxidation catalyst composition disposed on a substrate in fluid communication with the exhaust gas stream; at least one selective catalytic reduction (SCR) composition disposed on a substrate downstream from the oxidation catalyst composition, and a hydrogen injection article configured to introduce hydrogen into the exhaust gas stream upstream of the oxidation catalyst composition or downstream of the oxidation catalyst composition and upstream of the at least one SCR composition. The invention also provides a method of treating an exhaust gas stream, the method including receiving the exhaust gas stream into the emission control system of the invention and intermittently introducing hydrogen upstream of the oxidation catalyst article or downstream of the oxidation catalyst article and upstream stream of the SCR article.

Provided is a method for producing an inexpensive, high-performance AEI type zeolite and an AEI type zeolite having a Si/Al ratio of 6.5 or less and an acidity of 1.2 mmol/g or more and 3.0 mmol/g or less, by using neither an expensive Y type zeolite as a raw material nor dangerous hydrofluoric acid. The method for producing an AEI type zeolite having a Si/Al ratio of 50 or less includes: preparing a mixture including a silicon atom material, an aluminum atom material, an alkali metal atom material, an organic structure-directing agent, and water; and performing hydrothermal synthesis of the obtained mixture, in which a compound having a Si content of 20% by weight or less and containing aluminum is used as the aluminum atom material; and the mixture includes a zeolite having a framework density of 14 T/1000 Å.sup.3 or more in an amount of 0.1% by weight or more with respect to SiO.sub.2 assuming that all Si atoms in the mixture are formed in SiO.sub.2.

The invention provides an emission control system for treatment of an exhaust gas stream that includes an oxidation catalyst composition disposed on a substrate in fluid communication with the exhaust gas stream; at least one selective catalytic reduction (SCR) composition disposed on a substrate downstream from the oxidation catalyst composition, and a hydrogen injection article configured to introduce hydrogen into the exhaust gas stream upstream of the oxidation catalyst composition or downstream of the oxidation catalyst composition and upstream of the at least one SCR composition. The invention also provides a method of treating an exhaust gas stream, the method including receiving the exhaust gas stream into the emission control system of the invention and intermittently introducing hydrogen upstream of the oxidation catalyst article or downstream of the oxidation catalyst article and upstream stream of the SCR article.