The present disclosure provides a method for operating a three-way catalyst system at high temperatures. The method includes passing a high-temperature exhaust stream exiting an engine over a thermally stable three-way catalyst system including a metal oxide support; two or more catalytically active metals disposed on the support; and a porous metal oxide coating disposed on one or more exposed surfaces of the support. At least one of the catalytically active metals may be platinum (Pt). The method further includes reducing an amount of the nitrogen oxides (NO.sub.x), carbon monoxide (CO), and non-methane hydrocarbons (HCs) in an effluent stream exiting the thermally stable three-way catalyst system so that the effluent stream has a combined amount of nitrogen oxides (NO.sub.x) and non-methane hydrocarbons (HCs) of less than or equal to about 30 mg/mile and less than or equal to about 0.5 g/mile of carbon monoxide (CO).

The present disclosure provides a method for operating a three-way catalyst system at high temperatures. The method includes passing a high-temperature exhaust stream exiting an engine over a thermally stable three-way catalyst system including a metal oxide support; two or more catalytically active metals disposed on the support; and a porous metal oxide coating disposed on one or more exposed surfaces of the support. At least one of the catalytically active metals may be platinum (Pt). The method further includes reducing an amount of the nitrogen oxides (NO.sub.x), carbon monoxide (CO), and non-methane hydrocarbons (HCs) in an effluent stream exiting the thermally stable three-way catalyst system so that the effluent stream has a combined amount of nitrogen oxides (NO.sub.x) and non-methane hydrocarbons (HCs) of less than or equal to about 30 mg/mile and less than or equal to about 0.5 g/mile of carbon monoxide (CO).

The invention relates to an exhaust gas aftertreatment system for an internal combustion engine, in particular for a gasoline engine that is spark-ignited by means of spark plugs. A first three-way catalytic converter is situated in an exhaust gas system that is connected to an outlet of the internal combustion engine in a position close to the engine. Downstream from the first three-way catalytic converter, a four-way catalytic converter or a combination of a particle filter and a second three-way catalytic converter downstream from the particle filter is situated in the underbody position of the motor vehicle. An exhaust gas burner with which hot exhaust gas is introducible into the exhaust gas system downstream from the first three-way catalytic converter and upstream from the four-way catalytic converter or the particle filter is provided at an exhaust duct of the exhaust gas system. The exhaust gas burner is supplied with fresh air by a secondary air pump. The invention further relates to a method for exhaust aftertreatment of an internal combustion engine having such an exhaust gas aftertreatment system.

The present invention relates to a three-way catalyst (TWC) for treatment of exhaust gases of internal combustion engines operated with a predominantly stoichiometric air/fuel ratio, so called spark ignited engines.

A method is provided for operating an internal combustion engine in a motor vehicle, The internal combustion engine has at least one cylinder with a combustion chamber, a water injection unit with a tank and at least one injection nozzle for directly or indirectly injecting water into the combustion chamber, an exhaust gas system with at least one exhaust gas catalytic converter and a particulate filter device which has a particulate filter for filtering particles out of an exhaust gas flow guided in the exhaust gas system. A control unit is provide for a state monitoring process and for controlling the combustion in the cylinder.

A three-way catalyst article, and its use in an exhaust system for compressed natural gas engines, is disclosed. The catalyst article for treating exhaust gas from compressed natural gas (CNG) engine comprising: a substrate comprising an inlet end, an outlet end with an axial length L; a first catalytic region beginning at the inlet end and extending for less than the axial length L, wherein the first catalytic region comprises a first platinum component; a second catalytic region beginning at the outlet end and extending for less than the axial length L, wherein the second catalytic region comprises a second palladium component; and a third catalytic region, wherein the third catalytic region comprises a third rhodium component.

A method for operating a petrol engine, in which air is introduced into an exhaust tract through which exhaust gas from the petrol engine can flow, bypassing the petrol engine, includes introducing the air into the exhaust tract at a point arranged downstream of a first three-way catalytic converter arranged in the exhaust tract and upstream of a second three-way catalytic converter arranged in the exhaust tract downstream of the first three-way catalytic converter, while the petrol engine is operated with a sub-stoichiometric combustion air ratio, where a desulphurization of the second three-way catalytic converter is effected.

Provided herein is a catalytic article including a catalytic coating disposed on a substrate, wherein the catalytic coating comprises a bottom coating on the substrate and a top coating layer on the bottom coating layer, one such coating layer containing a platinum group metal on a refractory metal oxide support and the other such coating layer containing a ceria-containing molecular sieve. Such catalytic articles are effective toward treating exhaust gas streams of internal combustion engines and exhibit outstanding resistance to sulfur.

An apparatus includes a housing and at least one substrate enclosed within the housing and extending along an axis. The substrate includes at least one internal open area that is of a predetermined size and at a predetermined location within the substrate. At least one heater is configured to heat the at least one substrate by directing heat into the at least one internal open area.

A method of controlling an oxygen purge of a three-way catalyst (TWC) may include: rapidly adjusting, by a controller, an air-fuel ratio (AFR) at an upstream of the TWC to a target AFR when the oxygen purge of the TWC after a fuel cut-off is performed; and maintaining the target AFR until an oxygen purge finish time has passed. According to the method, concentration of NOx slipped from the TWC after the oxygen purge may be reduced.