An exhaust gas control apparatus for an internal combustion engine includes a NO.sub.X storage reduction catalyst, a selective catalytic reduction catalyst, and an electronic control unit configured to shift an operation state of the engine from a rich operation state to a lean operation state, in a case where an acquired temperature of the NO.sub.X storage reduction catalyst is higher than a storage limit temperature, and an acquired NH.sub.3 adsorption amount is equal to or larger than a lower limit adsorption amount when a lean operation restart request is made, and not to shift the operation state from the rich operation state to the lean operation state in a case where the acquired temperature of the NO.sub.X storage reduction catalyst is higher than the storage limit temperature and the acquired NH.sub.3 adsorption amount is smaller than the lower limit adsorption amount when the lean operation restart request is made.

Methods and systems are featured for reducing harmful exhaust gas components of combustion devices such as gasoline-powered combustion engines (e.g., predominately stoichiometric running engines). The methods and systems include an underbody combination of a hydrocarbon trap (HCT), suited for cold start hydrocarbon adsorption, as well as an associated NOx trap. The system is inclusive of a control unit for extending a lean exhaust condition reaching the desorbing HCT as to avoid a deficiency in oxygen during the time period of HCT desorption. The system is also inclusive of one or more TWCs as in one associated with the underbody HCT-NOx-trap combination and/or one positioned in a close coupled position. Platinum group metals as in Pd, Rh and Pt are also featured on one, two or all three of the HCT, NOx-trap, and TWC when present.

A lean NO.sub.x trap catalyst and its use in an emission treatment system for internal combustion engines is disclosed. The lean NO.sub.x trap catalyst comprises a first layer for storing nitrogen oxides (NOx) under lean exhaust gas conditions and releasing and/or reducing stored NOx during rich exhaust gas conditions, and a second layer, said second layer comprising a first zone for oxidizing carbon monoxide (CO) and/or hydrocarbons (HC), and a second zone for oxidizing nitric oxide (NO), and a substrate having an inlet end and an outlet end.

Provided are a novel form of AFX zeolite, a novel synthesis technique for producing pure phase small pore zeolites, a novel synthesis method for producing a zeolite with an increased Al pair content, a catalyst comprising the AFX zeolite in combination with a metal, and methods of using the same.

An exhaust gas purification system for vehicle includes: a housing disposed on an exhaust pipe to receive a exhaust gas discharged from an engine and to exhaust the exhaust gas passed rearward; a front end catalyst disposed in the housing to purify the exhaust gas flowing into the housing through a front end of the housing; a rear end catalyst disposed in the housing to purify the exhaust gas passing through the front end catalyst before the exhaust gas flows out to a rear end of the housing; and a controller connected to the exhaust pipe at a front end of the housing to control a concentration of unburned fuel contained in the exhaust gas flowing into the housing.

A vehicle engine aftertreatment system includes: a purification module including a plurality of aftertreatment devices having different characteristics, the aftertreatment devices being arranged in parallel; an upstream selection device provided at one side of the purification module for selectively supplying exhaust gas from an engine to one of the aftertreatment devices; and a downstream selection device provided at the other side of the purification module for discharging exhaust gas from one of the aftertreatment devices to out of the purification module.

The present invention relates to a catalyst comprising a carrier substrate of the length L, a passive nitrogen oxide adsorber and means to control the temperature of the carrier substrate, as well as a process for cleaning of an exhaust gas emitted from a lean burn engine.

Provided are a novel form of AEI zeolite, a novel synthesis technique for producing pure phase AEI zeolite, a catalyst comprising the AEI zeolite in combination with a metal, and methods of using the same.

An after treatment method for a lean-burn engine is disclosed. The after treatment method is configured to control an after treatment system sequentially equipped with an ammonia production catalyst module, a selective catalytic reduction (SCR) catalyst, and a CO clean-up catalyst (CUC) on an exhaust pipe through which an exhaust gas flows and which is connected to a lean-burn engine. NH.sub.3 generation in the ammonia production catalyst module is changed according to a temperature and a temperature change rate of the SCR catalyst.

The invention relates to the use of a catalyst as a passive nitrogen oxide adsorber, which has a carrier substrate, a zeolite, palladium, and platinum, wherein the palladium is provided in a quantity of 0.01 to 10 wt. %, based on the sum of the weights of zeolite, platinum, and palladium and calculated as a palladium metal, and platinum in a quantity of 0.1 to 10 wt. %, based on the weight of the palladium and calculated as a platinum metal. The invention also relates to the use of said catalyst in connection with a SCR catalyst in an exhaust gas system.