An exhaust gas purifying system includes: a NOx trapping agent (2) which adsorbs nitrogen oxide when an excess air ratio of exhaust gas is more than 1, and releases nitrogen oxide when the excess air ratio is 1 or less; a NOx purifying catalyst (13) which reduces nitrogen oxide to nitrogen; and an oxygen concentration controller which controls oxygen concentration in the exhaust gas. When the excess air ratio of the exhaust gas is more than 1, nitrogen oxide is adsorbed to the NOx trapping agent (2). When the excess air ratio of the exhaust gas is 1 or less, the oxygen concentration controller controls the oxygen concentration of the exhaust gas at an inlet of the NOx purifying catalyst between 0.8 and 1.5% by volume, so that the NOx purifying catalyst reduces nitrogen oxide released from the NOx trapping agent.

Systems, apparatuses, and methods include an upstream exhaust analysis circuit structured to determine a characteristic of an exhaust gas stream entering a nitrous oxide (NOx) storage catalyst; a prediction circuit structured to predict a downstream NOx concentration of an exhaust gas stream exiting the NOx storage catalyst based on a model of a NOx storage capacity or a dynamic response of the NOx storage catalyst; a downstream exhaust analysis circuit structured to determine a downstream NOx concentration of the exhaust gas stream exiting the NOx storage catalyst; and a comparison circuit structured to compare the predicted downstream NOx concentration to the determined downstream NOx concentration, and determine a health of the NOx storage catalyst based on the comparison.

An exhaust gas purification apparatus includes a three-way catalyst. The three-way catalyst includes a downstream catalyst layer and an upstream catalyst layer. The downstream catalyst layer is to be provided in an exhaust pipe. The downstream catalyst layer contains a noble metal material containing at least one of Pd, Rh, or Pt, and an OSC material containing at least ceria. The upstream catalyst layer is to be provided in the exhaust pipe closer to an engine than the downstream catalyst layer is. The upstream catalyst layer contains the noble metal material and the OSC material. The upstream catalyst layer contains the ceria at a content less than a content of the ceria in the downstream catalyst layer.

The disclosure provides a monolithic wall-flow filter catalytic article including a substrate having an aspect ratio of from about 1 to about 20, and having a functional coating composition disposed on the substrate, the functional coating composition including a first sorbent composition, an oxidation catalyst composition, and optionally, a second sorbent composition. The monolithic wall-flow filter catalytic article may be in a close-coupled position close to the engine. The disclosure further provides an integrated exhaust gas treatment system including the monolithic wall-flow filter catalytic article and may additionally include a flow-through monolith catalytic article. The flow-through monolith catalytic article includes a substrate having a selective catalytic reduction (SCR) coating composition disposed thereon. The integrated exhaust gas treatment system simplifies the traditional four-article system into a two-article Catalyzed Soot Filter (CSF) plus Selective Catalytic Reduction (SCR) CSF+SCR arrangement.

An exhaust aftertreatment system for use with over-the-road vehicle is disclosed. The exhaust aftertreatment system includes a reducing agent mixer with a mixing can and a flash-boil doser configured to inject heated and pressurized reducing agent into the mixing can for distribution throughout exhaust gases passed through the mixing can.

The present invention relates to a VOC reduction system and a VOC reduction method that applies pulse type thermal energy to a catalyst to activate the catalyst and oxidizes and removes the VOC.

An exhaust system for treating an exhaust gas produced by a lean burn engine comprising: (i) a NO.sub.x absorber catalyst comprising a molecular sieve catalyst disposed on a substrate, wherein the molecular sieve catalyst comprises a noble metal and a molecular sieve, wherein the molecular sieve contains the noble metal; (ii) means for introducing hydrocarbons into the exhaust gas; and (iii) a lean NO.sub.x trap; wherein the NO.sub.x absorber catalyst is upstream of both the means for introducing hydrocarbons into the exhaust gas and the lean NO.sub.x trap.

An exhaust gas purification device includes a first catalyst, a bypass pipe, a second catalyst, and a switching controller. The first catalyst is provided in an exhaust pipe. The bypass pipe branches from a first portion of the exhaust pipe. The first portion is located upstream of the first catalyst. The bypass pipe is recoupled to a second portion of the exhaust pipe. The second portion is located upstream of the first catalyst. The second catalyst is provided in the bypass pipe. The switching controller is configured to switch a flow path of an exhaust gas to the bypass pipe based on a deterioration degree of the first catalyst.

The present disclosure is directed to a method for treating a gaseous exhaust stream containing nitrogen oxides (NO.sub.x) from a diesel or lean-burn gasoline engine following a cold-start of the engine The method involves contact of the gaseous exhaust stream with at least a low temperature NO.sub.x adsorber (LT-NA) component. The LT-NA component includes a rare earth metal component, a platinum group metal (PGM) component, and a dopant. The present disclosure is also directed to a method of modulating a NO.sub.x adsorption/desorption profile of an LT-NA composition, a NO.sub.x desorption temperature range of an LT-NA composition, or both.

Provided is an exhaust gas purification catalyst having an improved catalyst performance while securing an OSC in an air-fuel ratio (A/F) rich atmosphere where HC poisoning is likely to occur. The present disclosure relates to an exhaust gas purification catalyst including a substrate and a catalyst coating layer coated on the substrate. The catalyst coating layer has an upstream coat layer formed from an end portion in an upstream side with respect to an exhaust gas flow direction in the exhaust gas purification catalyst and a downstream coat layer formed from an end portion in a downstream side with respect to the exhaust gas flow direction in the exhaust gas purification catalyst. The downstream coat layer includes Rh as a catalytic metal, alumina-ceria-zirconia complex oxide, and alkaline earth metal.