An object of the present invention is to provide an exhaust gas purification system including a first exhaust gas treatment section provided upstream in an exhaust pathway of an internal-combustion engine, a second exhaust gas treatment section provided upstream in the exhaust pathway of the internal-combustion engine, wherein the exhaust gas purification system allows rhodium element contained in a catalyst layer of the second exhaust gas treatment section to efficiently exhibit the catalytic activity, and the present invention provides an exhaust gas purification system (1) configured to purify exhaust gas emitted from an internal-combustion engine, the exhaust gas purification system (1) including an exhaust gas path (2) through which exhaust gas flows, a first exhaust gas treatment section (3) provided upstream in the exhaust gas path (2), and a second exhaust gas treatment section (4) provided downstream in the exhaust gas path (2); wherein first catalyst layers of the first exhaust gas treatment section (3) each contain cerium element; wherein a percentage of the mass of the cerium element contained in the first catalyst layers in terms of cerium oxide, to the mass of the first catalyst layers, is 5.0% by mass or more and 13.0% by mass or less; and wherein second catalyst layers of the second exhaust gas treatment section (4) each contain rhodium element.

A three-way catalyst article, and its use in an exhaust system for internal combustion engines, is disclosed. The catalyst article for treating exhaust gas comprising: a substrate comprising an inlet end, an outlet end with an axial length L; an inlet catalyst layer beginning at the inlet end and extending for less than the axial length L, wherein the inlet catalyst layer comprises an inlet palladium component; an outlet catalyst layer beginning at the outlet end and extending for less than the axial length L, wherein the outlet catalyst layer comprises an outlet rhodium component; and wherein the outlet catalyst layer overlaps with the inlet catalyst layer.

A exhaust gas purification apparatus is provided with: a substrate having a wall-flow structure and including entry-side cells, exit-side cells, and a porous partition; a first catalyst region formed in small diameter pores having relatively small pore diameters among internal pores in the partition; and a second catalyst region formed in large diameter pores having relatively large pore diameters among the internal pores in the partition. The first catalyst region contains a support and any one or two species of precious metal selected from Pt, Pd, and Rh loaded on the support, while the second catalyst region contains a support and any one or two species of precious metal selected from Pt, Pd, and Rh loaded on the support and other than at least the precious metal present in the first catalyst region.

Ceramic candle filter and use of the filter in the removal of particulate matter in form of soot, ash, metals and met-al compounds, together with hydrocarbons and nitrogen oxides being present in process off-gas or engine exhaust gas, the filter includes a combined SCR and oxidation catalyst being arranged on the dispersion side and within wall of the filter; and a palladium including catalyst arranged on the permeation side and within wall of the filter facing the permeation side.

Ceramic candle filter and use of the filter in the removal of particulate matter in form of soot, ash, metals and metal compounds, together with hydrocarbons and nitrogen oxides being present in process off-gas or engine exhaust gas, the filter comprises a combined SCR and oxidation catalyst arranged at least on the dispersion side and/or within wall of the filter, the combined SCR and oxidation catalyst comprises palladium, a vanadium oxide and titania.

An object of the present invention is to provide an exhaust gas purification catalyst including a wall-flow substrate and a catalyst layer, and having an improved exhaust gas purification performance, and, in order to achieve such an object, the present invention provides an exhaust gas purification catalyst including: a wall-flow substrate, first catalyst layers; and second catalyst layers; wherein the first catalyst layers and the second catalyst layers satisfy the following expressions (1) to (3):

L1<L2  (1)

T1<T2  (2)

WC1>WC2  (3)

wherein L1 represents the length of the first catalyst layers, L2 represents the length of the second catalyst layers, T1 represents the thickness of the rising portions of the first catalyst layers, T2 represents the thickness of the rising portions of the second catalyst layers, WC1 represents the mass of the first catalyst layers per unit volume of the portion of the substrate provided with the first catalyst layers, and WC2 represents the mass of the second catalyst layers per unit volume of the portion of the substrate provided with the second catalyst layers.

The present disclosure generally relates to emission control catalyst articles comprising a platinum group metal (PGM) enriched zone, methods of making such emission control catalyst articles, and methods of using such emission control catalyst articles.

The present invention relates to an exhaust gas treatment system for treating exhaust gas from a lean burn combustion engine, wherein said exhaust gas comprises hydrocarbons and NOx, the exhaust gas treatment system comprising: (i) a means for injecting hydrocarbons into an exhaust gas stream; (ii) a diesel oxidation catalyst (DOC) comprising a substrate and a catalyst coating provided on the substrate, wherein the catalyst coating comprises one or more platinum group metals, wherein the one or more platinum group metals comprise platinum; (iii) a means for injecting a nitrogenous reducing agent into an exhaust gas stream; and (iv) a multifunctional catalyst (MFC) comprising an oxidation catalyst, and a selective catalytic reduction (SCR) catalyst for the selective catalytic reduction of NOx, wherein the MFC comprises a substrate and a catalyst coating provided on the substrate, wherein the catalyst coating comprises the oxidation catalyst and the SCR catalyst, wherein the oxidation catalyst comprises one or more platinum group metals, wherein the one or more platinum group metals comprise palladium and/or platinum, and wherein the SCR catalyst comprises a zeolitic material loaded with copper and/or iron; wherein the means for injecting hydrocarbons, the DOC, the means for injecting a nitrogenous reducing agent, and the MFC are located in sequential order in a conduit for exhaust gas, wherein the means for injecting hydrocarbons into an exhaust gas stream is located upstream of the DOC, wherein the DOC is located upstream of the MFC, and wherein the means for injecting a nitrogenous reducing agent into the exhaust gas stream is located between the DOC and the MFC. Furthermore, the present invention relates to a method for the treatment of exhaust gas using the exhaust gas treatment system according to the present invention, and to a method for the preparation of an exhaust gas treatment system according to the present invention.

The present disclosure provides an exhaust gas purification catalyst improved in OSC performance while maintaining an exhaust gas purification performance, which comprises a substrate and at least one catalyst layer formed on the substrate, wherein an uppermost catalyst layer contains a catalyst metal, a first OSC material having a pyrochlore structure, and a second OSC material having a higher oxygen storage/release rate than the first OSC material, wherein the uppermost catalyst layer consists of an upstream catalyst layer and a downstream catalyst layer, and wherein a proportion of a mass of the second OSC material based on a total mass of the first OSC material and the second OSC material is in a specific range in each of the upstream catalyst layer and the downstream catalyst layer.

The present disclosure provides SCR catalyst compositions capable of reducing nitrogen oxide (NO.sub.x) emissions in engine exhaust. The catalyst compositions include a reducible metal oxide support containing ceria, one or more transition metal oxides as a redox promotor; and an oxide of niobium, tungsten, silicon, molybdenum, or a combination thereof as an acidic promotor. The redox promotor and the acid promotor are both supported on the reducible metal oxide support. Further provided are SCR catalyst articles coated with such compositions, processes for preparing such catalyst compositions and articles, an exhaust gas treatment system including such catalyst articles, and methods for reducing NO.sub.x in an exhaust gas stream using such catalyst articles and systems.