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.

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.

Provided are: a hydrocarbon adsorbent capable of adsorbing hydrocarbons, storing the adsorbed hydrocarbons up to a relatively high temperature, and desorbing the adsorbed and stored hydrocarbons at a relatively high temperature; an exhaust gas purifying catalyst composition using the same; an exhaust gas purifying catalyst; and a method for treating an exhaust gas. The hydrocarbon adsorbent comprises a zeolite having an MRT-type framework structure. The hydrocarbon adsorbent comprises a small-pore zeolite having a total desorption amount ZD.sub.1 of propylene desorbed at 50° C. or higher and lower than 300° C. being 3.5 mmol/g or less and a total desorption amount ZD.sub.2 of propylene desorbed at 300° C. or higher and 500° C. or lower being 0.5 mmol/g or more, per 1 g by mass of the small-pore zeolite, when adsorbing propylene at 50° C. and then heating from 50° C. to 500° C. under the condition of 10° C./min by a temperature-programmed desorption method.

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.

The present application relates to a cerium-tin-based composite oxide catalyst for catalyzing purification of a nitrogen oxide, a preparation method and an application thereof. The catalyst has the following chemical composition: a cerium-tin oxide and an M oxide, wherein the M is selected from any one of or a combination of at least two of P, Ti, Zr, V, Mn, Fe, Cu, Al, Si, Ni, Hf, Nb, Ta, Cr, Mo, W, or Re. According to the present application, a cerium-tin-based composite oxide catalyst having the characteristics such as high catalytic activity, high hydrothermal stability, excellent N.sub.2 generation selectivity, a wide operation temperature window, and adaptation to high space velocity reaction conditions is prepared by means of a non-toxic and harmless raw material and a simple method, and the present application is applicable to a device for catalyzing purification of a mobile source nitrogen oxide represented by diesel vehicle exhaust gas and a fixed source nitrogen oxide represented by flue gas from a coal-fired power plant.

A method for treating exhaust gas of a thermal power plant comprises the steps of: (A) forming a contact exhaust gas by contacting a reducing agent including a hydrocarbon-based reducing agent and an ammonia-based reducing agent, with a nitrogen oxide-containing exhaust gas at 300° C. to 500° C. at the front end of a denitration catalyst; and (B) forming a catalyst-contacted exhaust gas by contacting the denitration catalyst with the contact exhaust gas. According to the method, the exhaust gas of a thermal power plant can be treated very effectively and efficiently.

The present invention relates to a catalyst comprising two layers on an inert catalyst carrier, a layer A containing at least palladium as a platinum group metal, in addition to a cerium/zirconium/lanthanum/yttrium mixed oxide, and a layer B, which is applied to layer A, containing at least rhodium as the platinum group metal, in addition to a cerium/zirconium/lanthanum/yttrium mixed oxide.

The present invention relates to a method for adaption of an exhaust treatment system arranged for treating an exhaust stream produced by an engine, where the exhaust treatment system includes at least a first additive dosage device, a first selective catalytic reduction catalyst arranged downstream of the first additive dosage device, a second additive dosage device arranged downstream of the first selective catalytic reduction catalyst, and a second selective catalytic reduction catalyst arranged downstream of the second additive dosage device. The method includes initiating an adaption of the second selective catalytic reduction catalyst, and controlling, during the adaption of the second selective catalytic reduction catalyst, the first additive dosage device to inject additive in accordance with at least one injection rule being designed for the adaption.

A reductant injecting device, including: a honeycomb structure including: a pillar shaped honeycomb structure portion having partition wall that defines a plurality of cells each extending from a fluid inflow end face to a fluid outflow end face; and at least one pair of electrode portions arranged on a side surface of the honeycomb structure portion; an outer cylinder having an inlet side end portion and an outlet side end portion, the inlet side end portion comprising a carrier gas introduction port being configured to introduce a carrier gas, the outlet side end portion comprising an injection port being configured to inject ammonia; a urea sprayer arranged at one end of the outer cylinder; and a spray direction switcher configured to be able to switch a spray direction of the aqueous urea solution.

A SCR catalyst composition comprises a SCR catalyst; and a binder comprising a porous inorganic material, wherein the porous inorganic material comprises a disordered arrangement of delaminated layers, has a disordered porous structure, and has a multimodal pore size distribution comprising at least a first modal maximum having a macroporous or mesoporous pore size and a second modal maximum having a microporous pore size. The SCR catalyst composition can be manufactured using the method comprising the steps of: (i) providing an inorganic material having a layered structure; (ii) contacting the material with a cationic surfactant to form a swollen material; (iii) agitating the swollen material to form an agitated material; and (iv) calcining the agitated material to recover a delaminated inorganic material, wherein an SCR catalyst is mixed with the inorganic material prior to step (iv).