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 porous composite includes a porous base material, and a porous collection layer. The collection layer is provided on the base material. The collection layer contains praseodymium oxide.

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.

The present invention discloses a molecular sieve and its preparation method. The molecular sieve has micromorphology in a football shape and consists of molecular sieve framework and active elements. The molecular sieve framework comprises silicon element and aluminum element; the active elements comprise copper element and rare earth elements. The rare earth elements are one or more selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Sc and Y. The mass ratio of the silicon element to the aluminum element is 3-9:1. The content of the copper element in the molecular sieve is 1.5-3.2 wt %. The mass of rare earth elements is 50 ppm-2 wt % of the molecular sieve framework. The mass of the silicon element is calculated by silicon dioxide, the mass of aluminum element is calculated by aluminum oxide, the mass of copper element is calculated by copper oxides, and the mass of rare earth elements is calculated by rare earth oxides. The molecular sieve has a high catalytic activity in a temperature range of 175-550° C. and a good resistance to hydrothermal aging.

A hydrocarbon adsorbent having high hydrocarbon adsorbing properties even after exposed to a high temperature/high humidity reducing atmosphere, includes a FAU type zeolite having in ESR measurement a spin concentration of a least 1.0 × 10^19 (spins/g) and a ratio of a peak intensity at a magnetic field of at least 260 mT and at most 270 mT to a peak intensity at a magnetic field of at least 300 mT and at most 320 mT of at least 0.25 and at most 0.50 Å and containing bivalent copper. The hydrocarbon adsorbent may be used for a method for adsorbing hydrocarbons to be exposed to a high temperature/high humidity environment, and may be used particularly for a method for adsorbing hydrocarbons in an exhaust gas of an internal combustion engine, such as an automobile exhaust gas.

A composition is provided that has heat resistance sufficient for use as a hydrocarbon adsorbent and desorbs hydrocarbons slowly with respect to an increase in temperature. The composition includes an alkali metal and a zeolite having a YFI structure. A content of the alkali metal is 1 to 40 mass% based on a total mass of the composition, and a content of the zeolite having a YFI structure is 99 to 60 mass% based on the total mass of the composition.

An object of the present invention is to increase the reduction performance of nitrogen oxides compared to existing three-way catalysts; simultaneously inhibit the emission of ammonia and nitrous oxide; simplify a process by means of a method of further doping an iridium-ruthenium catalyst into a commercial three-way catalyst; and expand the scope of application. The present invention provides a catalyst for simultaneously inhibiting the emission of ammonia and nitrous oxide by doping an iridium-ruthenium catalyst component into a three-way catalyst (TWC), a diesel oxidation catalyst, or a lean NOx trap supported on a honeycomb support.

This exhaust gas purifying catalyst is provided with a substrate and a catalyst layer formed on a surface of the substrate. The catalyst layer contains zeolite particles that support a metal, and a rare earth element-containing compound that contains a rare earth element. The rare earth element-containing compound is added in such an amount that the molar ratio of the rare earth element relative to Si contained in the zeolite is 0.001 to 0.014 in terms of oxides.

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.