An apparatus for purifying exhaust gas includes: an engine; an exhaust gas air-fuel ratio adjustor for adjusting an air-fuel ratio of the exhaust gas; a lean NO.sub.x trap (LNT) mounted on the exhaust pipe and generating ammonia or reducing nitrogen oxides or desorbed nitrogen oxides contained in the exhaust gas using a reducing agent including carbon monoxide, hydrocarbon, or hydrogen contained in the exhaust gas; a three way catalyst (TWC) mounted on the exhaust pipe at a rear end of the LNT, and converting noxious gas in the exhaust gas into harmless components through a redox reaction; and a controller controlling the air-fuel ratio of the exhaust gas to a stoichiometric air-fuel ratio when the nitrogen oxide storage or purification performance of the LNT is in the operating period of the engine less than a predetermined level.

An exhaust gas post processing apparatus of a gasoline vehicle may include a housing mounted on the exhaust pipe to receive the exhaust gas discharged from the engine and to exhaust the exhaust gas passed through rearward thereof, a front end honeycomb catalyst unit embedded in the housing to primarily purify the exhaust gas introduced into the housing through a front end portion of the housing, and a rear end honeycomb catalyst unit embedded in the housing to secondarily purify the exhaust gas via the front end honeycomb catalyst unit before flowing out to a rear end portion of the housing, wherein the front end honeycomb catalyst unit includes a powder type catalyst in which an iridium-ruthenium alloy is supported on an aluminum oxide support powder, and the rear end honeycomb catalyst unit includes three-way catalyst powder which is configured to remove carbon monoxide, nitrogen oxides, and hydrocarbons simultaneously.

This invention provides a multinary solid solution fine particle represented by Pd.sub.xRu.sub.yM.sub.z (M is at least one member selected from the group consisting of Rh, Pt, Cu, Ag, Au and Ir. x+y+z=1, x+y=0.01 to 0.99, z=0.99 to 0.01, x:y=0.1:0.9 to 0.9:0.1), a method for producing the same, and a supported catalyst.

The invention discloses a method for simultaneously removing SO.sub.2 and NO.sub.x in flue gas: uniformly mixing a water-soluble ruthenium salt with ammonia water to obtain an aqueous solution of a ruthenium-amine complex; subjecting the flue gas and the aqueous solution of the ruthenium-amine complex to a countercurrent contact reaction under the temperature of 5-60 C., pH of 7.5-12 to obtain a solution A and purified gas; discharging the solution A of the step (2) into a crystallization tank to crystallize and separate an ammonium salt to obtain a solution B, returning the solution B to replace the aqueous solution of the ruthenium-amine complex. The invention utilizes the ruthenium-amine complex having a strong capability of complexing with NO as well as residual oxygen in the flue gas to carry out liquid phase catalytic oxidation to convert the NO.sub.x into ammonium nitrate, the removal efficiency of the NO.sub.x and the SO.sub.2 is high.

An exhaust gas purification device includes: a substrate of wall-flow structure having an inlet cell, an outlet cell and a porous partition wall; an upstream catalyst layer provided inside the partition wall and disposed in an upstream portion, including an exhaust gas inflow end section, of the substrate; and a downstream catalyst layer provided inside the partition wall and disposed in a downstream portion, including an exhaust gas outflow end section, of the substrate. The downstream catalyst layer contains a carrier, and Rh supported on the carrier. The upstream catalyst layer contains a carrier, and Pd and/or Pt supported on the carrier.

The current embodiments relate to ruthenium-containing supported catalysts, including processes for their manufacture and use, which destroy, through catalytic oxidation, hazardous compounds contained in chemical industrial emissions and otherwise produced from industrial processes.

A passive NO.sub.x adsorber is disclosed. The passive NO.sub.x adsorber is effective to adsorb NO.sub.x at or below a low temperature and release the adsorbed NO.sub.x at temperatures above the low temperature. The passive NO.sub.x adsorber comprises a noble metal and a molecular sieve having an LTL Framework Type. The invention also includes an exhaust system comprising the passive NO.sub.x adsorber, and a method for treating exhaust gas from an internal combustion engine utilizing the passive NO.sub.x adsorber.

Synergized platinum group metals (SPGM) with ultra-low PGM loadings employed as close-coupled (CC) three-way catalysts (TWC) systems with varied material compositions and configurations are disclosed. SPGM CC catalysts in which ZPGM compositions of binary or ternary spinel structures supported onto support oxides are coupled with commercialized PGM UF catalysts and tested under Federal Test Procedure FTP-75 within TGDI and PI engines. The performance of the TWC systems including SPGM CC (with ultra-low PGM loadings) catalyst and commercialized PGM UF catalyst is compared to the performance of commercialized PGM CC and PGM UF catalysts. The disclosed TWC systems indicate that SPGM CC TWC catalytic performance is comparable or even exceeds high PGM-based conventional TWC catalysts, with reduced tailpipe emissions.

This invention provides a multinary solid solution fine particle represented by Pd.sub.xRu.sub.yM.sub.z (M is at least one member selected from the group consisting of Rh, Pt, Cu, Ag, Au and Ir. x+y+z=1, x+y=0.01 to 0.99, z=0.99 to 0.01, x:y=0.1:0.9 to 0.9:0.1), a method for producing the same, and a supported catalyst.

A gas clean-up unit includes a first conversion unit configured to perform a first conversion process of converting hydrogen cyanide contained in gas to be treated to ammonia, in presence of a first catalyst and at a first predetermined temperature; a second conversion unit configured to perform a second conversion process of converting carbonyl sulfide in the gas that has been subjected to the first conversion process to hydrogen sulfide, in presence of a second catalyst and at a second predetermined temperature lower than the first predetermined temperature; a cleaning unit configured to perform a cleaning process of bringing the gas into gas-liquid contact with cleaning liquid to remove the ammonia by cleaning; and a desulfurization unit configured to absorb and remove hydrogen sulfide in the gas by bringing the gas that has been subjected to the cleaning process into gas-liquid contact with absorbent.