Abstract: As a device for the purification of exhaust gas, a three-way catalyst A purifying hydrocarbon, carbon monoxide and nitrogen oxide in the vicinity of theoretical air-fuel ratio is disposed at an upstream side of the exhaust gas and an adsorption catalyst B provided with zeolite effective for the adsorption of hydrocarbon is disposed at a downstream side of the exhaust gas.

Abstract: As a device for the purification of exhaust gas, a three-way catalyst A purifying hydrocarbon, carbon monoxide and nitrogen oxide in the vicinity of theoretical air-fuel ratio is disposed at an upstream side of the exhaust gas and an adsorption catalyst B provided with zeolite effective for the adsorption of hydrocarbon is disposed at a downstream side of the exhaust gas.

Abstract: As a device for the purification of exhaust gas, a three-way catalyst A purifying hydrocarbon, carbon monoxide and nitrogen oxide in the vicinity of theoretical air-fuel ratio is disposed at an upstream side of the exhaust gas and an adsorption catalyst B provided with zeolite effective for the adsorption of hydrocarbon is disposed at a downstream side of the exhaust gas.

Abstract: As a device for the purification of exhaust gas, a three-way catalyst A purifying hydrocarbon, carbon monoxide and nitrogen oxide in the vicinity of theoretical air-fuel ratio is disposed at an upstream side of the exhaust gas and an adsorption catalyst B provided with zeolite effective for the adsorption of hydrocarbon is disposed at a downstream side of the exhaust gas.

Abstract: A nitrogen oxide absorbing material (38) which absorbs nitrogen oxide when the reduction component concentration of exhaust gas in the exhaust passage (31) of an engine (1) is lower than a predetermined concentration, and discharges nitrogen oxide when the reduction component concentration of exhaust gas in the exhaust passage (31) of the engine (1) is higher than the predetermined concentration, and a catalyst (38) which promotes reduction of the discharged nitrogen oxides by a reduction component are provided. A controller (40) first reduces the reduction component concentration of the exhaust gas over a first predetermined time period by, for example, advancing the fuel injection timing. The controller (40) then increases the reduction component concentration of the exhaust gas over a second predetermined time period by, for example, retarding the fuel injection timing.

Abstract: A catalyst for the purification of exhaust gas comprises a first coat layer of a palladium-carried activated alumina containing Ce, Zr and La formed on a honeycomb carrier, a second coat layer of an activated alumina containing Ce, Zr and La formed on the first coat layer, and a third coat layer of copper ion-exchanged zeolite powder formed on the second coat layer and efficiently purifies NOx, HC and CO in the exhaust gas under conditions from theoretical air-fuel ratio to excessive oxygen atmosphere.

Abstract: A catalyst for the adsorption of hydrocarbons is used in an apparatus for the purification of exhaust gas from an internal engine and comprises a honeycomb monolith carrier, a first layer of at least one zeolite having a different crystalline structure, a second layer containing at least one of Pt and Pd as a catalytic component, and a third layer containing Rh as a catalytic component.