EXHAUST GAS PURIFYING CATALYST SYSTEM

• Main Authors: IWAKUNI HIDEHARU, MIYOSHI SEIJI, SHIGETSU MASAHIKO, MINOSHIMA KOJI, TAKAMI AKIHIDE
• Format: Patent
• Language: English
• Published: 02.04.2009
• Subjects: BLASTING; ENGINE PLANTS IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNALCOMBUSTION ENGINES; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES ORENGINES IN GENERAL; HEATING; LIGHTING; MACHINES OR ENGINES IN GENERAL; MECHANICAL ENGINEERING; STEAM ENGINES; WEAPONS

Disclosed is an exhaust gas purifying catalyst system, which comprises an upstream catalyst disposed in an exhaust gas passage of an engine at a position on an upstream side with respect to a direction of an exhaust gas stream, and a downstream catalyst disposed in the exhaust gas passage at a position on a downstream side with respect to the direction of the exhaust gas stream. In the exhaust gas purifying catalyst system, the downstream catalyst includes a cerium (Ce)-containing rhodium-doped composite oxide and an Ni component, and the upstream catalyst includes a cerium (Ce)-containing composite oxide other than the rhodium-doped composite oxide, and a Ni component. A ratio of Ni to CeO2 in the upstream catalyst is in the range of 15 to 20 mass %, and a ratio of Ni to CeO2 in the downstream catalyst is in the range of 10 to 60 mass %. The exhaust gas purifying catalyst system of the present invention can reduce an amount of H2S emission while achieving high purification performance.