| 摘要 |
PROBLEM TO BE SOLVED: To provide a NOx occlusion reduction type catalyst capable of realizing an intended NOx purification rate in a wide temperature range and an exhaust gas purification system using it.SOLUTION: An NOx occlusion reduction type catalyst contains an NOx occlusion material which occludes NOx in lean exhaust gas air-fuel ratios and discharges occluded NOx in stoichiometric and rich air-fuel ratios and a catalytic ingredient. The NOx occlusion material contains zirconia, ceria and at least one element selected from indium, gallium, thallium and neodymium, and the catalytic ingredient contains at least one noble metal ingredient. An exhaust gas purification system is configured by arranging the NOx occlusion reduction type catalyst and another NOx occlusion reduction type catalyst containing e.g. an alkaline earth metal in an exhaust passage. |
