| 摘要 |
PURPOSE:To provide a catalyst which can effectively reduces and removes NOx in exhaust gas at relatively low temp. even for such an exhaust gas having extremely little fine particles of carbon material and a small amt. of combustible material such as unburnt hydrocarbons (namely, in an oxidative atmosphere), for example, an exhaust gas from a gasoline engine having a lean air-fuel ratio. CONSTITUTION:This catalyst consists of one or more alkali metal elements, one or more elements selected from transition metals of groups IB, IIB, VA, VIA, VIII excluding platinum groups in the periodical table and Sn, and one or more rare earth elements. This catalyst promotes the reduction reaction of nitrogen oxides with using unburnt hydrocarbons in the exhaust gas as the reducing agent. |
