| 摘要 |
PURPOSE:To remove NOx in an exhaust gas efficiently. CONSTITUTION:From a viewpoint that in the reduction reaction between NOx and hydrocarbons on a reduction catalyst in an oxidative atmosphere, NO2, is reduced more easily than NO, an exhaust gas is previously contacted with an oxidation catalyst to oxidize NO in the exhaust gas into NO2. The treated exhaust gas, in an oxidative atmosphere containing excessive oxygen and in the presence of hydrocarbons, is contacted with a reduction catalyst selected from zeolite of a proton type, zeolite of an alkali metal type, and acid metal oxide (metal oxide treated with a compound having sulfate group to reduce NO2, in the exhaust gas into nitrogen. |
