| 摘要 |
PURPOSE:To purify a nitrogen oxide contained in combustion exhaust gas containing oxygen on the practical level by using hydrocarbon in the presence of a catalyst of specified value of SiO2/Al2O3 ratio containing indium and alkaline earth metal. CONSTITUTION:A nitrogen oxide contained in combustion exhaust gas containing oxygen is purified by using a hydrocarbon in the presence of a catalyst composed of zeolite having the molar ratio of 10 or more in terms of SiO2/Al2O3 ratio containing indium and alkaline earth metal. It is required that the molar ratio of SiO2/Al2O3 should be 10 or more from the viewpoint of heat resistance and resistance to water vapor. As for the alkaline earth metal, for example, beryllium, magnesium, calcium, strontium or barium can be used. It is preferable that hydrogen ions are contained in the catalyst. The nitrogen oxide can be removed efficiently from the combustion exhaust gas containing oxygen with the catalyst. The removal can be carried out efficiently even in the presence of a sulfur oxide. |
