| 摘要 |
PROBLEM TO BE SOLVED: To use a catalyst in which Cu, siver chloride and silver bromide are incorporated into zeolite that is treated by a soluble phosphorus compound and has SiO2 /Al2 O3 molar ratio of a specified value and durability at a high temperature is excellent in existence of steam in the case of treating exhaust gas containing nitrogen oxide. SOLUTION: In the case of removing nitrogen oxide by bringing a catalyst into contact with exhaust gas which is discharged from an automobile engine or the like and contains excess oxygen, the catalyst is used in which Cu, siver chloride and silver bromide are incorporated into zeolite that is treated by a soluble phosphorus compound and has SiO2 /Al2 O3 molar ratio of at least 15. As the kind of zeolite, mordenite, ferrierite, zeolite β, ZSM-5, ZSM-8, ZSM-11, ZSM-12, etc., are used. ZSM-5 is suitable in particular. A method for introducing the soluble phosphorus compound into zeolite is performed by an ordinary impregnation carrying method using an aqueous solution and an organic solvent and an evaporation to dryness method. |
