CATALYST FOR CONTACT REDUCING NITROGEN OXIDE

PROBLEM TO BE SOLVED: To efficiently reduce a nitrogen oxide in exhaust gas without using a large amount of a reducing agent by carrying a silver chloride and at least one kind selected from silver ions, silver and a silver oxide on a solid acid carrier in a nitrogen oxide contact reducing catalyst using hydrocarbon as a reducing agent. SOLUTION: A nitrogen oxide contact reducing catalyst suitable for reducing and removing a harmful nitrogen oxide contained in exhaust gas exhausted out of a factory, an automobile and the like is composed of a solid acid carrier carrying (a) a silver chloride and (b) at least one kind selected from silver ions, silver and a silver oxide, and the (a) component in the range of 0.01-100 to the (b) component based on the molar ratio of conversion to silver. Also the total carrying amount of (a) component and (b) component is set as 0.01-10wt.%. As the solid acid carrier, a zeolite solid acid carrier such as Na - mordenite, Na - ZSM - 5, an oxide solid acid carrier such as Al2 O3 , ZrO2 or SiO2 /Al2 O3 or the like is used.