To decompose ammonia in a waste gas containing no oxygen into nitrogen and water by a reaction at relatively low temperature by brining the ammonia-containing waste gas into contact with a nickel catalyst which is previously oxidized by being brought into contact with an oxygencontaining gas.
After a nickel oxidation process of oxidizing a nickel catalyst by bringing the nickel catalyst into contact with an oxygen containing gas, an ammonia decomposition process by brining an oxygen free and ammonia- containing waste gas into contact with the oxidized nickel catalyst (nickel oxide) is carried out. Further, the nickel oxidation process and the ammonia decomposition process are reciprocally repeated to make the nickel catalyst almost permanently usable while the nickel catalyst being kept as it is packed in a filled tower. The nickel catalyst comprises nickel which is a main reactive component and at least one metal component selected from iron, cobalt, manganese, chromium, copper, and zinc. The ammonia decomposition process is preferably carried out within a temperature range from 330°C to 370°C.
YAMADA MAYA
NITTA AKIHIKO
KOSEKI SHUICHI
