| 摘要 |
PROBLEM TO BE SOLVED: To provide a cleaning method for exhaust gas in which the ternary component of nitrogen oxide, hydrocarbon and carbon monoxide contained in exhaust gas is purified by alternately oscillating the treatment atmosphere of exhaust gas between the oxygen excess atmosphere and the reduction atmosphere. SOLUTION: Exhaust gas is brought into contact with a first catalyst which consists of at least one kind of metal selected from a group consisting of silver, copper, zinc, aluminum, gallium, tin, zirconium, chromium, manganese, iron, cobalt and nickel or its compound or its ion. Then, exhaust gas is brought into contact with a second catalyst consisting of at least one kind of oxide selected from a group consisting of alumina, titania, zirconia, silica, silica- alumina, vanadium oxide, molybdenum oxide, tungsten oxide, tin oxide and gallium oxide. And, exhaust gas is brought into contact with a third catalyst consisting of at least one kind of element selected from a group consisting of (a) a nitrogen oxide occlusion body and (b) Pt, Rh, Pd and Ir. |
