Comprising supported silver sulfate or silver chloride or silver with sulfuric acid

摘要

Nitrogen oxides are removed from an exhaust gas containing nitrogen oxides and oxygen in an amount larger than its stoichiometric amount relative to unburned components in the exhaust gas, by (i) disposing an exhaust gas cleaner in a flow path of the exhaust gas, the exhaust gas cleaner comprising 0.2-15 weight % (on a metal basis) of fine silver or silver oxides having an average diameter of 10-1,000 nm and supported on a porous inorganic oxide; (ii) introducing hydrocarbons and/or oxygen-containing organic compounds into the exhaust gas on the upstream side of the exhaust gas cleaner; and (iii) bringing the exhaust gas into contact with the exhaust gas cleaner at a temperature of 200 DEG -600 DEG C., thereby causing a reaction of nitrogen oxides with the hydrocarbons and/or oxygen-containing organic compounds.