초록 ▼

Nitrogen oxides are efficiently removed frown an exhaust gas containing nitrogen oxides and an excess amount of oxygen, by (i) disposing an exhaust gas cleaner in a flow path of the exhaust gas, the exhaust gas cleaner comprising a first catalyst comprising 0.2-15 weight % (on a metal basis) of silv

Nitrogen oxides are efficiently removed frown an exhaust gas containing nitrogen oxides and an excess amount of oxygen, by (i) disposing an exhaust gas cleaner in a flow path of the exhaust gas, the exhaust gas cleaner comprising a first catalyst comprising 0.2-15 weight % (on a metal basis) of silver or silver oxide supported on a porous inorganic oxide on the inlet side and a second catalyst comprising 0.2-15 weight % (on a metal basis) of silver or silver oxide and 2 weight % or less (on a metal basis) of copper or copper oxide supported on a porous inorganic oxide on the outlet side; (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°-600°C.

대표청구항 ▼

A method for removing nitrogen oxides from an exhaust gas containing nitrogen oxides and oxygen in an amount larger than its stoichiometric amount relative to unburned components in said exhaust gas, which consists essentially of (i) disposing an exhaust gas cleaner in a flow path of said exhaust ga

A method for removing nitrogen oxides from an exhaust gas containing nitrogen oxides and oxygen in an amount larger than its stoichiometric amount relative to unburned components in said exhaust gas, which consists essentially of (i) disposing an exhaust gas cleaner in a flow path of said exhaust gas, said exhaust gas cleaner consisting essentially of a first catalyst on an inlet side of said exhaust gas cleaner and a second catalyst on an outlet side of said exhaust gas cleaner, said first catalyst consisting essentially of 0.2-15 weight % on a metal basis of silver or silver oxide supported on a porous inorganic oxide, and said second catalyst consisting essentially of 0.2-15 weight % on a metal basis of silver or silver oxide and copper or copper oxide in an amount up to 2 weight %, on a metal basis, supported on a porous inorganic oxide; (ii) introducing a reductant selected from the group consisting of hydrocarbons and oxygen-containing organic compounds into said exhaust gas on an upstream side of said exhaust gas cleaner, said reductant being added to the exhaust gas so as to maintain the amount of oxygen in the exhaust gas larger than its stoichiometric amount relative to unburned components in said exhaust gas; and (iii) bringing said exhaust gas into contact with said exhaust gas cleaner at a temperature of 200°-600°C., thereby causing a reaction of said nitrogen oxides with said reductant to remove said nitrogen oxides.