Method for removing nitrogen oxides and organic chlorine compounds from combustion waste gas

In a method for removing nitrogen oxides and organic chlorine compounds from a combustion waste gas, which comprises the steps of:

• adding ammonia (NH.sub.3) as a reducing agent to a combustion waste gas containing nitrogen oxides and organic chlorine compounds;
• contacting said combustion waste gas containing said ammonia as the reducing agent, while keeping the temperature of said combustion waste gas within a range of from 150.degree. to 500.degree. C., with a catalyst for reducing nitrogen oxides, in an effective amount to achieve a catalytic function, said catalyst comprising vanadium, supported on the surface of a carrier, to reduce said nitrogen oxides contained in said combustion waste gas so as to decompose said nitrogen oxides, thereby removing said nitrogen oxides from said combustion waste gas;
• and
• contacting said combustion waste gas from which said nitrogen oxides have thus been removed, while keeping the temperature of said combustion waste gas within a range of from 150.degree. to 500.degree. C., with a catalyst for oxidizing organic chlorine compounds, in an effective amount to achieve a catalytic function, said catalyst comprising at least one selected from the group consisting of platinum (Pt), palladium (Pd), ruthenium (Ru), manganese (Mn), copper (Cu), chromium (Cr) and iron (Fe) and oxides thereof, supported on the surface of another carrier, to oxidize said organic chlorine compounds and residual ammonia contained in said combustion waste gas so as to decompose the same, thereby removing said organic chlorine compounds and said residual ammonia from said combustion waste gas;
• wherein the improvement comprises:
• said carrier to support said catalyst for reducing nitrogen oxides on the surface thereof consists essentially of titanium oxide (TiO.sub.2), and said another carrier to support said catalyst for oxidizing organic chlorine compounds on the surface thereof comprises a substrate comprising mullite (3Al.sub.2 O.sub.3.SiO.sub.2) and a layer comprising titanium oxide (TiO.sub.2) formed on the surface of said substrate.