Abstract: 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; causing the combustion waste gas added with ammonia to contact with, while keeping the temperature of the combustion waste gas within a prescribed range, with a 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 a carrier comprising at least one selected from the group consisting of titanium oxide (TiO.sub.2), silicon oxide (SiO.sub.2), aluminum oxide (Al.sub.2 O.sub.3) and zirconium oxide (ZrO.sub.2), thereby removing nitrogen oxides and organic chlorine compounds from the combustion waste gas.

Abstract: A method for removing detrimental organic chlorine compounds such as polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans from a combustion waste gas, which comprises the steps of: bringing organic chlorine compounds contained in a combustion waste gas at a temperature within a range of from 150.degree. to 350.degree. C. into contact with a catalyst comprising at least one selected from the group consisting of platinum, palladium, ruthenium, manganese, copper, chromium and iron and oxides thereof, which catalyst is supported on the surface of a carrier containing at least titanium oxide, Aluminum oxide and silicon oxide, to cause a decomposition reaction of the organic chlorine compounds, thereby removing organic chlorine compounds from the combustion waste gas at a high efficiency.

Abstract: A catalyst composition including component A and component B, the component A being a carrier, preferably having a honeycomb structure, and being a single-component oxide or a multi-component composite oxide of at least one metal of titanium, silicon and zirconium, and the component B being a catalyst component deposited on the carrier of component A and being at least one member selected from the group of noble metals and other specifically limited metals and their oxides, is very effective for decomposing and removing poisonous organic chlorine compounds, such as dioxin and the like, or poisonous organic chlorine compound-forming substances contained in an exhaust gas exhausted from an incinerator of an incineration plant provided with the incinerator and a dust collector. In addition, and the generation of the poisonous organic chlorine compound from the incineration plant can be prevented.

Abstract: An excellent method of decomposing flon is provided which can decompose flon economically with high decomposition efficiency without necessitating high temperature and high pressure by contacting a gas containing a flon with a catalyst at a condition of a temperature of not less than 200.degree. C. and space velocity of not over than 50,000 (hr.sup.-1).