Catalytic purification of flue gases

Cleaned metal cuttings are pickled in diluted acid containing the metal salt(s) of catalytically-active noble metal, transition metal or transition metal oxide. The prepared cuttings are dried. The flue gases are passed through a packed bed of the treated cuttings. Independent claims are included for the corresponding equipment and use of industrial metal cuttings cleaned of cutting lubricants. Equipment includes a packed bed reactor (3) for the catalyst. A temperature sensor (8) and sensors (5, 6) for raw and purified gas pollutant concentrations, are provided. Preferred features of reactor: The reactor is located in a section of the flue gas duct. A process computer (7) evaluates the concentrations. A differential pressure instrument (9) measures pressure loss. The reactor includes a heater (4). Preferred features of method: The metal salt is palladium(II) acetyl acetonate, with nitric acid. The cuttings are chrome-nickel, optionally containing molybdenum, titanium and vanadium. Their careful drying takes place in a cabinet at 70-90 deg C for 2-3 hours. They remain there, in a nitrogen atmosphere following drying, for several hours. The nitrogen atmosphere is at 400 deg C. Before first use, they are heated to an initial temperature. The temperature of catalytic initiation is less than 200 deg C. The temperature in the reaction region can be over 350 deg C.