Patent ID: 7160527
Filing Date: 2007-01-09
Classification: B01D,C02F,Y02C

Abstract:
1. A method for treating an ammonia-containing effluent comprising a stripping step in which the ammonia (NH 3 ) contained in the NH 3 -containing effluent is transferred with a carrier gas from the effluent into a gas phase, a step for adding an oxygen-containing gas to the NH 3 -containing gas produced at the stripping step, and an NH 3 decomposing step in which the oxygen-containing gas and the NH 3 -containing gas are contacted with a catalyst used for decomposing NH 3 , at a temperature in the range of 250° C. to 450°, which catalyst comprises, as a first component, an oxide of titanium (Ti) and an oxide of one or more elements selected from the group consisting of tungsten (W), vanadium (V), and molybdenum (Mo), and, as a second component, a silica, zeolite, and/or alumina having one or more noble metals selected from the group consisting of platinum (Pt), iridium (Ir), rhodium (Rh), and palladium (Pd) supported thereon, the concentration of oxygen in the gas mixture introduced into the NH 3 decomposing step being controlled within a range of 2 to 15% in the NH 3 decomposition step such that the N 2 O concentration is reduced while the NH 3 decomposition ratio remains generally unchanged.