Low Temperature Selective Catalytic Oxidation of Ammonia in Lean Oxygen over TiO2 Supported Catalyst

Selective catalytic oxidation (SCO) of ammonia to nitrogen is a promising approach for dealing with the main fixed nitrogen species. Corresponding nitrates of Fe, Cu, Ni, Co and Mn transition metals supported on TiO₂ were prepared with incipient wetness impregnation and have been tested in the low temperature range from 50°C to 350 V. The catalysts were investigated under 500 ppm NH₃, 2.5% O₂, and gas hourly space velocity (GHSV) was 35, 000 h^-1. The SCO of ammonia activity tests results indicated that Cu/TiO₂ obtained the highest performance among catalysts, which achieved the 100% ammonia conversion at 200°C. Ni/TiO₂ and Co/TiO₂ have a little bit lower activity, with 100% ammonia conversion when the temperatures were 250°C and 300°C respectively. However, Mn/TiO₂ and Fe/TiO₂ had better selectivity into N₂. The activity or selectivity of transition metals catalysts were more or less improved by introducing CeO_x, especially, the activity of most catalysts were greatly increased at low temperature.