Catalytic reduction of NOx over NiSO4 supported on Al2O3 at low reaction temperature

Nickel (II) sulfate supported on gamma-Al2O3 (NiSO4/Al2O3) was prepared and its catalytic activity for low temperature selective reduction of NOx with ammonia was examined. The catalyst (NiSO4/Al2O3) was effective for the catalytic reduction of NOx at high concentration of NH3 and of SO2. Thus, it exhibited about 80% NOx conversion under the following conditions: NO: 250 ppm, NH3: 1000 ppm, SO2: 800 ppm, O-2: 4%, CO2: 14%, and N-2 balance and GHSV 750 h(-1) at 90 degre es C. It is inferred that the high NOx reduction activity of NiSO4 catalyst resulted from the presence of the Bronsted acidity and oxidation ability o f ammonia. The catalytic activity of NiSO4 was stable for 100 h, but gradua lly decreased by further reaction. The characterization by XRD revealed tha t the reason of catalytic deactivation was accumulation of ammonium sulfate s and ammonium nitrate plugged the pores of the catalyst. The activity of d eactivated catalyst was easily regenerated by water washing treatment.