Catalytic Reduction of NOx over NiSO4 Supported on Al2O3 at Low Reaction Temperature

Shigeru NOJIMA*, Hiroshi SUZUMURA, Masayoshi HIRANO and Eiji SASAOKA††

Hiroshima R & D Center, Mitsubishi Heavy Industries LTD; 4-6-22 Kanonshin-machi, Nishi-ku, Hiroshima-shi 733-8553 Japan
Electrotechnology Applications R & D Center, Chubu Electric Power Co., Inc.; 20-1 Kitasekiyama, Ootaka-tyou, Midori-ku, Nagoya-shi 459-8001 Japan
†† Department of Environmental Chemistry and Materials, Okayama University; 2-1-1 Tsushima, Okayama-shi 700-8530 Japan

Nickel (II) sulfate supported on γ-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, O2: 4 %, CO2: 14%, and N2 balance and GHSV 750 h−1 at 90 °C. It is inferred that the high NOx reduction activity of NiSO4 catalyst resulted from the presence of the Bronsted acidity and oxidation ability of ammonia. The catalytic activity of NiSO4 was stable for 100 h, but gradually decreased by further reaction. The characterization by XRD revealed that the reason of catalytic deactivation was accumulation of ammonium sulfates and ammonium nitrate plugged the pores of the catalyst. The activity of deactivated catalyst was easily regenerated by water washing treatment.

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