Selective catalytic reduction of NOx with NH3 and tolerance to H2O & SO2 at high temperature over zeolite supported indium-copper bimetallic catalysts for gas turbine

Abstract

An indium and copper-doped mordenite catalyst (InCu/MOR) was prepared and tested as a potential catalyst for high temperature NH3 selective catalytic reduction (NH3-SCR) of NOx in the gas turbine. The InCu/MOR catalyst exhibited excellent catalytic activity (over 83 % NOx conversion) in the presence of 5 % H2O and 100 ppm SO2 above 550 °C. A series of characterization (XRD, Py-TR, XPS, NH3-TPD, H2-TPR and in-situ DRIFTS) were applied to analyze the catalyst. The obtained results showed that the addition of indium promoted the formation of isolated Cu2+ and more Brønsted acid sites, which could improve the tolerance to sulfur dioxide and inhibit the occurrence of high temperature ammonia oxidation side reactions. Meanwhile, the ammonia on InO+/In2O3 sites was activated and reacted with the nitrate/nitrite species on the catalyst surface to form nitroammonium (NH4NO3/NH4NO2), which was a short lived intermediate for NH3-SCR. The superior catalytic performance of InCu/MOR could attribute to these comprehensive effects.