Reduction of NO2 in flue gas by CO and propylene over CuO-CeO2/SiO2 in the presence of O-2.

Catalytic reduction of NO2 with CO and/or propylene in the presence of NO and excess oxygen, a model mixture for flue gas, was studied over a series of CuO-CeO2/SiO2 catalysts between 120-260 °C. The effect of HCl, an impurity in flue gas, on the activity of the catalysts was evaluated. It was found that a binary oxide catalyst, 2% CuO-8% CeO2/SiO2, was active for the reduction of NO2 by CO and/or propylene. CO was effective for selective reduction of NO2 in the presence of NO and O2 in a temperature window between 160-200 °C while propylene was effective at temperature higher than 200 °C. In the presence of HCl, the activity of the catalyst for reduction of NO2 with CO was irreversibly deactivated. However, the activity for reduction of NO2 with propylene was not influenced by HCl.