Catalytic reduction of nitrogen oxides with methane in the presence of excess oxygen

We discovered a family of catalysts that can effectively reduce NO_x with methane in the presence of excess oxygen. This new catalytic chemistry offers an alternative means for controlling NO_x emissions. Complete reduction of nitric oxide was obtained at 400°C over a Co-ZSM-5 catalyst. The presence of oxygen in the feed greatly enhances the nitric oxide reduction activity on Co-ZSM-5, and the nitric oxide conversion is strongly related to the inlet methane level. On the other hand, Cu-ZSM-5, which is a unique catalyst for the direct nitric oxide decomposition, is a poor catalyst for nitric oxide reduction by methane in the presence of excess of oxygen.