Effect of Ammonium Formate and Mixtures of Urea and Ammonium Formate on Low Temperature Activity of SCR Systems

The urea based SCR technology will face problems with the high freezing point (-11°C) of the reductant. In many parts of the world temperatures regularly fall much lower than this. With ammonium formate-urea solution the freezing point can be as low as - 30 °C.

The reduction capacity of various ammonium formate solutions and its mixtures with urea were studied. When using ammonium formate and its mixtures as reductant in SCR experiments a significant improvement in the DeNO_x activity in the low temperature operation was seen. In general in the engine experiments the ammonium formate-urea mixtures showed a reduction capacity comparable to standard urea.