[**DK**]

I am doing an assignment on the chemical Urea, while researching it i realized it is destined for use as a nitrogen-release fertilizer and also used in Selective non-catalytic reduction reactions to reduce the NOx pollutants in exhaust gases from cars, Im unsure how this occurs though and why this happens. Can someone please explain or help me out?

[Hunter2]

It has something to do that Nitrogen has negative Oxidationnumbers in urea and positiv ones in NOx.  The numbers will be balanced to zero, what means Nitrogen gas.

2 H₂N-CO-NH₂  + 6 NO => 5 N₂ + 4 H₂O + 2 CO₂ or

4 H₂N-CO-NH₂  + 6 NO₂ => 7 N₂ + 8 H₂O + 4 CO₂