46) HNO₃ → NH₄ NO₃ → NH₃ → NO

1. HNO₃ + NH₃ → NH₄NO₃
2. NH₄NO₃ → N₂O + 2H₂O (thermal decomposition)
3. N₂O + 2H₂ → 2NH₃
4. NH₃ + O₂ → NO + H₂O (catalytic oxidation)