The kinetics of the oxidation of ammonia by nitrous oxide

Abstract

Ammonia is oxidized by nitrous oxide smoothly and homogeneously at temperatures between 658 and 730° and total pressures up to 250 mm. The products of reaction, nitrogen, water, and hydrazine are accounted for by a free-radical mechanism initiated by oxygen atoms which result from the thermal decomposition of nitrous oxide. Ammonia labelled with the 15N-isotope was used to distinguish between the nitrogen formed from the nitrous oxide and that from the ammonia. The kinetics follow an empirical rate equation,               Rate = k'[N₂O]^1.56 + k"[N₂O]^0.61[NH₃]. This is of a form which shows the importance of the ammonia molecule participating in the activation of nitrous oxide through bimolecular collision. Assigning a collisional efficiency of unity for like N₂O-N₂O collisions, the efficiency of ammonia in the process              NH₃ + N₂O → NH₃ + N₂O^* is determined as 0.85.