Re-Examination of the N2O + O Reaction

The reaction of N2O with O is a key step inconsumptionof nitrous oxide in thermal processes. It has two product channels,NO + NO (R2) and N-2 + O-2 (R3). The rate constantfor R2 has been measured both in the forward and the reverse directionat elevated temperature and is well established. However, the rateconstant for the N-2 + O-2 channel (R3) has beendifficult to quantify and has significant error limits. The directreaction on the triplet surface has a barrier of around 40 kcal mol(-1), and it is too slow for the N-2 + O-2 channel to have any practical significance. Recently, Phamand Lin (2022) suggested an alternative low activation energy reactionpath that involves intersystem crossing and reaction on the singletsurface. In the present work, we re-examined a wide range of experimentsrelevant for the N2O + O reaction through kinetic modeling,paying attention to the impact of artifacts such as impurities andsurface reactions. Experimental results from shock tubes and batchreactors on the final NO yield in N2O decomposition, coveringtemperatures of 973-2200 K and pressures of 0.013-11.5atm, support k (3) & SIM; 0, consistentwith the high activation energy for reaction on the triplet surfaceand a low probability of ISC.