Decomposition of Ammonia in a Microwave Discharge

Abstract

Ammonia is decomposed in a microwave discharge to give hydrazine, nitrogen and hydrogen. Product yields have been measured as a function of ammonia flow-rate, pressure, power input, temperature and added allyl alcohol and propylene. Hydrazine yields are increased with these additives, although the effect falls off at high powers, whereas gas yields (which approximate to the overall ammonia decomposition) are not appreciably affected. Kinetic and analytical evidence shows that the effect of allyl alcohol in increasing the hydrazine yield is by scavenging H atoms and that few NH2 radicals are scavenged. The remaining hydrazine destruction mechanism (particularly at high power) is probably electron-induced.