Mechanistic analysis of oxygen-assisted coupling of methane and ammonia to hydrogen cyanide over polycrystalline Pt and Rh

Abstract

Partial oxidation of methane and ammonia to hydrogen cyanide (HCN) over Pt and Rh wires was studied between 850 and 1000 °C in a temporal analysis of products reactor. It was established that HCN formation over these metals occurred via the same reaction scheme, i.e. ammonia is primarily oxidized to nitric oxide, which further reacts with methane to the target product. Despite the mechanistic similarities, Rh is less selective than Pt. In order to understand the origins of different performance of these metals, reaction pathways of HCN formation via interactions of methane with ammonia (in the presence and the absence of oxygen) and nitric oxide as well as oxidative conversion of HCN were studied using isotopic tracers.