Abstract
Hydrogen cyanide (HCN) is synthesized from ammonia (NH(3)) and methane (CH(4)) at ~1200°C over a Pt catalyst. Ammonia synthesis entails several complex, highly emitting processes. Plasma-assisted HCN synthesis directly from CH(4) and nitrogen (N(2)) could be pivotal for on-demand HCN production. Here, we evaluate the potential of dielectric barrier discharge (DBD) N(2)/CH(4) plasma for decentralized catalyst-free selective HCN production. We demonstrate a single-step conversion of methane and nitrogen to HCN with a 72% yield at <300°C. HCN is favored at low CH(4) concentrations with ethane (C(2)H(6)) as the secondary product. We propose a first-principles microkinetic model with few electron impact reactions. The model accurately predicts primary product yields and elucidates that methyl radical (·CH(3)) is a common intermediate in HCN and C(2)H(6) synthesis. Compared to current industrial processes, N(2)/CH(4) DBD plasma can achieve minimal CO(2) emissions.