Direct HCN synthesis via plasma-assisted conversion of methane and nitrogen.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 38552025.
- Also identified by DOI 10.1126/sciadv.adl4246 and PMC identifier 10980260.
- Licence recorded as CC BY-NC.
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Abstract
Hydrogen cyanide (HCN) is synthesized from ammonia (NH<sub>3</sub>) and methane (CH<sub>4</sub>) at <b><i>~</i></b>1200°C over a Pt catalyst. Ammonia synthesis entails several complex, highly emitting processes. Plasma-assisted HCN synthesis directly from CH<sub>4</sub> and nitrogen (N<sub>2</sub>) could be pivotal for on-demand HCN production. Here, we evaluate the potential of dielectric barrier discharge (DBD) N<sub>2</sub>/CH<sub>4</sub> 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<sub>4</sub> concentrations with ethane (C<sub>2</sub>H<sub>6</sub>) 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<sub>3</sub>) is a common intermediate in HCN and C<sub>2</sub>H<sub>6</sub> synthesis. Compared to current industrial processes, N<sub>2</sub>/CH<sub>4</sub> DBD plasma can achieve minimal CO<sub>2</sub> emissions.