Plasma-Triggered CH₄/NH₃ Coupling Reaction for Direct Synthesis of Liquid Nitrogen-Containing Organic Chemicals

Nitrogen-containing organic chemicals such as amines, amides, nitriles, and hydrazones are crucial in chemical and medical industries. This paper reports a direct synthesis of N,N-dimethyl cyanamide [(CH₃)₂NCN] and amino acetonitrile (NH₂CH₂CN) through a methane/ammonia (CH₄/NH₃) coupling reaction triggered by dielectric barrier discharge plasma, with by-products of hydrazine, amines, and hydrazones. The influence of CH₄/NH₃ molar ratio, feedstock residence time, and specific energy input on the CH₄/NH₃ plasma coupling reaction has been investigated and discussed. Under the optimized conditions, the productivities of (CH₃)₂NCN and NH₂CH₂CN reached 0.46 and 0.82 g·L^-1·h^-1, respectively, with 8.83% CH₄ conversion. In addition, through combining the optical emission spectra diagnosis and the reaction results, a possible CH₄/NH₃ plasma coupling reaction mechanism has been proposed. This paper provides a potential fine application of CH₄ and NH₃ in green synthesis of liquid nitrogen-containing organic chemicals, such as nitriles, amines, amides, and hydrazones.