Cold plasma is an effective technology converting methane to more valuable products such as C2H2 and C2H4, but the reaction mechanisms was not clear due to the complex nature of plasma. In this paper, optical emission spectroscopy (OES) was adopted for the first time by our group for in situ diagnosis of the conversion of methane under cold plasma. The excited species, such as excited radicals and atoms (CH, C2 and C) were detected in the spectra range of 250 ～ 670 nm. Based on the detection of these excited species, the analysis of products by gas chromatograph andthe characterization of plasma, the micro-process of the conversion reaction of CH4 under plasma was suggested to be radical process.%冷等离子体是甲烷无氧活化制C2烃较为有效的技术手段之一,由于等离子体反应体系的复杂性,甲烷无氧活化制C2烃反应机理及过程尚不十分清楚.本文采用发射光谱原位诊断技术对冷等离子体作用下甲烷无氧活化制C2烃反应中若干激发态物种进行诊断研究,在250nm～670nm波长范围内检测到下列激发态物种:CH、C和C2.依据激发态物种检测结果、气相色谱反应产物分析结果及等离子体特性,推断了等离子体作用下甲烷无氧活化制C2烃的自由基反应历程.
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