离子液体在甲烷等离子体转化中作用机理的光谱研究

在直流等离子体甲烷转化反应体系中分别引入C₆MIMBF₄，C₆MIMCF₃COO，C₆MIMHSO₄三种离子液体，采用光谱在线技术检测反应中活性物种的种类和光谱谱峰相对强度的变化，研究了离子液体在气液等离子体甲烷转化反应中的作用机理。结果表明：向甲烷等离子体体系中引入离子液体可得到稳定的气液界面，并提高了甲烷转化率和C₂烃产物收率，C₆MIMCF₃COO和C₆MIMBF₄有助于提高C₂烃选择性，而C₆MIMHSO₄则导致C₂烃选择性下降。在气液等离子体甲烷放电体系中检测到了C，C₂，C₃，CH，H等活性物种的发射光谱，与未引入离子液体时相比大多数活性物种的谱线强度均有增加。核磁共振研究表明反应后离子液体C₆MIMBF₄结构稳定，可认为离子液体作为液体导电介质提高了等离子体放电强度，促进等离子体区气相反应过程，同时离子液体在气液表面反应过程起催化作用。

Study on Mechanism of Ionic Liquid for Methane Plasma Conversion Using Spectra Method

C₆MIMBF₄, C₆MIMCF₃COO and C₆MIMHSO₄ were introduced into a direct current discharge plasma system respectively for methane conversion. The kinds of active species and relative intensity of spectral peaks were detected via online spectrum diagnosis technique of optical emission spectroscopy. Mechanism of ionic liquid for methane conversion in gas-liquid plasma was investigated. The results showed that a spatially and temporally stable gas-liquid interface was obtained in ionic liquid incorporated plasma system. With introduction of ionic liquid, methane conversion and C₂ hydrocarbons yields increased. The C₂ hydrocarbon selectivity greatly increased when C₆MIMCF₃COO and C₆MIMBF₄ were introduced to the plasma, and decreased when C₆MIMHSO₄ was used. Active species like C, C₂, C₃, CH and H were detected in gas-liquid plasma system of methane discharge. Compared with the absence of ionic liquid in the plasma system, the relative intensity of spectral peaks of most active species increased when ionic liquid was introduced into the plasma system. 1H NMR results showed that the structure of ionic liquid kept stable during plasma discharge progress. Those indicated that ionic liquid could improve the plasma discharge intensity. At the same time, ionic liquid showed good catalytic activity in gas-liquid surface reaction.