A new experimental setup coupled a dielectric barrier discharge flow reactor with a molecular beam mass spectrometer (MBMS) was developed for detailed species diagnostics on plasma assisted oxidation and pyrolysis system. The mixture of methane and oxygen diluted by argon was selected as the feed gas. The MBMS technique with photoionization or electron ionization provided access to not only stable molecules but also highly reactive species involved in the methane plasma, including ions, excited species and radicals. The qualitative identification of various components is achievable based on the information of exact mass and ionization energy. The corresponding quantitative information can be obtained by integrated ion signal and ionization cross-sections. The experimental results showed that oxidation and pyrolysis of methane were triggered by plasma at room temperature. For the pyrolysis case, hydrocarbons ranging from C2 up to C5 were detected. While for the oxidation case, the formation of acetaldehyde and ketene together with formaldehyde and methanol was observed. The parameters of applied voltage and oxygen concentration in the feed gas were found to have effective control on the reactivity and selectivity of the plasma respectively. The degree of methane consumption is the largest when the oxygen concentration in the feed gas is less than half of that at stoichiometric conditions and a higher voltage is applied.

开发了一种新的实验装置，该装置将介电势垒放电流反应器与分子束质谱仪（MBMS）结合在一起，用于对等离子体辅助氧化和热解系统的详细物种诊断。选择由氩气稀释的甲烷和氧气的混合物作为进料气。具有光电离或电子电离的MBMS技术不仅使人们可以接触稳定的分子，而且还可以接触甲烷等离子体中涉及的高反应性物质，包括离子，受激物质和自由基。基于精确质量和电离能的信息，可以对各种成分进行定性鉴定。相应的定量信息可以通过积分离子信号和电离横截面获得。这实验结果表明，室温下等离子体触发了甲烷的氧化和热解。对于热解情况，检测到的碳氢化合物含量范围从C2到C5。对于氧化情况，观察到乙醛和乙烯酮与甲醛和甲醇一起形成。发现进料气体中的施加电压和氧气浓度的参数分别对等离子体的反应性和选择性具有有效的控制。当进料气体中的氧气浓度小于化学计量条件下的氧气浓度并施加更高的电压时，甲烷消耗的程度最大。