【作者】 王达望；

【导师】 马腾才；

【作者基本信息】 大连理工大学 ， 等离子体物理， 2006， 博士

【摘要】 随着石油资源的日益枯竭，合理利用天然气不仅关系到未来能源的利用和资源配置，对于保护环境也有重要意义。由于甲烷分子C-H键解离能高及其热力学上的不利反应，在甲烷传统催化偶联研究方面一直未取得很大进展，因此人们对开发新方法的研究越来越多。等离子体对于甲烷偶联来说是一种高效率的绿色工艺，近年来人们利用低温等离子体技术对甲烷的活化与转化进行了大量的研究。 大气压下的辉光放电是具有较高电子能量的非平衡等离子体，且不需要真空系统，非常适合工业化应用。由于辉光放电既可以提供反应活性物种，同时又能使体系保持非平衡状态，因此对甲烷偶联转化是一种非常合适的方法。本论文利用常压辉光放电等离子体，采用新型旋转螺旋状电极等离子体反应器用于CH₄转化制C₂烃，提高了CH₄单程转化率、C₂烃单程收率及选择性，并首次对旋转电极辉光等离子体作用下CH₄-H₂转化反应进行了发射光谱诊断研究。 本文的主要研究内容和结论如下： （1）本文采用新型旋转螺旋状电极等离子体放电反应器用于转化CH₄制C₂烃的反应，实现了常压下空间均匀的辉光放电等离子体，且其反应效率高于旋转多尖端三排圆盘电极。该反应器的特点是首次采用了旋转的螺旋状电极，反应中不仅能及时切换放电通道，有利于导出热量和控制荷电粒子的密度，从而抑制了热电离不稳定性，减少了积碳，提高了C₂烃的选择性。与旋转多尖端三排圆盘电极相比，克服了轴向电场不均匀性，扩大了放电空间和反应空间，提高了反应效率。同时，由于螺旋状电极的搅拌作用，增加了反应气体在放电空间中的紊流程度，使电离反应更充分、更均匀，从而也提高了CH₄转化率和C₂烃收率。 （2）工艺实验的研究结果表明：采用金属铜材料好于不锈钢材料，螺旋型结构优于三排圆盘结构。采用旋转三排圆盘电极反应器时，最高的CH₄转化率为66.45％，C₂烃单程收率及其选择性分别为63.62％和95.75％。采用旋转螺旋电极反应器最高的CH₄转化率为77.66％，C₂烃单程收率及其选择性分别为76.91％和99.03％。采用螺旋铜电极反应器在能量密度为800 kJ／mol时，能效最高为13.5％。 （3）利用发射光谱原位技术首次对旋转电极辉光等离子体作用下CH₄-H₂转化反应进行了诊断研究，在300 nm～700 nm波长范围内检测到C、CH、C₂、H和C等激发态物种。利用H原子的发射光谱，通过Boltzmann图解法计算得到等离子体的激发温度在6280 K～6629 K之间。由谱线展宽计算了电子密度，其数量级在10²⁰／m³。依据等离子体作用下CH₄-H₂反应的产物分析和发射光谱检测结果，探讨和推测了常压辉光等离更多还原

【Abstract】 With the increasingly decreased reserves of usable petroleum resource, rational use of natural gas was involved in not only utilization and allotment of future resources but also environmental conservation which was a matter of significance. Due to the high dissociation energy of the C-H bond of methane and the thermodynamically unfavorable reactions, no great progress had been made in the research of conventionally catalytic coupling of methane, and more attention had been paid to the study of new methods. Plasma was an efficient and green chemical processing for methane activation. In recent years, more and more attention and evaluation had been focused on plasma catalysis of methane conversion.The glow discharge at atmospheric pressure can generate no-equilibrium plasma which has high electronic energy. And it adapted to industrialization for its using without vacuum system. The experiments of glow discharge plasma conversion of methane to C₂ hydrocarbons were conducted by a novel reactor with rotary electrode at room temperature and atmospheric pressure. The results showed that CH4 conversion, single pass yield and selectivity of C₂ hydrocarbons were advanced. And the optical emission spectroscopy diagnosis of CH4-H2 conversion reaction using rotary electrode was conducted for the first time.The content and results of this paper was as following:（1） At the ambient temperature and pressure, an even glow discharge plasma was used as a new method for the coupling of methane with developed rotary multidentate helix electrode. The reaction efficiency using helix electrode was high than that of three discs electrode. The using of the reactor with rotary helix electrode improved the uniformity of the electric fields and CH₄ was treated uniformly. Also, the exhaust of heat in helix electrode was easier than that in three-disc electrode and the selectivity of C₂ rose accordingly. Besides the factors which led to uniform electric fields discussed above, the axial ununiformity of electric fields was overcome and the discharge and reaction zone was extended. Further more, the mixing of helix electrode improved the intensity of turbulent flow and the uniformity of gas mixture was enhanced correspondingly.（2） Results of the technics experiment: The result of copper electrode was better than that of stainless steel electrode and the structure of helix was superior to that of three discs. The maximum conversion of methane, the single pass yield and the selectivity of C₂ hydrocarbons using three discs electrode were 66.45%, 63.62% and 95.75%, and those using helix electrode更多还原