脉冲介质阻挡放电等离子体催化CH_4直接转化

研究了微秒脉冲和纳秒脉冲介质阻挡放电等离子体CH_4转化过程。对比了两种脉冲电源激励的CH_4介质阻挡放电等离子体特性,考察了不同脉冲电源激励时重复频率、流速和输入功率对CH_4转化效率及气态产物分布的影响,并对不同实验条件下CH_4转化反应路径的选择进行了分析。实验结果发现,CH_4转化气态产物均以H_2、C2H_6为主,CH_4转化率和H_2产率随着重复频率的上升而下降,但随流速的增大而减小。相同重复频率和流速条件下,微秒脉冲电源激励时CH_4转化率和H_2产率较高,而纳秒脉冲电源激励时具有能量利用率高的优势。在高重复频率、低流速条件下,在石英管内壁和金属电极上会产生更多的积炭和液态烃,因此导致反应的碳氢平衡降低。微秒脉冲电源激励时,随着输入功率的升高氢气和乙烷选择性下降,纳秒脉冲电源激励时呈现出相反的趋势。

Plasma Enhanced CH4 Direct Conversion in Pulsed Dielectric Barrier Discharges

In this paper,plasma catalytic reforming of CH4 is carried out by both microsecondpulse and nanosecond-pulse dielectric barrier discharges (DBDs).Characteristics of DBD plasma for microsecond-pulse and nanosecond-pulse had been compared.Effects of pulse repetition rate,CH4 flow rate and input power on the convention rate of CH4 and distribution of gaseous products are investigated.Moreover,the corresponding selection of chemical reaction paths is analyzed.The results show that main parts of the gaseous products are H2 and C2H6.The conversion rate of CH4 and the yield of hydrogen increase with the pulse repetition rate,but they decrease with the CH4 flow rate.Furthermore,the conversion rate of CH4 and the yield of hydrogen are high for microsecond-pulse DBD when the pulse repetition rate and the CH4 flow rate are fixed.The energy efficiency in the case of nanosecond-pulse DBD is higher than that in the case of microsecond-pulse DBD.In addition,coking and liquid hydrocarbons appear on the quartz tube and inner electrode at the conditions of high pulse repetition rate and low CH4 flow rate,leading to the reduction of C&H balance.The selectivities of H2 and C2H6 decreases with the increase of the input power in the case of microsecond-pulse DBD,while they increase with the input power in the case of nanosecond-pulse DBD.