纳秒脉冲介质阻挡放电等离子体氮还原合成氨的研究

氨气(NH3)可以合成富含氮的化肥,还是不含碳的能量载体。工业合成氨工艺通常在高温高压条件下进行,会消耗大量能源且伴随着温室气体的排放。低温、常压下的非热平衡等离子体为合成氨提供了一种有潜力、可持续的途径。为此以氮气和氢气为原料,在低温常压下用脉冲介质阻挡放电等离子体合成氨,主要探究了脉冲参数(脉冲峰值电压、脉冲重复频率、脉冲上升沿)对合成氨体积分数的影响。此外,还考察了气体体积比例、填充氩气和放电间隙对合成氨的影响,分析电学特性和发光图像。结果表明,在电压12 kV、重复频率3k Hz、气体体积比例N2:H2=2:1条件下,NH3体积分数最高可达17 600×10–6,相应的能量效率为1.61 g/k Wh。脉冲重复频率对氨气体积分数有显著影响,增大脉冲重复频率,单位时间内高能电子的数量增加并且运动加剧,更多的N2、H2分子被激发或解离从而NH3体积分数增大。

Study on Reduction of Nitrogen to Ammonia by Nanosecond Pulse Dielectric Barrier Discharge Plasma

Ammonia (NH3) can be synthesized as a nitrogen-rich fertilizer and also a carbon-free energy carrier.The traditional ammonia synthesis process is carried out under high temperatures and high pressures,with a large amount of energy consumption and greenhouse gas emissions.Non-thermal plasma(NTP) can be employed to synthesize ammonia at room temperature and atmospheric pressure,providing a potential and sustainable way to synthesize ammonia.In this paper,the synthesis process of ammonia from N2 and H2 driven by nanosecond pulsed dielectric barrier discharge (DBD)was studied.The effects of different pulse parameters,including pulse peak voltage,repetition frequency,pulse rising time,on the volume fraction of synthetic ammonia were investigated.In addition,the effects of gas ratio,discharge gap,and different proportions of Ar on the effect of synthetic ammonia were also explored,and the electrical characteristics and luminescent images of the discharge were analyzed.The results show that the maximum NH3 volume fraction of17 600×10–6 and energy efficiency of 1.61 g/k Wh can be acquired at 12 k V,3 k Hz and volume ratio for N2:H2 is 2:1.The pulse repetition frequency has a significant effect on ammonia volume fraction,and the volume fraction of ammonia increases with the increase of repetition frequency.As the repetition frequency increases,the number of high-energy electrons per unit of time also increases,and more N2 and H2 gas molecules are excited or dissociated,which increases the volume fraction of NH3.