双针-板结构脉冲气泡放电等离子体固氮研究

Study of nitrogen fixation by nanosecond pulsed gas-liquid discharge with needle-plate configuration

大气压低温等离子体可以利用空气直接进行氧化固氮,具有反应条件温和、参数灵活可控、避免温室气体排放等优点.本文利用双针-板电极在水中形成气泡放电等离子体,以空气为放电气体进行了固氮研究,分析了产物浓度和固氮能耗的影响因素.研究结果表明,等离子体中含有丰富的氮原子、氧原子、氢原子、激发态氮分子等活性物种,可高效合成硝态含氮产物.研究发现,脉冲参数、电极间隙、工作气体组分对气泡放电等离子体的固氮性能有重要影响.装置最高NO~-_x合成速率为19.2μmol/min,最小能耗约为11 MJ/mol.此外还发现,电极间隙为6 mm时,固氮性能最优;空气中增加适量氧气(氧气/氮气比例为0.4)可以增强产物合成,降低能耗.

Atmospheric pressure low-temperature plasma can directly oxidize and fix nitrogen from the air,offering advantages such as mild reaction conditions,flexible and controllable parameters,and avoiding greenhouse gas emissions.In this paper,a nitrogen fixation study was carried out by using a double needle-plate electrode to form a bubble discharge plasma in water,with air as the discharge gas.The influencing factors of product concentration and energy consumption in the nitrogen fixation process were analyzed.The results show that the plasma contains varied active species such as nitrogen atoms,oxygen atoms,hydrogen atoms,and excited state nitrogen molecules,enabling efficient synthesis of nitric nitrogenous products.It is found that the pulse parameters,electrode gap,and working gas components have an important influence on the nitrogen fixation performance of the bubble discharge plasma.The highest NO^(-)_(x) synthesis rate of the device is 19.2μmol/min,corresponding to a minimum energy consumption of 11 MJ/mol.The optimal nitrogen fixation performance is observed at an electrode gap of 6 mm.Addition of an appropriate amount of oxygen in the air(with the ratio of oxygen/nitrogen of 0.4)can enhance the product synthesis and reduce the energy consumption.