低温等离子体裂解液态水辅助温室气体甲烷固定减排的研究

Study on the fixation and emission reduction of greenhouse gas methane assisted by low temperature plasma cracking liquid water

在当前碳中和、碳达峰的环境背景下,甲烷作为主要的温室气体,其减排技术与措施已经引起了全球关注.在众多的甲烷减排措施中,将甲烷在降解过程中转化为液态增值产物甲醇的技术措施,是缓解温室效应和解决能源危机的重要途径.低温等离子体可在常温常压条件下将气态的甲烷和液态的水活化裂解,并通过自由基反应直接生成液态甲醇,在固碳的同时达到甲烷增值转化的效果.本研究构建了气-液等离子体连续流反应装置,利用脉冲电源驱动甲烷与水在气-液界面形成等离子体,实现了甲烷的高效降解和固定,为非集中式排放的甲烷提供了一条可行的增值减排途径.同时,本研究系统考察了甲烷转化率和甲醇产率与输入功率和溶液pH之间的关系,并通过发射光谱、自由基淬灭和同位素示踪等方法研究了甲烷活化和甲醇生成的主要反应机理.性能优化结果表明,输入功率与甲醇产率之间存在火山峰关系,增加溶液电导率可以增加甲醇的产率且碱性溶液甲醇产率最高.机理研究结果表明,甲烷和水被等离子体分别活化为·CH_(3)和·OH,且·CH_(3)+·OH→CH_(3)OH为甲醇生成的主要路径.

Methane,as the main greenhouse gas,its emission reduction technologies has attracted global attention in the context of current carbon neutrality and carbon peak.Among the many methane reduction measures,the technology of converting methane into liquid value-added product methanol in the degradation process is an important way to alleviate the greenhouse effect and solve the energy crisis.Low-temperature plasma can activate gaseous methane and liquid water at room temperature and pressure,and directly produce liquid methanol through free radical reaction,achieving the effect of methane value-added conversion while carbon fixation.In this study,a continuous flow reaction device of gas-liquid plasma was constructed,and methane and water were driven to form plasma by pulse power at the gas-liquid interface,which realized the efficient degradation and fixation of methane,providing a feasible value-added and reduction pathway for de-centralized methane emissions.The relationship between methane conversion and methanol yield with input power,solution pH was studied in this system.The main reaction mechanism of methane activation and methanol production were studied by optical emission spectroscopy,radical spin-trapping/quenching experiment and isotope tracing experiment.Performance optimization results show that there is a volcano-shaped relationship between input power and methanol yield.Increasing the solution conductivity can increase the methanol yield,and an alkaline solution has the highest methanol yield.Mechanistic study show that methane and water are activated by plasma into·CH_(3) and·OH,respectively,and·CH_(3)+·OH→CH_(3)OH is the main pathway for methanol generation.