甲烷等离子体法制氢气和碳材料研究进展

Research progresses on production of hydrogen and carbon materials by methane pyrolysis using plasma

关键词:  等离子体  直流电弧放电  甲烷裂解  低碳排放  碳材料 

Key words:  plasma  direct current arc discharge  methane pyrolysis  low carbon dioxide emission  carbon material

摘要:

传统甲烷制氢技术会伴随大量的二氧化碳排放,甲烷等离子体法裂解技术将甲烷中的碳元素直接转化为固体碳材料,过程无二氧化碳排放,并有效提高了甲烷的利用价值。通过文献调研方式回顾和分析了甲烷等离子体法裂解技术在国内外的发展现状。研究结果表明:①甲烷等离子体法裂解中等离子体的类别主要分为热等离子体和冷等离子体,冷等离子体中主要的活性粒子是高能电子,热等离子体中的活性物质为高能电子和重粒子；②冷等离子体的产生方式主要有电晕放电、介质阻挡放电、滑动电弧放电等,所需功率较低；热等离子体的产生方式主要为直流电弧放电、直流-射频耦合放电,所需功率较高；③甲烷在等离子体中的转化率和氢气的产率与工作气体类别、工作气体与甲烷物质的量比、气体电解功率大小、电极构型、反应腔体结构等工艺参数都有直接关系；④通过调整工艺参数和电极结构设计,甲烷在等离子体中可裂解生成如炭黑、碳纳米管、石墨烯纳米薄片等不同形貌的固体碳材料,产品多样。结论 认为,甲烷等离子体法裂解技术不仅可以降低温室气体排放,还是甲烷高附加值利用的一个重要方向；提高甲烷等离子体法制氢的能量利用效率和生成碳材料的选择性是该技术的发展方向。

Abstract:

Production of hydrogen from methane in traditional way is accompanied by a mass of carbon dioxide emission. Pyrolysis of methane via plasma for the production of hydrogen and carbon materials could avoid the carbon dioxide emission and provide a way for the high added-value utilized of methane. Therefore, this paper reviews and analyzes domestic and foreign main research progresses on the production of hydrogen and carbon materials by methane pyrolysis using plasma in recent years by means of literature investigation. And the following research results were obtained. First, thermal and cold plasma are the mainly used in the methane pyrolysis. The active species in cold plasma are the high-energy free electrons, the active species in thermal plasma are the high-energy free electrons and heavy particles. Second, the ways to produce cold plasma mainly include corona discharge, dielectric barrier discharge, gliding arc and the power need for generation cold plasma is low. The ways to produce thermal plasma mainly include direct current arc discharge, direct current-radio frequency discharge and the power need for generation thermal plasma is high. Third, the methane conversion and the hydrogen productive rate are related to the plasma gas, the molar ratio between methane and plasma gas, the gas discharge power, the configuration of electrode and the structure of reaction chamber. Fourth, the morphology of carbon materials from methane pyrolysis by plasma differs significantly. The form of carbon materials cloud be carbon black, carbon nanotube, carbon graphene nanosheet and so on, different morphology could be obtained by adjusting the operational condition and configuration of electrode. In conclusion, methane pyrolysis by plasma can reduce the emission of greenhouse gas, moreover, provide a new way for the high added-value utilization of methane. In the future, increasing the energy efficiency for hydrogen production and the selectivity for production of carbon materials are the development direction of methane pyrolysis by plasma.