SOFC中干甲烷浓度对Ni-YSZ阳极上反应的影响

为探讨固体氧化物燃料电池(solid oxide fuel cell, SOFC)中干甲烷浓度对反应的影响,采用色谱在线测量阳极尾气,总结阳极尾气的变化规律。在此基础上,分析干甲烷在固体氧化物燃料电池Ni-YSZ阳极上的反应,寻找干甲烷浓度与电流对电池阳极反应影响的数学关系。结果表明,随着电流密度的增加,低浓度甲烷按顺序发生CH₄+O^2- → CO+2H₂+2e^-、CH₄+2O^2- → CO+H₂O+H₂ +4e^-、CH₄+3O^2- → CO+2H₂O + 6e^-、CH₄+4O^2- → CO₂+2H₂O+8e^-反应,高浓度甲烷只发生甲烷的第一个氧化反应,中浓度甲烷发生前两个或前三个反应。依据法拉第第一定律及反应物之间的关系,确定甲烷的低、中、高浓度的判定依据分别为:q_v(CH₄)≤I/(4F)、I/(4F)≤q_v(CH₄)≤I/(2F)、q_v(CH₄)≥I/(2F)。

Effects of dry methane concentration on the methane reactions at Ni-YSZ anode in solid oxide fuel cell

The dry methane with different concentration was used to research the dry methane reactions at Ni-YSZ anode in solid oxide fuel cell (SOFC). The anode exhaust gases were measured by on-line chromatography. The reactions of dry methane with different concentration at SOFC Ni-YSZ anodes were analyzed by summarizing the anode exhaust gases regular pattern for different reactions. The mathematical relationships between dry methane concentration and current for different anode reaction were studied. As the oxygen ion concentration at the anode three-phase boundary increasing continuously, the following reactions with low concentration methane occurs in sequence of CH₄+O^2- → CO+2H₂+2e^-, CH₄+2O^2- → CO+H₂O+H₂+e^-, CH₄+3O^2- → CO+2H₂O+6e^- and CH₄+4O^2- → CO₂+2H₂O+8e^-. The first two or three reactions occurred with medium methane concentration, while the first reaction occurred only with high methane concentration. The judgment for methane in low, medium or high concentrations were q_v(CH₄)≤I/(4F)、I/(4F)≤q_v(CH₄)≤I/(2F)、q_v(CH₄)≥I/(2F) which are based on Faraday's first law and the relationship among the reactant species.