摘要
针对Fe3O4化学链制氢和CO2分离过程,研究了Fe3O4在CO气氛下还原以及铁在水蒸气下氧化的动力学特性.用Coats-Redfen单升温速率积分法、Ozawa组合升温速率法和lnln恒温分析法对反应机理进行了探讨,并计算了动力学参数.热重数据计算结果表明:在CO和N2体积分数分别为5%和95%时,还原反应属于一级反应,750～900,℃时反应活化能为112,kJ/mol;在CO、CO2和N2体积分数分别为42.9%、14.3%和42.8%时,还原反应可用Jander扩散模型描述,750,～950,℃时反应活化能为49.828,kJ/mol;经Ozawa法验证,加入CO2后的还原反应活化能明显降低.铁与水蒸气的氧化反应接近二维核生长模型,反应活化能较低,为29.633,kJ/mol,且随着温度升高,反应速率常数增大.
Kinetics of chemical looping hydrogen generation （CLHG）with inherent separation of CO2 using Fe3O4 as the oxygen carrier have been studied through reducing Fe3O4 by CO and oxidizing Fe by steam vapor. Coats-Redfen equation, Ozawa equation and lnln equation were successfully applied to describe the different processes. It was found that the reduction of Fe3O4 by volume fraction of CO and N2 is 5% and 95% （within 750--900 ℃ range） could be interpreted theoretically as the first order reaction and the activation energy was estimated to be 112 kJ/mol.When the reaction gas changed into volume fraction of CO, CO2 and N2 are 42.9%, 14.3% and 42.8%, the mechanism of the reduction process turned out to be diffusion controlled, which was described by Jander equation, and the activation energy remarkably dropped to 49.828 kJ/mol, which was validated by Ozawa equation. Oxidation process of Fe by steam vapor could be interpreted as the 2D crystals＇ nucleation. The activation energy of the oxidation process was 29.633 kJ/mol, and the frequency factor improved as the temperature increased.
出处
《燃烧科学与技术》
EI
CAS
CSCD
北大核心
2011年第6期534-540,共7页
Journal of Combustion Science and Technology
基金
国家自然科学基金资助项目(50776018)
国家重点基础研究发展计划(973计划)资助项目(2007CB210101)
关键词
化学链燃烧
制氢
动力学特性
活化能
chemical-looping combustion
hydrogen production
kinetics characteristic
activation energy
