Sukma Made Santihayu, Zheng Yaoyao, Hodgson Paul, Scott Stuart Ashley
Department of Engineering, University of Cambridge, Trumpington Street, CB2 1PZ Cambridge, United Kingdom.
Energy Fuels. 2022 Sep 1;36(17):9410-9422. doi: 10.1021/acs.energyfuels.2c01065. Epub 2022 Aug 17.
Previous work on calcium ferrites showed they were able to convert syngas to hydrogen via chemical looping. The mixture of iron and calcium and their oxides has different thermodynamic properties than iron oxide alone. Here, the use of methane, an abundant fuel, is investigated as the reductant in chemical looping syngas production. In contrast to syngas-fueled cycles, the looping materials became more active with cycling using methane as the fuel. When reduced by methane, the looping material often showed a significant induction period, indicating that products of reduction (in particular metallic Fe) acted as a catalyst for further reduction. The behavior in a thermogravimetric analyzer (TGA) and a fluidized bed was comparable, i.e., no degradation with cycling. The reduced CF appeared to be easily reformed when oxidized with CO, and there was little evidence of bulk phase segregation. The improved kinetics on cycling was likely due to the separation of metallic Fe onto the surface. Using hydrogen to partially reduce CF promotes the catalytic pyrolysis of methane.
先前关于钙铁氧体的研究表明，它们能够通过化学链反应将合成气转化为氢气。铁、钙及其氧化物的混合物具有与单独的氧化铁不同的热力学性质。在此，研究了使用丰富的燃料甲烷作为化学链合成气生产中的还原剂。与以合成气为燃料的循环相比，使用甲烷作为燃料时，循环材料变得更加活跃。当被甲烷还原时，循环材料通常会显示出明显的诱导期，这表明还原产物（特别是金属铁）起到了进一步还原的催化剂作用。热重分析仪（TGA）和流化床中的行为具有可比性，即不会随循环而降解。还原后的CF在用CO氧化时似乎很容易重整，几乎没有体相分离的迹象。循环时动力学的改善可能是由于金属铁在表面的分离。用氢气部分还原CF可促进甲烷的催化热解。
