Takacs M, Ackermann S, Bonk A, Neises-von Puttkamer M, Haueter Ph, Scheffe J R, Vogt U F, Steinfeld A
Dept. of Mechanical and Process Engineering ETH Zurich Zurich 8092 Switzerland.
Laboratory of Materials for Energy Conversion EMPA Dübendorf 8600 Switzerland; Institute for Geo- and Life Sciences, Crystallography, Albert-Ludwigs-Universität Freiburg Freiburg 79085 Germany.
AIChE J. 2017 Apr;63(4):1263-1271. doi: 10.1002/aic.15501. Epub 2016 Oct 5.
Thermochemical splitting of CO via a ceria-based redox cycle was performed in a solar-driven thermogravimetric analyzer. Overall reaction rates, including heat and mass transport, were determined under concentrated irradiation mimicking realistic operation of solar reactors. Reticulated porous ceramic (RPC) structures and fibers made of undoped and Zr-doped CeO, were endothermally reduced under radiative fluxes of 1280 suns in the temperature range 1200-1950 K and subsequently re-oxidized with CO at 950-1400 K. Rapid and uniform heating was observed for 8 ppi ceria RPC with mm-sized porosity due to its low optical thickness and volumetric radiative absorption, while ceria fibers with μm-sized porosity performed poorly due to its opacity to incident irradiation. The 10 ppi RPC exhibited higher fuel yield because of its higher sample density. Zr-doped ceria showed increasing reduction extents with dopant concentration but decreasing specific CO yield due to unfavorable oxidation thermodynamics and slower kinetics.
通过基于二氧化铈的氧化还原循环对CO进行热化学分解，是在太阳能驱动的热重分析仪中进行的。在模拟太阳能反应堆实际运行的集中辐照下，测定了包括热传递和质量传递在内的总反应速率。由未掺杂和Zr掺杂的CeO制成的网状多孔陶瓷（RPC）结构和纤维，在1200 - 1950 K的温度范围内，于1280个太阳的辐射通量下进行吸热还原，随后在950 - 1400 K下用CO进行再氧化。由于其低光学厚度和体积辐射吸收，对于具有毫米级孔隙率的8 ppi二氧化铈RPC，观察到快速且均匀的加热，而具有微米级孔隙率的二氧化铈纤维由于其对入射辐照的不透明性，表现较差。10 ppi的RPC由于其较高的样品密度而表现出更高的燃料产率。Zr掺杂的二氧化铈随着掺杂剂浓度的增加，还原程度增加，但由于不利的氧化热力学和较慢的动力学，特定CO产率降低。
