Tou Maria, Michalsky Ronald, Steinfeld Aldo
Department of Mechanical and Process Engineering, ETH Zürich, 8092 Zürich, Switzerland.
Joule. 2017 Sep 6;1(1):146-154. doi: 10.1016/j.joule.2017.07.015.
Splitting CO with a thermochemical redox cycle utilizes the entire solar spectrum and provides a favorable path to the synthesis of solar fuels at high rates and efficiencies. However, the temperature/pressure swing commonly applied between reduction and oxidation steps incurs irreversible energy losses and severe material stresses. Here, we experimentally demonstrate for the first time the single-step continuous splitting of CO into separate streams of CO and O under steady-state isothermal/isobaric conditions. This is accomplished using a solar-driven ceria membrane reactor conducting oxygen ions, electrons, and vacancies induced by the oxygen chemical potential gradient. Guided by the limitations imposed by thermodynamic equilibrium of CO thermolysis, we operated the solar reactor at 1,600°C, 3·10 bar [Formula: see text] and 3,500 suns radiation, yielding total selectivity of CO to CO + ½O with a conversion rate of 0.024 μmol·s per cm membrane. The dynamics of the oxygen vacancy exchange, tracked by GC and XPS, further validated stable fuel production.
利用热化学氧化还原循环分解一氧化碳可利用整个太阳光谱，并为以高速率和高效率合成太阳能燃料提供了一条有利途径。然而，还原步骤和氧化步骤之间通常采用的温度/压力摆动会导致不可逆的能量损失和严重的材料应力。在此，我们首次通过实验证明，在稳态等温/等压条件下，一氧化碳可单步连续分解为一氧化碳和氧气的独立流。这是通过一个由太阳能驱动的氧化铈膜反应器实现的，该反应器传导由氧化学势梯度诱导的氧离子、电子和空位。在一氧化碳热解热力学平衡所施加的限制条件指导下，我们在1600°C、3×10巴[公式：见原文]和3500个太阳辐射强度下运行太阳能反应器，一氧化碳转化为一氧化碳 + ½氧气的总选择性为0.024 μmol·s每平方厘米膜，转化率为0.024 μmol·s每平方厘米膜。通过气相色谱法（GC）和X射线光电子能谱（XPS）追踪的氧空位交换动力学，进一步验证了稳定的燃料生产。
