(664g) Reduction Kinetics of Iron Aluminate (FeAl2O4) for Solar Thermochemical H2O Splitting

Authors: 
Al-Shankiti, I., University of Colorado at Boulder
Al-Salik, Y., Sabic
Idriss, H., Sabic
Weimer, A. W., University of Colorado Boulder
Solar Thermochemical Water Splitting Processing (STWS) is a promising technology for producing renewable H2[1]. A metal oxide, such as hercynite (FeAl2O4), is first reduced with high temperature concentrated sunlight to produce O2[2]. Then, the reduced material is exposed to steam to re-oxidize it and produce H2. Low O2 partial pressure is required to drive the reduction reaction. An intriguing potentially highly efficient process is the recycle of inert sweep gas at near atmospheric pressure using a high temperature O2 ionic transport membrane (ITM)[3], since the recycled gas is already at the required high temperature. In this work, we present preliminary experimental results for hercynite reduction using a TGA and separately the removal of O2 from 1% O2/inert down to ppm levels using a laboratory high temperature ITM. The impact of separation energy requirements is evaluated for the overall solar to H2 cycle.

1. Muhich, C.L., et al., A review and perspective of efficient hydrogen generation via solar thermal water splitting. WIREs Energy Environ 2016, 5:p. 261â??287. doi: 10.1002/wene.174

2. Muhich, C.L., et al., Predicting the solar thermochemical water splitting ability and reaction mechanism of metal oxides: a case study of the hercynite family of water splitting cycles. Energy & Environmental Science, 2015. 8(12): p. 3687-3699.

3. Ehrhart, B.D., et al., System efficiency for two-step metal oxide solar thermochemical hydrogen production â?? Part 3: Various methods for achieving low oxygen partial pressures in the reduction reaction. Int. J Hydrogen Energy (online) http://dx.doi.org/10.1016/j.ijhydene.2016.07.106.