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Energies 2018, 11(9), 2451; https://doi.org/10.3390/en11092451

Solar-Driven Thermochemical Water-Splitting by Cerium Oxide: Determination of Operational Conditions in a Directly Irradiated Fixed Bed Reactor

1
Unit of High Temperature Processes, IMDEA Energy Institute, Avda. Ramón de la Sagra 3, 28935 Móstoles, Spain
2
Department of Chemical and Energy Technology, ESCET, Universidad Rey Juan Carlos, c/Tulipán s/n, 28933 Móstoles, Madrid, Spain
*
Author to whom correspondence should be addressed.
Received: 6 June 2018 / Revised: 16 August 2018 / Accepted: 12 September 2018 / Published: 15 September 2018
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Abstract

Concentrated solar energy can be transformed into electricity, heat or even solar fuels, such as hydrogen, via thermochemical routes with high exergetic efficiency. In this work, a specific methodology and experimental setup are described, developed to assess the production of hydrogen by water splitting making use of commercial cerium oxide, ceria (CeO2), in a solarized reactor. A fixed bed reactor, directly irradiated by a 7 kWe high flux solar simulator (HFSS) was used. Released H2 and sample temperature levels were continuously monitored. Three tests were carried out consisting of three consecutive redox cycles each, with irradiances in the range of 1017–2034 kWm−2. It was necessary to achieve a compromise between sample temperatures (higher temperatures lead to higher reduction rates) and sample stability, since absorbed radiation can degrade a sample at lower temperature (1280–1480 °C) than in a conventional infrared oven (T > 2000 °C). Irradiating the surface of the sample with an irradiance of 2034 kWm−2 (270 W of total radiation power) during 9.5 min eventually degraded the sample, resulting in a conversion into stoichiometrically reduced oxide (Ce2O3) of 11%. A similar conversion was achieved (9.7%) after 2 min of irradiation at 270 W (100% of radiation), but without irreversibly damaging the sample. View Full-Text
Keywords: hydrogen; solar fuels; water splitting; directly irradiated reactor; fixed bed; cerium oxide hydrogen; solar fuels; water splitting; directly irradiated reactor; fixed bed; cerium oxide
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
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Arribas, L.; González-Aguilar, J.; Romero, M. Solar-Driven Thermochemical Water-Splitting by Cerium Oxide: Determination of Operational Conditions in a Directly Irradiated Fixed Bed Reactor. Energies 2018, 11, 2451.

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