Investigation of long term reactive stability of ceria for use in solar thermochemical cycles

摘要

The use of an intermediate reactive material composed of cerium (IV) oxide (ceria) is explored for solar fuel production through a CO2-splitting thermochemical redox cycle. To this end, powder and porous ceria samples are tested with TGA (thermogravimetric analysis) to ascertain their maximum fuel production potential from the CeO2 -> CeO2-delta cycle. A maximum value of the non-stoichiometric reduction factor delta of ceria powder was 0.0383 at 1450 degrees C. The reactive stability of a synthesized porous ceria sample is then observed with carbon dioxide splitting at 1100 degrees C and thermal reduction at 1450 degrees C. Approximately 86.4% of initial fuel production is retained after 2000 cycles, and the mean value of delta is found to be 0.0197. SEM (scanning electron microscopy) imaging suggests that the porous ceria structure is retained over 2000 cycles despite apparent loss of some surface area. EDS (energy dispersive x-ray spectroscopy) line scans show that oxidation of porous ceria becomes increasingly homogenous throughout the bulk material over an increasing number of cycles. Significant retention of reactivity and porous structure demonstrates the potential of porous ceria for use in a commercial thermochemical reactor. (C) 2015 Elsevier Ltd. All rights reserved.