Hercynite Cycle
Like the traditional iron oxide cycle, the hercynite is based on the oxidation and reduction of iron atoms. However unlike the traditional cycle, the ferrite material reacts with a second metal oxide, aluminum oxide, rather than simply decomposing. The reactions take place via the following two reactions:
(1) M(II)Fe2(III)O4 + 3Al2O3 → M(II)Al2(III)O4 + 2Fe(II)Al2(III)O4 + ½O2 (Reduction)
(2) M(II)Al2(III)O4 + 2Fe(II)Al2(III)O4 + H2O → M(II)Fe2(III)O4 + 3Al2O3 + H2 (Oxidation)
The reduction step of the hercynite reaction takes place at temperature ~ 200 oC lower than the traditional water splitting cycle ( 1200 oC). This leads to lower radiation losses, which scale as temperature to the fourth power.
Read more about this topic: Iron Oxide Cycle
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