In chemical looping, hydrogen is produced from water splitting
during the oxidation with water. Nevertheless, in these experiments
water was substituted by carbon dioxide, thermodynamically
equivalent at 850 C. The values of DG for reactions (2) and
(3) at 850 C are very similar, as well as the corresponding equilibrium
constants. The validity of the substitution of steam by carbon
dioxide was experimentally verified in a previous work by Liu et al.
[13] reproducing the same cyclic conversion in a fluidized bed at
850 C with both gases.