“…The reduced oxygen carrier is then regenerated with steam, which enables the production of high-purity hydrogen without an additional separation step. The chemical-looping process can be performed using a number of different reductants, such as gas from coal [13] or biomass [14][15][16] gasification, light hydrocarbons reforming [17], methane [18][19][20], a CH 4 /CO 2 and CH 4 /H 2 mixture [20,21], pyrolysis oil [22,23], methanol [24], and pure H 2 (as a method for H 2 storage) [25,26]. Furthermore, the nature of the oxide, used as the ionic oxygen and electron carrier, and the reaction conditions are important parameters because they determine the potential for low costs and high efficiency of this process in order to have a commercial impact.…”