Cerium(IV) oxide–cerium(III) oxide cycle

The cerium (IV ) oxide cerium (III) -oxide or a two-stage CeO2/Ce2O3-Verfahren thermochemical process for producing hydrogen from water making use of solar energy. The cerium oxides are oxidized and reduced in the circuit. The method comprises the separate Redoxschritten dissociation and hydrolysis:

Dissociation:

Hydrolysis:

The first endothermic step is performed under an inert atmosphere at about 2000 ° C, produced by concentrated sunlight in a heliostat. In the second step exothermic ° C, water vapor is supplied in a fixed bed reactor at 400 to 600, ( IV) oxide is formed by oxidation of the hydrogen from the cerium (III) to cerium oxide.

Since oxygen and hydrogen occur in separate steps, a complex gas separation is unnecessary. The process is not yet industrially in use, but is developed by several research groups worldwide.