Cerium (IV) oxide-cerium (III) oxide process

The cerium (IV) oxide-cerium (III) oxide or CeO ₂ / Ce ₂ O ₃ process is a two-stage thermochemical process for generating hydrogen from water using solar energy . The cerium oxides are oxidized and reduced in the circuit. The process consists of the separate redox steps of dissociation and hydrolysis :

Dissociation:

${\displaystyle \mathrm {2\,CeO_{2}\longrightarrow Ce_{2}O_{3}+{\tfrac {1}{2}}\,O_{2}} }$

Cerium (IV) oxide dissociates to form cerium (III) oxide and oxygen

Hydrolysis:

${\displaystyle \mathrm {Ce_{2}O_{3}+H_{2}O\longrightarrow 2\,CeO_{2}+H_{2}} }$

Cerium (III) oxide reacts with water to form cerium (IV) oxide and hydrogen

The first endothermic step takes place under inert gas at around 2000 ° C, which is generated by concentrated sunlight in a heliostat . In the second exothermic step, steam is fed into a fixed-bed reactor at around 400 to 600 ° C., from which hydrogen is formed through oxidation of the cerium (III) oxide to cerium (IV) oxide .

Since oxygen and hydrogen occur in separate steps, there is no need for complex gas separation. The process is not yet in industrial use, but is being developed by several research groups around the world.

See also

• Hydrosol project
• Zinc-zinc oxide process

literature

• Water-splitting via Thermochemical Cycling of Ceria . In: ECS Meeting Abstracts . tape 901 , no. 7 , May 2009, p. 381 (English).
• Stéphane Abanades, Gilles Flamant: Thermochemical hydrogen production from a two-step solar-driven water-splitting cycle based on cerium oxides . In: Solar Energy . tape 80 , no. December 12 , 2006, pp. 1611–1623 , doi : 10.1016 / j.solener.2005.12.005 (English).