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

The cerium(IV) oxide–cerium(III) oxide cycle or CeO₂/Ce₂O₃ cycle is a two-step thermochemical process that employs cerium(IV) oxide and cerium(III) oxide for hydrogen production.^[1] The cerium-based cycle allows the separation of H₂ and O₂ in two steps, making high-temperature gas separation redundant.

Process description

The thermochemical two-step water splitting process (thermochemical cycle) uses redox systems:^[2]

• Dissociation

2CeO₂ → Ce₂O₃ + 0.5 O₂

• Hydrolysis

Ce₂O₃ + H₂O → 2CeO₂ + H₂

For the first endothermic step, cerium(IV) oxide is thermally dissociated in an inert gas atmosphere at 2000°C and 100-200 mbar into cerium(III) oxide and oxygen. In the second exothermic step cerium(III) oxide reacts at 400°C–600°C in a fixed bed reactor with water and produces hydrogen and cerium(IV) oxide.

See also

• Copper–chlorine cycle
• Heliostat
• Hybrid sulfur cycle
• HYDROSOL
• Iron oxide cycle
• Solar thermal energy
• Sulfur–iodine cycle
• Zinc–zinc oxide cycle

External links

• Thermochemical hydrogen production from a two-step solar-driven water-splitting cycle based on cerium oxides

Notes and References

1. Web site: Hydrogen production from solar thermochemical water splitting cycles. https://web.archive.org/web/20090830011704/http://www.solarpaces.org/Tasks/Task2/HPST.HTM. dead. August 30, 2009.
2. High-Flux Solar-Driven Thermochemical Dissociation of CO2 and H2O Using Nonstoichiometric Ceria. Aldo. Steinfeld. Sossina M.. Haile. Philipp. Furler. Danien. Scipio. Mandy. Abbott. Christoph. Falter. William C.. Chueh. December 24, 2010. Science. 330. 6012. 1797–1801. 10.1126/science.1197834. 21205663. 14494021.