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

Simplified diagram of the cerium(IV) oxide–cerium(III) oxide cycle

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 2,000 °C (3,630 °F) and 100-200 mbar into cerium(III) oxide and oxygen. In the second exothermic step cerium(III) oxide reacts at 400 °C (752 °F)–600 °C (1,112 °F) 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

References

1. Hydrogen production from solar thermochemical water splitting cycles Archived August 30, 2009, at the Wayback Machine.
2. High-Flux solar-driven thermochemical dissociation of CO2 and H2O using nonstoichiometric ceria

External links

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