Equilibrium-Reduction of Ceria-based Materials for Solar Fuel ProductionFriedemann Call1, Martin Roeb1, Christian Sattler1, Martin Schmücker2, Brendan Bulfin3, Igor Shvets3

1Institute of Solar Research (DLR) ²Institute of Material Research (DLR)

³School of Physics, Trinity College Dublin

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Institute of Solar Research

-Evaluation Renewable Energies – 26th January 2009

-Prof. Dr. Robert Pitz-Paal – p 2

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Thermochemical Redox Cycles for Synthesis Gas

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The Bottle Neck: The Redox Material

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Doping Results

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F. Call et al., The American Journal of Analytical Chemistry, Vol. 117, No. 46, pp. 24129–24137, 2013.

Reduction in Equilibrium

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Results in Equilibirum

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F. Call et al., Journal of Physical Chemistry C, under revision

Feeding a Physical Reaction Model

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[Bul 13] B. Bulfin et al. The Journal of Physical Chemistry C, Vol. 117, No. 46, pp. 24129–24137, 2013.

Feeding a Physical Reaction Model

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Ellingham Diagrams of Doped-Materials

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Basic Efficiency Calculations

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F. Call et al., PhD Thesis. Will be submitted next month.

DLR.de  •  Folie 12 > Wettbewerb der Visionen >  Dünger für die Welt > Friedemann Call, Jan Felinks und Matthias Lange > 27.10.2014

Haber‐Bosch ProcessNH3

H HO

H H

CeO2‐x

O

‐1100°C ‐1400°C

H2from water

CuOx

N N

O O

O O

‐880°C ‐840°C

N2from air

New Idea: Ammonia Production

Conclusions

- Ceria-based materials are the most promising materials for Solar Fuels- Doping yields significant improvements

- Data of equilibrium measurements (varying T and p(O2)) can feed physical reaction model yielding a δ(T, p(O2))-function that can be used to construct Ellingham diagrams (reduction enthalpy and entropy)

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Thank you for your attention!

TGA

, O, O-function

reaction model Ellingham-function

∆∆

- New idea: Using a combined thermochemical cycle to produce H2 and N2, the precursor for Ammonia