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Redox kinetics of Zr+4 and Sm+3 doped ceria used for thermochemical hydrogen production

Knoblauch, Nicole and Dörrer, Lars and Fielitz, P. and Seeliger, Felix and Schmücker, Martin and Borchardt, G. (2015) Redox kinetics of Zr+4 and Sm+3 doped ceria used for thermochemical hydrogen production. International Conference on Ceramic Materials and Components for Energy and Environmental Applications., 14-19. Jun. 2015, Vancouver.

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Abstract

The kinetic of Zr+4 and Sm+3 doped CeO2, synthesized via citric acid combustion and Pechini method, have been investigated in view of their applicability as redox material in solar thermochemical cycles. Characterization by XRD indicates that single phase solid solutions with fluorite structure were formed. The microstructure and the molar ratio were analyzed by SEM and EDS. Thermo gravimetric measurements (TG) were performed on dense and porous samples between 1543 and 1753K at various oxygen partial pressures. The TG data suggest that doping with Zr+4 enhances the reduction of CeO2. A high porosity lowers the characteristic time constant of the mass change during redox reaction. For the water splitting reaction the porosity of the sample and O2 impurities of carrier gas and steam are found to be crucial. Moreover the hydrogen production rate of dense pellets is significantly lower as compared to powder samples. The XRD investigations indicate a structural evolution of CeO2-δ at high reduction state leading to the formation of a second phase that might hinder the following oxidation. Sm+3 doping prevents this evolution and hence the re-oxidation is facilitated. Furthermore a calculation of kinetic parameters based on the TG data, SIMS profile and dilatometry suggest that the reduction as well as oxidation is controlled by surface reactions.

Item URL in elib:https://elib.dlr.de/100341/
Document Type:Conference or Workshop Item (Speech)
Title:Redox kinetics of Zr+4 and Sm+3 doped ceria used for thermochemical hydrogen production
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Knoblauch, NicoleWF-KSWUNSPECIFIED
Dörrer, LarsTechnische Universität Clausthal, Institut für MetallurgieUNSPECIFIED
Fielitz, P.Institut für Metallurgie, Technische Universität Clausthal, Clausthal-ZellerfeldUNSPECIFIED
Seeliger, FelixDLR SF-SOLUNSPECIFIED
Schmücker, MartinWF-SFKUNSPECIFIED
Borchardt, G.Institut für Metallurgie, Technische Universität Clausthal, Clausthal-ZellerfeldUNSPECIFIED
Date:June 2015
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:Ceroxid
Event Title:International Conference on Ceramic Materials and Components for Energy and Environmental Applications.
Event Location:Vancouver
Event Type:international Conference
Event Dates:14-19. Jun. 2015
Organizer:The American Ceramic Society
HGF - Research field:Energy
HGF - Program:Renewable Energies
HGF - Program Themes:Concentrating Solar Systems (old)
DLR - Research area:Energy
DLR - Program:E SF - Solar research
DLR - Research theme (Project):E - Solar Process Technology (old)
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Research > Keramische Strukturwerkstoffe
Deposited By: Knoblauch, Nicole
Deposited On:13 Jan 2016 13:05
Last Modified:10 May 2016 23:37

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