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Kinetic investigations of the hydrogen production step of a thermochemical cycle using mixed iron oxides coated on ceramic substrates

Neises, Martina und Roeb, Martin und Schmücker, Martin und Sattler, Christian und Pitz-Paal, Robert (2010) Kinetic investigations of the hydrogen production step of a thermochemical cycle using mixed iron oxides coated on ceramic substrates. International Journal of Energy Research, 34 (8), Seiten 651-661. Wiley Interscience. DOI: 10.1002/er.1565.

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Offizielle URL: http://www3.interscience.wiley.com/journal/3343/home

Kurzfassung

A two-step thermochemical cycle for solar hydrogen production using mixed iron oxides as the metal oxide redox system has been investigated. The ferrite is coated on a honeycomb structure, which serves as the absorber for solar irradiation and provides the surface for the chemical reaction. Coated honeycomb structures have already been tested in a solar receiver reactor in the solar furnace of DLR in Cologne with respect to their water splitting capability and their long-term stability. The concept of this new reactor design has proven feasible and constant hydrogen production during repeated cycles has been shown. For a further optimization of the process and in order to gain reliable performance predictions more information about the process especially concerning the kinetics of the oxidation and the reduction step are essential. To examine the hydrogen production during the water splitting step a test rig has been built up on a laboratory scale. In this test rig small coated honeycombs are heated by an electric furnace. The honeycomb is placed inside a tube reactor and can be flushed with water vapour or with an inert gas. A homogeneous temperature within the sample is reached and testing conditions are reproducible. Through analysis of the product gas the hydrogen production is monitored and a reaction rate describing the hydrogen production rate per gram ferrite can be formulated. Using this test set-up, SiC honeycombs coated with zinc ferrite have been tested. The influences of the temperature and the water concentration on the hydrogen production during the water splitting step have been investigated. An analysis of the ferrite conversion was performed using the Shrinking Core Model. A mathematical approach for the peak reaction rate at the beginning of the water splitting step was formulated and the activation energy was calculated from the experimental data. An activation energy of 110 kJ mol1 was found.

Dokumentart:Zeitschriftenbeitrag
Titel:Kinetic investigations of the hydrogen production step of a thermochemical cycle using mixed iron oxides coated on ceramic substrates
Autoren:
AutorenInstitution oder E-Mail-Adresse der Autoren
Neises, MartinaTT-SF
Roeb, MartinTT-SF
Schmücker, MartinWF-KS
Sattler, ChristianTT-SF
Pitz-Paal, RobertTT-SF
Datum:25 Juni 2010
Erschienen in:International Journal of Energy Research
Referierte Publikation:Ja
In Open Access:Nein
In SCOPUS:Ja
In ISI Web of Science:Ja
Band:34
DOI :10.1002/er.1565
Seitenbereich:Seiten 651-661
Herausgeber:
HerausgeberInstitution und/oder E-Mail-Adresse der Herausgeber
Dincer, IbrahimNICHT SPEZIFIZIERT
Verlag:Wiley Interscience
Status:veröffentlicht
Stichwörter:mixed iron oxides; ferrite; thermochemical cycle; water splitting; hydrogen; kinetics
HGF - Forschungsbereich:Energie
HGF - Programm:Erneuerbare Energie
HGF - Programmthema:E SF - Solarforschung (alt)
DLR - Schwerpunkt:Energie
DLR - Forschungsgebiet:E SF - Solarforschung
DLR - Teilgebiet (Projekt, Vorhaben):E - Solare Stoffumwandlung (alt)
Standort: Köln-Porz
Institute & Einrichtungen:Institut für Technische Thermodynamik > Solarforschung
Hinterlegt von: Dr.rer.nat. Christian Sattler
Hinterlegt am:14 Jul 2010 10:53
Letzte Änderung:07 Feb 2013 20:25

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