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Redox kinetics of co-doped Ceria ceramics for solar-thermochemical fuel production

Knoblauch, Nicole and Lee, Kangjae and Mechnich, Peter and Alkan, Gözde and Roeb, Martin (2023) Redox kinetics of co-doped Ceria ceramics for solar-thermochemical fuel production. Helmholtz Energy Conference 2023, 2023-06-12 - 2023-06-13, Koblenz, Deutschland.

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Abstract

The utilization of clean and sustainable energy becomes important for solving global environmental problems and securing future energy supply. A possible method for producing CO for fuels is a two-step CO2 splitting reaction in a solar thermo-chemical cycle. Especially doped CeO2 are considered as promising redox materials for thermochemical purposes [1]. So, the oxidation kinetics of Zr doped ceria and co-doped ceria with Zr–La, Zr–Yb and Zr-Y were investigated by thermogravimetric analysis in synthetic air and CO2 to specify the influence of ionic radii and valence of dopants. Samples co-doped with Zr–La, Zr–Yb and Zr-Y exhibited high reduction states and oxidation kinetics that were much faster than 10mol% Zr-doped ceria. The extrinsic oxygen vacancy induced by the trivalent dopants improves the kinetics especially at oxidation temperatures below 700 ◦C, where the oxidation is more diffusion than surface exchange controlled. In the case of the oxidation with air the ionic radii of the dopant have a little influence. At lower temperature La doped ceria reoxidizes a little faster than Yb and Y doped ceria. However, the ionic radii become more important in the CO2 splitting reaction. Here La doped ceria shows significantly faster reoxidation both as a single doping and in combination with Zr. Since, in addition to the perfect doping, the sample shape is also crucial for fast oxidation also compacts consisting of fibers with diameters in the range of 8–10 µm have been successfully prepared by direct infiltration of commercial YSZ fibers with a cerium oxide matrix and subsequent sintering. The resulting chemically homogeneous fiber-compacts are sinter-resistant up to 1923 K and retain a high porosity of around 58 vol%. An evaluation of redox kinetics shows that the relaxation time of oxidation is five times faster than that of dense samples of the same composition. The fiber compacts show a high potential for the application in thermochemical redox cycling due its fast redox kinetics. [1] e.g. Jonathan R. Scheffe, Aldo Steinfeld, Oxygen exchange materials for solar thermochemical splitting of H2O and CO2: a review, Volume 17, Issue 7, September 2014, Pages 341-348

Item URL in elib:https://elib.dlr.de/196072/
Document Type:Conference or Workshop Item (Speech)
Title:Redox kinetics of co-doped Ceria ceramics for solar-thermochemical fuel production
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Knoblauch, NicoleUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Lee, KangjaeUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Mechnich, PeterUNSPECIFIEDhttps://orcid.org/0000-0003-4689-8197139005265
Alkan, GözdeUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Roeb, MartinUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Date:12 June 2023
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:Redoxmaterialien, Ceroxid, CSP
Event Title:Helmholtz Energy Conference 2023
Event Location:Koblenz, Deutschland
Event Type:international Conference
Event Start Date:12 June 2023
Event End Date:13 June 2023
Organizer:Helmholtz
HGF - Research field:Energy
HGF - Program:Materials and Technologies for the Energy Transition
HGF - Program Themes:Chemical Energy Carriers
DLR - Research area:Energy
DLR - Program:E SW - Solar and Wind Energy
DLR - Research theme (Project):E - Solar Fuels
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Research > Structural and Functional ceramics
Deposited By: Knoblauch, Nicole
Deposited On:20 Jul 2023 10:45
Last Modified:24 Apr 2024 20:56

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