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Oxidation and Reduction Reaction Kinetics of Mixed Cerium Zirconium Oxides

Bulfin, Brendan and Call, Friedemann and Vieten, Josua and Roeb, Martin and Sattler, Christian and Shvets, Igor (2016) Oxidation and Reduction Reaction Kinetics of Mixed Cerium Zirconium Oxides. Journal of Physical Chemistry C, 120 (4), pp. 2027-2035. ACS Publications. DOI: 10.1021/acs.jpcc.5b08729 ISSN 1932-7447

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Official URL: http://pubs.acs.org/journal/jpccck

Abstract

The oxidation and reduction of mixed cerium zirconium oxides, Ce1−xZrxO2, with x varied in the range 0−0.3 in steps of 0.05, in a low-pressure oxygen atmosphere were experimentally investigated. The experiments utilized a novel method developed by the authors, in which the samples are reduced and oxidized in a sealed vacuum chamber by irradiating them with a xenon arc lamp. The changes in pressure due to the release or consumption of oxygen are used to quantify the extent and rates of the reactions. The System can achieve heating rates in excess of 100 °C s−1, which is hundreds of times faster than is possible with a thermobalance. In addition, the gas phase transport is very rapid as it is driven by pressure gradients. The combined high heating rate and fast gas phase transport offers unique conditions in which to measure the actual kinetics of the reactions. The oxidation kinetics showed a strong dependence on the amount of Zr4+ in the samples, where the rate of oxidation decreased with increasing Zr4+ concentration. The effect of adding 2.5% Sm3+ or La3+ to the Ce0.85Zr0.15O2 was also investigated with the hope of improving the kinetics. The addition of La3+ to Ce0.85Zr0.15O2 was seen to offer an increase in the reaction rates, although the oxidation kinetics were still slower than that of pure CeO2. Finally, the reduction kinetic data are presented, but even with the optimal conditions the reduction reaction still appeared to be limited by the heating rate; thus, it was concluded that the reduction kinetics were too rapid to quantify by this method.

Item URL in elib:https://elib.dlr.de/103205/
Document Type:Article
Title:Oxidation and Reduction Reaction Kinetics of Mixed Cerium Zirconium Oxides
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Bulfin, Brendanbrendan.bulfin (at) dlr.deUNSPECIFIED
Call, Friedemannfriedemann.call (at) dlr.deUNSPECIFIED
Vieten, Josuajosua.vieten (at) dlr.deUNSPECIFIED
Roeb, MartinMartin.roeb (at) dlr.deUNSPECIFIED
Sattler, Christianchristian.sattler (at) dlr.deUNSPECIFIED
Shvets, Igorivchvets (at) tcd.ieUNSPECIFIED
Date:4 February 2016
Journal or Publication Title:Journal of Physical Chemistry C
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:120
DOI :10.1021/acs.jpcc.5b08729
Page Range:pp. 2027-2035
Publisher:ACS Publications
ISSN:1932-7447
Status:Published
Keywords:Cerium oxide, Zirconium oxide, thermochemical cycle, redox reactions
HGF - Research field:Energy
HGF - Program:Renewable Energies
HGF - Program Themes:Solar Fuels
DLR - Research area:Energy
DLR - Program:E SF - Solar research
DLR - Research theme (Project):E - Solar Fuels (old)
Location: Köln-Porz
Institutes and Institutions:Institute of Solar Research > Solare Verfahrenstechnik
Deposited By: Sattler, Prof. Dr. Christian
Deposited On:14 Mar 2016 15:17
Last Modified:06 Sep 2019 15:22

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