elib
DLR-Header
DLR-Logo -> http://www.dlr.de
DLR Portal Home | Imprint | Privacy Policy | Contact | Deutsch
Fontsize: [-] Text [+]

Evidence of entropy effects and changes in re-oxidation behavior of Ceria-Zirconia solutions as function of thermal pre-treatment

Knoblauch, Nicole and Schmücker, Martin (2019) Evidence of entropy effects and changes in re-oxidation behavior of Ceria-Zirconia solutions as function of thermal pre-treatment. The 13th Pacific Rim Conference of Ceramic Societies (PACRIM13), 27. Okt.-1. Nov., Japan.

Full text not available from this repository.

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 fuels is a two-step water splitting reaction in a solar thermo-chemical cycle. Especially doped and undoped CeO2 are considered as promising redox materials for thermochemical purposes [1]. So redox kinetics of pure CeO2-d and Ce0.85Zr0.15O2-d, synthesized via Pechini method [2] and thermally pre-treated at 1473K and 1923K, respectively, have been investigated in view of their applicability as redox material for thermochemical hydrogen production. Reduction values d of thermal pre-treated samples were determined by thermal analyses as function of temperature and pO2. With these data redox-enthalpies and entropies were identified. The investigation indicates that the redox behavior of Ce0.85Zr0.15O2-d mixed oxide is influenced by high-temperature pre-treatment at ambient pressure conditions. Both, enthalpy and entropy of redox-reaction are found to be affected by thermal pre-treatment apart from the fact that Zr addition anyway affects the redox thermodynamics of CeO2. In particular, the redox entropy of higher pre-treated (1923K) samples is strikingly reduced. This finding is explained by a decrease of configuration entropy, which in turn is attributed to a pyrochlore-based superstructure. Furthermore, the oxygen vacancy-stabilizing pyrochlore-type structure counteracts the re-oxidation and water splitting behavior. So Ce0.85Zr0.15O2 samples pre-treated at 1923K need temperatures above 700K to re-oxidize in air and are not able to split water in contrast to samples pre-treated at 1473K/1573K which re-oxidize in air already at 400K and could be re-oxidized by water vapour.

Item URL in elib:https://elib.dlr.de/128669/
Document Type:Conference or Workshop Item (Speech)
Title:Evidence of entropy effects and changes in re-oxidation behavior of Ceria-Zirconia solutions as function of thermal pre-treatment
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Knoblauch, NicoleNicole.Knoblauch (at) dlr.deUNSPECIFIED
Schmücker, MartinMartin.Schmuecker (at) dlr.deUNSPECIFIED
Date:November 2019
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:Ceria-Zirconia, two-step water splitting reaction
Event Title:The 13th Pacific Rim Conference of Ceramic Societies (PACRIM13)
Event Location:Japan
Event Type:international Conference
Event Dates:27. Okt.-1. Nov.
HGF - Research field:Energy
HGF - Program:Renewable Energies
HGF - Program Themes:Solar Fuels
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
Deposited By: Knoblauch, Nicole
Deposited On:06 Nov 2019 15:46
Last Modified:06 Jan 2020 13:20

Repository Staff Only: item control page

Browse
Search
Help & Contact
Information
electronic library is running on EPrints 3.3.12
Copyright © 2008-2017 German Aerospace Center (DLR). All rights reserved.