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Title:Operando XAS analysis of CuO/SiO2 and CuO/CeO2 catalysts
Authors:ID Arčon, Iztok, UNG (Author)
ID Teržan, Janvit, Kemijski inštitut Ljubljana (Author)
ID Djinović, Petar, Kemijski inštitut Ljubljana (Author)
ID Zabilsky, Maxim, Kemijski inštitut Ljubljana (Author)
ID Pintar, Albin, Kemijski inštitut Ljubljana (Author)
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Language:English
Work type:Not categorized
Typology:1.12 - Published Scientific Conference Contribution Abstract
Organization:UNG - University of Nova Gorica
Abstract:The possibilities of the operando XAS analysis of catalysts will be presented on two case studies of promising new catalytic materials: alkali doped nano-dispersed copper oxide clusters on ordered mesoporous SiO2, which is highly active and selective towards propylene epoxidation [1], and nanoshaped CuO/CeO2 catalysts used in N2O decomposition reaction [2]. Operando Cu K-edge and Ce L3-edge XANES and EXAFS analysis was performed during catalytic reactions under controlled reaction conditions in a tubular reactor filled with protective He atmosphere at 1 bar. The spectra were measured before the reaction at RT, then during heating, and during catalytic reaction at 400 °C under controlled atmosphere. Operando XANES analysis is used to monitor the changes in valence states and local symmetries of Cu and Ce cations in the catalysts. A partial reduction of Cu2+ to Cu+ and Cu0 and Ce4+ to Ce3+ species was detected during catalyst activation, and re-oxidation during catalytic reaction. Different dynamics of reaching a quasi-steady oxidation state were revealed as the tested catalysts approached the quasi-steady state after 300 min of reaction. Operando EXAFS spectra are used to precisely determine local structure of Cu and Ce cations, to identify structural characteristics and changes of Cu and Ce species during the catalytic reactions. In this way, the active site in the catalytic reactions can be identified and the mechanism of the reaction clarified. The results of operando XAS analyses are crucial to guide further material modification, to obtain more effective catalyst, and material which is more resistant to inhibiting effects that cause catalyst deactivation during catalytic reaction.
Keywords:katalizatorji, Cu XANES, EXAFS
Year of publishing:2018
Number of pages:1
PID:20.500.12556/RUNG-4069-8b7a3b25-9cad-42e8-f256-bad3683b58bf New window
COBISS.SI-ID:5219835 New window
NUK URN:URN:SI:UNG:REP:F7QCUZKZ
Publication date in RUNG:12.09.2018
Views:3820
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Record is a part of a monograph

Title:Book of abstracts, European Conference on X-Ray Spectrometry - EXRS-2018
Editors:Matjaž Kavčič
Place of publishing:Ljubljana
Publisher:Inštitut Jožef Stefan
Year of publishing:2018
ISBN:978-961-264-126-9
Conference organizer:Inštitut Jožef Stefan

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