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Preferential CO oxidation on well-defined ceria nanoparticles promoted by Pt, Au and Cu: Deciphering the structure of reactive sites using in situ high-energy-resolution XAS / XES and infra-red spectroscopy

Applicant Safonova Olga
Number 140750
Funding scheme Project funding (Div. I-III)
Research institution Paul Scherrer Institut
Institution of higher education Paul Scherrer Institute - PSI
Main discipline Physical Chemistry
Start/End 01.05.2013 - 30.06.2017
Approved amount 237'562.00
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All Disciplines (2)

Discipline
Physical Chemistry
Inorganic Chemistry

Keywords (12)

RIXS; Au; infra-red spectroscopy; Cu; Pt; CeO2; in situ ; high-energy-resolution XAS / XES; combined techniques ; CO preferential oxidation; valence-to-core XES; HERFD XAS

Lay Summary (German)

Lead
Das Ziel der präferenziellen Oxidation von CO ist, die CO Konzentration von 1 % auf 1 - 100 ppm zu senken, während andere Gase (z.B. H2) nicht oxidiert werden sollten. Die Zielsetzung dieses Projektes ist es, den Mechanismus der PROX Reaktion auf einer atomaren Ebene zu verstehen, wobei die Katalysatoren mit einer gut definierten Nanostruktur hergestellt werden und mit struktursensitiven spektroskopischen Methoden charakterisiert werden.
Lay summary

Inhalt und Ziel des Forschungsprojekts.

Das Ziel dieses Forschungsprojektes ist es, die Struktur der aktiven Zentren in Ceroxid-basierten Katalysatoren für die präferentielle Oxidation (PROX) von CO mittels einer einzigartien Kombination von struktursensitiven in situ Charakterisierungsmethoden: Röntgenabsorptions- und -emissionspektroskopie (XAS und XES) mit hoher Energieauflösung sowie Infrarotspektroskopie. Die Katalysatoren besitzen massgeschneiderten Nanostrukturen (stab-, kubus- und polyederförmig) und sind mit Platin, Gold und/oder Kupfer dotiert. Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojekts. Wir erwarten eine Korrelation zwischen der Aktivität und Selektivität von PROX mit den Redoxeigenschaften der exponierten kristallographischen Oberflächen des Ceroxids, der Grösse und des Oxidationszustandes der Nanopartikel die mit Pt, Au und Cu geformt werden, sowie der Koordinierung von CO und anderen reaktiven Spezies an der Katalysatoroberfläche, zu finden. Mit diesem Wissen kann besser verstanden werden, welche strukturellen Eigenschaften des Metall-Ceroxid systems entscheidend für eine selektivere und stabile PROX Katalyse sind.  
Direct link to Lay Summary Last update: 16.04.2013

Responsible applicant and co-applicants

Employees

Name Institute

Publications

Publication
X-ray emission spectroscopy: highly sensitive techniques for time-resolved probing of cerium reactivity under catalytic conditions
Kopelent Rene, van Bokhoven Jeroen, Nachtegaal Maarten, Szlachetko Jakub, Safonova Olga (2016), X-ray emission spectroscopy: highly sensitive techniques for time-resolved probing of cerium reactivity under catalytic conditions, in Physical Chemistry Chemical Physics, 18, 32486.
Catalytically Active and Spectator Ce3+ in Ceria Supported Metal Catalysts
Kopelent Rene, van Bokhoven Jeroen A., Szlachetko Jakub, Edebeli Jacinta, Paun Cristina, Nachtegaal Maarten, Safonova Olga V. (2015), Catalytically Active and Spectator Ce3+ in Ceria Supported Metal Catalysts, in Angewante Chimie International Edition, 54(30), 8728-8731.

Collaboration

Group / person Country
Types of collaboration
Kovalenko Lab - Funtional inorganic materials/ ETH Zurich Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Department of Solid State Physics/Southern Federal University, Rostov-on-Don Russia (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
EMRS Fall meeting, Symposium S Talk given at a conference CO oxidation on ceria-based catalysts: Complexity of reaction mechanisms uncovered by time-resolved X-ray spectroscopy 16.09.2019 Warsaw, Poland Safonova Olga;
ACS Fall meeting Talk given at a conference Time-resolved XAFS spectroscopy uncovers multiple roles of the Ce4+/Ce3+ redox couple in the mechanism of low temperature CO oxidation. 20.08.2018 Boston, United States of America Safonova Olga;
Operando VI Talk given at a conference The multiple roles of the Ce4+/Ce3+ redox couple in the mechanism of low temperature CO oxidation on ceria-based catalysts uncovered by time-resolved XAFS spectroscopy 14.04.2018 Malaga, Spain Safonova Olga;
SCS Fall meeting 2016 Talk given at a conference Rational design of ceria-based supported noble metal catalysts for low temperature CO oxidation using transient X-ray absorption spectroscopy 15.09.2016 Zurich, Switzerland Kopelent René; van Bokhoven Jeroen Anton; Safonova Olga; Nachtegaal Maarten;
SCS Fall Meeting 2015 Talk given at a conference Active and spectator Ce3+ species in a ceria-based platinum catalyst during low-temperature CO oxidation 04.09.2015 Lausanne, Switzerland Kopelent René; Safonova Olga;
XAFS16 Talk given at a conference Identification of active species during low-temperature CO oxidation on a ceria-based catalyst using in situ time-resolved resonant X-ray emission spectroscopy 23.08.2015 Karlsruhe, Germany Nachtegaal Maarten; Safonova Olga; Kopelent René; van Bokhoven Jeroen Anton;
XAFS16 Poster Transient fluorescence detected X-ray absorption spectroscopy provides deeper insight in the CO oxidation mechanism on ceria based catalyst 23.08.2015 Karlsruhe, Germany van Bokhoven Jeroen Anton; Safonova Olga; Kopelent René; Nachtegaal Maarten;
SCS Fall Meeting 2014 Poster In Situ Resonant X-Ray Emission Spectroscopy of Ce3+ Formation During CO Oxidation at Low Temperatures over Platinum Nanoparticles Supported on Ceria. 11.09.2014 Zurich, Switzerland Nachtegaal Maarten; Safonova Olga; Kopelent René; van Bokhoven Jeroen Anton;


Awards

Title Year
Rene Kopelent has got a Prize for Runners‘ up at SCS Fall Meeting 2015 for his talk "Active and spectator Ce3+ species in a ceria-based platinum catalyst during low-temperature CO oxidation" [CE-026] 2015

Associated projects

Number Title Start Funding scheme
170743 An ultra-high resolution scanning electron microscope (SEM) for low-energy imaging and analysis 01.02.2017 R'EQUIP

Abstract

The goal of the proposed research is to determine the structure-performance relations in ceria-based CO preferential oxidation (PROX) catalysts using specifically tailored nanostructures based on shaped ceria nanocrystals (rods, cubes, polyhedra) promoted by Pt, Au and Cu surface species and a unique combination of in situ structure sensitive techniques: high-energy-resolution X-ray absorption and emission (XAS and XES) spectroscopic methods and infra-red spectroscopy. Shaped ceria (CeO2) nanoparticles: polyhedra, rods and cubes exposing particular crystallographic planes (111, 100 or 110) of CeO2 in fluorite structure were recently synthesized at PSI and ETH using hydrothermal methods. These structures will be promoted by different concentrations of Pt, Au and Cu using wet-chemistry synthetic methods. High resolution transmission electron microscopy (HRTEM) will provide statistical information on the size distribution of the nanoparticles and clusters formed by promoters on the planes of shaped ceria supports. The catalytic activity of the well-defined nanostructures will be evaluated in a fixed-bed reactor. The structure of the catalysts with highest activity will be further studied in situ.The high-energy-resolution XAS and XES spectroscopies: high-energy-resolution fluorescence detected (HERFD) XAS, resonance inelastic X-ray scattering (RIXS), and valence-to-core XES recently became available at the SuperXAS beam line of the Swiss Light Source. Due to enhanced energy resolution these methods show improved sensitivity compared to standard XAS to the geometric and electronic structure (oxidation state) of Ce, Pt, Au and Cu. A new state-of-the-art plug-flow reactor will be developed for combination of in situ high-energy-resolution XAS and XES methods with infra-red spectroscopy. This reactor will be made available to the wide community of SLS users.The element sensitive synchrotron-based spectroscopies applied in situ under industrially relevant PROX conditions will provide the information about the reactivity of shaped ceria nanocrystals (formation of Ce3+ and oxygen vacancies) and the oxidation state, the local symmetry and the coordination of Pt, Au and Cu dopants participating in CO activation. The structure and concentration of adsorbed molecules (CO, OH, H2O, formates, carbonates etc.) coordinated on the metal centers and ceria support will be analyzed in situ by infra-red spectroscopy. The performance of the catalysts will be probed online using mass-spectroscopy and gas-chromatography. Combination of in situ and complementary new and state-of-the-art characterization and synthesis techniques will uniquely allow accessing information that will enable deciphering the structure of the active sites. We expect to find the correlation between the PROX activity and selectivity, the redox properties of exposed crystallographic planes of ceria, the size and the oxidation state of nanoparticles formed by Pt, Au and Cu and the way how CO and what intermediates coordinate to the catalyst surface. This knowledge will help to determine which structural features of the metal-CeO2 system are essential for more selective and stable PROX catalysts.
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