Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Surface adsorbates during CO2 Hydrogenation on Rh(111) probed in-situ by x-ray photoelectron spectroscopy at 150 mbar
Stockholm University, Faculty of Science, Department of Physics.ORCID iD: 0000-0001-6085-2916
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
Show others and affiliations
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The catalytic CO2 hydrogenation reaction was examined in situ by High Pressure X-ray Photoelectron Spectroscopy (HP-XPS) at 150 mbar and between 150 and 350°C. The results indicate two temperature regimes; the first one with temperature dependent desorption of carbon species between 150°C and 200°C. The second temperature regime is between 250 and 350 °C. In this interval, the carbon species are formed and immediately reacted away, resulting in a lower temperature dependence on surface coverage. The XPS coverage calculations and the component analysis indicate that water is the most abundant surface adsorbate, and that CHx fragments and CO are the most abundant carbon species. The hydrogenation state of the CHx species varies with temperature, where higher temperatures result in a larger population of more hydrogenated species.

Keywords [en]
HP-XPS, XPS, catalysis, in situ
National Category
Other Physics Topics
Research subject
Chemical Physics
Identifiers
URN: urn:nbn:se:su:diva-168274OAI: oai:DiVA.org:su-168274DiVA, id: diva2:1307710
Funder
Swedish Research CouncilAvailable from: 2019-04-29 Created: 2019-04-29 Last updated: 2019-05-02Bibliographically approved
In thesis
1. BUILDING AN X-RAY PHOTOELECTRON SPECTROSCOPY ENDSTATION FOR OPERANDO STUDIES OF CATALYTIC CO AND COHYDROGENATION REACTIONS
Open this publication in new window or tab >>BUILDING AN X-RAY PHOTOELECTRON SPECTROSCOPY ENDSTATION FOR OPERANDO STUDIES OF CATALYTIC CO AND COHYDROGENATION REACTIONS
2019 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

X-ray Photoelectron Spectroscopy (XPS) provides an element-specific surface sensitive probe of the chemical composition in a system, and is consequently one of the workhorses of surface science and catalysis research. The obtained information on the chemical and physical state of the catalyst and adsorbates is essential in the endeavor to achieve a fundamental understanding how chemical reactions are facilitated by the catalyst. Due to the short mean free path of electrons in gaseous media most of the XPS experiments so far are done in the range between ultra-high vacuum (<10-7 mbar) and near-ambient pressure (1-10 mbar) regimes. For certain reactions, such as the hydrogenation of CO and CO2, higher pressures (comparable to one bar or higher) are needed in order to give a more realistic representation of the system.

This thesis concerns the theoretical background, design, build-up and the first results of an instrument with the goal to bridge the pressure gap between operando conditions at the solid gas interface and surface science model systems. Thanks to a new design of the electron analyzer front cone we have built an instrument where the relevant length scales are reduced to match the electron inelastic mean free path in pressurized atmospheres above one bar. A number of key factors make this possible, but most prominently it is the unique sample environment using a “virtual pressure cell” in combination with a grazing incidence geometry below the critical angle of total reflection. Furthermore, the instrument utilizes hard x-rays to generate high-kinetic energy electrons and thereby increase the mean free path in the pressurized atmosphere. Lastly, the instrument uses a laser-based heating solution which removes the effect of electric and magnetic fields.

With this we have been able to (1) record spectra of Rh above 2 bar of inert atmosphere, as well as with reaction mixtures of CO2 + O2 up to 1 bar and (2) probe surface species and observe temperature dependent chemistry during CO2 hydrogenation during ongoing reactions at 150 mbar.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University, 2019. p. 52
National Category
Other Physics Topics
Research subject
Chemical Physics
Identifiers
urn:nbn:se:su:diva-168657 (URN)
Presentation
2019-05-22, AlbaNova, FA 31, Roslagstullsbacken 21, Stockholm, 11:18 (English)
Opponent
Supervisors
Available from: 2019-06-11 Created: 2019-05-02 Last updated: 2019-06-11Bibliographically approved

Open Access in DiVA

No full text in DiVA

Search in DiVA

By author/editor
Degerman, DavidAmann, PeterShilpilin, MikhailWang, Hsin-YiGladh, JörgenNilsson, Anders
By organisation
Department of Physics
Other Physics Topics

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 283 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf