On the Function of Ceria Supported Rhodium Catalysts for Methanation of Carbon Dioxide
In this work, Rh/CeO2 catalysts were prepared by incipient wetness impregnation and studied in situ during CO2 hydrogenation in regards to its structural behaviour, by the use of high-energy X-ray diffraction and ambient pressure X-ray photoelectron spectroscopy, as well as the surface reactions using diffuse reflectance infrared spectroscopy. As signals from processes and adsorbates that truly participate in the reaction may be hidden by spectator signals, these studies were performed transiently as to enhance the response of active species while decreasing that of spectators.
It was revealed that CeO2 is active during reaction conditions, possibly partaking in a cycle of formation and healing of oxygen vacancies during the reaction cycle as evidenced by the cycling of Ce4+ and Ce3+. Furthermore, while predominantly reduced, a RhOx phase was observed, showing the strong metal support interaction of Rh and CeO2. Regarding surface reactions, several carbonyl species (b-CO, h-CO, m-CO) were shown to be active on the catalyst, as well as some carbonates (b-CO3, p-CO3) and formate (b-HCOO) species.
While the complete pathway need more experimental data to be determined, the activity of the carbonyl species suggests that the reaction follows a carbon monoxide based pathway such as the carbide pathway.
In situ spectroscopy
Chalmers, Kemi och kemiteknik, Tillämpad kemi
Structure-function relationship for CO2 methanation over ceria supported Rh and Ni catalysts under atmospheric pressure conditions
Catalysis Science and Technology,; Vol. 9(2019)p. 1644-1653
Artikel i vetenskaplig tidskrift
Hemmingsson, F., Schaefer, A., Skoglundh, M., Carlsson, P.-A. CO2 Methanation over Rh/CeO2 Studied with Infrared Modulation Excitation Spectroscopy and Phase Sensitive Detection
Atomär design av katalysatorer
Knut och Alice Wallenbergs Stiftelse (KAW2015.0058), 2016-01-07 -- 2021-06-30.
Licentiatuppsatser vid Institutionen för kemi och kemiteknik, Chalmers tekniska högskola
Pater Noster, Kemivägen 10