In-situ analysis of Ni/CeZrO2 during CH4 reforming with CO2
Conversion of methane and carbon dioxide into H2 and CO represents a lasting academic and industrial challenge. Appropriately designed catalysts based on nickel nanoparticles, dispersed on CeO2 or CeZrO2 are active and resistant to side reactions, especially carbon accumulation. The latter often leads to premature catalyst deactivation.
Unraveling the mechanism of methane and CO2 conversion over Ni/CeO2 catalyst enables further improvements of the catalyst. In order to obtain relevant information on the working state of the catalyst, characterization must be performed at conditions which mimic closely those under the reaction conditions. This can be a substantial technical challenge.
This research is a collaboration between the Department of Inorganic Chemistry and Technology (D09) from the National Institute of Chemistry (Kristijan Lorber, Janvit Teržan and dr. Petar Djinović) and BNL, Argonne National Laboratory and NSLS, where several in-situ techniques (XRD, AP-XPS and XAFS) were used to investigate the role of zirconium dopant (Zr) in the Ni/CeO2 catalyst.
Presence of Zr manifests itself as higher catalytic activity and H2 selectivity in comparison with pure Ni/CeO2. The origin of observed catalytic improvements are higher fraction of Ce3+ achieved during Ni/CeZrO2 catalyst activation, which is maintained also during catalytic reaction. Nickel is during reaction present exclusively in metallic state, Zr remains 4+ and does not change its valence. Zr4+ is incorporated in the structure of CeO2 and forms a solid solution. This improves thermal stability of CeO2, prevents its sintering and also prevents incorporation of Ni into CeO2 lattice, causing formation of NiCeOx solid solution. The result is a higher fraction of catalytically active nickel on the surface of CeZrO2 support.
The published research brings direct evidence of important properties of the active Ni/CeZrO2 catalyst which enables simultaneous conversion of methane and carbon dioxide into syngas at relatively mild conditions.
Research was published in ACS Catalysis magazine:
ZHANG, Feng , LIU, Zongyuan, CHEN, Xiaobo, RUI, Ning, BETANCOURT, Luis E., LIN Lili, XU, Wenqian, SUN, Chengjun, ABEYKOON, A. M. Milinda, RODRIGUEZ, José A., TERŽAN, Janvit, LORBER, Kristijan, DJINOVIĆ, Petar, SENANAYAKE, Sanjaya D. Effects of Zr Doping into Ceria for the Dry Reforming of Methane over Ni/CeZrO2 Catalysts: in Situ Studies with XRD, XAFS, and AP-XPS. ACS Catalysis, 2020, 10, 3274−3284.
For further information please contact: petar.djinovic[at]ki.si