Professor Hilde J. Venvik, Department of Chemical Engineering, NTNU – Norwegian University of Science and Technology, Trondheim, Norway

Pd alloy and cobalt single crystal surfaces as catalytic model systems

Hilde J. Venvik works in the Catalysis group at the Dept. of Chemical Engineering, NTNU, and obtained her PhD from the Dept. of Physics at the same university. She is currently also Director of iCSI (industrial Catalysis Science and Innovation), a Centre for research-based innovation (SFI) granted by the Research Council of Norway for the period 2015-22. The research institutions in the Centre are University of Oslo and SINTEF in addition to NTNU, and the industrial partners are Yara, KA Rasmussen AS, Dynea, INOVYN and Haldor Topsøe AS.

The lecture will give an overview over recent results from investigating Co(11-20) as a Fischer-Tropsch model systems, and Pd alloy surfaces as model systems for Pd based membranes for hydrogen purification as well as catalysts. With respect to cobalt, restructuring is proposed as playing a role under FTS conditions, under which several issues remain debated, such as the reaction and deactivation mechanisms. The CO induced, anisotropic restructuring of Co(11-20) was investigated by DFT, STM, XPS, and TPD without and with K pre-deposited to further understand the role of CO in the migration of Co and the (deactivating) effect of K under FTS conditions. A similar approach was taken to investigate the decomposition of C2H4 on this surface, from which a (2x5) carbon overlayer is formed at approx. 200 C. Recent TPD results will be emphasized for this part.

Pd75Ag25(100) and Pd3Au(100) have been investigated with DFT and XPS, and compared with Pd(100), in order to elucidate the segregation dynamics under different exposures and reaction conditions. The alloy surfaces are known to exhibit Ag or Au as the energetically favored termination under vacuum, whereas Pd termination is preferred with O/CO/H adsorbed. All three surfaces may form a characteristic (5 x 5)R27° surface oxide under oxygen exposure at elevated temperature. Recent results exploring CO oxidation as a probe reaction for near-ambient pressure photoelectron spectroscopy (NAPPES) investigations of the surface reconstruction and segregation behavior will be presented.

If time allows, the lecture will give a brief overview of the iCSI Centre research topics and the potential for model systems investigations. 

Host: Associate professor Jeppe Vang Lauritsen, iNANO & Dept. of Physics and Astronomy, AU