Regensburg 2016 – scientific programme
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O: Fachverband Oberflächenphysik
O 40: Heterogeneous Catalysis: Experiment
O 40.5: Talk
Tuesday, March 8, 2016, 15:00–15:15, S053
High-pressure scanning tunneling microscopy during hydrodesulfurization catalysis — •Rik V. Mom1, Joost W.M. Frenken1,2, and Irene M.N. Groot3 — 1Huygens-Kamerlingh Onnes Laboratory, Niels Bohrweg 2, Leiden, The Netherlands — 2Advanced Research Center for Nanolithography, Science Park 104, Amsterdam, The Netherlands — 3Gorlaeus Laboratories, Einsteinweg 55, Leiden, The Netherlands
Many catalysts show reversible physical and chemical changes during operation. To capture these changes, in situ studies at elevated temperatures and pressures are essential. Using a home-built high-pressure scanning tunneling microscope we have studied reversible changes during the desulfurization reaction, in which sulfur is removed from hydrocarbons.
CxHyS + H2 → CxHy + H2S
To mimic the industrial catalyst, MoS2 nanoparticles were deposited on Au(111). We have studied the surface dynamics of this model catalyst during the conversion of CH3SH to CH4 in 1 bar of various CH3SH/H2 mixtures at temperatures up to 250∘C. From our observations, it is clear that the atomic arrangement of the active sites depends on the gas environment. We show that the sulfur coverage of the active sites during catalysis is higher than expected from DFT equilibrium calculations [1]. We show that this can be explained by kinetic effects based on the high-energy barriers involved in the reaction.
Lauritsen et al., Journal of Catalysis 221 (2004) 510-522