Universiteit Leiden

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Research project

Surface and Interface Science

The nanoscale structure of a catalyst under reaction conditions determines its activity, selectivity, and stability. For the production of sustainable energy and materials, new catalysts are needed. By understanding the structure-activity relationships of catalysts under reaction conditions, insight in the development of these new catalysts can be obtained. Using in situ imaging techniques under industrial conditions, Prof. Irene Groot is currently studying Fischer-Tropsch synthesis, NO reduction and oxidation, hydrodesulfurization, and chlorine production.

Irene Groot

Recently it has become clear that essential differences can exist between the behavior of catalysts under industrial conditions (high pressure and temperature) and the (ultra) high vacuum conditions of traditional laboratory experiments. Differences in structure, composition, reaction mechanism, activity, and selectivity have been observed. These observations indicated the presence of the so-called pressure gap, and made it clear that meaningful results can only be obtained at high pressures and temperatures. However, most of the techniques traditionally used to study catalysts and their reactions were designed to operate under (ultra) high vacuum conditions. To bridge the pressure gap, the last years have seen a tremendous effort in designing new instruments and adapting existing ones to be able to investigate catalysts in situ under industrially relevant conditions.

The ReactorSTM/AFM setups

The research group of Prof. Irene Groot uses set-ups that combine an ultrahigh vacuum environment for model catalyst preparation and characterization with a high-pressure flow reactor cell, integrated with either a scanning tunneling microscope or an atomic force microscope. With these set-ups, the ReactorSTM and ReactorAFM, the group is able to perform atomic-scale investigations of well-defined model catalysts under industrial conditions. Additionally, the group combines the structural information from scanning probe microscopy with time-resolved mass spectrometry measurements on the gas mixture that leaves the reactor. In this way, they can correlate structural changes of the catalyst due to the gas composition with its catalytic performance.

Scanning tunneling microscopy image of Pt(111) at 423 K and 4 mbar NO2 in Ar (1.2 bar)

Furthermore, Prof. Groot is currently working on the integration of STM and AFM in a single microscope, and on the integration of scanning probe microscopy with surface X-ray diffraction (in collaboration with Roberto Felici, ESRF Grenoble). In collaboration with Patricia Kooyman (University of Cape Town) the group investigates industrial reactions using operando transmission electron microscopy. In collaboration with Gertjan van Baarle (Leiden Probe Microscopy) operando optical microscopy is used to shed light on the structure-activity relationship of catalysts. Further collaborations exist with theory (Karsten Reuter, TU Munich) and industry (Albemarle, Bayer MaterialScience, Haldor Tops√łe, and Shell).

With these dedicated operando techniques Prof. Groot focuses on the investigation of industrially relevant reactions to produce sustainable energy and materials. Topics that are currently studied are Fischer-Tropsch synthesis, NO reduction and oxidation, hydrodesulfurization, and chlorine production.

Key publications

  1. Spronsen M.A. van, Frenken J.M.W., Groot I.M.N., Surface science under reaction conditions: CO oxidation on Pt and Pd model catalysts. Chem. Soc. Rev. 2017, 46, 4347-4374. DOI: 10.1039/c7cs00045f
  2. Mom R.V., Rost M.J., Frenken J.W.M., Groot I.M.N., Tuning the properties of molybdenum oxide on Al2O3/NiAl(110): metal versus oxide deposition. J. Phys. Chem. C. 2016, 120, 19737-19743. DOI: 10.1021/acs.jpcc.6b06040
  3. van Spronsen, M.A., G.J.C. van Baarle, C.T. Herbschleb, J.W.M. Frenken, I.M.N. Groot, "High-pressure operando STM studies giving insight in CO oxidation and NO reduction over Pt(110)", Catalysis Today, vol. 244, pp. 85 - 95, 2015. DOI: 10.1016/j.cattod.2014.07.008
  4. Martynova, Y., B.-H. Liu, M.E. McBriarty, I.M.N. Groot, M.J. Bedzyk, S. Shaikhutdinov, H.-J. Freund, "CO oxidation over ZnO films on Pt(111) at near-atmospheric pressures", Journal of Catalysis, vol. 301, pp. 227 - 232, 2013. DOI: 10.1016/j.jcat.2013.02.018
  5. Groot, I.M.N., A.W. Kleyn, L.B.F. Juurlink, "The Energy Dependence of the Ratio of Step and Terrace Reactivity for H2 Dissociation on Stepped Platinum", Angewandte Chemie International Edition, vol. 50, issue 22, pp. 5174 - 5177, 2011. DOI: 10.1002/anie.201007093

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