Dresden 2003 – wissenschaftliches Programm

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SYSE: Simulation and experiment

SYSE 2: Poster (gemeinsam mit SYCN und CPP)

SYSE 2.13: Poster

Dienstag, 25. März 2003, 19:00–21:00, ZEU/250

First-principles study of oxygen activation of nanoporous carbon for styrene catalysis — •Johan M. Carlsson and Matthias Scheffler — Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Deutschland

Dehydrogenation of ethylbenzene (ET) to styrene is an economically important and scientifically most puzzling chemical reaction. The industrial process uses iron oxide catalysts to enhance the conversion. However, recent theoretical work showed that the composition of iron oxide surfaces may be very different to what was hitherto believed, i.e. they are oxygen (if not OH) terminated.[1] Subsequently performed experimental work showed that indeed ET does not get in contact with iron, and that the active catalyst may be a carbon material that forms on the metal oxide during the catalyst’ induction period.[2] We therefore studied the chemical activity of various motifs expected to be present in nanoporous carbon [3] by first-principles calculations. The calculations show that vacancies and edges are very reactive, e.g., they dissociate O2 without a barrier. Oxidation of the single vacancy leads to CO-formation while the O-atoms bound into larger vacancies or at edges may form active sites for ET dehydrogenation. [1] X-G Wang et al., Phys. Rev. Lett. 81, 1038 (1998). [2] G. Mestl et al., Angew. Chem. Int. Ed 40, 2066 (2001). [3] V. Petkov et al., Phil. Mag. B 79, 1519 (1999).