SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 7: Poster Session I: Heterogeneous catalysis I
O 7.6: Poster
Montag, 1. März 2021, 10:30–12:30, P
A highly sensitive gas chromatograph for operando STM of catalytic reactions — •Katharina Maria Durner1, Bernhard Böller1, Günter Stienen2, and Joost Wintterlin1 — 1Chemie Department, Ludwig-Maximilians-Universität München, Deutschland — 2S+H Analytik GmbH, Mönchengladbach, Deutschland
Operando STM experiments of catalytic reactions can provide direct correlations between surface structure elements as possible active sites and catalytic activity. However, a major experimental difficulty is the extremely low product concentrations that result from the small size of the single crystal model catalysts and the usually relatively large volumes of STM cells. We present a special gas chromatograph (GC) that has been developed to solve this problem. The setup combines a common GC with a specially designed injection unit. Gas samples, produced at typical experimental pressures between 100 mbar and 1 bar, are compressed to the working pressure of the GC column. In the column the gas samples are condensed in a liquid nitrogen-cooled trap from which they evaporate during the temperature program. In this way the gas sample volumes are strongly enhanced without causing peak broadening. The GC has been used in operando STM experiments on the Fischer-Tropsch synthesis. Hydrocarbons from C1 to C4 produced well separated peaks, and a detection limit of 0.45 ppb was reached.