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Chemische Prozesse und Phasenübergänge Poster: Mi., 14:00–16:30 M-P174
Low energy XAS at the S K-edge for in situ catalyst characterization
Anderas Jentys 1 , Hendrik Dathe 1 , Johannes Lercher 1
1 TU München, Department Chemie
Fig. 1: Experimental
setup for time resolved
low energy XAS (H =
Heating; T = Thermocouple;
S = Sample; K =
Kapton window)
XANES on the S K-edge is a powerful technique for studying
sulphur species present on catalytic materials. The possibility
of following the oxidation state of sulphur in situ during
the reactions reveals new insights into the formation sulfur
species on solid catalysts.
The design of the reaction chamber and the sealing against
the vacuum is shown in Figure 1. The sample chamber is inserted
into a modified 6-way cross, which can be directly attached
to the equipment used at the ANKA XAFS beamline.
The in situ cell is applicable for experiments in the temperature
range between 303 and 673 K at a maximum pressure of
1 bar. The sample is placed inside the reaction chamber and
sealed against the vacuum to minimize absorption and scattering
of the gas phase with a 0.0075 mm Kapton window.
The cell allows experiments in transmission and fluorescence
mode. Reaction gas mixtures containing H2, O2, SO2, H2S
were tested in absence as well as in presence of water.
Sucessful examples for the use of low energy XAS for the SOx trapping under oxidizing
conditions using novel metal organic framework materials and the characterization of
novel hydro-isomerization catalysts will be presented.