The Oxidation of Ru in a carbon supported Pt-Ru catalyst

C. Roth ⁽¹⁾, T. Hartmann⁽²⁾

⁽¹⁾ Angewandte Physikalische Chemie, FB Biologie, Chemie, Pharmazie Physikalische und Theoretische Chemie, FU Berlin, Germany.
⁽²⁾ STOE & Cie GmbH Darmstadt, Germany

Preliminary tests with the STOE IN-SITU HT2 (Figure 1) to observe the temperature calibration by investigating the phase transitions from a to b-quartz (Figure 2) at 573 °C and from orthorhombic to cubic celestine at 1150 °C (Figure 3) had been carried out with a steady flow of 0.06 l/min N₂ in a quartz capillary with 1.5 mm inner diameter for the first, and sapphire capillaries (1 mm diameter) for the latter experiment.

Though these results had already been very encouraging, the combination of the new STOE INSITU HT2 and reactive gases had still to prove functionality. Therefore a series of test measurements have taken place in the laboratories of the Applied Physical Chemistry group at the FU Berlin.

30 to 40 mm³ of a carefully ground carbon supported Pt-Ru catalyst ¹⁾ has been fixed between two pads of rock wool in the middle of a quartz capillary with 1.0 mm inner diameter. Then the capillary has been mounted in the STOE INSITU HT2, a flow of 0.5 l/min N₂ has been led through the chamber to protect the graphite heating element from ignition. O₂ as reactive gas streamed through the capillary with a flow of 0.03 ml/min. The heating rate has been chosen to 5 °C/min.

X-ray patterns from the catalyst exposed to O₂ at room temperature, 200 °C, 250 °C and 300 °C have been taken on STOE STADI P powder diffractometer with a sealed molybdenum tube, Ge(111) monochromator yielding pure Mo Ka₁ radiation and a Dectris MYTHEN 1K detector (1 mm chip), the X-ray patterns are shown in Figure 4.