Copper and manganese-based catalysts (5 per cent Cu/Al2O3, 5 per cent Mn/Al2O3) modified with different amount of Pt or Pd (0.2 or 1 wt. per cent) have been studied in oxidation of thiophene. The activity experiments reveal that samples containing Cu display higher activity for thiophene oxidation in relation to manganese-based catalysts. It is shown that lower activity of Mn catalyst is accompanied by pronounced non-homogenous distribution of Mn phase on the catalyst surface and lower reducibility. Further more, catalytic and reduction be haviour of monometallic catalysts is in fluenced by the presence of small amounts of Pt or Pd, suggesting synergism of the components of bimetallic catalysts.
In this work hopcalite-based catalysts, modified with noble metals, have been studied in oxidation of thiophene. It was shown that modified hopcalite displays higher activity for thiophene oxidation relative to commercial hopcalite. Moreover, differences in catalytic activity of hopcalite modified with different metals (Pt, Pd, Au) were observed. To explain these differences in catalyst activity both surface and bulk properties of catalyst were studied with Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS), Scanning Electron Microscopy with Energy Dispersive Spectrometer (SEM-EDS) and X-ray diffraction method (XRD). Au modified hopcalite shows the lowest activity for oxidation of thiophene. Obtained images of catalyst surfaces indicate that lowest Au modified catalysts activity is accompanied by pronounced non-homogeneous distribution of Au atoms on the catalyst surface.
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