LAUSR

Leptothrix genus bacteria were cultivated in Lieske medium in presence of anodic Al2O3/Al to synthesize γ-FeOOH as a biogenic precursor for catalyst preparation. Different amounts of biogenic iron (0.6, 0.9, 9.2% Fe) were deposited. γ-FeOOH deposition on the support was identified the process being determined by the anodic Al2O3 surface structure. The catalytic activity in the CO oxidation reaction was examined by in situ diffuse-reflectance infrared spectroscopy up to 250 °C. A maximum conversion of 42% was achieved with 9.2% Fe sample. However, the lowest amount of reaction product CO2 was determined. Lepidocrocite conversion into maghemite occurred during catalytic experiments. Static adsorption study showed presence of carbonate (bidentate, monodentate) species and formates on the samples surface indicating that oxidation occurred at room temperature by CO interaction with (sub)surface oxygen. Bidentate carbonate species were not registered with 9.2% Fe sample. Additionally, inhibited formate species formation was registered on the same sample. In this case the biogenic iron coverage could be considered thicker and denser determining CO2 adsorption–desorption to/from the surface of iron-containing compound and anodic alumina. So, the higher CO conversion with 9.2% Fe sample was at the expense not only for transformation to CO2 but some part remained on the surface as strongly adsorbed species.