In situ magnetic characterisation of supported cobalt catalysts under steam-reforming of ethanol Original Research Article

Various supported cobalt catalysts (Co/MgO, Co/Al2O3, Co/SiO2, Co/TiO2, Co/V2O5, Co/ZnO, Co/La2O3, Co/CeO2 and Co/Sm2O3), were characterised by magnetic measurements under ethanol steam-reforming conditions, in situ diffuse reflectance infrared spectroscopy and UV-Vis-NIR diffuse reflectance spectroscopy. Their magnetic behaviour was analysed as a function of reaction temperature and hydrogen treatment and was related to the cobalt species in the catalysts and to their catalytic behaviour in the steam-reforming of ethanol. The catalysts were prepared from Co2(CO)8 and used without previous calcination or reduction. All samples showed a paramagnetic or diamagnetic behaviour before reaction. The catalysts that performed well in the steam-reforming of ethanol presented under reaction conditions, metallic (ferromagnetic) cobalt particles and oxidised cobalt species. An easy exchange between small metallic cobalt particles (produced under H2 or under ethanol steam-reforming conditions) and oxidised cobalt species (produced under ethanol steam-reforming conditions) was found in these catalysts.