Conversion of ethanol over supported cobalt oxide catalysts

Conversion of ethanol was investigated on supported (ceria, zirconia and ceria–zirconia) cobalt oxide catalysts. The catalysts were prepared by support impregnation with cobalt nitrate–citric acid solution and they were explored by comparing results from different characterization techniques: X-ray fluorescence, X-ray diffraction, Raman spectroscopy and nitrogen adsorption techniques. Their catalytic properties at 693 K were characterized in a fixed-bed reactor. The CoOx/CeO2 catalyst displayed the highest catalytic activity. The conversion of ethanol decreased with the increase of the ZrO2/CeO2 ratio in the support of catalyst. All catalysts exhibited high selectivity of ethanol conversion to hydrogen and acetone. The coking of catalysts under reaction conditions was also characterized by gravimetric method. The results indicated that the increase of the ZrO2/CeO2 ratio in the support exerts significant influence on the coke formation. The amount of carbon deposited on CoOx/ZrO2 at 693 K was higher than on any other catalyst. Raman studies of used catalysts proved that their surface was almost completely covered with carbonaceous deposit, which was probably the main reason of deactivation of catalysts under reaction conditions.