Transformation of Co3O4 during Ethanol Steam-Re-forming. Activation Process for Hydrogen Production

The transformation of Co3O4 during steam-re-forming of ethanol was investigated at atmospheric pressure in the 523−673 K temperature range using a bioethanol-like mixture. The initial and after reaction materials were characterized by the Brunauer−Emmett−Teller method, X-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, and in situ magnetic measurements. The performance in the ethanol steam-re-forming of the initial material and of those materials obtained under the reaction conditions was determined. During the activation process, in situ magnetic measurements and catalytic evaluation were carried out simultaneously. At 573 K, ethanol is dehydrogenated to acetaldehyde over Co3O4. At higher temperatures, Co3O4 is reduced to CoO and small metallic cobalt particles. Simultaneously, the material becomes active for the ethanol steam-re-forming reaction. Up to 5.2 mol of H2/mol of ethanol is obtained at temperatures as low as 623 K, and only methane (<3%) is obtained besides hydrogen (>72%) and carbon dioxide (>25%).