X-ray diffraction study of Co3O4 activation under ethanol steam-reforming

The evolution of Co3O4 during ethanol steam-reforming was investigated under operando conditions by using XRD measurements. The study was carried out at atmospheric pressure as a function of reaction temperature, flowing a 1/6 ethanol/water mixture. XRD measurements and catalytic evaluation were simultaneously accomplished using a reactor-cell specially designed for these purposes. Up to 548 K, only the presence of Co3O4 crystalline phase was determined, and under these conditions ethanol was dehydrogenated to acetaldehyde. At higher temperatures, Co3O4 reduced to crystalline CoO and small metallic cobalt particles. Simultaneously, the material became active for the ethanol steam-reforming reaction. At 623 K, the material which showed by XRD the presence of both CoO and Co phases, was very selective in the steam-reforming of ethanol.