Towards an improved process for hydrogen production: the chemical-loop reforming of ethanol

Abstract

M-modified ferrospinels with the formula M_0.6Fe_2.4O_y (M = Co, Mn or Co/Mn) were employed as ionic oxygen and electron carrier materials for an alternative sustainable route to produce hydrogen via chemical-loop reforming of ethanol. The new materials were tested in terms of both redox properties and catalytic activity to generate hydrogen by oxidation with steam, after a reductive step carried out with ethanol. In addition, the research includes in situ DRIFTS and in situ XPS studies that allowed the extraction of information at the molecular level and following surface changes within the reduction/re-oxidation processes during ethanol chemical-loop reforming. It was found that Co(II)-incorporation in spinels effectively improves decomposition/oxidation of ethanol, however a greater amount of coke is accumulated. On the other hand, addition of Mn(II) into the system helps to significantly reduce the amount of coke and hence to avoid fast deactivation of the material. Thus, the behavior of Co_0.3Mn_0.3Fe_2.4O_y was shown to be the most promising one, as this material forms less coke during the reduction step, and consequently less CO_x is generated during the re-oxidation step with water, nevertheless a high hydrogen yield is maintained.