Chemical-loop reforming of ethanol over metal ferrites: An analysis of structural features affecting reactivity

Abstract

This paper deals with an investigation of the reactivity of spinel type mixed oxides, i.e., magnetite and Ni-ferrite, in the chemical-loop reforming of ethanol to COx and H2. The two compounds showed a similar behavior during the oxide reduction, but the Ni ferrite showed a higher activity in ethanol anaerobic oxidation and decomposition, which was also confirmed by TPR experiments. During the first minutes of reaction, when the materials still acted as reactants while being reduced at the same time, the two oxides showed differences in regard to the nature of the products formed. During reduction, the structural evolution was monitored by means of several physical techniques, thus showing the formation of Fe carbide and metallic species as well. The re-oxidation step, carried out with steam, led to the generation of H2 but also to COx arising from the carbide transformation and the refoming of the carbon residues accumulated during the reduction step. Although the iron carbide was totally oxidized, the carbon residues could not be completely removed during steaming.