The Chemical-Loop Reforming of Alcohols on Spinel-Type Mixed Oxides: Comparing Ni, Co, and Fe Ferrite vs Magnetite Performances

Ferrospinels with different metals—Fe, Ni, Co, and Cu—were investigated as oxygen ion and electron carrier materials for the chemical-loop reforming of ethanol, aimed at the production of H2 with intrinsic separation from CO and CO2. The materials used showed different behaviours both during the first step of the loop—the reduction of the annealed spinel with ethanol—and the second step—the re-oxidation with steam—as well as with the increasing cycle number. The differences shown were rationalised in terms of redox behaviour, carbon residue accumulation during the cycle, and ability to restore the starting spinel structure during cycling. Mixed ferrospinels showed enhanced reducibility when compared to magnetite; however, since coke accumulation was unavoidable, the best-performing material amongst the materials tested was Co ferrite, which underwent the greatest reduction and was able to maintain it throughout repeated cycles.