Hydrogen production on Pd_0.01Zn_0.29Mg_0.7Al₂O₄ spinel catalyst by low temperature ethanol steam reforming reaction

This study investigated the low-temperature ethanol steam reforming (LTESR) performance of a Pd_0.01Zn_0.29Mg_0.7Al₂O₄ catalyst. Although it was present in a very small amount, the Pd component was the key to the partial CO-water gas shift and CO-methanation that, eventually, helped to increase the yield of H₂ during LTESR. An 80% yield of H₂ was maintained even after 30 h at 450 °C on the Pd_0.01Zn_0.29Mg_0.7Al₂O₄ catalyst with 100% ethanol conversion. Furthermore, the spinel structure of the catalyst remained unchanged after the reaction, and there was no increase in size owing to particle-to-particle aggregation. This study demonstrated that the Pd and Zn components could be stably located in the spinel structure of the MgAl₂O₄ with no sintering of the particles. Moreover, the oxygen transfer capacity of the MgAl₂O₄ spinel structure helped maintain the catalytic performance for long time periods by transferring oxygen to the reduced catalytic metal species (Zn or Pd) during the reaction, even though this induced oxygen defects in the spinel crystal. Overall, improved catalyst activity and an extended catalyst lifespan were observed.