The effect of the absence of Ni, Co, and Ni–Co catalyst pretreatment on catalytic activity for hydrogen production via oxidative steam reforming of ethanol

• The increase of reducibility, basicity, and oxygen mobility improve H2 production.
• H2 production order: OMCo < OM2Ni1Co < OM1Ni2Co < OMNi = OM1Ni1Co for non-reduced solids.
• Nickel-rich catalysts can be reduced “in situ” during OSRE, contrary to the OMCo.
• Cooperative effect between Ni and Co increases the properties of the OM1Ni1Co.

This article presents a study of the catalytic performance of Ni, Co, and Ni–Co–Mg–Al mixed oxides obtained from hydrotalcite precursors for the oxidative steam reforming of ethanol (OSRE) when no pretreatment (pre-reduction) is accomplished. Two catalysts (a Ni-based monometallic and an equimolar Ni–Co-based catalyst) achieve in situ reduction over shorter time periods compared with the other bimetallic catalysts and also, exhibit the best catalytic activity. On the contrary, the monometallic Co catalyst did not exhibit good catalytic performance, likely because of the existence of resistant spinel phases to soft reduction processes and/or to the re-oxidation of Co. The equimolar presence of Ni and Co generates a synergistic effect evidenced by the increase in the reducibility, basicity, and mobility of electrophilic oxygen species of the solid. The results yield important information for better understanding the catalytic system under study.