Nanoarchitectured Ni-ZrO2 Catalysts for Hydrogen Production From Steam Reforming of Ethanol

Hydrogen has been considered as an important alternative energy vector and a bridge to a sustainable energy future. Production of hydrogen efficiently and economically from renewable sources, however, remains a challenge. Among diversified hydrogen production technologies, steam reforming of ethanol has been considered as an attractive route for the low toxicity, easy deliverability, and widely availability of bioethanol. This work focuses on the design of nanoarchitectural Ni-ZrO₂ catalysts with high activity in ethanol steam reforming.

The use of nanograined NiO to prepare nanoarchitectural Ni-ZrO₂ catalysts could avoid the use of hazardous reagents during the preparation of nickel metal nanoparticles and simplify the preparation process. The presence of ammonium ion during the precipitation of zirconia precursor led to the production of ZrO₂ species with active sites catalyzing the dehydration of ethanol, thus lowering the catalytic activity and hydrogen yield. However, we have successfully shown that the introduction of Al₂O₃ into the zirconia matrix (Ni-AZ) could greatly improve specific area of the catalyst, the dispersion of nickel metal and catalytic activity and stability. The presence of Al₂O₃ could also effectively block active sites for dehydration of ethanol. The nanoarchitectured Ni-AZ catalyst yielded high activity in both water gas shift reaction as well as the steam reforming of ethanol, at the temperature range of 673-973 K. CO₂, CO and CH₄ were detected as the only byproducts even at low temperature (e.g., 673 K). Yield of hydrogen and selectivities of carbonaceous products were all close to the thermodynamic equilibrium temperatures investigated.