Ni-based catalysts derived from nickel aluminate spinel for hydrogen production by Aqueous-Phase Reforming of glycerol

Résumé

Hydrogen, as an energy carrier, plays an important role in decarbonizing the energy system. Among different alternatives, Aqueous-Phase Reforming (APR) of biomass-derived feedstock, such as glycerol, is a promising catalytic process to produce H2. In order to provide high selectivity and reaction rates, under mild operating conditions (235 ºC/35 bar), the APR catalyst must be effective in breaking C-C, C-H, and O-H bonds, as well as active for the WGS reaction. Besides, it should present resistance to deactivation under the harsh hydrothermal conditions of the APR.In this thesis, the potential of nickel aluminate spinel (NiAl2O4) as a catalytic precursor is determined. The effect of the reduction temperature on the catalytic precursor is studied establishing correlations between the physicochemical properties and the catalytic performance. Complementarily, two strategies for the NiAl2O4 optimization are examined. First, the addition of Mg and Ce surface promoters, and then, the alternative synthesis by the novel nanocasting method. Upon reduction, the spinel precursor allows the formation of small (< 14 nm) and stable metallic Ni particles. Besides, its adequate stability leads to stable H2 yield during long term runs (50 h TOS) and shows potential to be used in the APR.