Unveiling the Role of Ceria in MgO-Supported Ni Catalysts for Hydrogen Production via CO₂ Reforming of Biomass-Derived Glycerol

Glycerol dry reforming (GDR) over Ni-based catalysts presents a promising route for hydrogen production, although it remains hindered by challenges such as coking and sintering. This work aims to enhance the catalytic performance and stability of Ni/MgO in GDR by incorporating ceria into the support structure. The XPS spectra indicate that Ce addition increases surface defects and induces lattice distortion in ceria, thereby promoting oxygen vacancy generation (Vo sites). The Ce-containing catalyst with a Ce/Mg molar ratio of 0.25 shows the highest concentration of Vo sites among those of the other catalysts. Results confirm that the increased surface defects over the Ni/MgCe0.25Ox catalyst facilitate CO2 dissociation, enhancing reactive oxygen species generation that promotes catalytic activity and reduces coke deposition. Furthermore, incorporating ceria at Ce/Mg = 0.25 led to the formation of a Ni(Mg)-Ce solid solution, which curtailed the NiO–MgO phase formation. This, in turn, moderated the metal–support interaction and increased the Ni0 availability, thereby enhancing the catalytic performance in GDR. The Ni/MgCe0.25Ox catalyst exhibits the highest glycerol and CO2 conversions of 77.6% and 35.9%, respectively.