Ceria-stabilized meso-Al₂O₃: synthesis, characterization and desorption kinetics

A highly stable mesoporous ceria-doped alumina for steam gasification of biomass was synthesized using a template free method. Aluminum nitrate nonahydrate and cerium nitrate hexahydrate were used as the precursors to synthesize the ceria-doped alumina support by hydrolyzing it with ammonium carbonate. The thermogravimetric analysis indicates that the ceria-doped alumina support was stable up to 750 °C. By varying the amount of Ceria from 0.5 to 1.5 wt%, the structural and physico-chemical properties of the mesoporous support could be tuned. X-ray diffraction patterns showed that the newly prepared stabilized supports (calcined at 750 °C), exhibit γ-phase, while the textural characterization confirmed that all the catalyst supports are indeed mesoporous. The sample containing 1.0 wt% ceria on alumina has the highest post calcination (to 750 °C) surface area of 152 m²/g, pore volume of 0.43 mL/g, total acidity of 6.87 cm³/g, indicating its suitable application in biomass gasification. NH₃-desorption kinetics studies revealed that 1.0 wt % Ce containing Ce/Al₂O₃ sample has higher activation energy for NH₃ desorption than bare Al₂O₃, implying a moderate Ce/Al₂O₃ matrix interaction and that ceria incorporation will not impair active site availability of the alumina support. Finally, the high oxygen carrying capacity of ceria coupled with the synthesis method, which ensured a high dispersion of ceria in alumina matrix are responsible for the observed thermal stability. The favorable properties of these new alumina supports, can serve them as potential candidates for steam gasification of biomass among other applications, when loaded with the appropriate metal, metal oxide, or an organic functional group.