Effect of preparation methods on the structure and catalytic performance of CeO₂ for toluene combustion

CeO₂ aerogel (CeO₂-A), nanorod (CeO₂-R) and nanoflake (CeO₂-F) were prepared via sol-gel, hydrothermal and coprecipitation methods, respectively. The effect of morphology and structure of CeO₂ on the catalytic performance in toluene combustion reaction was investigated based on structure analysis provided by characterization. The results revealed that the activity of both CeO₂-R and CeO₂-F was inferior to that of CeO₂-A, due to CeO₂-R and CeO₂-F smaller specific surface area only exposed (111) crystal plane dominantly detected from their TEM images. While, the CeO₂-A had a larger specific surface area and more exposed (111) and (100) facet, which contributed to exposure and formation of more oxygen vacancies and further to the adsorption of more gaseous oxygen. In addition, highly mobile lattice oxygen was another critical factor for influencing the catalytic performance of CeO₂, which was beneficial to the redox cycle of Ce³⁺/Ce⁴⁺ and could further accelerate the toluene combustion. As a result, the CeO₂-A catalyst exhibited the superior performance in toluene catalytic combustion with t₅₀ of 223℃ and t₉₀ of 239℃, respectively, owing to the larger specific surface area, higher exposure of reactive crystal plane and stronger mobility of lattice oxygen.