Development of ordered mesoporous ceria from metal-organic frameworks for efficient acetone oxidation: Morphologic and surficial advantages induced by surfactant-templated strategies.

Abstract

Cerium oxide (CeO₂) is one of the most effective catalysts for volatile organic compound (VOC) oxidation. However, the construction of ordered mesoporous CeO₂ architectures through sustainable synthesis routes remains highly challenging. Metal-organic frameworks (MOFs) are promising sacrificial templates for the synthesis of oxides. Herein, we report a surfactant-regulated, alkali-metal-assisted aqueous strategy to construct ordered mesoporous CeO₂ via UiO-66(Ce) templating. Pluronic was employed as a soft template, while inorganic bases (LiOH, NaOH, and KOH) were used to promote H₂BDC deprotonation in water. The Li⁺, Na⁺, and K⁺ cations are believed to influence the self-assembly of UiO-66(Ce) framework (CeULi, CeUNa, and CeUK, respectively), leading to differences in the properties of the resulting particles. CeO₂ derived from CeULi at low temperature, denoted as cCeULi, exhibited outstanding acetone conversion, reaching 90% at 207 °C. This is due to its mesoporous structure, the presence of Ce³⁺defects, and surface oxygen mobility. The cCeULi catalyst performed well over 10 cycles, averaging 87.9% efficiency over 25 h at 200 mg catalyst, 100 cc/min flow rate, and 600 ppm acetone. Also, cCeULi proved highly resistant to water vapor (5-10 vol%). In-situ DRIFTS analysis indicates that the acetone oxidation on cCeULi follows a Mars-van Krevelen mechanism involving lattice oxygen. Overall, the combination of morphological structure and surface chemical properties plays a key role in catalytic activity. This study is an important reference for the future development of ordered mesoporous CeO₂ derived from MOFs.