CeO2 from pyrolysis of MOFs for efficient catalytic combustion of VOCs

Nano CeO2 (CeMOF) maintaining the primary micromorphology and pore structure of MOFs was successfully synthesized by controlled pyrolysis of UiO-66(Ce) in air. CeMOFs showed excellent activity for catalytic combustion of VOCs, including toluene, benzene and xylene. The results showed that the T10%, T50% and T90% of toluene over CeMOF were 185, 198 and 206 ℃ (GHSV = 22500 h−1, toluene concentration = 1000 ppm), respectively, which are the lowest among ever reported ceria catalysts. According to various characterization results, the high catalytic activity of CeMOF can be ascribed to its neat pore structure and high percentage of Ce with low chemical valence. The latter leads to massive surface oxygen species and oxygen vacancies which provides abundant oxidative sites for VOCs. The low-temperature reducibility and multiple weakly acidic sites also enhanced the catalytic activity. In addition, CeMOF shows good ability to resist H2O and thermal stability. The in-situ DRIFTs study of CeMOF shows toluene is degraded by continuous stages through quick conversion of toluene to benzaldehyde and adsorbed benzoate, and forms CO2 and H2O at last.