Roles of Oxygen Species in Low-Temperature Catalytic -Xylene Oxidation on MOF-Derived Bouquetlike CeO.

To realize efficient low-temperature catalytic -xylene oxidation, MOF-derived CeO-X catalysts were prepared via the pyrolysis of MOF precursors with different ratios of cerium nitrate to trimesic acid. Among the synthesized catalysts, the bouquet like CeO-1 exhibited the best activity with and of 156 and 198 °C and the lowest activation energy of 60.67 kJ·mol (WHSV= 48 000 mL·g·h, -xylene concentration = 500 ppm). -Xylene was completely mineralized, and no change in conversion efficiency or CO yield was found at 5 vol % HO for over 50 h. The rich active oxygen species (XPS: O/O = 0.69) and abundant oxygen vacancies (Raman: / = 0.036) of CeO-1 made crucial contribution to its superior catalytic activity. The O-TPD and H-TPR results confirmed that CeO-1 had more surface active oxygen and better mobility of bulk oxygen. Moreover, the reaction routes under different atmospheres were probed through DRIFTS, in which oxygen vacancy played a key role in promoting the adsorption and activation of molecular oxygen and facilitating the migration of the bulk lattice oxygen.