Investigation of defect-rich CeO2 catalysts for super low-temperature catalytic oxidation and durable styrene removal

Spherical cerium dioxide (CeO 2 –S) nanoparticles were successfully prepared using a solvothermal method, and their performances in catalytic oxidation reactions were studied. The CeO 2 –S catalyst showed superior low-temperature catalytic activity for styrene removal (T 90  = 118 °C, GHSV = 18,000 h −1 ) compared with commercial CeO 2 . The characterization results showed that there were numerous oxygen defects in CeO 2 –S that were key to its catalytic performance at low temperatures, high redox properties, and high adsorption capacity for the reaction gases (O 2 and styrene). Moreover, the catalytic performance of CeO 2 –S was highly stable (132 h), and the particles were reusable. FTIR and in-situ DRIFTS results showed that the type of intermediates formed during the oxidation of styrene determined the CeO 2 catalytic stability, and the main intermediates were bidentate carbonate species that accumulated on the surface of deactivated CeO 2 –S and were not thermally stable. Moreover, the soft carbon that also deposited on CeO 2 –S during the reaction was easily decomposed at higher temperatures. The role of the oxygen vacancies on the CeO 2 –S catalyst was further revealed by correlating the concentration of oxygen vacancies and the accumulation of coke on the catalyst surface.