(532cq) Impact of Pretreatment on the CeO2 Structure and Catalytic Activity for CO Oxidation

Carbon monoxide (CO) oxidation reaction with metal and metal oxide catalysts has been of great interest for a variety of practical applications, such as three-way catalytic converter, fuel cell, and gas sensor. Traditionally, supported platinum group metals (PGMs) have been investigated for CO oxidation. In addition to the surface species, supports have affected the CO oxidation reaction. Cerium oxide (CeO₂) and ceria-based materials have been extensively investigated as catalyst and support materials for various catalytic reactions, due to higher oxygen storage capacity and excellent redox properties. In the current work, we investigated the impact of pretreatment conditions (e.g., oxidation and reduction) on the physical properties of bulk CeO₂ and catalytic activity for CO oxidation as a model reaction. To understand the physical properties of pretreated CeO₂ catalysts, several characterization techniques, such as XRD, BET, and Raman (UV and visible), were applied. The results showed that higher pretreatment temperature led to decreased specific surface area (SSA), a decrease in oxygen vacancy/defect sites, and increased crystallite size. When comparing the activity of the oxidized and the reduced samples, it was seen that the oxidized samples had a slightly higher CO conversion than their reduced counterparts at the same temperature. Overall, it can be noted that the temperature of the pretreatment has much more of an impact on the catalytic activity of the catalyst compared to the type of treatment (oxidation/ reduction). The catalytic performances were mainly controlled by the physical properties, such as SSA, oxygen vacancies/defect sites, and crystallite size.