Influence of CeO₂ and ZrO₂ on the Thermal Stability and Catalytic Activity of SBA-15-Supported Pd Catalysts for CO Oxidation

Abstract

Alterations in catalyst morphology under various pretreatment catalyst preparation conditions were studied with different characterization techniques to evaluate the primary source of catalytic performance during CO oxidation. This work includes modification in catalyst morphology, elucidation of their behavior, characterization, and description of catalytic performance for catalysts prepared upon different calcination temperature ranges (500–800 °C) and time durations (5 h to 3 days). Pd-modified (CeO2 or ZrO2) supported mesoporous SBA-15 catalysts were prepared via the impregnation method and tested for selective CO oxidation reaction. The characterization data of XRD and STEM demonstrated that the catalyst prepared with CeO2 (CeO2-Pd/SBA-15) has shown a uniform Pd NP structure with a particle size of nearly 4 nm inside the SBA-15 channels and retain smaller NP size even after severe aging treatment (3 days at 800 °C) when compared to the ZrO2-containing (ZrO2-Pd/SBA-15-800) catalyst, presumably due to the increased interfacial area and strong interaction that developed between Pd and CeO2, resulting in the formation of a Pd–O–Ce bond. According to the catalytic performance results, ceria-promoted Pd-supported SBA-15 (CeO2-Pd/SBA-15) catalysts exhibited better catalytic activity and stability for CO oxidation as compared with that of the ZrO2-promoted Pd-supported SBA-15 (ZrO2-Pd/SBA-15) catalyst.