SiO@Pd@CeO catalyst with improved thermal stability: Effect of interaction between Pd and CeO on activity for CO oxidation

Thermally stable Pd/CeO2@SiO2 with a core-shell structure for catalytic lean methane combustion

Noble metal catalysts exhibit high catalytic activity in lean CH4 combustion at low temperatures. However, the high surface energy of noble metal nanoparticles makes them susceptible to deactivation due to migratory-aggregation during the catalytic process. Herein, a core-shell structure with a Pd/CeO2 core and a SiO2 shell (denoted as Pd/CeO2@SiO2) was designed and prepared to enhance the thermal stability for catalytic lean CH4 combustion. A series of characterization methods demonstrated the successful encapsulation of SiO2 and the modified thermal stability. The results of activity tests indicated that Pd/CeO2@SiO2 exhibited the optimal catalytic performance. After seven runs, Pd/CeO2@SiO2 achieved 90% conversion of CH4 at 385 °C compared to Pd/CeO2 at 440 °C. The remarkable catalytic performance was attributed to the synergistic effect of strengthened metal-support interactions and the core-shell structure. On the one hand, the migration and aggregation of Pd nanoparticles were limited due to the protection of the SiO2 shell layer. On the other hand, the SiO2 shell layer further enhanced the interactions between the Pd nanoparticles and CeO2, thus promoting the formation of PdxCe1-xO2-δ solid solutions and active oxygen species, which were beneficial for the improvement of the stability and redox capacity of the catalyst.

Recent advances in catalytic systems in the prism of physicochemical properties to remediate toxic CO pollutants: A state-of-the-art review

Carbon monoxide (CO) is the most harmful pollutant in the air, causing environmental issues and adversely affecting humans and the vegetation and then raises global warming indirectly. CO oxidation is one of the most effective methods of reducing CO by converting it into carbon dioxide (CO₂) using a suitable catalytic system, due to its simplicity and great value for pollution control. The CO oxidation reaction has been widely studied in various applications, including proton-exchange membrane fuel cell technology and catalytic converters. CO oxidation has also been of great academic interest over the last few decades as a model reaction. Many review studies have been produced on catalysts development for CO oxidation, emphasizing noble metal catalysts, the configuration of catalysts, process parameter influence, and the deactivation of catalysts. Nevertheless, there is still some gap in a state of the art knowledge devoted exclusively to synergistic interactions between catalytic activity and physicochemical properties. In an effort to fill this gap, this analysis updates and clarifies innovations for various latest developed catalytic CO oxidation systems with contemporary evaluation and the synergistic relationship between oxygen vacancies, strong metal-support interaction, particle size, metal dispersion, chemical composition acidity/basicity, reducibility, porosity, and surface area. This review study is useful for environmentalists, scientists, and experts working on mitigating the harmful effects of CO on both academic and commercial levels in the research and development sectors.