Investigation of palladium catalysts in mesoporous silica support for CO oxidation and CO(2) adsorption

The oxidation of Carbon monoxide (CO) to Carbon dioxide (CO(2)) is one of the most extensively investigated reactions in the field of heterogeneous catalysis, and it occurs via molecular rearrangements induced by catalytic metal atoms with oxygen intermediates. CO oxidation and CO(2) capture are instrumental processes in the reduction of green-house gas emissions, both of which are used in low-temperature CO oxidation in the catalytic converters of vehicles. CO oxidation and CO(2) adsorption at different temperatures are evaluated for palladium-supported silica aerogel (Pd/SiO(2)). The synthesized catalyst was active and stable for low-temperature CO oxidation. The catalytic activity was enhanced after the first cycle due to the reconditioning of the catalyst’s pores. It was found that the presence of oxide forms of palladium in the SiO(2) microstructure, influences the performance of the catalysts due to oxygen vacancies that increases the frequency of active sites. CO(2) gas adsorption onto Pd/SiO(2) was investigated at a wide-ranging temperature from 16 to 120 °C and pressures ∼1 MPa as determined from the isotherms that were evaluated, where CO(2) showed the highest equilibrium adsorption capacity at 16 °C. The Langmuir model was employed to study the equilibrium adsorption behavior. Finally, the effect of moisture on CO oxidation and CO(2) adsorption was considered to account for usage in real-world applications. Overall, mesoporous Pd/SiO(2) aerogel shows potential as a material capable of removing CO from the environment and capturing CO(2) at low temperatures.