(108e) In-Situ FTIR Spectroscopy to Study the Size Effect of Cobalt Nanoparticles On Carbon Monoxide Oxidation

Catalytic oxidation of carbon monoxide is a topic of significant interest due to its scientific and industrial importance. CO oxidation becomes important in air purification, lowering the toxicity of automobile exhausts, during selective oxidation of the feed stream to a fuel cell, and for several other potential applications. Noble metals are highly active catalysts that are moisture tolerant and stable against deactivation.  However, the popularity of these catalysts is affected by their higher cost and limited availability. Recently, CO oxidation using cobalt has been the subject of attention due to the relatively lower cost of cobalt compared to the noble metal counterparts. A systematic understanding of the catalytic activity of cobalt metal nanoparticles, especially the role of the nanoparticle size, has yet to be established. Here, we use a temperature programmed method with an in-situ FTIR spectroscopic characterization to systematically study nanoparticle size effect on catalytic CO oxidation. For a well-defined and model catalyst, stable cobalt nanoparticles of sizes 1 to 14nm were synthesized by thermal decomposition technique in the presence of a surfactant. The nanoparticles were then immobilized on surface tailored SiO₂ colloidal supports. The experimental data was interpreted using kinetic modeling, which allowed a determination of the reactivity as well as the kinetic parameters such as pre-exponential factor and activation energy alongside the impact of nanoparticle size.