(711f) Catalytic Conversion of Methane and Carbon Dioxide to Higher Value Products

The possibilities for chemical utilization of methane and carbon dioxide to higher value products at mild conditions are investigated. Although the abundance of these two greenhouse gases makes them attractive raw materials for fuels and chemical synthesis, most of their reactions require significant energy inputs as well as properly designed catalytic systems that lower kinetic barriers in their direct conversion. Based on molecular modeling analysis, bifunctional system, comprised of well-shaped Pt nanoclusters deposited on ceria support is chosen as potential candidate for this study. The presence of low-coordinated sites, such as edge and corner sites on transition metal active centers has been shown to facilitate the methane conversion by reducing the energy barriers and stabilizing reaction intermediates. Tetrahedral colloidal platinum nanoparticles that contain numerous surface steps and kinks, are obtained by wet chemical preparation by carefully adjusting the concentration ratio between the metal precursor and the capping agent. Ceria nanorods which expose more reactive (110) and (100) planes are prepared by hydrothermal method. Influence of different cluster and support morphologies on direct conversion is investigated by reacting methane and carbon-dioxide at mild temperatures (< 350°C) in small lab scale packed-bed reactor. These studies should advance the fundamental understanding of the methane adsorption mechanisms on different cluster morphologies as catalytic active centers. It will also be studied whether improved oxygen storage capacity of ceria nanorods plays a role in CO₂ adsorption. This integrated approach to the catalyst development, based on theoretical considerations and including catalyst synthesis and characterization, and finally, its testing in a lab scale reactor, should help in determining the key features needed for catalyst design.