(359b) Surface Decoration of Cobalt Nanoparticles On Silica Colloids

Mankidy, B. - Presenter, University of South Florida

The growing concerns of pollution and depletion of natural oil resources have made it inevitable to produce clean and effective synthetic fuels to meet future demands. Oxide supported metal nanoparticles have shown enhanced catalytic properties for reactions such as Fischer-Tropsch reaction to produce synthetic fuels. Conventional methods of preparation that rely on reduction of cobalt precursor to metallic cobalt at high temperatures (~350-700oC) and pose challenges due to catalyst deactivation from sintering of pores of the support, agglomeration of cobalt nanoparticles, and reaction with the silica support to cobalt silicates. We have focused on synthesis of novel composite colloids such as surface modified silica supports that are decorated with nanoparticles of cobalt. Cobalt nanoparticles of different sizes (~5-15 nm) with extended stability in solution are synthesized by two methods: (A) inverse micelle technique and (B) thermal decomposition of a cobalt pre-cursor. These cobalt nanoparticles can then be easily immobilized onto the surfaces of silica micro-particles that are surface modified with both small ligands and polymer chains. The interaction of cobalt nanoparticles with the modified silica depends upon parameters such as the functional groups of the small molecule ligands and polymer chains as well as the cobalt precursor and solvent medium that are used. Our approach not only avoids the limitations of conventional impregnation techniques but also provides several benefits such as increased availability of monodisperse cobalt nanoparticles on the surface of the silica supports, ease of preparation, and manipulation of cobalt loading. In this presentation, the various methods of preparation will be discussed along with the characterization of the novel nanomaterial using FTIR spectroscopy, X-ray diffraction, dynamic light scattering, transmission electron microscopy and temperature programmed reduction.