(341b) Controlled Deposition of Iron Oxide Nanoparticles Using a Novel Gas-Expanded Liquid (GXL) Process to Generate Supported Fischer-Tropsch Catalysts

Authors: 
Vengsarkar, P. S., Auburn University
Xu, R., Auburn University
Roberts, C. B., Auburn University

Fischer-Tropsch synthesis is a catalytic process used in industry to convert carbon monoxide and hydrogen to heavier hydrocarbons. Active metals like iron, cobalt, nickel and ruthenium are required as catalysts for this process. Supporting these metals on an oxidic support (silica/alumina) has many advantages including an influence in mass selectivity due to the pore structure of the support and stability of the support. Attrition or fracturing inside a fixed-bed or slurry reactor is also reduced. Nano-sized particles also offer several advantages due to their easy dispersability in organic solvents which makes homogeneous loading on supports easier. The usual methods of supported catalyst preparation (ex. incipient wetness impregnation, ion exchange and coprecipitation) rely on various solvent-based transport phenomenon including diffusion and capillary action to disperse the iron into the catalyst pores. Gas expanded liquids (GXLs) have various advantages over conventional solvents due to their pressure tunable transport properties. The diffusion of various molecules is usually enhanced in a GXL due to the lower density/viscosity of solvents at high pressure. We have developed a novel method to controllably deposit iron oxide nanoparticles on a support in the presence of a GXL. This method allows for a more uniform deposition of the metal particles into the pores of the support hence improving the performance of the catalyst in Fischer-Tropsch synthesis. In this study we have carried out preliminary experiments on the synthesis of these supported iron catalysts and tested the effect of various operating parameters on the performance of this catalyst under Fischer-Trosch synthesis conditions.