Synthesis of Ce- and Zr-doped Alumina Nanoparticles in W/O Microemulsions: Potential Application in Fischer Tropsch Synthesis

Fischer Tropsch synthesis (FTS) allows the production of valuable long chain hydrocarbons from Natural Gas, Biomass and Coal. The catalytic material for FTS consists of Cobalt nanoparticles well dispersed onto alumina [1]. The nature of the catalytic support influences several important properties of the Co catalysts such as their dispersion, reducibility and electronic structure [2]. We investigated the use of the water-in-oil (w/o) microemulsion method for the synthesis of Al₂O₃ as well as Ce- and Zr-doped Al₂O₃ nanoparticles. This technique offers various advantages such as high control of the nanoparticle size and composition, and high surface area [3]. Zr and Ce ions were chosen as Al₂O₃ promoters, since the first prevents the formation of cobalt-aluminate species that are unfavorable for activity of the catalysts; the second enhances the mechanical property of Al₂O₃ at high temperatures. The aim is to obtain well-defined Al₂O₃, Zr-Al₂O₃ and Ce-Al₂O₃ nanoparticles and to investigate their role as supports for Co nanoparticles in FTS. The synthesis of doped and undoped Al₂O₃ nanoparticles was performed in nonionic W/O microemulsions. The materials were purified, calcined at 550°C, and impregnated with 12wt % cobalt. Characterization by XRD, TPR, BET, chemisorption, TEM and SEM was carried out, in order to investigate the role of doping on the characteristics of the obtained Co supported nanoparticles.