Ru-doped cobalt-zirconia nanocomposites by flame synthesis: Physiochemical and catalytic properties

Nanocomposites of Ru-doped cobalt-zirconia (20 wt % Co) were made by rapid and scalable flame spray pyrolysis (FSP). They were characterized by nitrogen adsorption, X-ray diffraction, electron microscopy, and X-ray photoelectron spectroscopy revealing that cobalt clusters were highly dispersed within the zirconia matrix. Adding traces of Ru (0.04 and 0.4 wt %) to this unique structure during FSP significantly lowered the two-step reduction temperature of Co₃O₄ to CoO and metallic Co^o, further resulting in a 4-fold increase in CO chemisorption compared to undoped ones. The catalytic properties of the nanocomposites were further studied in a Fischer-Tropsch reaction and compared to those prepared by incipient wetness impregnation and mechanical mixing. The enhanced reducibility and CO chemisorption through doping with 0.4 wt % Ru was highly beneficial to the catalytic property of the flame-made composites. © 2008 American Chemical Society.