Ru-Doped Cobalt−Zirconia Nanocomposites by Flame Synthesis: Physicochemical 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 Co 3 O 4 to CoO and metallic Co 0, 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.