Catalytic CO Oxidation over Well-Defined Cobalt Oxide Nanoparticles: Size-Reactivity Correlation
journal contributionposted on 02.10.2015, 00:00 by Viacheslav Iablokov, Roland Barbosa, Glenn Pollefeyt, Isabel Van Driessche, Sergey Chenakin, Norbert Kruse
Co nanoparticles of well-defined size were synthesized by temperature-controlled injection of Co2(CO)8 into dichlorobenzene. After intercalation into mesoporous MCF-17 and temperature-programmed oxidation, Co3O4/MCF-17 model catalysts were obtained with cobalt oxide particle sizes varying between 3.5 and 12.2 nm. We demonstrate here the occurrence of a distinct particle size effect for the CO oxidation. Maximum reaction rates of about 0.77 nm–2 s–1 at 150 °C were observed for Co3O4 particles with a size in the range of 5 to 8 nm. The reaction rates decreased for either smaller or larger sizes. X-ray photoelectron spectroscopy allowed establishing a clear correlation between the Co3+ trivalent oxidation state and the CO oxidation rate.