Nanosize Effects, Physicochemical Properties, And Catalytic Oxidation Pattern of the Redox-Precipitated MnCeOx System

A series of nanostructured MnCeOx catalysts with superior textural and redox properties in comparison to coprecipitated systems was synthesized via the "redox-precipitation" route (Chem. Mater. 2007, 19, 2269). Characterization data prove that the redox-precipitated system consists of uniformly sized (d approximate to 20 nm) spherical nanoparticles ensuring large surface area (120-260 m(2)/g) and pore volume (0.5-0.6 cm(3)/g), and a regular pore size distribution in a wide range of Mn/Ce ratios (1/3 to 3/1). The lack of long-range crystalline order and a homogeneous chemical composition signal that Mn and Ce oxides form composite nanodomains with a molecular dispersion of the active phase. Superior MnOx accessibility, strong MnOx-CeO2 interaction, and higher average oxidation number of both Mn and Ce ions strongly promote the reactive surface oxygen availability and the CO oxidation activity in the range of 323-423 K, also accounting for the better stability of the redox-precipitated system under reaction conditions.