MnOx Nanoparticles Supported on a New Mesostructured Silicate with Textural Porosity

A two-step synthesis of a novel mesostructured silicate. KIL-2, and its manganese-containing analogue. Mn/KIL-2, has been developed. KIL-2 possesses interparticle mesopores with pore dimensions between 5 and 60 urn and a surface area of 448 m(2). The mespores are formed by the aggregation of silica nanoparticles, which creates a network with interparticle voids. The particle size and the pore diameters depend on the temperature of the ageing step (first step) and on the solvothermal treatment in ethanol (second step), respectively. Mn/KIL-2 contains octahedrally coordinated Mn3+ (80%) and tetrahedrally coordinated Mn2+ (20 %) ions. Mn3+ ions are present in the extra-framework MnOx nanoparticles with typical dimensions of 2 nm, which are homogeneously distributed throughout the material. Mn2+ ions occur as isolated manganese framework sites. The material is also able to retain its structure characteristics after the hydrothermal treatment in boiling water. Because of its nontoxic nature and cost-effective synthesis, Mn/KIL-2 thus exhibits properties that are needed for an environment-friendly catalyst.