Single-Step Synthesis of Ruthenium Catalytic Nanocrystallites in a Stable Carbon Support

Metallic Ru nanoparticles have been prepared and incorporated in a protective carbon support by the decomposition of a single organometallic precursor, RuIII acetylacetonate, under autogenic conditions in a single-step process in the absence of any solvents or stabilizers. The product structure was confirmed by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, scanning transmission electron microscopy, transmission electron microscopy and high resolution transmission electron microscopy. Measurements demonstrated the exclusive presence of hexagonal metallic ruthenium nanoparticles with a homogeneous size of 2-4 nm in a carbon supporting matrix, forming a high loading Ru catalyst with a muffin cookie like structure. The mechanism of the process is explained by the nucleation of Ru crystalline nuclei before carbon deposits on the Ru nanocrystallites, in an early stage of nanoparticle growth, during the single precursor decomposition. The carbon acts as a protective support, preventing further Ru nanoparticle growth, agglomeration or sintering. The catalytic properties have been tested by the hydrogenation of benzene to cyclohexane, and show high activity, full conversion of benzene, 100% selectivity for cyclohexane and good recyclability.