Maria Girleanu

Biosourced mesoporous carbon with embedded palladium nanoparticles by a one pot soft-template synthesis: application to Suzuki reactions

A simple, direct and environmentally-friendly one-pot preparation of a palladium-containing mesoporous carbon (Pd@MC) from a cheap, non-hazardous and easily accessible biopolymer (tannin) as a carbon precursor, Pluronic® F127 surfactant as a pore structuring agent and a palladium salt is reported. This material has the peculiarity to have palladium nanoparticles entrapped in irregular voids connected to the worm-like mesoporous network limiting palladium leaching while keeping good access to the reactants. It was successfully used as a catalyst for ligand-free Suzuki–Miyaura couplings of aryl bromides in a green solvent (propane-1,2-diol) in the presence of extremely low amounts of supported palladium (usually 30 μequiv.). It is noteworthy that almost palladium-free products (containing less than 1.5 μequiv. of precious metal) can be obtained. The possibility to reuse the catalyst was also ascertained.

Magnifying the Morphology Change Induced by a Nickel Promoter in Tungsten(IV) Sulfide Industrial Hydrocracking Catalyst: A HAADF‐STEM and DFT Study

Changes in the two‐dimensional (2D) morphology of nonpromoted WS2 and Ni‐promoted WS2 (NiWS) catalytically active nanolayers supported on amorphous silica‐alumina (ASA) are revealed by aberration‐corrected scanning transmission electron microscopy and rationalized by density functional theory calculations. The presence of the Ni atoms modifies the triangular shape of nonpromoted WS2/ASA nanolayers into a more hexagonal one for NiWS/ASA by stabilizing the S edge more strongly than the W edge. The higher catalytic activity induced by the addition of the promoter confirms the relevance of such a morphology effect for industrial catalysts.

Synthesis and structure of ruthenium-fullerides

We report a simple and original procedure for preparing Ru-C60 polymeric chains, which spontaneously self-assemble as polymeric spherical particles. The size of the particles can be controlled by the choice of the solvent used during the reaction. In addition, these Ru-C60 polymeric spheres can be surface decorated with Ru nanoparticles using the same mild reaction conditions by changing the Ru/C60 ratio. Several techniques (TEM in high resolution, scanning and electron tomography modes, IR, NMR, Raman, WAXS, EXAFS and XPS) together with theoretical calculations allowed us to have an insight into the structure of these Ru-C60 species.