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Rhodium nanoparticles supported on gamma-Al2O3 have been prepared by Metal Vapour Synthesis (MVS), using mesitylene solvated Rh atoms as starting material and working in the absence and in the presence of trioctylamine (TOA), as stabilizer. The size and surface features of the metal particles have been studied by Transmission Electron Microscopy (TEM) and by FT-IR spectroscopy of adsorbed carbon monoxide, and they have been compared with those of a commercial Rh/gamma-Al2O3 sample. The results indicated that by MVS technique nanoparticles significantly smaller in size and with a narrower size distribution than those present on the commercial sample were produced. The addition of TOA during the MVS process resulted in a further decrease in the metal particle size. IR spectra of adsorbed CO indicated that metal particles produced via MVS expose at their surface a larger fraction of Rh atoms in low coordination. They can be extracted by CO, forming volatile Rh carbonyls which migrate onto the support, where the metal atoms are oxidised to Rh(l). For Rh particles produced via MVS in the presence of TOA, such low coordinated sites appeared stabilised by adsorbed amine molecules.

Very small metal aggregates (nanoaggregates) embedded in an inert polymer matrix, which simply stabilizes the nanodispersion, show unique catalytic and optical behaviour. Indeed Ru-nanoparticles in vinyl-aromatic polymers or polyphosphazenes display an enhanced reactivity for hydrogenation of different groups, such as aromatic rings, keto and nitro groups, oximes and nitriles which are converted into the corresponding saturated derivatives under mild conditions. The optical properties of terthiophenethiol-coated gold nanoparticles in UHMWPE (concentration lower than 4 wt.%) are characterized by poor dichroism due to their centrosymmetric structure. High dichroism (R = 30 at 400 nm, DR = 30) is on the contrary recorded for the terthiophene band showing the chromophores to be sensitive to mechanical orientation also when complexed with gold. On the other hand, nanocomposites based on polymers containing vinyl alcohol units and dispersed gold nanoparticles with average diameter ranging from 3 to 20 nm have been efficiently prepared by an UV photo-reduction process. Uniaxial drawing of the irradiated Au/polymer nanocomposites favours the anisotropic distribution of packed assemblies of gold particles, providing oriented films with polarization-dependent tunable optical properties.

The methane reforming with CO2 seems to be a promising reaction system useful to reduce the greenhouse contribution of both gases into the atmosphere. On this basis, and considering the potentiality of this reaction system, the dry reforming reaction has been carried out in an Ru-based ceramic tubular membrane reactor, in which two Ru depositions have been performed using the co-condensation technique. Experimental results in terms of CH4 and CO2 conversion versus temperature during time are presented, as well as product selectivity and carbon deposition. These experiments have also been carried out using a traditional reactor. A comparison with literature data regarding dry reforming reaction is also provided. Experimental evidence points out a good catalyst activity for the methane dry reforming reaction, confirming the potentiality of a catalytic membrane applied to the reaction system.

Adiponitrile was hydrogenated to hexamethylenediamine in a three phase stirred slurry reactor at 353 K and 3 MPa using rhodium on -alumina powder as a catalyst. Rhodium, with a very high metal dispersion, was deposited on the alumina support using the metal vapour synthesis technique. The performances of this supported catalyst were compared to those of one currently used in industrial processes (Raney Ni). The Rh/Al2O3 catalyst showed interesting hexamethylenediamine selectivity and adiponitrile conversion.

Supported Ru nanoparticles on a number of polyorganophosphazenes were prepared and tested for the hydrogenation of unsatured compounds. The complex Ru(eta6-cycloocta-1,3,5-triene)(eta4-cycloocta-1,5-diene) was found to be a suitable precursor to deposit metallic nanoparticles on polyorganophosphazenes; upon removal of cycloolefin ligands under hydrogen atmosphere, highly dispersed metal particles on the polymeric support can be obtained. Ru on polydimethylphosphazene hydrogenation of a wide range of unsaturated substrates (olefins, carbonyl compounds, aromatic compounds) under mild conditions. Polyorganophosphazenes are interesting in their ability to act as either soluble or insoluble catalyst supports, depending upon the dispersing liquid; thus it is possible to operate in heterogeneous phase as well as in homogeneous phase. The reaction in homogeneous phase can be performed in environmentally friendly solvents such as alcohols and water. The catalyst exhibits high stability towards agglomeration. No significant change in the ruthenium nanoparticles surface as well as catalyst activity was observed.