Catalytic materials for biomass-derived secondary raw materials transformations.

The thesis work has been focused on the nanostructuring of heterogeneous catalytic materials for biomass-derived compounds conversion to chemicals and hydrogen. The impact of the nanostructuring is investigated and correlated to the reaction pathways as well. Two biomass-derived model molecules and one by-product of an industrial process were used in as many different catalytic reactions. Acetic acid, as of the most abundant components of the bio-oil derived from the pyrolysis of biomass, and glycerol, as by-product of the emerging biodiesel industry, were used in steam and aqueous phase reforming for hydrogen production. The reduced defectivity of supported Ru nanoparticles, prepared by a novel colloidal method, in the reaction of the steam reforming of acetic acid led in enhanced catalyst stability due to lower coke deposition rates. The addition of Mn as promoter to a Pt-based catalyst was studied and tested in both the steam and aqueous phase reforming reaction of glycerol. The higher hydrogen production shown by the bimetallic catalyst was ascribed to its peculiar acidic surface features. Finally, the direct conversion of cellobiose, a model molecule of the saccharidic-derived biomass, to 5-hydroxymethyl-2-furaldehyde (HMF), which is a platform molecule for the sustainable production of many compounds with high commercial interest, was deeply studied. A series of HCl-treated niobium phosphate catalysts was tested in a recirculating flow reactor. From the complete characterization of the surface acidic features of the catalysts, it appeared that a proper balance of the amount and the nature of the acid sites is fundamental for the catalytic activity toward HMF.