A universal method to form Pd nanoparticles on low-surface-area inorganic powders and their support-dependent catalytic activity in hydrogenation of maleic acid

Abstract

A simple method for preparation of Pd catalysts supported on low-surface-area inorganic powders as carbons, oxides (SiO2, diatomites, WO3, Ta2O5, Nb2O5, V2O5, TiO2, CeO2, ZrO2, Ga2O3, In2O3, Cr2O3, Fe2O3, Al2O3) and salts (CaF2, BaSO4, Ca3(PO4)2) was developed. It implies hydrolytic deposition of Pd(II) precursors onto a support in basic solutions. Regularities of the hydrolysis process without and in the presence of the support are studied by various physicochemical methods. A scheme of the formation of catalytically active component was put forward. Reduced with H2 at 50–120°C, the palladium catalysts demonstrate strong dependence of their specific activity in hydrogenation of aqueous maleic acid on the support nature. TOF value for palladium nanoparticles supported onto an oxide surface slows down with increasing polarizing ability of cations in the lattice of the oxide, that testifies to the influence of the electrostatic field intensity at the support surface on the reaction rate.