Hydrogenation of tetralin on silica–alumina-supported Pt catalysts I. Physicochemical characterization of the catalytic materials

A series of well-defined catalysts based on platinum nanoparticles supported on amorphous silica–alumina with varying composition was prepared by incipient wetness impregnation. Quantitative structural characterization of alumina and aluminosilicate domains by 27Al (3Q) MAS NMR spectroscopy showed that the concentration of Brønsted acid sites determined by pyridine adsorption is related solely to the concentration of the aluminosilicate domain. However, only a very small fraction of the tetrahedrally coordinated aluminum led to the formation of Brønsted acid sites, because the negative charge on most of the tetrahedral Al–O was balanced by cationic aluminum oxide clusters. The preparation method led to small, uniform (0.6–0.8 nm) Pt particles on all aluminum-containing supports.