Preparation and hydrogen sorption of Pd nanoparticles on Al2O3 pillared clays

Abstract Pd nanoparticles were prepared in the solid–liquid adsorption layer on pillared clays and the subcolloids with a diameter of 3–5 nm obtained were characterized by various methods. Based on the liquid sorption isotherms determined in ethanol–toluene mixtures, the composition of the interfacial layer as a “nanophase reactor” may be determined; equilibrium conditions for the formation of Pd nanocrystals were selected. The surfacial binding of Pd 0 particles may be monitored by spectrophotometry throughout the preparation. N 2 adsorption measurements indicate a gradual decrease in micropores and external surface areas with increasing Pd content of the samples. According to TEM pictures, samples with higher Pd contents contain particles with larger diameters. These results are supported by SAXS and H 2 adsorption measurements as well. The relationship between catalytic activity and size of Pd subcolloids is revealed by microcalorimetric monitoring of hydrogen adsorption and by the results of catalytic hydrogenation reactions. These measurements indicate that smaller particles have larger catalytic activities.