Abstract :
Alumina-supported bimetallic Au-Pd catalysts were prepared by the simultaneous reduction of palladium and gold
precursors by ethanol in the presence of the polyvinylpyrrolidone (PVP) and classical incipient wetness co-impregnation
method (iwi). The catalysts were characterized by a variety of techniques (AAS, N2 adsorption–desorption, XRD, TEM, CO
chemisorption, TGA, FTIR-CO, DRIFTS-NH3, and XPS). According to X-ray diffraction measurements and FTIR-CO spectra,
an AuPd alloy formed on the sample prepared by the PVP method, whereas distinct phases of gold and palladium metals formed
on the iwi samples. The effect of the presence of the AuPd alloy on the catalytic activity was investigated in the simultaneous
hydrogenation (HYD) of toluene (T) and naphthalene (NP) in the presence of dibenzothiophene (DBT) at P = 5.0 MPa,
T = 523 K, WHSV = 41.2 h 1. Under the selected conditions, all the catalysts were resistant to poisoning with 113 ppm of S (as
DBT). The enhancement in activity observed for the sample prepared by PVP method as compared to those prepared by
impregnation is related to the geometric effect resulting from the dilution of the Pd ensemble in the AuPd alloy and also to the
presence of smaller Pd0 particles
