Silica-alumina (SA)-supported Pt, Pd, and PtPd catalysts were compared for the hydrogenation of toluene and naphthalene in the presence of dibenzothiophene (DBT). The relative intrinsic hydrogenation activity suggested that PtPd catalysts are very active with respect to their monometallic (Pt and Pd) counterparts. The greater resistance of PtPd samples to poisoning by sulfur compounds was confirmed by dosing variable amounts(113-1200 ppm) of DBT into the feed. The structure of the catalysts was revealed by Fourier transform infrared spectroscopy (FTIR) of chemisorbed CO, temperature-programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS) techniques. TPR, FTIR, and XPS analyses of bimetallic catalysts revealed the strong Pt-Pd interaction in the bimetallic particles formed. Structural analysis of the used bimetallic sample indicated that the electro-deficient character of platinum (isolated Pt clusters on the Pd surface) is responsible for the strong sulfur resistance of the PtPd samples. (C) 2000 academic Press.