Abstract: USY zeolite supports with different acid amounts were obtained by steam dealumination. Dual metal catalysts with a total loading of Pd and Pt of 1.15% were prepared by the ion-exchange method. The supports and catalysts were characterized by temperature-programmed desorption of ammonia, X-ray diffraction, nitrogen adsorption, and X-ray photoelectron spectroscopy. The catalytic activity for the hydrogenation of tetralin was examined with a fixed-bed continuous-flow reactor operating at 4.0 MPa. The sulfur tolerance was tested with a feed of 200 μg/g sulfur in the form of 4,6-dimethyldibenzothiophene. The two catalysts supported on USY zeolites with surface acid amounts of 626 and 203 μmol/g, respectively, showed excellent sulfur tolerance, while the catalysts of higher and lower acid amount showed decreased sulfur tolerance. Energy dispersive spectroscopic analysis proved that the support with a large acid amount adsorbed more sulfur, which might lead to the lower sulfur tolerance of the catalyst. The low sulfur tolerance of the catalyst with a low acid amount was attributed to the insignificance of the electron deficiency of the metal particles.

Key words: Y zeolite, steam, dealumination, palladium, platinum, tetralin, hydrogenation, sulfur tolerance, spill-over hydrogen