Hydrogenation of Toluene over Supported Pt and Pd Catalysts: Influence of Structural Factors on the Sulfur Tolerance

Pt, Pd, and PtPd metallic precursors are deposited on dealuminated FAU zeolites and on one amorphous silica–alumina. The catalytic activity is measured in the hydrogenation of toluene at 30 MPa total pressure, either in the absence or in the presence of sulfur (200 ppm in toluene). In the absence of sulfur, alloying Pt with Pd decreases the hydrogenation activity. In general, catalysts made from ammoniated precursors are the most active, with one remarkable exception. In the presence of sulfur, thioresistance is a function of reaction temperature, i.e., sulfur coverage of the metallic phase. Pd increases substantially the sulfur tolerance. The effect of support acidity on S tolerance is observed only at high sulfur coverage.