Sulfur Poisoning of Bi- and Trimetallic ç-Al2O3-Supported Pt, Re, and Sn Catalysts

Abstract

Bifunctional metal/acid catalysts with Pt, Pt−Re, Pt−Sn, and Pt−Re−Sn as metallic functions supported on chlorided γ-alumina were prepared by successive impregnation or by coimpregnation of aqueous solutions of the metal precursors. They were tested in cyclohexane dehydrogenation (400 °C, 1 atm, weight hourly space velocity = 10, and H2/CH = 30) with an intermediate step of sulfur poisoning (1, 3, 5, or 7 ppm S). The addition of Sn and/or Re produces a decrease in the catalytic activity of Pt. Both this activity decrease and the increase in sulfur poisoning follow the order trimetallic > bimetallic > monometallic catalysts. The catalysts prepared by coimpregnation are more affected than those prepared by successive impregnations. In the last case, the activity and poisoning depend on the order of addition of the metal precursors during preparation.