Desulfurization of 2-phenylcyclohexanethiol over Pd and Pt catalysts on γ-Al2O3

The desulfurization of 2-phenylcyclohexanethiol (2-PCHT) was studied over Pd and Pt catalysts supported on γ-Al2O3 under 5.0 MPa H2 or Ar at 240 °C. The infrared spectra of the two catalysts during the reactions of 2-PCHT (PCHT-IR) were measured between 180 and 300 °C at 0.2 MPa H2 and Ar. The hydrodesulfurization (HDS) of 2-PCHT over Pd/Al2O3 and Pt/Al2O3 followed pseudo-first-order kinetics, and occurred mainly through β-elimination. Pd/Al2O3 was more active than Pt/Al2O3, mainly due to its higher β-elimination activity. Piperidine showed different inhibiting effects on their HDS performances. The species adsorbed on Pd/Al2O3 and Pt/Al2O3 were different under H2. Strong adsorption of 1-phenyl-1-cyclohexene on both catalysts was observed under Ar, which could be responsible for Langmuir-Hinshelwood kinetics and low activities. Pd/Al2O3 and Pt/Al2O3 were less active than transition-metal phosphides in the HDS of 2-PCHT, but were more active than the Mo-based sulfides.