Desulfurization of 2-phenylcyclohexanethiol over transition-metal phosphides

The desulfurization of 2-phenylcyclohexanethiol (2-PCHT) was studied over Ni2P, MoP, and WP under 4.0 MPa H-2 or Ar at 240 degrees C. The hydrodesulfurization of 2-PCHT proceeded through three parallel pathways: beta-elimination, hydrogenolysis, and dehydrogenation. Under Ar, the parallel pathways were beta-elimination, hydrogenolysis or homolytic C-S bond cleavage, and dehydrogenation. MoP and WP were more active than Ni2P. beta-Elimination dominated the hydrodesulfurization of 2-PCHT over Ni2P, while hydrogenolysis was as fast as beta-elimination over MoP and WP. Under Ar, beta-elimination and dehydrogenation pathways were about equal over Ni2P, whereas beta-elimination was the major pathway over MoP and WP. The inhibiting effects of piperidine depended on the reaction and catalyst. Phosphosulfide phases were formed under both H-2 and Ar, but the sulfidation behavior of Ni2P was different from that of MoP and WP. Ni2P was more difficult to sulfide than MoP and WP under H-2. (C) 2020 Elsevier Inc. All rights reserved.