Desulfurization of 2-phenylcyclohexanethiol over transition-metal phosphides

Abstract

The desulfurization of 2-phenylcyclohexanethiol (2-PCHT) was studied over Ni2P, MoP, and WP under 4.0 MPa H2 or Ar at 240 °C. The hydrodesulfurization of 2-PCHT proceeded through three parallel pathways: β-elimination, hydrogenolysis, and dehydrogenation. Under Ar, the parallel pathways were β-elimination, hydrogenolysis or homolytic C–S bond cleavage, and dehydrogenation. MoP and WP were more active than Ni2P. β-Elimination dominated the hydrodesulfurization of 2-PCHT over Ni2P, while hydrogenolysis was as fast as β-elimination over MoP and WP. Under Ar, β-elimination and dehydrogenation pathways were about equal over Ni2P, whereas β-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 H2 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 H2.