In situ FT-IR study of thiophene adsorbed on the surface of sulfided Mo catalysts

► The adsorption of thiophene on the surface of sulfided Mo catalysts was theoretically and experimentally investigated. ► In situ FTIR technique confirmed the weak chemical absorption of thiophene on the catalyst surface. ► Four complexes were formed through the coordination of S, CC and CC with unsaturated Mod+ sites. ► The larger binding energy suggests the favorable absorption is through the coordination of CC with unsaturated Mod+ sites.