Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

Hydrodesulphurization of benzo[b]thiophene (BT) on sulphided Mo, W, Co-Mo, Co-W, Ni-Mo, and Ni-W catalysts has been studied at total pressure 2.1 MPa and temperature 543 K. The catalysts were laboratory preparations with alumina or active carbon as a support and also commercial samples. The formation of intermidate 2,3-dihydrobenzo[b]thiophene (DHBT) was observed with all catalysts. On non-promoted catalysts, large quantities of it were formed; partial equilibrium BT-DHBT-H₂ was attained already at low desulphurization conversions. On promoted catalysts (Co-W, Co-Mo, Ni-W, Ni-Mo) the amount of DHBT formed was small; the partial equilibrium BT-DHBT-H₂ was not attained even at high desulphurization conversions. The data were correlated by kinetic equations derived from consecutive reaction scheme assuming steady state conditions for adsorbed species. The separation of individual reaction steps was not possible and only formal kinetic constants were obtained. It was concluded that the effect of Co or Ni in the reaction sequence is localized in the steps between partially hydrogenated BT on the surface and gaseous hydrogen sulphide and hydrocarbons.