Catalysts for second-stage deep hydrodesulfurisation of gas oils

Abstract

The interest for new deep hydrodesulfurisation (HDS) processes is expected to rise since more stringent legislation for the maximum sulfur concentration in automotive diesel fuel has been proposed. A realistic option is the application of a separate deep HDS reactor following the existing HDS process in which alternative catalysts may be applied. It was shown that ASA-supported Pt and PtPd catalysts are very active in model feed deep HDS reactions. Moreover, in the deep HDS of a pre-hydrotreated straight-run gas oil (P-SRGO) under relevant industrial conditions, PtPd/ASA showed a very promising performance. The applicability of ASA-supported noble metal catalysts in practice will be largely determined by the H 2S concentration in the second-stage reactor and the price of noble metals. In addition, NiW/γ-Al 2O 3 is also considered to be a promising catalyst for second-stage deep HDS. From the differences in the relative performance between model and real feed experiments, it is found that the suitability of a catalyst for deep HDS of gas oils cannot be evaluated by single-component model studies alone. The H 2S concentration and the presence of other competing reactants largely determine the outcome of model experiments and should therefore be chosen carefully.