Deep desulfurization: reactions, catalysts and technological challenges

Very stringent regulation in the maximal S content of gas oil have led to an intense activity of research dealing with all the aspects of desulfurization. The design of future processes is based on the identification of the refractory sulfur compounds and the knowledge of their individual reactivity and in the presence of inhibitors, as illustrated in this paper. This knowledge have oriented the research towards new catalysts such as molybdenum sulfide supported on zeolites, combination of sulfide and noble metal catalysts, and molybdenum carbides. Non-catalytic approaches like charge transfer complex were also examined. This paper summarises these various aspects of desulfurization.