Hydrotreatment of Oil Fractions For The Production of Low-Sulfur Diesel

摘要

In Europe there is a continuous increase in the demand forrndiesel fuel. Also, regulations to reduce tail pipe emissions tornthe atmosphere impose new and more stringent specifications;rnfor diesel transportation fuel, main pressure being on thernreduction of sulphur and polyaromatic concentration ,rnreduction of density and decrease of final boiling point. Forrnexample, maximum sulphur level allowed now is 350 ppm,rnwith reductions to levels of around 50 ppm foreseen in thernshort term. Further reductions (even to less than 10 ppm) arernalso on the horizon.rnHydrotreatment (HDT), as a variety of processes, is the mainrntool available to the refinery industry to improve dieselrnquality. This paper deals with the reach of hydrotreatmentrn(HDT) technologies to adapt diesel fuel to the new regulations.rnThe discussion is centred on three aspects: feedrnprocessability, process conditions and catalysts employed.rnFeed processability is studied in terms of how some feedrnproperties such as sulphur content and specific gravity have anrneffect on the HDS conversion. Correlations are shown thatrnexplain the effect of such variables. Main process conditionsrnsuch as space velocity and hydrogen partial pressure arernstudied, and their effect on the product sulphur level isrnshown. Typical CoMo and NiMo hydrotreatment catalysts arerncompared upon on the perspective of actual and futurernspecifications. Changes in product properties occurring duringrnhydrotreatment (aromatic content, cetane index and specificrngravity) are also shown.rnThis comprehensive study of the HDT process allows us tornestimate hydrotreatment requirements to adapt our refineriesrnto future specifications of the diesel fuel.