Theneedforcleanerfuelshasresultedinacontinuingworldwidetrendtoreducedieselsulfurandaromatics.Therearemanyapproachestoreducingsulfurandaromaticsindiesel.Mostofthemhaveacommondrawbackofhighcostbecauseofadoptingtwostagesofhydrotreatingandusingnoble-metalcatalyst,especiallyforreducingaromatics.TheattempttoresolvethisissuehasledtotherecentdevelopmentoftheSingleStageHydrotreating(SSHT)processbyResearchInstituteofPetroleumProcessing(RIPP),SINOPEC.TheSSHTprocessisasingle-stagehydrotreatingtechnologyforproducinglowsulfurandlowaromaticsdiesel.Theprocessusesoneortwonon-noble-metalcatalystssystemandoperatesatmoderatepressure.Whenrevampinganexistingunittomeetlowaromaticsdieselspecification,theonlythingtodoistoaddareactororreplacetheexistingreactor,Inpilotplanttests,theSSHTtechnologyhassuccessfullytreatedSRGO(StraightRunGasOil),LCO(LightCycleOil)ortheblendofthem.ItisshownthatbyusingtheSSHTprocessdieselwithsulfurof30ppmandaromaticsof15m%canbeproducedfromMiddle-EastSRGOanddieselwitharomaticscontentof25m%canbeproducedfromcrackedfeed,suchasFCC-LCO.Highdieselyieldandcetanenumbergain(fromcrackedfeedstocks)givetheSSHTtechnologyaperformanceadvantagecomparedtoconventionalhydrocrackingandhydrotreatingprocesses.Thelowerinvestmentandoperatingcostisanotheradvantage.ThefirstcommercialapplicationoftheSSHTtechnologyhasbeeninoperationsinceSeptember2001.
