IMPACT OF CATALYST AND DIESEL PROPERTIES ON PRODUCTION OF ULTRA LOW SULPHUR DIESEL

摘要

This paper investigates hydrodesulphurisation (HDS)of straight run gas oils (SRGO)and their blends with light cycle oil (LCO)and heavy cycle oil (HCO)from fluid catalytic cracking (FCC), and middle distillate fraction from thermal cracking (MDFTC)in order to achieve hydrogenate sulphur of 50 and 10 ppm.The diesel fractions have been hydrotreated on a fresh Co-Mo KF-757 catalyst, regenerated in situ once KF-757 catalyst, regenerated in situ twice KF-757 catalyst, and the fresh Co-Mo catalyst B in a trickle bed pilot plant at following conditions:reactor inlet temperature range (RIT)of 300-400deg C;liquid hourly space velocity (LHSV)range of 0.5-2.0 h~(-1), total reactor pressure of 3.5 MPa;treating gas/feedstock ratio of 250 Nm~3/m~3.It was found that sulphur in the hydrogenate, obtained by hydrotreatment of the HDS feed stocks containing SRGO, LCO and MDFTC on the fresh KF-757 catalyst, could be described by an exponential function of the 340deg C + (TBP)fraction content in the HDS feed and a linear function of the LHSV.The sulphur in hydrogenate, obtained by hydrotreatment of the SRGO 240-360deg C, was described by an exponential function of the RIT and a linear function of the LHSV.A relationship was found between the 340deg C + (TBP)fraction content in the HDS feed and the required RIT at a given LHSV to attain ultra low sulphur level in hydrogenate.It was established that an increase of RIT by 18deg C was equivalent to a decrease of LHSV by a factor of two.The regenerated in situ once and twice KF-757 catalysts were found to have the same activity, but it was 50% of the fresh KF-757 catalyst activity.The fresh catalyst B activity was found to be twice as high as the fresh KF-757 catalyst activity when SRGO was hydrotreated.However, it got much higher (between 3 and 35 times)when the HDS feed stock contained refractory stuff like HCO.