Opportunities Of Feed Potential For Production Of Ultra-Low Sulphur Diesel By Hydrodesulphurisation Of Conversion Gas Oils

摘要

An investigation was carried out to test the feasibility of producing 50 and 10 ppm sulphur diesel at the conditions of conventional hydrotreating unit operating at low pressure by hydrotreating straight run gas oils (SRGO) and their blends with light cycle oil (LCO) and heavy cycle oil (HCO) from catalytic cracking,and middle distillate fraction from thermal cracking (MDFTC).Middle distillate fractions have been hydrotreated on the Akzo Nobel Stars family Co-Mo KF-757 catalyst in a trickle bed pilot plant at the following conditions:reactor inlet temperature in the range 320-360degC;liquid hourly space velocities (LHSV) in the range 1-2 h~(-1);total reactor pressure of 3.5 MPa;treating gas :feedstock ratio of 250 Nm~3/m~3.It was found that LCO and MDFTC,regardless of their higher arenes,alkenes,and nitrogen content,had the same reactivity like the SRGO 200-300degC,and can be desulphurised to a product with sulphur level below 10 ppm at the conditions studied.This finding shows that the absence of the most refractory sulphur compounds which boil above 340degC makes the SRGO and the conversion gas oils have the same behaviour during hydrotreatment.Thus,refiners have the opportunity to increase the feed potential for production of near zero sulphur diesel (NZSD) at the conditions of conventional hydrotreating unit operating at low pressure by involving in the feed pool conversion gas oils which have final boiling point not higher than 340degC (according to TBP).HCO was the most refractory to desulphurise of all studied gas oils.Its blend with SRGO 240-360degC (80% SRGO 240-360degC/20% HCO) was able to desulphurise up to 100 ppm sulphur in the product while the SRGO 240-360degC itself was desulphurised up to 49 ppm product sulphur at the most severe conditions studied (LHSV of 1 h~(-1);reactor inlet temperature of 360degC).This shows that HCO can not be used even as a feedstock for ultra-low sulphur diesel (ULSD) where the sulphur limit is 50 ppm.The HCO was also the most refractory to hydrogenate as the cetane index of the hydrogenate of the feed blend SRGO/HCO was only 1.5 numbers higher than that of the feed while for the feed blends SRGO/LCO and MDFTC the hydrogenate cetane index was 3 numbers higher than that of the feeds.