Different Pathways to Preserve the Sulphid State of the Catalyst During the Hydroprocessing of Triglycerides

Abstract

During the experimentals a special case of the hydrogenation of triglycerides was studied on a sulphided NiMo/Al2O3 catalyst (P = 40 and 80 bar, T = 320-380 °C, LHSV = 0.75-2.0 h-1, H2/feed ratio = 600 m3/m3). The sulphur containing compounds were covered with a small amount (10 %) of sulphur containing (0.9 %)gas oil in the sunflower oil to ensure the sulphided state of the catalyst. In comparison, the hydrogenation of another feedstock was examined, which sulphur content was adjusted approx. to the same concentration (905 mg/kg) with an easily decomposable sulphur compound (dimethyl disulphide). In case of the both feedstocks, by applying the favourable process parameters (T = 360-380 °C, P = 80 bar, LHSV= 0.75 to 1.0 h-1, H2/feed ratio = 600 m3/m3) the properties of the products - obtained in high yield - satisfied the requirements of the EN 590:2013 standard except their CFPP value and density. Thecomposition of the feedstocks had a significant impact on the quality of products, but the difference is reduced by increasing temperature. Based on these results, we concluded that to preserve the sulphide state of the catalyst in case of the catalytic hydrogenation of triglycerides a suitable and cost-effective solution to increase the sulphur content of the feedstock with straight run (high sulphur containing) gas oil. With the blending of the high cetane and low density products they were able to improve the quality of low- quality gas oil streams to produce better quality diesel fuel with bio-component content.