Influence of rapeseed oil hydrotreating on hydrogenation activity of CoMo catalyst

Novel approaches for the production of liquid fuels from biomass are continuing to be explored; these approaches are enabled by the improved properties of advanced biofuels. The production of synthetic biodiesel via catalytic hydrotreating of vegetable oils and other feed with high triglyceride content is among these possibilities. The aim of the study was to hydrotreat rapeseed oil for the production of hydrocarbons in the diesel fuel range. We assessed what proportions of rapeseed oil were converted into n-alkanes through three different reactions (hydrodecarbonylation, hydrodecarboxylation, and hydrodeoxygenation) and what compounds other than n-alkanes were produced from rapeseed oil. The mixture of rapeseed oil and tetralin with a mass ratio of 2:8 was hydrotreated (320–380°C, 4MPa, co-current reactor) on a commercial Co–Mo/Al2O3+SiO2 hydrotreating catalyst. The proportion of C17 and C18 isoalkanes in liquid products increased with increasing reaction temperature from 16wt.% at 320°C to 28wt.% at 380°C. Hydrodecarboxylation/hydrodecarbonylation dominated over hydrodeoxygenation in the hydrotreating mechanism. This dominance increased with increasing reaction temperature. The products of rapeseed oil conversion suppressed hydrogenation of tetralin into decalin. Therefore, the hydrotreating of a middle petroleum feedstock with a rapeseed oil addition will impair the ability of the Co–Mo/supporter catalyst to reduce content of monoaromatic and polycyclic aromatic hydrocarbons in the feedstock.