Detailed Characterization of Diesel Fractions from Co-Hydroprocessing Vegetable Oil and Petroleum Heavy Vacuum Gas Oil Blends

In this study, 20 diesel fractions were obtained by co-hydroprocessing blends of low-grade canola oil and Canadian oil sand bitumen-derived heavy vacuum gas oil (HVGO) at different canola oil/HVGO blending ratios, reaction temperatures and pressures, and liquid hourly space velocities. A commercial hydroprocessing catalyst was used in the experiments under typical commercial operating conditions. The obtained diesel fractions were fully characterized by using standard ASTM methods and advanced two-dimensional gas chromatography. Characterization results of the diesel fractions showed that, with the increased canola oil content in the feed blends, the contents of aromatics and cycloparaffins decreased and the content of isoparaffins remained relatively constant. In contrast, the content of normal paraffins (n-paraffins) increased. The observed increase in the n-paraffins in the diesel fractions was attributed to the hydrodeoxygenation and hydrodecarboxylation of triglycerides in the canola oil. The n-paraffins in the diesel were mostly n-heptadecane (product of hydrodecarboxylation) and n-octadecane (product of hydrodeoxygenation) with traces of other lighter or heavier n-paraffins. The formation of n-heptadecane and n-octadecane resulted in improved physical and combustion properties of the diesel fractions, such as density, boiling point distribution, and cetane index/number.