Composition and Properties of Rapeseed Oil Hydrotreating Products over CoMo/Al2O3 and NiMo/Al2O3 Catalysts

Abstract

Currently, there is an effort to achieve a more widespread use of biofuels, which are an alternative to conventional, petroleum-based fuels in mobile and stationary applications. The conversion of vegetable oils via catalytic hydrotreating to hydrotreated vegetable oil (HVO) is one of the most promising alternatives to produce high-quality biofuels. In this work, the composition and properties of rapeseed oil hydrotreating products gained over sulfided CoMo/γ-Al2O3 and NiMo/γ-Al2O3 catalysts were studied. The experiments were carried out in a laboratory trickle bed reactor in a temperature range of 320–380 °C and pressures of 4 and 8 MPa. The mixture of a rapeseed oil and isooctane was hydrotreated to simulate the coprocessing of rapeseed oil and petroleum fractions. Small amounts of aromatic hydrocarbons and, at higher reaction temperatures, considerably high contents of cycloalkanes and isoalkanes were found in the obtained liquid products. These were specifically alkylated cyclopentanes, cyclohexanes, decalines, benzenes, indanes, tetralines, and naphthalenes. The content of isoalkanes and aromatics in the liquid hydrotreating products gained over both catalysts increased with an increasing reaction temperature. A higher total amount of aromatics was found in the products of the NiMo catalyst because of its higher dehydrogenation activity compared with the CoMo catalyst. The liquid products with a high content of n-alkanes had a very high cetane index and cold filter plugging point, which decreased with an increasing reaction temperature due to the increasing content of isoalkanes and aromatics.