Study into the effects of the feedstock properties and stability on the catalytic hydrocracking of heavy oil

Abstract

Various heavy oil feedstocks were investigated using several methods that are commonly employed to evaluate the stabilities of such feedstocks. More specifically, the microcarbon residue (MCR) content, the colloidal instability index (CII), the stability index (SI), and the Heithaus parameter (P value) were employed. The catalytic hydrocracking of heavy oils was carried out in a slurry-phase semi-batch reactor at 410 °C under 110 bar of hydrogen and in the presence of a Mo-octoate precursor (1000 wppm). The correlation between the feedstock properties (i.e., the MCR content and the CII) and the reaction performance in the upgrading process was established. It was found that feedstocks with higher MCR contents also contained greater numbers of aromatic components and shorter alkyl side chains, resulting in a higher tendency for coke formation and a lower yield of de-asphalted oil (DAO). Stability evaluation showed that stable feedstocks tended to produce less coke, greater DAO yields, and lower amounts of impurities compared to unstable feedstocks. In addition, it was revealed that the CII was sensitive to the reaction performance, suggesting that improving the stabilities of asphaltenes by means of the solvency effect is the key to obtaining high product quality.