A molecular insight into deoiled asphalt’s slurry-phase hydrocracking process

Abstract

Qilu vacuum residue with Ni + V content of 120 ppm and Ca content of 40 ppm, is hard to process for fixed bed hydrocracking technology. In this work, solvent deasphalting process was used as a pretreatment for processing Qilu vacuum residue, and the yield of deasphalted oil could be up to 48.3 %, with less metal (Ni + V + Ca < 15 ppm) and asphaltene (<0.1 %) in deasphalted oil. The n-butane solvent in solvent deasphalting (SDA) process had higher selectivity for HC class, and correspondingly the relative abundance of HC class of deasphalted oil (DAO) was much higher than that of deasphalted oil (DAO). The abundance of DAO was higher than that of DOA when double bond equivalent (DBE) < 14 or carbon number (CN) < 46, and the relative abundance of SDA1-DOA was higher than that of SDA2-DOA when DBE < 20 or CN < 46. Deoiled asphalt was taken as the feed of slurry-phase hydrocracking (SHC) process, and the conversion ratio of deoiled asphalt in slurry-phase hydrocracking process could be more than 80 % for 240 min reaction. The conversion ratios of SDA1-DOA for SHC1-120 min and SHC1-240 min reactions were 66.92 % and 81.64 % respectively, and the conversion ratios of SDA2-DOA for SHC2-120 min and SHC2-240 min reactions were 70.19 % and 85.71 % respectively. Sulfur species and asphaltene changing rules at molecular level were determined to evaluate DOA’s slurry-phase hydrocracking process.

Keywords

• Vacuum residue
• Solvent deasphalting
• Slurry-phase hydrocracking
• Asphaltene structure