Slurry phase hydrocracking of heavy oil and residue to produce lighter fuels: An experimental review

The constraints of conventional oils, stringent environmental regulations, and increasing demand for lighter distillates have shifted interest towards heavy crude oils, and atmospheric and vacuum residues upgrading. Therefore, refineries are looking for promising hydrogen addition-based technologies. Slurry phase hydrocracking is an emerging and capable technology for achieving a high conversion of heavy feedstocks and minimizing byproducts such as gas, coke, and fuel oil. Slurry phase hydrocracking is operated at high temperature (over 400 degrees C) and pressure (over 100 bar), the feedstock is premixed with the nanosized catalyst precursors. The premixed catalyst and feedstock are fed into the reactor and hydrogen is injected from the bottom. As catalyst premixing is an important step, it is crucial to identify an active and effective catalysts. The activity of slurry catalysts is generally influenced by active sites, dispersion, type of metal used, and their concentration. This review aims to summarize the potential for slurry phase hydrocracking to produce lighter fuels. It describes in detail the different types of slurry catalysts, such as homogeneous (water-soluble and oil-soluble dispersed catalysts) and heterogeneous (solid powder catalysts), and their performances in slurry phase hydrocracking of heavy oils and residues. This review presents the numerous disadvantages of the known technologies's attributed to the low hydrotreating and hydrocracking conversions. Also, innovative research approaches including nanosized solid powder catalysts; the synergistic effect of surfactants, ultrasonication, and supercritical fluids in overcoming these challenges were critically reviewed. This review would promote future research on the slurry phase hydrocracking for lighter fuel production.