Hydrotreating of petroleum vacuum residue in supercritical aromatic solvents with activated carbons

Petroleum vacuum residue (VR) isthe heaviest fraction of refine petroleum processes, which contains higherportions of asphaltene and higher concentration ofcontaminants such as sulfur, nitrogen, and heavy metals. Conversion of VR intolight fraction without heteroatoms becomes important more and more in the refinerybecause of the short supply of light sweet crude oil as well as the steep increaseof crude oil price. In the study, the hydrotreating of VR in supercritical hydrocarbon solvents was conducted with activated carbon (AC) as a catalyst in batch reactor. Two kinds ofsupercritical hydrocarbon solvents were applied: n-alkanes (n-hexane and n-dodecane) and aromatic solvents (toluene and m-xylene). Along with the conversion level andcoke formation of hydrotreating VR reaction, the distribution of oil product (naphtha, middle distillate, vacuum gas oil andresidue) in each supercritical hydrocarbon solvent was evaluated. The supercritical aromatic solvent gave much smaller naphtha fraction but higher middle distillate fraction than the supercritical n-alkanes did. It implies that the conversion level and product quality can be controlled by the selected supercritical solvent. In addition, the effect of hydrogen partial pressure and surface properties of AC on the hydrotreating VR reaction were also investigated.