Hydrocracking of vacuum residue with activated carbon in supercritical hydrocarbon solvents

Hydrocracking of vacuum residue with activated carbon was conducted in a batch reactor with two types of supercritical hydrocarbon solvents, aromatic hydrocarbons (m-xylene and toluene) and normal alkane hydrocarbons (n-hexane and n-dodecane). The supercritical reactions were performed at 400°C with H ₂ partial pressures of 3.45 MPa and 6.89 MPa. The supercritical hydrocarbon solvent affected the levels of conversion and coke formation as well as the distribution of oil products (naphtha, middle distillate, vacuum gas oil, and residue). The mass ratio of each oil product to the unreacted residue differed among the supercritical solvents. Compared to the product profile in n-alkane solvents, aromatic solvents yielded much smaller naphtha fractions and larger middle distillate fractions. An increase of surface acidity of the activated carbon led to the conversion improvement observed in the supercritical reactions. However, the increased partial pressure of hydrogen was not associated with significant changes in conversion. High conversion (69.2 wt.%) with low coke (13.5 wt.%), and high quality oil products (13.0 wt.% of naphtha, 34.9 wt.% of middle distillate, 27.1 wt.% of vacuum gas oil, and 11.2 wt.% of residue) could be obtained with supercritical m-xylene and acid-treated activated carbon.