Beneficial roles of H-donors as diluent and H-shuttle for asphaltenes in catalytic upgrading of vacuum residue

Abstract

The effects of various organic solvents having different H-donor index, asphaltene solubility, and alkyl-substitution on the upgrading of vacuum residue (VR) were investigated under thermal cracking or catalytic hydrocracking conditions at 673K and 10.0MPa N2 or H2. Molecular dynamics simulations were also adopted to verify physical interaction between asphaltene species with H-donor solvents. Thermal cracking led to a considerable amount of coke formation, close to 29.8wt.%, but the addition of H-donors reduced the coke formation down to 23.4, 19.0, 12.4, and 4.1wt.% in the presence of naphthalene, 1-methyl naphthalene(1-MN), decalin, and tetralin, respectively. The coke formation was considerably reduced to 7.2wt.% in the hydrocracking condition, and further down to 2.9 and 1.2wt.% in the presence of naphthalene and tetralin, respectively. It was demonstrated that H-donors retaining the H transfer capability coupled with the solubility of asphaltene contributed to the marked performance of VR hydrocracking in the presence of dispersed MoS2 catalyst.