Visbreaking Of Heavy Oil In Supercritical Cyclohexane

The visbreaking of heavy oil in supercritical cyclohexane environment as a solvent was investigated at the temperature ranging from 320 to 400℃,the cyclohexane density from 0.20 to 0.35 g/mL,and the cyclohexane to heavy oil ratio from 2:1 to 4:1(wt).First,the performance of viscosity reduction was evaluated under various cyclohexane environments.Then,the visbreaking performance in supercritical cyclohexane was compared with the visbreaking under supercritical water and benzene environments.Despite the variation of supercritical fluids,the dealkylation involved in the visbreaking,which determines the viscosity reduction efficiency,could be effectively accelerated by the superior diffusivity in supercritical fluid solvents.Accordingly,the rapid reduction in product viscosity and average molecular weight together with the increasing light fractions could be obtained.Unfortunately,the condensation always playing an important role in the visbreaking although dealkylation and condensation are in the tandem structure at the applied temperatures.Different from supercritical water and supercritical benzene considered as inert supercritical fluid solvents,supercritical cyclohexane participates in the visbreaking as a hydrogen donor.Consequently,the viscosity reduction efficiency at the early visbreaking stage is retarded but the condensation in the middle and late visbreaking stages are suppressed.