LAUSR

Abstract The slurry phase hydrocracking (HCK) of vacuum residue (VR) in the presence of dispersed MoS 2 catalyst was investigated under varying temperature, pressure, and reaction time. Extended X-ray absorption fine structure (EXAFS) measurements were used to obtain structural information about the dispersed MoS 2 phase during the reaction. Under a standard reaction condition of temperature 673 K and pressure 10.0 MPa in an autoclave batch reactor, kinetic analysis for VR HCK confirmed that the reaction occurs in a parallel manner in the production of 77% liquid oils as major products such as vacuum gas oil and distillates with the generation of gas and of 23% coke in the presence of dispersed MoS 2 catalyst (0.113 mmol or 360 ppm Mo). Although temperatures below 653 K at 9.5 MPa were found beneficial in coke reduction to less than 1.0 wt.% in favor of hydrogenation at 33 h of reaction, higher pressures over 15 MPa at 673 K were more influential in accelerating the VR conversion into liquid products, reaching 90% at 4 h of reaction with coke reduction down to 1.2 wt.% than the cases under conditions below 10 MPa. Analysis of the spent catalysts by EXAFS and TEM demonstrated that the nanosized MoS 2 phase was well developed from Mo(CO) 6 in the early stage of the reaction, with lower Mo S and Mo Mo coordination verifying the small MoS 2 particles having more exposed and defect sites as active phases.