Effects of dispersed MoS2 catalysts and reaction conditions on slurry phase hydrocracking of vacuum residue

The slurry phase hydrocracking (HCK) of vacuum residue (VR) in the presence of dispersed MoS2 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 MoS2 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 MoS2 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 MoS2 phase was well developed from Mo(CO)(6) in the early stage of the reaction, with lower Mo-S and M-Mo coordination verifying the small MoS2 particles having more exposed and defect sites as active phases. (C) 2016 Elsevier Inc. All rights reserved.