Comparison of unsupported WS2 and MoS2 catalysts for slurry phase hydrocracking of vacuum residue

Abstract

Oil-dispersed WS2 catalysts were prepared in situ using an oil-soluble W precursor of W(CO)6 in the hydrocracking (HCK) of vacuum residue (VR). Smaller size of WS2 catalyst (WS2-DMDS) was also obtained by the addition of dimethyl disulfide (DMDS) with the W precursor in the VR HCK. The activity tests were performed in a batch reactor at 692 K at 9.5 MPa H2 with the same metal loading of 0.113 mmol. Oil-dispersed MoS2 catalyst was also employed to compare the structure and activity with WS2. Extended X-ray absorption fine structure (EXAFS) and transmission electron microscopy (TEM) analysis were used to examine structural properties of the dispersed catalysts. The activity based upon the H2 consumption rate per lateral metal numbers, TOFS, in the VR HCK turned out that WS2 (0.709 s−1) is better than MoS2 (0.573 s−1), which leads to higher asphaltene conversion for WS2 (39.2%) than MoS2 (35.8%). Moreover, it was noted that the dispersibility of WS2 (58.0%) was found better than MoS2 (3.3%).