Electron microscopy investigation of the microstructure of unsupported Ni–Mo–W sulfide

An exploration was made on structure and active sites of the unsupported Ni–Mo–W sulfide hydrodesulphurization catalyst prepared by a thiosalt decomposition method. More insights into the nanocomposite structure were provided by introducing the concept of average curvature of Mo(W)S2 and establishing a new structure model. The defects of cross and mixed stacks, steps along c-axis, expansion of (002) interplanar spacing and mixing structure of Mo(W)/Ni sulfides were investigated using advanced electron microscopy. All these defects in Mo(W) sulfides are closely correlated with increasing active sites of unsupported Ni–Mo–W sulfide catalyst.

Graphical AbstractFrom the top schematic of unsupported Ni–Mo–W sulfide, the MoS2, WS2, or MoxW1 − xS2 are surrounded by the dispersed Ni sulfide, which make the formation of nanocomposite phases possible. For the bottom colorized high-resolution transmission electron microscopy image with 3D rotation, the variation in sample thickness leads to a varying representation of the contrast of the Ni–Mo–W sulfide sheet, …Figure optionsDownload as PowerPoint slideResearch Highlights
► Rich microstructural features of unsupported Ni–Mo–W sulfide catalyst were revealed.
► Curvature of HDS catalyst was firstly proposed, also illustrative for other catalysts.
► Insights into the nano-composite were gained from its new structure model.