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.