Catalytic Study of WS2 Undergoing Electron Irradiation

Tungsten disulfide is irradiated with electrons at 1000 kGy and used as a catalyst in the hydrodesulfurization of dibenzothiophene. Catalytic conversion, selectivity, surface area, and other physical properties are then compared to those of crystalline WS2 and exfoliated WS2 for the same reaction. The dibenzothiophene conversion of irradiated samples is found to be 3.8 times greater than that of crystalline WS2, while the surface area decreases by 30%. Irradiation of WS2 lowers the selectivity for dicyclohexane, increasing the selectivities for biphenyl and phenylcyclohexane. Consequently, the hydrogenation/hydrodesulfurization ratio decreases by 42%. Microstructural characteristics of irradiated WS2 are analyzed by scanning electron microscopy and X-ray diffraction techniques. Scanning electron micrographs show evidence of crystal damage due to irradiation. The X-ray diffraction patterns of irradiated WS2 have weaker peak intensities compared to crystalline WS2, especially in the case of the (002) reflection. Peak width analysis indicates that the average crystal size of WS2 is smaller after irradiation. The enhanced catalytic activity of irradiated WS2 is discussed in terms of structural changes brought about by electron irradiation.