Catalytic study of WS2 undergoing electron irradiation

Tungsten disulfide is irradiated with electrons at 1000 kGy and used as a c atalyst in the hydrodesulfurization of dibenzothiophene, Catalytic conversi on, selectivity, surface area, and other physical properties are then compa red to those of crystalline WS2 and exfoliated WS2 for the same reaction. T he dibenzothiophene conversion of irradiated samples is found to be 3.8 tim es greater than that of crystalline WS2, while the surface area decreases b y 30%, Irradiation of WS2 lowers the selectivity for dicyclohexane, increas ing the selectivities for biphenyl and phenylcyclohexane, Consequently, the hydrogenation/hydrodesulfurization ratio decreases by 42%. Microstructural characteristics of irradiated WS2 are analyzed by scanning electron micros copy and X-ray diffraction techniques. Scanning electron micrographs show e vidence of crystal damage due to irradiation. The X-ray diffraction pattern s of irradiated WS2 have weaker peak intensities compared to crystalline WS 2, especially in the case of the (002) reflection. Peak width analysis indi cates that the average crystal size of WS2 is smaller after irradiation. Th e enhanced catalytic activity of irradiated WS2 is discussed in terms of st ructural changes brought about by electron irradiation. (C) 2000 Academic P ress.