Synthesis, characterization and evaluation of unsupported porous NiS2 sub-micrometer spheres as a potential hydrodesulfurization catalyst

Nanostructured NiS2 has attracted interest due to its wide applications and special properties. Synthesis of a pure phase NiS2 in a single step has been a challenge. In this work, a new method for direct synthesis of uniform NiS2/SiO2 sub microspheres has been developed by ultrasonic spray pyrolysis. Colloidal silica was used as a sacrificial template to create the porous structure. After silica removal, hollow, porous NiS2 nano spheres were obtained. The product was characterized by using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction (XRD), transmission electron microscopy and N2 adsorption/desorption isotherm. XRD confirmed the formation of single phase pyrite NiS2. It was found that the porous spherical NiS2 has a surface area of ca. 300 m2 g−1. The HDS catalytic activity of NiS2 was evaluated using a model compound, dibenzothiophene (DBT). It showed a first order reaction rate constant of 1.51 × 10−4 s−1 g cata−1 at 320 °C for HDS of DBT, which is significantly promising for further exploration.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (255 K)Download as PowerPoint slideHighlights► Ultrasonic spray pyrolysis method was used to prepare nanostructured NiS2. ► Pure phase cubic NiS2 submicrometer porous spheres were synthesized. ► High surface area of 300 m2 g−1 was observed for the NiS2 spheres. ► Hydrodesulfurization catalytic activity was tested using dibenzothiophene (DBT). ► A first order rate reaction rate constant of 1.51 × 10−4 s−1g cata−1 at 320 °C was observed.