Ni-MoS2 supported on carbon nanofibers as hydrogenation catalysts: Effect of support functionalisation

Fishbone carbon nanofibers (CNF) were functionalised in acidic media using nitric or nitric/sulfuric mixtures in order to introduce variations in their surface chemistry. The textural properties and surface chemistry of the functionalised CNF were characterized by Transmission Electron Microscopy (TEM), N2 adsorption, X-ray diffraction, temperature programmed desorption and X-ray photoelectron spectroscopy. Functionalised CNF thus prepared were used as catalytic support for NiMo catalysts. Resulting catalysts were composed by CNF coaxially coated by Ni-decorated MoS2 slabs, with different lengths and stacking degrees as a function of the functionalisation treatment, as TEM study revealed. Catalysts were evaluated in the hydrogenation of anthracene, a model compound representing polyaromatic groups present in heavy oil fractions. Catalysts prepared with the support functionalised by the less severe treatment, which led to short and defective MoS2 slabs, showed higher hydrogenation activity. On the other hand, harsher functionalisation treatment led to the formation of long stacked MoS2 slabs, resulting in lower performance towards anthracene hydrogenation.