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Catalysts based on functionalised carbon nanofibers (FCNF) coated with Ni-decorated MoS 2 nanosheets were obtained by direct decomposition of ammonium thiomolybdate and nickel nitrate impregnated on the FCNF under controlled temperature conditions in inert atmosphere. The catalysts were characterised by X-ray Diffraction (XRD), N 2 adsorption, Raman spectroscopy, temperature programmed reduction of sulfur species (TPR-S), NH 3 temperature programmed desorption (NH 3 -TPD) and transmission electron microscopy (TEM). Decomposition temperature was found to have a paramount importance in the formation of uniform MoS 2 slabs, as revealed by the TEM study: at 600 °C, non-uniform covering of the carbon nanofiber (CNF) was observed Higher asphaltene conversions were obtained for the CNF-supported catalysts prepared at 450 °C, which overperformed the Al 2 O 3 -supported benchmark catalyst. However, the catalytic performance in hydrodesulfurisation and hydrodemetallisation of the CNFbased catalysts was slightly lower than that of the benchmark catalyst.

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One of the main problems that our society must deal with in a near future is the progressive substitution of traditional fossil fuels by different energy sources, such as renewable energies. In this context, biogas will play a vital role in the future. Nowadays, one of the most important uses of biogas is the production of heat and electricity from its direct combustion in co-generation plants. An interesting alternative consists on its direct valorisation to produce a syn-gas that can be further processed to produce chemicals, liquid fuels, or hydrogen. Results showed in this work evidenced that catalytic decomposition of biogas (CH 4 /CO 2 mixtures) can be carried out with a Ni/Al 2 O 3 catalyst obtaining simultaneously a syn-gas with high H 2 content together with carbonaceous nanostructured materials with high added value. The parametric study revealed that temperature, WHSV (Weight Hourly Space Velocity, defined here as the total flow rate at normal conditions per gram of catalyst initially loaded) and CH 4 :CO 2 feed ratio influence directly in CH 4 and CO 2 conversion, H 2 :CO ratio and carbon generation (gC/g cat). It was also evidenced that carbon structure depends on temperature. At 600ºC, fishbone like nanofibers with no hollow core are obtained while at 700ºC a mixture of fishbone and ribbon like nanofibers with a clear hollow core are formed.