CO_x-free hydrogen and carbon nanofibers produced from direct decomposition of methane on nickel-based catalysts

Direct decomposition of methane was carried out using a fixed-bed reactor at 700 °C for the production of CO_x-free hydrogen and carbon nanofibers. The catalytic performance of NiO-M/SiO₂ catalysts (where M=AgO, CoO, CuO, FeO, MnO_x and MoO) in methane decomposition was investigated. The experimental results indicate that among the tested catalysts, NiO/SiO₂ promoted with CuO give the highest hydrogen yield. In addition, the examination of the most suitable catalyst support, including Al₂O₃, CeO₂, La₂O₃, SiO₂, and TiO₂, shows that the decomposition of methane over NiO-CuO favors SiO₂ support. Furthermore, the optimum ratio of NiO to CuO on SiO₂ support for methane decomposition was determined. The experimental results show that the optimum weight ratio of NiO to CuO fell at 8:2 (w/w) since the highest yield of hydrogen was obtained over this catalyst.