Catalytic thermal decomposition of methane to CO x -free hydrogen and carbon nanotubes over MgO supported bimetallic group VIII catalysts

Bimetallic Ni-Fe, Ni-Co and Fe-Co supported on MgO catalysts with a total metals content of 50 wt.% were evaluated for decomposition of methane to CO/CO 2 free hydrogen and carbon nanomaterials. The catalytic runs were carried out at 700°C under atmospheric pressure using fixed bed horizontal flow reactor. The materials were characterized by XRD, TEM, Raman spectroscopy, surface analysis and TGA-DTG. The data showed that the bimetallic 25% Fe-25%Co/MgO catalyst exhibited remarkable higher activity and stability up to ∼10 h time-on-stream with respect to H 2 production. However, the catalytic activity and durability was greatly declined after incorporating 25%Ni to either 25%Fe or 25%Co/MgO catalysts at all time on stream. The main reason for the catalytic inhibition of Ni containing catalysts is consuming NiO during the formation of rock-salt Mg x Ni (1-x) O solid solution. However, the almost complete segregation of Fe 2 O 3 and Co 3 O 4 oxides played an important role for the high activity of the Fe-Co based catalyst. TEM images illustrate that the accumulated carbon over all catalysts are multi-walled carbon nanotubes in nature. The TG data showed that a higher yield of MWCNTs was achieved over bimetallic Fe-Co catalyst compared to the Ni-Fe or Ni-Co containing catalysts. © 2014 Elsevier B.V. All rights reserved.