Effect of Catalyst Structure on Growth and Reactivity of Carbon Nanofibers over Ni/MgAl2O4

The structure of Ni catalyst has a significant effect on the growth and reactivity of carbon nanofibers (CNFs) formed from methane decomposition. We present here a detailed study on this structure effect with Ni/MgAl2O4 as model catalyst. Different catalyst structures were obtained via dielectric barrier discharge (DBD) plasma and thermal decomposition. For the thermal decomposed catalyst, a complex combination of microfacets presents with a higher content of defects. A diffusion interfacial region is formed due to the migration of Ni atoms into the support. However, a higher concentration of close-packed plane is observed for the DBD decomposed catalyst with less defects and a clean interface between Ni particle and support. The CNFs over the DBD decomposed sample show smaller diameter and narrower distribution with a smaller slope of graphene layers but enhanced activity toward O2 and CO2, indicating better coke resistance for methane conversion.