A study of catalyst particles encapsulated inside multiwalled carbon nanotubes on zeolite and montmorillonite

Synthesis of carbon nanotubes on zeolite and montmorillonite is presented. Prior to synthesis, minerals were enriched by particles of iron. Synthesis of carbon nanotubes was performed by hot filament chemical vapour deposition using methane as a source of carbon. A high density of carbon nanotubes was observed in the whole volume of zeolite and montmorillonite. Iron containing particles catalysing the formation and growth of carbon nanotubes were visualized at the ends of nanotubes by field-emission scanning electron microscopy in a combined mode of secondary and backscattered electrons. 57Fe Mo center dot ssbauer spectroscopy was employed to find the oxidation state of iron in Fe-montmorillonite before the synthesis of nanotubes and in the structures of nanocomposites after the synthesis. The metallic particles in the structures of nanocomposites at the ends of carbon nanotubes are characterized by Mo center dot ssbauer spectroscopy mainly as ferromagnetic cementite (Fe3C).