Selective formation of Fe-included carbon nanocapsules and nanotubes by fall-to-stop pyrolysis reactor with ferrocene

‘Fall-to-stop pyrolysis reactor’ is proposed to separately synthesize Fe-included carbon nanocapsules (CNCs) and multi-wall nanotubes (MWCNTs). In this method, ferrocene powders are fallen with H2 stream to a stage at the inlet of a furnace in which temperature profile is controlled. By this method, CNCs can be produced separately from MWCNTs at the relatively cold downstream zone, while MWCNTs are produced at the high temperature zone inside the furnace. This concept can enable one to conduct continuous productions of CNCs and MWCNTs. The selectivity of CNCs to MWCNTs is dependent on the temperature in the furnace. It was found that it was necessary to raise the furnace set temperature to 1000 °C to achieve the separated synthesis of CNCs and MWCNTs. In order to obtain high yield of MWCNTs, 900 °C was appropriate instead.