AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
High Throughput Carbon Nanotubes Aerosol Synthesis
Christian Hoecker, Fiona Smail, Martin Pick, ADAM M BOIES, University of Minnesota
Abstract Number: 721 Working Group: Nanoparticles and Materials Synthesis
Abstract The decomposition of ferrocene and the nucleation of iron catalyst nanoparticles for carbon nanotube (CNT) synthesis in a continuous gas phase process are studied. The production of iron catalysts from ferrocene occurs in a horizontal tube furnace at 300–1300°C, in a hydrogen atmosphere and at atmospheric pressure. The iron nanoparticles act as a catalyst to form CNTs from methane or other carbon sources. The resulting CNTs agglomerate to form an annulus concentric within the reactor. To date few studies have examined the phenomena associated with the ferrocene breakdown, catalyst nucleation and growth within the reactor. These phenomena are critical to the quality and throughput of the CNT production.
Studies along the axis of the furnace tube are carried out by means extractive analysis with a scanning mobility particle size spectrometer. Products of reactions inside the tube are analyzed by Fourier transform infrared spectroscopy.
The decomposition of ferrocene and nucleation and agglomeration of iron nanoparticles are modelled numerically by solving the general aerosol dynamic equation with inclusion of ferrocene decomposition, iron particle nucleation, coagulation and diffusion. The effect of different conditions (temperature, flow rate, gas chemistry and tube diameter) on the decomposition, nucleation and agglomeration processes is studied to increase iron catalyst density for purposes of increasing CNT production.
Experimental measurements indicate that particles form within a narrow axial location that is influenced by the ferrocene time and temperature history. Our results indicate that ferrocene decomposition is also influenced by background gas properties, whereby higher particle mass and number concentrations are present in non-hydrogen atmospheres. Axial measurements downstream indicate that particles disappear very abrupt; a phenomenon which cannot be predicted by the modelled results including thermophoretic and diffusional forces.
References
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