CFD modeling and experimental study of multi-walled carbon nanotubes production by fluidized bed catalytic chemical vapor deposition

A parametric study investigating the impact of temperature, gas velocity, and composition of the gaseous phase on the catalytic growth of multi-walled carbon nanotubes (CNT) has been performed. CNTs have been produced by catalytic chemical vapor deposition from methane decomposition over Co-Mo/MgO with average diameter of 188 μm with spherical shape in a fluidized bed reactor. The computational fluid dynamics (CFD) method was used for simulating the hydrodynamics of the reactor and investigating the operational and best velocity for producing high quality CNTs by this system. The operational and best velocities obtained by simulation were 0.015 to 0.05 m/s and near 0.015 m/s. Then the results used in the experiments with different temperature and gas compositions. CNTs products were characterized by Raman spectroscopy, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The results showed that temperature of 900 °C, methane to hydrogen volume ratio 1:4 and 0.02 m/s are the best quantities of the parameters for CNTs growth.