Formation of concentric shell carbon by homogeneous partial oxidation of methane

Abstract

It has been shown that the carbon soot produced as a byproduct of partial oxidation of methane consists of carbon nanoparticles of almost ideal spherical morphology and perfect concentric onion-like structure. The particles are unusually big for carbon onions and have outer diameter of 10–50 nm while the inner cage is rather typical for onions and has diameter below 1 nm. The concentric graphitic structure and spherical symmetry along with the absence of amorphous carbon are confirmed by transmission electron microscopy, electron diffraction, EDX spectroscopy and Raman investigation. The spherical particles get deposited on a wall of a partial oxidation reactor as loose particles embedded in a low density organic ovary, which can be detected by its luminescence or by cautious electron microscopy imaging. It is important that unlike literature reports on giant onions, the carbon deposit was dominated by these giant spheres. This process may be considered as a prototype for a production method for giant concentric shell carbon particle black.