The carbon nanotubes (CNTs) arrays were grown in a CVD reactor, and subjected to extensive characterization in different longitudinal positions of reactor and upon addition of small amount of acetic acid. Through optical microscopy, Raman spectroscopy, FESEM, XRD and HRTEM characterizations, it was consistently revealed that acetic acid alleviates amorphous carbon layer, which gradually thickens CNTs along the reactor. The added acetic acid also resulted in higher growth rate along the so-called growth window. HPLC of extracted byproducts confirmed the presence of some polycyclic aromatic hydrocarbons. The solid weight of these byproducts decreased upon addition of catalyst precursor, as well as acetic acid to pure xylene feed. The results suggest that primary light products of xylene pyrolysis can be competitive feeds for both catalytic and subsequent pyrolytic reactions. They may also be more efficient feeds for CNTs growth than xylene itself.

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