Influence of the Catalyst Supporting Material on the Growth of Carbon Nanotubes

Abstract

Catalytic chemical vapor deposition (CCVD) is considered as the most suitable technique for the large scale and low-cost production of carbon nanotubes (CNTs). Catalytic activity of Fe-Co, Fe-Ni and Co-Ni mixture supported on Al2O3 has been investigated in the production of carbon nanotubes (CNTs). Absolute ethanol was used as a source of carbon and nitrogen as the carrier gas. The Carbon nanotubes prepared by the catalytic decomposition of ethanol at 1173°K over iron supported alumina or silica catalysts with 5Wt% iron loading in a horizontal tube furnace under flow of nitrogen. The morphological structure of deposits CNTs were investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that the alumina supported catalysts more active towards CNTs formation than silica supported catalysts even with changing the percentage of metal loading (2.5% - 10%). Further investigation for alumina support with other metals and their binary metals heve been done to see for how far the alumina is suitable as a support. The yield of the carbon deposit obtained varied from 11.2 to 34.9% of the initial weight of the catalyst. The results revealed that CNTs prepared by Fe-Ni/Al2O3 catalyst has high length/diameter ratio and small tube diameter ≈ 17 nm.