Growth of Single-Walled Carbon Nanotubes by the Rapid Heating of a Supported Catalyst

Abstract

Single-walled carbon nanotubes (SWNTs) have been synthesized by the rapid injection of a nickel formate/silica gel catalyst/support into a hot fluidized-bed reactor. The initial rapid heating of the catalyst in the hydrocarbon feedstock was found to be essential for the nucleation of SWNTs since only amorphous or graphitic carbon particles were formed without it. These results suggest that the rapid heating of the catalyst precursor enables the formation of the small metal particles required for SWNT growth, probably due to the accelerated thermal decomposition of the catalyst precursor and enhanced nucleation rate. The growth of the SWNTs was investigated by the adoption of different methods for introducing the catalyst, and by varying the synthesis parameters including the catalyst loading, hydrocarbon gas flow rate, and concentration. The results found that SWNTs formed only under certain reaction conditions. The nanotubes produced were characterized by electron microscopy and Raman spectroscopy.

Synthesis of High‐Quality, Double‐Walled Carbon Nanotubes in a Fluidized Bed Reactor

“…However, the mass production of DWCNTs is hardly reported. Though some reports have discussed the mass production of SWCNTs [12][13][14], they may be different for DWCNTs. Recent study suggests that the wall number control of SWCNTs is relatively tough as compared to that of multi-walled carbon nanotubes (MWCNTs) [10,11].…”

“…In this case, the higher metal loading on the catalyst for the DWCNT growth than that for the SWCNT growth makes it more difficult to avoid sintering than for the latter, when operated in the same high temperature range. Moreover, to synthesize bulk DWCNTs, it is necessary to control the concentration of the carbon source and the gas velocity [14], the thermal stability of the catalyst [10,11], the contact time of the catalyst with the carbon source [12], as well as the agglomerate structure of the carbon products [14] so that these are similar to those in the synthesis of MWCNTs [15][16][17][18][19].…”

Synthesis of carbon nanofibers and nanotubes by chemical vapor deposition using a calcium carbonate catalyst

“…The nearly stable H 2 concentration of outlet gas suggests that the H 2 production rate of reaction (1) and (2) was nearly equivalent to the H 2 consumption rates of reaction (3), (4) and (5). Certainly, the decomposition of C 2 H 2 into CNFs according to reaction (6) also contributed to the H 2 production when the temperature was higher than about 500 1C.…”

“…The synthesis of the CNFs and CNTs using various metal catalysts such as Fe, Ni [1], Cu [2], Co [3] or their alloys [4,5] is still favored by most researchers because of its low production cost and possibility of commercial scale production. Lately, the applications of various supports, Na 2 CO 3 [6], NaCl [7,8], g-alumina [9] and clay [10] for Fe, Ni and Co catalysts to catalytically deposit the CNFs and CNTs have been studied.…”

Temperature Threshold and Water Role in CVD Growth of Single-Walled Carbon Nanotubes

“…Following our previous reports on chemical vapor deposition (CVD) growth of SWCNTs (Geng et al, 2002(Geng et al, , 2006Kleinsorge et al, 2004;Li et al, 2004;Golovko et al, 2005;Hofmann et al, 2005;Engels et al, 2011), we wish to develop an in-depth understanding of the role of water in the growth process. Here, we report that using a catalytic Ni/SiOx system, which is also supported by other catalytic systems, including Fe/ MgO, Fe/K2CO3, Ni/MgO, Fe/NaCl, and Ni/NaCl, as shown in this work, there is a threshold temperature in the CVD growth of single-walled carbon nanotubes.…”