Analysis of effluent gases during the CCVD growth of multi-wall carbon nanotubes from acetylene

Evidence of an Equimolar C2H2–CO2 Reaction in the Synthesis of Carbon Nanotubes

“…In a first approximation, the partial pressure of CO 2 and the average decomposition rate of the carbonate can be deduced from thermogravimetric analysis (TGA) of CaCO 3 . [13] Figure 1 a shows a significant and complex dependence of the quantity of produced MWCNTs on CaCO 3 decomposition. In the temperature range between 640 and 680 8C-at which about 5 % of CaCO 3 decomposes-about 350 mg of …”

Evidence of an Equimolar C2H2–CO2 Reaction in the Synthesis of Carbon Nanotubes

“…[14] Presumably, CO 2 (g) also limits acetylene polymerization, which occurs by a homogeneous radical chain reaction to produce more-stable oligomers along with heavy oils. [13] As observed with nitric oxides, [15] the polymerization process could be inhibited by the presence of gaseous CO 2 .…”

“…[11][12][13] We demonstrated in a previous report that the yield of multiwalled CNTs (MWCNTs) strongly correlates with the growth temperature (700 8C) and the decomposition temperature range of the carbonate support. [14] CaCO 3 stability is ruled by a dynamic equilibrium of the decomposition reaction CaCO 3 $CaO + CO 2 that proceeds at temperatures ranging from 600 8C to 820 8C.…”

“…In a first approximation, the partial pressure of CO 2 and the average decomposition rate of the carbonate can be deduced from thermogravimetric analysis (TGA) of CaCO 3 . [13] Figure 1 a shows a significant and complex dependence of the quantity of produced MWCNTs on CaCO 3 decomposition. In the temperature range between 640 and 680 8C-at which about 5 % of CaCO 3 decomposes-about 350 mg of MWCNTs are produced from 100 mg of Fe 2 Co/CaCO 3 catalyst in 30 minutes.…”

Effect of the Support on Structure of the Multi-Walled Carbon Nanotubes Grown By CCVD over Nickel Nanoparticles

“…NiO at these conditions reduced to the metallic Ni (2θ = 44 and 52 °, curve 2). Decomposition of the CaCO 3 at relatively low temperature can be explained by the presence of metallic component [22]. It is known that calcium carbonate may begin to decompose at a temperature of 600 °C.…”