Effect of Ni loading and reaction temperature on the formation of carbon nanotubes from methane catalytic decomposition over Ni/SiO2
- 222 Downloads
Since their discovery carbon nanotubes (CNT) have attracted much attention due to their singular physical, mechanical and chemical properties. Catalytic chemical vapor deposition (CCVD) of hydrocarbons over metal catalysts is the most promising method for the synthesis of CNT, because of the advantages of low cost and large-scale production and the relatively low temperature used in the process, compared to the other methods (laser ablation and discharge between graphite electrodes). In this study, CNT were synthesized by CCVD using Ni supported on SiO2 as a catalyst. The carbon deposited in the reaction was analyzed by Raman spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effects of reaction temperature and Ni loading on the carbon nanotube formation were evaluated. The catalyst with 5% Ni favored high yield of CNT at lower temperature, with abundant “multi-walled carbon nanotubes” (MWNTs) at 625 °C, while single-walled carbon nanotubes (SWNTs) and MWNTs were obtained at 650 °C. With an increase in the reaction temperature a marked decrease in the yield of CNT was observed, probably due to the sintering of the catalyst. The catalyst with 1% Ni gave SWNTs with a high degree of order at all reaction temperatures, but in low quantity.
KeywordsRaman Spectrum Radial Breathing Mode Carbon Filament Catalytic Chemical Vapor Deposition Ethanol Decomposition
Thanks to CNPq, Prodoc CAPES, Laboratory of Molecular Spectroscopy of Chemistry Institute, São Paulo University for the utilization of Renishaw Raman System 3000.
- 6.Colomer JF, Bister G, Willems I, Konya Z, Fonseca A, Van Tendeloo G, Nagy JB (1999) Chem Commun 1343Google Scholar
- 7.Peigney A, Laurent Ch, Dobigcon F, Roussel A (1997) J Mater Res 12:613Google Scholar
- 10.Cassel AM, Kong JA, Dai HJ (1999) Phys Chem B103:6484Google Scholar
- 16.Seidel R, Liebau M, Duesberg BS, Kreupl F, Unger E, Graham AP, Hoenlein W, Pompe W (2003) Nanoletters 3:965Google Scholar
- 17.Seidel R, Duesberg GS, Unger E, Graham AP, Liebau M, Kreupl F (2004) J Phys Chem B108:1888Google Scholar
- 20.Pimenta MA, Marucci A, Empedocles S, Bawendi M, Hanlon EB, Rao AM, Eklund PC, Smalley G, Dresselhaus RE, Dresselhaus MS (1998) Phys Rev B58:R16012Google Scholar
- 22.Liao H, Hafner JH (2004) J Phys Chem B108:6941Google Scholar