The use of bimetallic MCM-41 mesoporous catalysts for the synthesis of MWCNTs by chemical vapor deposition
2012
Atchudan, R. | Pandurangan, A.
Mesoporous MCM-41 molecular sieves incorporating chromium with different Si/Cr ratios (Si/Cr: 50, 75, 100 and 125) were synthesized hydrothermally and Co, Fe, Mn, Ni, Ti, Ru, and Pd were loaded on them using wet impregnation method. The synthesized materials were characterized by various physico-chemical techniques, such as ICP-AES, XRD, TGA, N₂ sorption isotherms, DRS-UV and TEM. The production of MWCNTs by CVD using metal-containing mesoporous MCM-41 was investigated using acetylene as the carbon source. Fe/Cr-MCM-41 and Pd/Cr-MCM-41 are the most active catalysts for the growth of MWCNTs when compared with the other mono and bimetallic mesoporous catalysts. The MWCNTs have been analyzed by XRD, SEM, TGA, TEM and Raman spectroscopy. The strongest peak of the graphite band and the weak disorder band in the Raman spectrum confirmed the high purity of the MWCNTs. The structure of MWCNTs was studied by TEM which suggests that they are highly ordered and well graphitized. The formation of MWCNTs with uniform inner diameter in the range of 4–5nm and outer diameter in the range of 12–13nm was observed over Fe/Cr-MCM-41. These studies suggest that the bimetallic MCM-41 could be a kind of promising supports for catalytically synthesizing MWCNTs by CVD method.
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