PYROLYTIC SYNTHESIS OF CARBON NANOTUBES ON Ni, Co, Fe/MCM-41 CATALYSTS

Abstract

The purpose of the accomplished work was to use the advantages (ordered porous structure and high surface area) of mesoporous MCM-41 silicas in the pyrolytic synthesis of carbon nanostructures. MCM-41 matrices were used for chemisorption of volatile nickel, cobalt, and iron acetylacetonates with following metal reduction. The synthesis of carbon nanotubes was carried out by two routes: (a)MCM-41 treatment with Ni(acac)₂ or Co(acac)₂ vapor at 150°C, metal reduction with H₂ at 450°C, C₂H₂ pyrolysis over the catalyst at 700°C; (b)MCM-41 modification with Co(acac)₂ or Fe(acac)₂, reduction of supported metal complexes with C₂H₂, and pyrolysis at 700°C (in situ reduction). The TEM data showed that carbon nanotubes were formed with external diameter 10-35 nm for Ni-, 42-84 nm for Co-, and 14-24 nm for Fecontaining matrices. In the absence of metals, low yield of nanotubes (up to 2%) was detected.