Influence of the composition of a H2-CH4 gas mixture on the catalytic synthesis of carbon nanotubes-Fe/Fe3C-Al2O3 nanocomposite powders

Alain Peigney (1) , Christophe Laurent (1) , Abel Rousset (1)

1 LCMI - Laboratoire de Chimie des Matériaux Inorganiques

CNTs-Fe/Fe3C-Al2O3 nanocomposite powders have been prepared by selective reduction of an a-Al1.9Fe0.1O3 solid solution in H2-CH4 gas mixtures (0, 1.5, 3, 4.5, 6, 9, 12, 14, 16, 18, 24, 30 and 45 mol% CH4). The powders have been studied using macroscopic and microscopic techniques. The CNTs are arranged in very long bundles homogeneously dispersed in the composite powder. Most CNTs have less than four walls and are free of pyrolytic or amorphous carbon deposits. The inner diameter is in the range 1-6 nm, which could indicate that the catalyst particles active for CNTs formation are in this size range. The reduction of the Fe3+ ions to metallic Fe is highly favoured by the presence of CH4 in the reduction atmosphere. There are more Fe3C than a-Fe particles located at the surface of the matrix grains for CH4 contents higher than 4.5 mol%, however, the exact nature of the catalytically active particles remains an open question. Compositions in the range 9-18 mol% CH4 give the best.

Mots clés: Carbon nanotubes; Nanocomposites; CCVD

Domaines: Matériaux

Alain Peigney, Christophe Laurent, Abel Rousset. Influence of the composition of a H2-CH4 gas mixture on the catalytic synthesis of carbon nanotubes-Fe/Fe3C-Al2O3 nanocomposite powders. Journal of Materials Chemistry, 1999, vol. 9, pp. 1167-1177. ⟨10.1039/a809114e⟩. ⟨hal-00940033⟩