Ruthenium catalysts supported on multi walled carbon nanotubes for the catalytic wet air oxidation of aniline

• Main Author: García, Juan
• Publication Date: 2004
• Other Authors: Gomes, Helder, Serp, Philippe, Kalck, Philippe, Figueiredo, José, Faria, Joaquim
• Language: eng
• Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Download full: http://hdl.handle.net/10198/1768

Oxidation of carbon multi-walled nanotubes (MWNTs) by nitric acid leads to the introduction of carboxylic groups that can be used to anchor a Ru metallic phase. Ruthenocene [Ru(C5H5)2], Ruthenium (1,5-cyclooctadiene, 1,3,5-cyclooctatriene) [Ru(COD)(COT)], and Ruthenium trichloride RuCl3.xH2O were used as precursors in the incipient-wetness (IW) and excess (EI) impregnation methods. The catalytic activity of the prepared materials in the wet air oxidation of aniline in aqueous solution, was found to depend on the type of Ru precursor in the following order: [Ru(COD)(COT)] > RuCl3.xH2O > [Ru(C5H5)2]. The high aniline conversions observed (complete conversion in the case of the most active catalyst) are attributed to the high external surface area of the MWNTs (SBET = 175 m2/g), which is compatible with end-closed nanotubes (zero micropore volume). This type of structure provides an efficient surface contact between the reactants (aniline) and the active sites, especially in the liquid phase where mass transfer limitations are very significant.