Multiwalled Carbon Nanotubes for Liquid-Phase Oxidation. Functionalization, Characterization, and Catalytic Activity

Multiwalled carbon nanotubes (CNTs) were functionalized with HNO3, HNO3/H2SO4, and HNO3/Na2CO3. The preparation of metal supported on mesoporous carbon nanotube catalyst is described. The catalysts were synthesized by impregnation of carbon nanotubes with different metallic precursors (H2PtCl6·6H2O, RuCl3·H2O, and CuCl2·2H2O) followed by reduction. The structures of the CNT modified with HNO3, HNO3/H2SO4, and HNO3/Na2CO3 and CNT-supported metal catalysts have been characterized by means of Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and nitrogen adsorption/desorption isotherms (BET), and their activity was tested in continuous catalytic wet air oxidation of aniline. For the catalysts prepared with metal precursors, activities were found in the order of Pt/N-CNT > Cu/N-CNT > Ru/N-CNT. The structure of carbon nanotubes supported metal catalyst is responsible for the activity, and the absence of micropores enhances the potential capabilities of carbon nanotubes as support material.