Heterogeneous hydroxylation catalyzed by multi-walled carbon nanotubes at low temperature

In this paper, multi-walled carbon nanotubes (MWCNTs) were directly used as catalysts for the hydroxylation of aromatic hydrocarbons at low temperature (50-70 degrees C). Without the assistance of any solvent or additive, high selectivity was still obtained. The catalysts were characterized by X-ray powder diffraction, infrared spectra, Raman spectra, and transmission electronic microscopy. These results prove that MWCNT was a highly-active, highly-selective, and well-reproductive heterogeneous catalyst. The curved sp(2)-hybridized carbon surfaces of MWCNT played an important role in these selective catalytic reactions. The reactions were proposed to occur via an oxene attacking process. The active oxygen species were generated through the interaction between the hydrogen peroxide and the MWCNTs and subsequently consumed by the aromatic hydrocarbons. This process was repeated in the catalytic reactions. (c) 2005 Elsevier B.V. All rights reserved.