Catalytic activity, stability and structure of multi-walled carbon nanotubes in the wet air oxidation of phenol

Multi-walled carbon nanotubes (MWCNTs), with no supported metal, were used as catalysts in the wet air oxidation of phenol. The MWCNTs were chemically modified using HCl or HNO(3)-H(2)SO(4). They were characterized by BET, SEM, TEM, FT-IR and Raman spectroscopy. The functionalized MWCNTs exhibited both high activity and good stability in the wet air oxidation of phenol. At 160 degrees C and 2.0 MPa with an initial phenol concentration of 1000 mg/L, 100% phenol conversion and 76% total organic carbon abatement could be achieved after 120 min reaction. Upon reaction, the short chain carboxylic acids mainly maleic/fumaric, malonic, oxalic, formic and acetic acid were produced. Surface functional groups (-COOH) were shown to play a key role in the high activity of the functionalized MWCNTs. A mechanism for the CWAO of phenol was proposed. (c) 2007 Elsevier Ltd. All rights reserved.