Abstract:
In this paper we show the synthesis and characterization of multiwall carbon nanotubes (CNT) doped with different transition metals, M-CNT (with M= V, Cr, Mo, Ni). The goal is to obtain acid catalysts active for the synthesis of Fine Chemicals. Other carbonaceous materials containing those metals, in particular, carbon xerogels, were tested in the synthesis of chalcones, resulting as active catalysts [4]. The solids have been prepared by treatment of commercial multiwall carbon nanotubes with nitric acid (CNTO) and subsequent doping with the metals by ionic exchange of the corresponding salts under ultrasonic activation. The materials thus obtained were dried at 60 °C and pyrolyzed at 500 °C to decompose the salts. A reference solid without metal was also prepared (CNTOp).
The analysis by different techniques shows that the doping of the CNT with the metals has been produced. Thus, FTIR-ATR spectra show the disappearing of the bands assigned to the carboxylic groups and the appearing of new bands. The TG curves in air of the pyrolyzed samples lead to a higher residue than that for CNTOp, following the V > Cr > Ni > Mo order. The thermal stability of C=C bonds of the skeleton of nanotubes functio...