Nitrogen-doped bamboo-shaped carbon nanotube supported catalysts for heterogeneous hydrogenation. The effect of surface polarity

Abstract

Nitrogen-doped bamboo-shaped carbon nanotubes (N-BCNTs) were produced by catalytic chemical vapor deposition using butylamine as carbon sources. The morphology of the nanotubes and the type of nitrogen incorporation was studied. The surface polarity of the synthetized nanotubes was tuned by using three different oxidizing agents, H2SO4/HNO3 mixture, cc. HNO3, and H2O2. It has been shown that due to the oxidation, the presence of oxygen containing functional groups (–COOH, –OH), and therefore, the hydrophilic character of the N-BCNTs considerably increased. The functionalized N-BCNTs and non-treated CNTs were used as support materials to prepare 5 wt% Pd catalysts. The synthesized Pd nanocomposites were successfully tested in liquid phase heterogeneous hydrogenation (octadecene to octadecane). Although, the catalytic activity decreased by the increasing surface polarity of the nanotubes, which can be attributed to the non-polar reactants, this effect could be beneficial in case of hydrophilic systems.