ИСТИНА

Carbon nanomaterials are widely studied in numerous fields of applications such as elctrochemistry or catalysis. In order to adjust the properties of carbon materials the implementation of heteroatoms (e.g. oxygen, nitrogen, boron…) to carbon structure is commonly used. As carbon materials are reasonably inert in relation to metal particles the interaction of the catalyst support with the reaction media was suggested [1]. The main charcteristic of interaction between gas media and solid support is the isosteric heat of sorption. Oxidized, nitrogen-doped and oxidized nitrogen-doped as well as untreated multiwalled carbon nanotubes (MWCNTs) were used as catalyst supports in Fischer–Tropsch synthesis. Cobalt nitrate was deposited on the support from the solution, then reduction of cobalt under hydrogen atmosphere and annealing at 400 C was performed. Cobalt particles wer further removed from nanotubes surface by HCl solution. The surface composition was studied by XPS. It was found that supports obtained from the oxidized and untreated MWCNTs have similar oxygen content. Therefore the catalyst preparation method plays crucial role in the surface composition. Vapour sorption was performed by DVS Advantage instrument. According to surface area calculated by BET model the adsorption of water proceeds inferior compared to hexane on all studied materials. Thus oxidized nanotubes surface does not rather adsorb water than hexane. Heats of sorption were calculated from measurements at temperatures 20 and 30 C, for each material 9 values were obtained. One-way analysis of variance demonstrates that the difference between all materials are not significant and all values belong to the general population with mean 32,7 kJ/mol.