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The paper represents investigation on the synthesis of carbon nanotubes by chemical vapor deposition. The products of thermal decomposition of polyethylene waste were used as source of carbon. The influence of the decomposition temperature of polyethylene on the carbon nanotubes synthesis was provided. Cenospheres, preliminarily impregnated with aqueous solutions of nickel and cobalt nitrates, were applied as catalysts for carbon nanotubes synthesis. It was determined that in the framework of research, the best results for CNTs production were achieved at polyethylene decomposition temperature of 450 °C with catalyst based on cenospheres impregnated with nickel and cobalt nitrate solutions.

This article presents results of carbon nanotubes synthesis from household high-density polyethylene waste by thermal decomposition. A specific feature of this work is that the decomposition of high-density polyethylene waste and synthesis of carbon nanotubes were carried out in one-step using three-zone chemical vapor deposition reactor. The effect of temperature in the range of 450‒550 °C on decomposition products of high-density polyethylene was investigated. The decomposition products of polyethylene wastes were investigated by IR Fourier spectroscopy. Cenospheres obtained from ash and slag waste from thermal power plants during coal combustion were used as a catalyst for the synthesis of carbon nanotubes. The cenospheres were impregnated with an aqueous solution of iron nitrate. It was found that as a result of thermal decomposition of high-density polyethylene waste at temperature of 450 °C, gaseous carbon-containing compounds are formed, which upon further heating to 800 °C lead to the formation of carbon nanotubes with a diameter of 16‒21 nm on the surface of catalyst. Physicochemical analysis showed that turbostratic carbon is almost completely absent in the formed product. Carbon nanotubes analysis was performed by scanning electron microscopy and Raman spectroscopy.

The paper presents the results of carbon nanotubes synthesis from benzene in fluidised bed reactor. Al2O3 spheres with iron and nickel nanoparticles coating were used as a catalyst for the synthesis of carbon nanotubes. To deposit nickel nanoparticles on the surface of Al2O3 spheres, the method of solution combustion was used. Optimum temperature conditions and gas flow rates were worked out for each of the catalysts. It was found that the best efficiency in the synthesis of carbon nanotubes from benzene is shown by catalysts based on aluminium oxide coated with iron. The obtained carbon nanotubes were studied by scanning electron microscopy and Raman spectroscopy. It was found that at temperatures above 850 °C from benzene on Al2O3 spheres with Ni/NiO, carbon frame structures are formed.