Nanocomposites and nanomaterials 
The use of ferrocene as a source of iron nanoparticles – an effective catalyst for the production of carbon nanotubes
1Alexey Sviatenko 1Denis Filonenko, 1Andriy Nebesnyi, 1Alexander Khovavko, 1Eugene Strativnov, 2NieGuochao, 3Anatoliy Minitskyi, 4Maksym Barabash

1Department of thermo-chemical processes and nanotechnologies
Gas Institute of National Academy of Sciences
39 Degtyarivska str., 03113 Kyiv, Ukraine 
E-mail: ingaskiev@gmail.com
2School of Physics and Telecommunication Engineering, 
Yulin Normal University, Yulin 537000, China
3National Technical University of Ukraine ‘Igor Sikorsky Kyiv Polytechnic Institute’ 37, Prospect Pobedy, UA-03056 Kyiv, Ukraine
4Technical Centre of National Academy of Science of Ukraine, 13, Pokrovs’ka Str., UA-04070 Kyiv, Ukraine

This paper presents the results of studying the process of carbon nanotubes (CNTs) synthesis in a converted gas (CG) atmosphere in a flow-type quartz reactor by the method of chemical vapor deposition CVD using ferrocene decomposition products as a catalyst. The products of air conversion of natural gas served for CNTs synthesis. Target carbon was obtained by disproportionation of carbon monoxide. The temperature regime for CNTs growth was about 650 °C and was chosen as optimal for the iron catalyst.
A schematic of a laboratory unit for CNTs synthesis is shown in Fig. 1.

Fig.1. Scheme of an experimental unit for studying CNTs deposition on dispersed iron particles in a converted gas atmosphere. 1- electric furnace for evaporation of ferrocene; 2- electric furnace for zone heating of CNTs growing; 3,4 - flowmeters and valves for converted gas and nitrogen supplying; 5- quartz reactor; 6- boat with ferrocene; 7- ceramic rods – deposition centers; 8- control system; 9- filter; 10- outcoming  gas.

Only precise control of the composition of the gas mixture and the ratio of the carbon source – carbon monoxide to hydrogen, as well as the temperature regime allows CNTs obtaining practically without external carbon impurities in the form of amorphous carbon.

Fig. 2. SEM photo of obtained CNTs
Experiments have shown that dispersed iron particles obtained from ferrocene have a high reactivity, in many respects not inferior to freshly reduced iron, which, due to its low reduction temperature, has a developed surface and, as a consequence, is one of the most effective catalysts for carbon deposition. But the process of preparing such a catalyst is a rather laborious and energy-consuming process, which consists in multiple repetitions of oxidation-reduction cycles in order to obtain the most developed substrate surface for CNT deposition. 
As a percentage of one unit of iron, approximately 14 weight units of carbon were obtained in the form of CNTs. The results on the yield of the target carbon product confirmed the possibility of using ferrocene as an effective catalyst for the growth of CNTs, as well as the possibility of using this technology on an industrial scale.