Nanocomposites and nanomaterials 
Influence of spent gases recirculation on carbon nanomaterial yield obtained from the products of methane air conversion 
Kotov V.G.1, Nebesniy A.A.1, Svyatenko A.M.1, Khovavko A.I.1, Filonenko D.S.1
1 Department of Thermo-chemical Processes and Nanotechnologies,
Gas Institute of the NAS of Ukraine. 
Degtyarivska, 39, Kyiv-03113, Ukraine. 
E-mail: ahova2005@ukr.net

The possibility of increasing of a specific yield of carbon nanomaterial from the products of methane-air conversion through the use of spent gases recirculation is considered. The analysis of the influence of water vapor and carbon dioxide contained in the recirculated gases on the methane conversion has been performed. According to the developed calculation method, the assessment of changes in the main parameters of carbon material synthesis was done. Evaluation was performed depending on the degree of recirculation of spent gases in the transition and steady-state periods of the process. It is shown that the use of gas recirculation increases the specific yield of the carbon material, but in this case, due to the accumulation of nitrogen in the gas phase, there is a decrease in the productivity of the process for the resulting product. The evaluation of the productivity enhancing by rising of the gases pressure in the system was made. It has been established that in order to increase the specific yield of carbon material, the obtained converted gas and reusable recirculated gas should be subjected to deep purification from water vapor. 

Fig. 1. Changes in the yield of carbon nanomaterial relative to the basic mode (æ = 0, Р = 1 atm) depending on the degree of spent gases recirculation at a pressure of P = 1, 2 and 5 atm (figures for curves).