Study of the Effect of Functionalization of Carbon Nanotubes on Gas Separation

Abstract

In order to improve the adsorption capacity and selectivity of CO 2 /CH 4 and CO 2 /N 2 , we have functionalized multi-walled carbon nanotubes (MWCNT) with 3-aminopropyltriethoxysilane (APTES). The functionalized MWCNT was characterized by Fourier transform infrared (FT-IR), energy dispersive X-ray spectroscopy (EDX) and BET analysis. CO 2 , CH 4 and N 2 adsorption at two different temperatures and P < 5 bar on the functionalized MWCNTs was investigated by the volumetric method. The selectivity of the functionalized MWCNTs for CO 2 /CH 4 and CO 2 /N 2 was studied and compared with MWCNTs. The functionalized MWCNTs show higher adsorption capacity of CO 2 and selectivity of CO 2 /CH 4 and CO 2 /N 2 in comparison with the MWCNTs at different pressures. The highest CO 2 /CH 4 and CO 2 /N 2 selectivities for the functionalized MWCNTs were 6.78 and 26.14, respectively, at a pressure of 0.2 bar and at 298 K. Two of the most common adsorption models, the Langmuir and Sips isotherms, were used to correlate the experimental data of CO 2 and CH 4 adsorption on the adsorbents. The results confirm that the functionalized MWCNTs are promising materials for the separation and purification of gases.