Modified carbon nanotubes/tetraethylenepentamine for CO2 capture

•Modified carbon nanotubes (MCNTs) were prepared using a KOH reagent.•MCNTs/tetraethylenepentamine was prepared as a CO2 sorbent.•Under optimal conditions, the CO2 sorption capacity reached 5mmol CO2/g.•High CO2 desorption rate of the sorbent can considerably reduce CO2 capture cost. In this work, a CO2 sorbent was prepared by immobilizing tetraethylenepentamine (TEPA) onto modified carbon nanotubes. Modification of carbon nanotubes (CNTs) using a KOH reagent was done to increase the surface area and pore volume of the CNTs. The prepared sorbents were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) thermogravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) analyses. At the optimal TEPA loading of 75wt% on modified CNTs (MCNTs), the CO2 sorption capacity reached 5mmol CO2/g-sorbent for 10vol% CO2 in N2 along with 1vol% H2O at 60°C. Kinetic and thermodynamic adsorption studies found activation energies for CO2 adsorption and desorption of MCNTs/TEPA being16.2kJ/mol and 39.9kJ/mol, respectively. The low activation energy for CO2 desorption using MCNTs/TEPA corresponds with a high CO2 desorption rate, resulting in a low CO2 capture cost. Therefore, the MCNTs/TEPA sorbent has potential for application to CO2 capture from gas mixtures.