Three adsorbents were prepared by different modification methods, which were grafting silica gel with (3-aminopropyl) trimethoxysilane, grafting silica gel with acrylamide polymer, and impregnating silica gel with acrylamide polymer, respectively. The characterization of materials was carried out by N-2 adsorption experiments, Fourier transform infrared spectroscopy, scanning electron microscopy, thermo-gravimetric analysis, and elemental analyses. The results showed that the amine group was successfully loaded on all three modified adsorbents; among that, the polymer-modified silica adsorbents had higher amine content and larger surface area than the aminopropyl-grafted silica adsorbent and displayed higher thermal stability than the other polymer-modified silica materials previously reported. The CO2 adsorption/desorption experiments performed at 25 degrees C by TGA-DSC method showed that the highest CO2 adsorption capacity (0.98 mmol/g) was observed for the polymer-impregnated silica adsorbent. CO2 adsorbed on all samples was completely desorbed by purging with inert gas at 60 degrees C except for the aminopropyl-grafted silica material, which showed the highest enthalpy of CO2 adsorption. Crown Copyright (C) 2012 Published by Elsevier Inc. All rights reserved.