Effect of chemical modification on carbon dioxide adsorption property of mesoporous silica

Abstract

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 N2 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°C by TGA–DSC method showed that the highest CO2 adsorption capacity (0.98mmol/g) was observed for the polymer-impregnated silica adsorbent. CO2 adsorbed on all samples was completely desorbed by purging with inert gas at 60°C except for the aminopropyl-grafted silica material, which showed the highest enthalpy of CO2 adsorption.