Synthesis of amine modified silica for the capture of carbon dioxide by a twice grafting method

A series of amine modified SBA-15 was prepared by a twice grafting method for CO₂ capture. The resulted materials were characterized by X-ray diffraction (XRD), N₂ adsorption/desorption, thermogravimetry (TG), elemental analysis, transmission electron microscopy (TEM) and Flourier transform infrared (FT-IR) spectrometry. CO₂ adsorption capacity of the adsorbents was obtained in a fixed bed through a breakthrough curve method. Effects of different preparation methods and different types of grafted organic amines were studied and recycled adsorption/desorption testing was carried out to evaluate the stability of the adsorbents. The results showed that, polyethylenimine(PEI) grafted SBA-15 prepared by supersonic method showed the best adsorption capacity, the optimist result was 1.72 mmol/g at 25 ℃ and 10 kPa CO₂ partial pressure. Furthermore, its adsorption capacity was found to be remaining constant after multiple adsorption/desorption cycles, indicating the high thermal stability of this adsorbent.