Adsorption capacity of carbon dioxide on amine modified mesoporous materials with larger pore sizes

Abstract

Mesoporous silica SBA-15-like materials with large pores were synthesized using tri-block copolymer P123 as a structure-directing agent, tetramethoxysilane as the silicon source, and different organic solvents as swelling agents. The resulting materials were characterized by powder X-ray diffraction (XRD), N 2 adsorption-desorption, scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy. The results showed that the introduction of swelling agents effectively enlarged the pore diameter and pore volume of the SBA-15 materials, and pore swelling with isooctane was larger than that with CCl 4. When modified with tetraethylenepentamine (TEPA), all of these composite materials exhibited excellent adsorption capacities for CO 2. The adsorption capacity of CO 2 was independent of the pore structure, if the template was removed before modification with TEPA. By contrast, the adsorption capacity increased with the pore diameter when the as-synthesized mesoporous material was modified with TEPA. The effects of temperature and pressure on the CO 2 adsorption capacity were investigated using adsorption isotherms and CO 2 temperature-programmed desorption (TPD). With CO 2 adsorption at higher temperature, the composite materials showed different adsorption capacities with pressure variation. As a result, the adsorption and separation of CO 2 on these TEPA modified mesoporous materials in ambient airflow can be realized via pressure swing adsorption. © Editorial office of Acta Physico-Chimica Sinica.