CO2 adsorption on branched polyethyleneimine-impregnated mesoporous silica SBA-15

Adsorption of pure CO2 on SBA-15 impregnated with branched polyethyleneimine (PEI) has been studied. Materials were prepared by impregnating the pore surface of SBA-15 mesoporous silica with different amounts of branched PEI (10, 30, 50 and 70 wt%). Textural properties, elemental analysis and low angle XRD measurements of the prepared samples showed a progressive pore filling of SBA-15 as PEI loading was increased. Pure CO2 adsorption isotherms on these modified SBA-15 materials were obtained at 45 °C, showing high adsorption efficiency for CO2 removal at 1 bar. Chemisorption of CO2 on amino sites of the modified SBA-15 seems to be the main adsorption mechanism. PEI content of impregnated SBA-15 influences the adsorption capacity of the material, being a relevant variable for CO2 removal by adsorption. Temperature effect on adsorption was also studied in the range 25–75 °C, showing that temperature strongly influences CO2 adsorption capacity. Adsorption capacity was also tested after regeneration of the PEI-impregnated SBA-15 materials. Our results show that these branched PEI-impregnated materials are very efficient even at low pressure and after several adsorption–regeneration cycles.