CO2 adsorption–desorption performances of PEI-impregnated mesoporous silica samples were also measured in a flow system. The sample (ca. 0.01 g) was loaded into an alumina holder in a TGA unit (SCINCO, S-1000) and examined for CO2 adsorption–desorption behavior. The adsorption and desorption were both performed at 75 ◦C. The initial activation of PEI impregnated mesoporous silica samples was carried out at 100 ◦C for 1 h in a nitrogen environment (99.999%). The adsorption run was carried out using high purity CO2 (99.999%) gas, whilst the desorption run was conducted under a N2 flow. The feed flow rate to the sample chamber was controlled to 20 ml/min by a mass flow controller.