Exploring the Role of Imidazoles in Amine-Impregnated Mesoporous Silica for CO2 Capture

A series of efficient adsorbents for CO2 capture was prepared by a wet-impregnation method. Mesostructured cellular silica foam (MF) was selected as a support and modified with a mixture of tetraethylenepentamine (TEPA) and imidazoles (Ims) to improve the initial and working CO2-adsorption capacity. The heat of adsorption was also evaluated. The impact of different amines and the adsorption temperature on CO2-adsorption performance was investigated. Some Ims showed a synergistic effect with TEPA regarding adsorption/desorption performance. Impregnating MF with such Ims and TEPA increased CO2-adsorption performance and decreased the heat of absorption compared with for MF impregnated only with TEPA. MF modified with 30 wt % 4-methylimidazole and 40 wt % TEPA exhibited a high first-pass CO2 adsorption capacity of 4.88 mmol/g at 100 kPa and 40 degrees C. Following vacuum regeneration, a working capacity of 4.15 mmol/g was observed for the same conditions. those obtained for the same conditions.