Promoting Effect of Inorganic Alkali on Carbon Dioxide Adsorption in Amine-Modified MCM-41

Three kinds of inorganic alkali are introduced into tetraethylenepentamine (TEPA)- and polyethyleneimine (PEI)-modified MCM-41 as the CO2 adsorbents. FT-IR and TGA are used to characterize the surface groups and the thermal stability of adsorbents. Chemical titration method is used to measure the alkali amounts of adsorbents. Thermo-gravimetric analysis with 10% CO2/90% N2 as the simulated flue gas is used to test the CO2 adsorption performance of adsorbents. The results show that all three kinds of inorganic alkali-containing adsorbents exhibit higher CO2 adsorption capability than traditional TEPA and PEI modified samples. Ca(OH)2 and PEI modified samples exhibit the highest adsorption capacity and recyclable property. The introduction of inorganic alkali changes the chemical adsorption mechanism between CO2 and adsorbent surface due to the increased hydroxyl groups. The CO2 adsorption capacities have a linear dependence relation with the alkali amounts of adsorbents, indicating that alkali amount is a critical factor for the exploration of novel adsorbents.