CO2 adsorption performance of different amine-based siliceous MCM-41 materials

A series of amine-based adsorbents were synthesized using siliceous MCM-41 individually impregnated with four different amines (ethylenediamine (EDA), diethylenetriamine (DETA), tetraethylenepentamine (TEPA) and pentaethylenehexamine (PEHA)) to study the effect of amine chain length and loading weight on their CO2 adsorption performances in detail. The adsorbents were characterized by FT-IR, elemental analysis, and thermo-gravimetric analysis to confirm their structure properties. Thermo-gravimetric analysis was also used to evaluate the CO2 adsorption performance of adsorbents. Longer chain amine-based materials can achieve higher amine loadings and show better thermal stability. The CO2 adsorption capacities at different temperatures indicate that the CO2 adsorption is thermodynamically controlled over EDA-MCM41 and DETA-MCM41, while the adsorption over TEPA-MCM41 and PEHA-MCM41 is under kinetic control at low temperature. The chain length of amines affects the CO2 adsorption performance and the adsorption mechanism significantly. The results also indicate that CO2 adsorption capacity can be enhanced despite of high operation temperatures, if appropriate amines (TEPA and PEHA) are applied. However, adsorbents with short chain amine exhibit higher adsorption and desorption rates due to the collaborative effect of rapid reaction mechanisms of primary amines and less diffusion resistance of shorter chain length amines.