Authors
Ara Cho, Korea Institute of Energy Research
Sungho Jo, Korea Institute of Energy Research
The macropore silica (MPS) adsorbent functionalized with pentaethylenehexamine (PEHA) at a 2:0 molar ratio using propylene oxide (PO) (2.0PO-PEHA/MPS) showed effective applicability not only to coal-fired power plant flue gas (15% CO₂) but also to NGCC flue gas (4% CO₂), as confirmed by CO₂ isotherm measurements. Based on this, the CO₂ and H₂O adsorption behaviors of 2.0 PO-PEHA/MPS and the regeneration heat requirements were experimentally and computationally evaluated using thermogravimetric analysis (TGA) and Temperature-programmed adsorption and desorption (TPAD) apparatus. By investigating the CO₂ uptake at various temperatures, the optimal adsorption and regeneration temperatures were determined to be 50℃ and 120℃, respectively. Additionally, periodic adsorption-regeneration experiments were conducted under adsorption conditions (4% CO₂, 3% H₂O, N₂ balance, 50℃) and regeneration conditions (100% CO₂, 120℃) to assess the adsorption behavior and stability over 20 cycles. The 2.0PO-PEHA/MPS adsorbent maintained stable working capacity with minimal decrease (< 8% decrease) from the second to the twentieth cycle. The H₂O uptake in TGA was calculated by subtracting the CO₂ uptake of 9.02 wt.% from the total CO₂ and H₂O amount of 13.43 wt.% measured in the cycle experiment. However, TGA overestimated the H₂O uptake to 4.41 wt.% by not considering the adsorption characteristics of CO₂ and H₂O, resulting in quantitative errors. In contrast, using the TPAD apparatus to analyze the simultaneous adsorption characteristics of CO₂ and H₂O, the CO₂ uptake was measured at 10.28 wt.% and the H₂O uptake at 3.51 wt.%, confirming that TPAD provides more reliable results than TGA. Based on the CO₂ and H₂O uptake measured by TPAD, the theoretical regeneration heat calculated was 2.96 GJ/tCO₂ at 120℃, showing the lowest value. This study demonstrates that the 2.0 PO-PEHA/MPS adsorbent can be effectively applied to CO₂ adsorption from NGCC flue gas and suggests the potential to maximize the efficiency of CO₂ capture processes by optimizing adsorption performance and regeneration heat requirements.
