Highly efficient silica adsorbent functionalized with propylene oxide-modified pentaethylenehexamine for CO2 capture under NGCC flue gas conditions

Carbon capture utilization and storage (CCUS) is a crucial strategy to mitigate climate change, with solid sorbents are promising option due to their energy efficiency. A macroporous silica (MPS) adsorbent functionalized with propylene oxide (PO)-modified pentaethylenehexamine (PEHA) (2.0PO-PEHA/MPS) showed effective CO 2 capture from both coal-fired power plant (CFPP) and natural gas combined cycle (NGCC) flue gases, as confirmed by CO 2 isotherm measurements. Building on our previous work with CFPP flue gas, this study investigates its performance under NGCC conditions using the programmed adsorption–desorption (TPAD) method with a stainless-steel fixed-bed reactor. The optimal conditions were identified as 50 ℃ for adsorption and 120 ℃ for regeneration. Cyclic adsorption–regeneration experiments performed by thermogravimetric analysis (TGA) showed stable working capacity over 20 cycles. Notably, TGA tended to overestimate H 2 O uptake because it did not fully account for the competitive adsorption between CO 2 and H 2 O. To overcome this limitation, Our TPAD method, a more process-relevant fixed-bed flow approach, was introduced, providing highly reliable and quantitative results (CO 2 : 10.28 wt%, H 2 O: 3.51 wt%). Based on TPAD data, the theoretical regeneration heat was calculated to be 2.96–79 GJ tCO 2 −1 at 120 ℃, representing a relatively low value compared with other materials. These results highlight the potential of 2.0PO-PEHA/MPS for CO 2 capture from NGCC flue gas, underscore the critical role of TPAD-based quantification for accurately determining low regeneration heat, thereby advancing the field of CO 2 capture. • 2.0PO-PEHA/MPS effectively captured CO₂ from NGCC flue gas (4 % CO₂). • Stable working capacity was maintained over 20 adsorption–regeneration cycles. • CO 2 and H 2 O uptakes were measured using a process-relevant fixed-bed flow approach. • Theoretical heat of regeneration was the lowest reported at 2.96 GJ tCO 2 −1 .