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

초록

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 CO2 capture from both coal-fired power plant (CFPP) and natural gas combined cycle (NGCC) flue gases, as confirmed by CO2 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 degrees C for adsorption and 120 degrees C for regeneration. Cyclic adsorption-regeneration experiments performed by thermogravimetric analysis (TGA) showed stable working capacity over 20 cycles. Notably, TGA tended to overestimate H2O uptake because it did not fully account for the competitive adsorption between CO2 and H2O. To overcome this limitation, Our TPAD method, a more process-relevant fixed-bed flow approach, was introduced, providing highly reliable and quantitative results (CO2: 10.28 wt%, H2O: 3.51 wt%). Based on TPAD data, the theoretical regeneration heat was calculated to be 2.96-79 GJ tCO(2)(-1) at 120 degrees C, representing a relatively low value compared with other materials. These results highlight the potential of 2.0PO-PEHA/MPS for CO2 capture from NGCC flue gas, underscore the critical role of TPAD-based quantification for accurately determining low regeneration heat, thereby advancing the field of CO2 capture.

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