Application of PEI–K₂CO₃/AC for capturing CO₂ from flue gas after combustion

Highlights: • A novel PEI–K₂CO₃/AC sorbent was prepared with the co-impregnation method. • The coupling characteristics of PEI and K₂CO₃ in the sorbent are expounded. • Both PEI and K₂CO₃ contribute to the total CO₂ capture capacity of PEI–K₂CO₃/AC. • PEI–K₂CO₃/AC presents high CO₂ capture capacity and long-term stability. • PEI–K₂CO₃/AC should be considered as a new option for post-combustion CO₂ capture. - Abstract: The capture of CO₂ from flue gas after combustion using solid sorbents is one of the efficient options for reducing CO₂ emissions from fossil fuel-fired power plants. To satisfy the requirement of large quantities flue gas treatment, the CO₂ capture capacities of the solid sorbents must be focused on. In order to obtain a sorbent with high CO₂ capture capacity, a novel PEI–K₂CO₃/AC sorbent was prepared by impregnating potassium carbonate (K₂CO₃) and polyethylenimine (PEI) on activated carbon (AC) in this work. The CO₂ capture performance of this sorbent was investigated using a fixed bed reactor system. The CO₂ capture capacity of PEI–K₂CO₃/AC with the total K₂CO₃ and PEI loadings of 50 wt% was measured as 3.60 mmol CO₂/g under the condition of 60 °C, 8% CO₂ + 10% H₂O. In addition, this sorbent is proved to be regenerable and stable during 5 cycle CO₂ sorption–desorption tests. Compared with K₂CO₃/AC (loading of 58 wt%) and PEI/AC (loading of 43 wt%), PEI–K₂CO₃/AC presents higher CO₂ capture capacity and long-term stability. Therefore, PEI–K₂CO₃/AC should be considered as a new option for capturing CO₂ from flue gas after combustion