Amine modified potassium-based composite adsorbents prepared by spray granulation method for enhanced CO2 capture performance

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 this study, K₂CO₃/Al₂O₃ adsorbents were prepared via spray granulation, achieving an optimal CO₂ adsorption capacity of 1.89 mmol/g at a potassium carbonate loading of 30 wt%. To address the limitations of potassium-based adsorbents, we further enhanced the performance by incorporating polyethyleneimine (PEI), an amine-functionalized material known for its high CO₂ affinity, in the K30Al adsorbent. A series of potassium-amine composite adsorbents were synthesized with varying PEI loadings (1 wt%, 3 wt%, 5 wt%, and 7 wt%). Remarkably, a synergistic effect between K₂CO₃ and PEI was observed, with the 5 wt% PEI loading yielding the highest CO₂ adsorption capacity of 2.19 mmol/g, representing a 16 % improvement over the unmodified adsorbent. This represents a novel K30Al-P5 composite adsorbent successfully fabricated through deposition of a small amount of PEI onto pre-synthesized K30Al substrate via the spray granulation method. Comprehensive characterization, including adsorption capacity, cyclic stability, and structural properties, revealed that the enhanced performance is attributed to the optimized interaction between K₂CO₃ and PEI, which facilitates CO₂ chemisorption and diffusion. This study not only demonstrates a significant improvement in CO₂ capture efficiency but also provides a scalable and cost-effective strategy for designing high-performance adsorbents.