(562as) Feasibility of Polyethylenimine-Based Silica Sorbent for Post-Combustion CO2 Separation

Yao Ma, Vishnu Sriram, and Joo-Youp Lee

Amino polymer-based adsorbents have been extensively investigated for post-combustion CO₂ separation for its low energy penalty as compared to amine solutions. However, most studies have focused on improving the CO₂ capacity, and have not reported the feasibility of separating CO₂ from the spent sorbents during the desorption phase.

In this study, the adsorption/desorption cyclic performances were investigated using polyethylenimine (PEI)-impregnated mesocellular silica foam (MCF) in a thermogravimetric analyzer (TGA) and a fixed-bed reactor. The sorbent could reach a working capacity of ~3.8 mmol/g (75 °C, 100% CO₂ for adsorption and 110 °C, 100% N₂ for desorption) using a multiple cyclic performance test. However, for the practical desorption phase, either temperature-vacuum swing or temperature swing need to be used. The adsorption capacity at ~75-80 °C is almost twice as much as that at 50 °C, which means the temperature control of the adsorber is critical for the maximum utilization of the sorbent. The temperature control of the reactor during the adsorption and desorption phases will be critical to achieving high CO₂ working capacity and minimum energy requirements. In addition, based on the performance results obtained from the fixed-bed reactor, the two desorption options will be compared for a techno-economic evaluation.