Epoxide-Modified Amine-Impregnated CO2 Adsorbent with Lower Regeneration Energy Requirement and Enhanced Durability

Amino polymer-based adsorbents have been extensively investigated for post-combustion CO₂ separation for its low energy penalty as compared to amine-based absorption. However, most studies have focused on improving the CO₂ capacity, and the regeneration process is still required to separate high purity CO2 (>95%), minimize energy requirements, and enhance the chemical and mechanical durability of the sorbent such as sorbent degradation in other flue gas constituents in a temperature window of the separation process.

In this study, the adsorption/desorption cyclic performances were investigated using 1,2-epoxybutane (EB)-modified polyethylenimine (PEI)-impregnated mesocellular silica foam (MCF) in a thermogravimetric analyzer (TGA) and a fixed-bed reactor. The sorbent could demonstrated a stable working CO₂ capacity of ~2-3 mmol CO₂/g sorbent (50 °C, 15% CO₂ + in N₂ for adsorption and 120 °C, 100% CO₂ for desorption) over a 100 adsorption-desorption cyclic test. The desorption under pure CO₂ condition enabled the sorbent to be regenerated by temperature swing adsorption (TSA) without any dilution caused by sweeping gas. Additional modification could reduce degradation by SO₂ present at ~30-100 ppm level in typical coal combustion flue gas. This approach using modified PEI-based sorbent can offer a CO₂ adsorption capacity close to MEA absorption at a reduced desorption energy requirement of ~2 GJ/tCO₂ without a need for wastewater treatment. The detailed synthesis, characterization and performance results will be presented.