Postcombustion CO 2 Capture in a Radial-Flow Adsorber Using Amine-Functionalized γ-Alumina from the Aluminum-Hydrolysis Byproduct

In this study, we demonstrated the utilization of the byproduct residue generated during the hydrolysis of beverage aluminum can to prepare high surface area γ-alumina supports, using a simple, easily adaptable process consisting of only neutralization, filtering, drying, and calcination. The calcined supports were then used to capture CO 2 from simulated flue gas after functionalization with polymeric polyethylenimine (PEI) in a radial-flow adsorber. The calcined supports and functionalized sorbents were characterized by using various analytical techniques to assess their morphological and textural properties. It was observed that a calcination temperature of approximately 550 °C resulted in γ-alumina support frameworks with textural properties comparable or even superior to those of commercially available γ-alumina. An optimal PEI loading of 40 wt % provided a maximum CO 2 uptake of 2.40 and 2.16 mmol CO 2 /g sorbents in pure CO 2 and 10% CO 2 /N 2 gas mixture, respectively, and it outperformed a similar sorbent prepared using commercially available γ-alumina. Furthermore, the breakthrough performance of the developed sorbents in a laboratory radial-flow adsorber demonstrated a working CO 2 uptake of 0.75 mmol of CO 2 /g of sorbents at the breakthrough point and 1.12 mmol of CO 2 /g of sorbents at the saturation point when studied under a 10% CO 2 /N 2 flue gas stream at 75 °C and atmospheric pressure. The synthesized amine-modified sorbents also exhibited good cyclic stability when tested for multicyclic CO 2 adsorption/desorption performance under a simulated flue gas environment.