Parametric study for an immobilized amine sorbent in a regenerative carbon dioxide capture process

•Polyethylenimine/silica sorbent evaluated for CO2 removal from simulated flue gas.•Sorbent achieves 3–3.5 mol CO2/kg absorption capacity between 45 °C to 60 °C.•Equilibrium H2O absorption loading is roughly ten times greater than CO2 loading.•Temperature swing regeneration using steam sweep gas is needed for CO2 delta loading.•Conceptual CO2 removal process (Basic Immobilized Amine Sorbent) was introduced.

An amine-based solid sorbent process to remove CO2 from flue gas has been investigated. The sorbent consists of polyethylenimine (PEI) immobilized onto a silica (SiO2) support. Experiments were conducted in a packed-bed reactor and exit gas composition was monitored using mass spectrometry. The effects of feed gas composition (CO2 and H2O), temperature, and simulated steam regeneration were examined for both the silica support as well as the PEI-based sorbent. The gas analysis artifact of the empty reactor was also quantified. Sorbent CO2 capacity loading was compared to past thermogravimetric (TGA) results to further characterize adsorption isotherms and better define CO2 working capacity. Sorbent stability was monitored by periodically repeating baseline conditions throughout the parametric testing and replacing with fresh sorbent as needed. The concept of using this sorbent within a system where sorbent continuously flows between the absorber and regenerator was introduced. A basic tenet is to manipulate or control the level of moisture on the sorbent as it travels around the sorbent circulation path between absorption and regeneration stages to minimize its effect on regeneration heat duty.