Combined CO₂ absorption/regeneration performance enhancement by using nanoabsorbents

The reduction of in the emissions of CO₂, which is the representative greenhouse gas, is actively investigated worldwide because of its contribution to global warming. Energy generation processes involving the gasification of fossil fuels separate the constituent gases before combustion occurs, rendering the capture of CO₂ more attainable. Generally, CO₂ is captured through an absorption method by using a liquid absorbent in large scale gasification systems. According to Henry's solubility law, the absorption and regeneration processes should be operated at low and high temperatures respectively, and these require high energy consumption. As a solution, nanoparticles are added to the absorbent (methanol) to reduce energy consumption required in the absorption and regeneration processes. In this study, the absorption/regeneration performance was evaluated through a lab-scale combined CO₂-absorption/regeneration system. The nanoparticles used are SiO₂ and Al₂O₃, which are added at a 0.01 vol% concentration. In the case of the Al₂O₃/methanol nanoabsorbent, the performance decreases as the number of cycle increases, whereas the performance is improved steadily in the case of the SiO₂/methanol nanoabsorbent. Thus, the SiO₂ nanoparticles are more suitable for the combined CO₂ absorption/regeneration process. Furthermore, the mass transfer enhancement mechanisms of the absorption/regeneration process according to the addition of nanoparticles are presented.