CO₂ regeneration performance enhancement by nanoabsorbents for energy conversion application

Due to the recent increase in the consumption of energy and the use of fossil fuels, global warming has become a serious issue. To address this problem, CO₂ gas, which is the major element of the greenhouse gases, should be captured, regenerated and converted to useful fuels. The Integrated Gasification Combined Cycle (IGCC) and cement process generate large amount of CO₂, which are controlled through pre-combustion capture. However, this method has a disadvantage because the system temperature should be decreased to -20 °C or lower. Therefore, the development of new absorbent is required to reduce the energy consumed for refrigeration. There is a study that improved the CO₂ absorption performance by adding Al₂O₃ nanoparticles to methanol. However, studies on the regeneration of CO₂ in nanofluid absorbents (nanoabsorbents) are insufficient. Therefore, in this study, the CO₂ regeneration performance in Al₂O₃ nanoabsorbents is evaluated. It is found that the regeneration performance of CO₂ is improved by 16% by using nanoabsorbents compared to methanol. Furthermore, the CO₂ regeneration characteristics of nanoabsorbents are analyzed by considering the detachment time of CO₂ bubbles from the surface, the cross-sectional area of CO₂ bubble, and the number of regeneration sites through the CO₂ regeneration and bubble visualization experiments. It is concluded that the mechanism of surface effect is the most plausible to explain the CO₂ regeneration performance enhancement by nanoabsorbents.