(446t) Performance Evaluation of PEI-Silica and KOH-Activated Carbon for Carbon Dioxide Capture in Power Plants

Many decision makers of energy supply such as governments have turned attention to CCS technology to deal with global climate change mainly caused by CO₂ emission. Post-combustion CO₂ capture process using dry-sorbents, which separates CO₂ from flue gas of industrial faculties, is one of the most promising capture technologies. It is because proper sorbents can be chosen by conditions of flue gas easily, and sorption process can be eco-friendly operated when compared to capture processes using wet-sorbent.
In this study, two types of dry sorbents (PEI-silica and KOH-AC) were evaluated for CO₂ sorption from power plant emission gas. Due to the PEI impregnation, PEI-silica had relatively small surface area and large pores. On the other hand, KOH-AC had high surface area and micro-pore was well developed. The adsorption amount of both sorbents was similar at 30^oC and 1 bar CO₂. Due to chemisorption, the sorption capacity of PEI-silica was almost independent of temperature, showing very strong sorption affinity. However, the sorption capacity of KOH-AC was significantly affected by sorption temperature, showing weak sorption affinity. With respect to sorption rate, both sorbents could reach approximately 80 % of sorption capacity within 1 min. According to the results of TGA and DTG analysis, the regeneration temperature for PEI-silica was limited at 130^oC while the regeneration of KOH-AC could be applied by gases up to 150^oC. Under hot N₂ regeneration condition, the working capacity in a cyclic test was 10 wt.% for PEI-silica and 8.5 wt.% for KOH-AC. However, PEI-silica was a little unstable in the cyclic operation. Furthermore, due to the sorption affinity of water vapor on PEI-silica, the working capacity in a wet flue gas condition decreased up to 6 wt.% in a cyclic test.