Study on CO₂ fixation using alkaline aqueous solution and fly ash

Carbon dioxide capture technology using potassium hydroxide (KOH) aqueous solution has the characteristic that the absorption solution is less likely to deteriorate compared to conventional methods using amines. Inorganic compounds such as CaO are required to regenerate the KOH aqueous solution, so there are still challenges to overcome in achieving comprehensive CO2 emission reduction. In this study, we focused on a method that uses KOH aqueous solution for CO2 capture and combustion fly ash emitted from coal-fired power plants to regenerate the KOH aqueous solution. K2CO3 and fly ash were mixed at room temperature, and the KOH regeneration rate was confirmed by neutralization titration with HCl. The feasibility of the CO2 capture and fixation cycle was experimentally verified. KOH regeneration of 4.5 % and 6.1 % was confirmed for Japanese fly ash and Indonesian fly ash. The CO2 absorption and fixation process using KOH can be realized using fly ash. Future challenges include improving KOH regeneration efficiency.