Fly ash as a cost-effective catalyst to promote sorbent regeneration for energy efficient CO2 capture

The use of catalysts to promote sorbent regeneration is currently considered an effective method to reduce the energy required in CO2 capture processes. Aiming at identifying stable and cost-effective catalysts with high CO2 desorption efficiency, here we investigated the performance of fly ash (FA) during thermal regeneration of aqueous amine solutions. The desorption rate, cyclic capacity and heat duty of a CO2-saturated aqueous ethanolamine with the addition of FA were experimentally measured, and the results were compared with those obtained for the same solution without and with eight different catalysts. Experimental results showed that catalysts significantly improved the regeneration compared to the non-catalyzed system, and FA was the most efficient of these. Further studies of CO2 desorption at different temperatures showed that FA provided desorption performance comparable to that of the non-catalyzed system at temperatures at least 5 °C higher and always significantly reduced the heat duty at the same temperature, especially at the beginning of the process. Finally, recycling tests demonstrated that FA had good stability and its catalytic efficiency remained high even after 20 cycles. In conclusion, FA could be considered a cost-effective catalyst for energy-efficient CO2 capture, deserving further investigation to promote its application in industrial-scale plants.