Effect of H2O impurity in marine exhaust on the CO2 capture performance of novel composite CaO–Al2O3–Fe2O3 absorbents

The CaO-based absorbent recycling carbon capture technology is an effective way to reduce CO₂ emissions from marine exhaust gas. Inert supports (MgO, Al₂O₃) and active additives (Fe₂O₃) were used to obtain economical and efficient CaO-based absorbents. The experiment results show that CaO–Al₂O₃–Fe₂O₃ (CAF) absorbent has the best CO₂ adsorption performance. Compare with the initial adsorption capacity of 0.64 g/g, the adsorption capacity after 20th cycle can still achieve 0.62 g/g. The characterizing results show that CAF absorbent has the largest pore size and specific surface area. The absorbents doped with active additives Fe₂O₃ can effectively improve the CO₂ adsorption capacity and cycle stability. In addition, the influence of H₂O impurity on the cycle performance of the developed CAF absorbent was studied deeply. Results show that the cyclic adsorption performance of CAF absorbent decreases with the increase of the H₂O concentration. With the increase of the cycle numbers, the existence of H₂O will reduce the anti-sintering performance of absorbents, which will lead to the aggregation of absorbents particles, thus reducing their adsorption performance. Therefore, the CAF absorbent developed in this study has excellent adsorption capacity and cycle stability.