Study on MNO3/NO2 (M = Li, Na, and K)/MgO Composites for Intermediate-Temperature CO2 Capture

Molten salt [MNO3/NO2 (M = Li, Na, and K)]-promoted MgO composite-type CO2 adsorbents with high capacity and cycling stability are fabricated by controlled hydrolysis along with an incipient impregnation approach. The remarkable results of molten salts on the CO, capture performance of MgO adsorbents and the CO, capture capacities with different loadings and calcination and adsorption temperatures were comprehensively investigated. Notably, optimized NaNO3-promoted MgO exhibited the highest CO, capture capacity of 17.0 mmol g(-1) at 350 degrees C and maintained excellent regenerability through multiple cycles. The initial CO, uptakes of MNO3/NO2 (M = Li, Na, and K)/MgO composites follow the order of NaNO3 (17.0 mmol g(-1)) > LiNO3 (14.1 mmol g(-1)) > NaNO2 (12.5 mmol g(-1)) > KNO2 (9.3 mmol g(-1)) > KNO3 (5.0 mmol g(-1)). Furthermore, NaNO3 and KNO3 with good chemical stability are the effective constituents for the NaNO3 system and KNO3/KNO2-promoted system, respectively, and preserved their original form after the interaction with CO,. The NaNO2 system consists of NaNO3 and Na2CO3 to form double carbonates Na2Mg(CO3)(2) after CO2 adsorption. The morphology and structure of the MgO skeleton and the introduction of promoters are essential factors for intermediate-temperature CO2 capture.