NaNO -Promoted Mesoporous MgO for High-Capacity CO Capture from Simulated Flue Gas with Isothermal Regeneration.

NaNO -promoted MgO composite materials have been prepared and their ability to sorb CO at a concentration relevant to CO capture from flue gas is explored. The uptake kinetics and capacities of sorbents of different NaNO /MgO ratios are measured at intermediate temperatures of 230-300 °C. The sorbent with a NaNO /MgO ratio of 0.10 has the highest 12 h sorption capacity among sorbents with different NaNO loadings, and the highest sorption capacity of 11.2 mmol  g is observed at 260 °C. Intriguingly, an induction period is observed in the initial stage of CO sorption. In situ XRD analysis, in situ FTIR spectroscopy, and a comparison of the CO sorption behavior under simulated flue gas conditions in comparison to prior studies employing pure CO indicated that the sorption of CO occurred through nucleation of MgCO crystallites in the material. The data indicate that the concentration of CO within the molten medium of NaNO , which is affected by both the solubility of CO in molten NaNO and the partial pressure of CO in the surrounding atmosphere, has a critical impact on the length of the induction period. A partially desorbed sample after sorption of CO displays much-improved sorption kinetics in the next cycle and was able to sorb and desorb CO over multiple cycles at isothermal conditions by simply switching the feed gas from CO to inert gas.