Adsorption of CO2 on MgAl-CO3 LDHs-Derived Sorbents with 3D Nanoflower-like Structure

In this paper, the porous MgAl-CO3 LDHs-derived mixed oxides with Mg/Al molar ratios of 2:1, 2.5:1, 3:1, 3.5:1, and 4:1 have been successfully prepared by a facile solvothermal method. With a 3D nanoflower-like structure, the MgAl-CO3 LDHs-derived mixed oxides with a Mg/Al molar ratio of 2 exhibit the best CO, sorption performance of about 0.9 mmol/g at the adsorption temperature of 200 degrees C. The addition of NaNO3 into the MgAl-CO3 LDHs-derived mixed oxides (Mg/Al = 2:1) can facilitate the sorption process by reducing the energy barrier between MgO and MgCO3. Introducing methanol to the preparation process of LDHs prior to drying can effectively increase the specific surface area and improve the porosity of the sorbents by substituting the water molecules of MgAl-CO3 LDHs. The sorbents co-modified by NaNO3 and methanol with a Mg/Al molar ratio of 2 show the favorable sorption performance with the CO2 uptake of 1.70 mmol/g over 100 sorption/desorption cycles about 300 h.