Layered Double Hydroxides for CO₂ Capture: Structure Evolution and Regeneration

Abstract

Mg−Al−CO 3 layered double hydroxide (LDH) was synthesized, and its thermal evolution was investigated using X-ray diffraction, FTIR spectroscopy, and thermogravimetric analysis (TGA). The resultant LDH derivatives showed excellent CO 2 adsorption capabilities, especially suitable for high-temperature CO 2 separation from flue gases. Calcination of crystalline LDHs at 400 °C led to phase transformation yielding amorphous Mg−Al mixed oxides having a CO 2 sorption capacity of 0.49 mmol/g at 200 °C. Reversible and irreversible CO 2 sorption was determined to be ∼88% and ∼12% of the total CO 2 sorption, respectively. Regeneration restored the Mg−Al mixed oxide to 98% of its initial CO 2 sorption after several cycles of CO 2 adsorption testing. This clearly indicates the desirable properties of Mg−Al mixed oxide for CO 2 capture from flue gases at high temperatures (up to 200 °C).