Synthesis of Multilayer Layered Double Hydroxide (LDH)/Bentonite Membranes for CO2 Separation

摘要

Layered double hydroxides (LDHs), with a typical formula of Mg6Al2(OH)16CO3·4H2O, have a reversible Mg-(OH)-Mg and Mg-(OH)-Al layered structure with interlayer spacing occupied by carbonate ions (CO_3~(2-)) and hydrated water. The octahedral crystal structure evolves to amorphous mixed solid oxide upon heat treatment at high temperatures. Specifically, the interlayer CO_3~(2-) will decompose and release CO2 by heating to above 400°C. At presence of CO2 and water vapor, the microporous structure of layered double hydroxides will be recovered, assigning the LDHs unique properties for membrane fabrication, particularly for application in high temperature CO2 separation.