Synthesis of LiAl 2 -layered double hydroxides for CO 2 capture over a wide temperature range

Although there are many reports on layered double hydroxide (LDH) derived CO2 adsorbents, none of them have studied the special case of LiAl2 LDHs. Here we report the first detailed investigation of the performance of LiAl2 LDHs as novel CO2 adsorbents. LiAl2 LDHs were synthesized using both traditional coprecipitation and gibbsite intercalation methods. All the materials were thoroughly characterized using XRD, SEM, TEM, FTIR, BET, and TGA. The CO2 capture performance of these LDHs were investigated as a function of charge compensating anions, Li/Al ratio in preparation solution, calcination temperature, adsorption temperature, and doping with K2CO3. The data indicated that LiAl2 LDHs derived compounds can be used as CO2 adsorbents over a wide temperature range (60–400 � C), with a CO2 capture capacity of 0.94 and 0.51 mmol g � 1 at 60 and 200 � C, respectively. By doping LiAl2–CO3 LDH with 20 wt% K2CO3, the CO2 adsorption capacity was increased up to 1.27 and 0.83 mmol g � 1 at 60 and 200 � C, respectively. CO2 adsorption–desorption cycling studies showed that both pure LiAl2 LDH and the K2CO3-promoted LiAl2 LDH had stable CO2 capture performance even after 22 cycles. Considering its high CO2 capture capacity and good cycling stability, LiAl2 LDH based novel CO2 adsorbents have significant potential for CO2 capture applications.