Impact of organic interlayer anions on the CO2 adsorption performance of Mg-Al layered double hydroxides derived mixed oxides

Herein we report a systematical investigation on the promoting effect of the carbon chain length of the intercalated carboxylic anions on the CO2 capture performance of Mg-Al layer double hydroxides (LDHs). A series of organo-LDHs were successfully synthesized via co-precipitation and calcination-rehydration methods. All as-prepared samples were characterized by many techniques including XRD, ATR-FTIR, BET, and TGA. The XRD and ATR-FTIR studies indicated that organic anions were successfully intercalated into LDHs. The influence of some important parameters such as calcination temperature, adsorption temperature, and coating with (Li-Na-K) NO3 molten salt was investigated. The results exhibited that when the number of carbon is greater than 10, the CO2 capture capacity steadily increased with the increase in carbon number. After coating with 55 mol% (Li-Na-K) NO3 molten salt, the CO 2 uptake of LDH-C16 sample with high Mg/Al ratios can be increased up to 3.25 mmol/g. The CO2 adsorption/desorption cycling stability was also studied using temperature swing adsorption, which showed a stable CO 2 capture performance even after 22 cycles. Considering its high CO2 capture capacity and good cycling stability, this novel CO2 adsorbent is very promising in the sorption-enhanced water gas shift (SEWGS) processes. (C) 2017Science press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.