Novel M (Mg/Ni/Cu)-Al-O-3 layered double hydroxides synthesized by aqueous miscible organic solvent treatment (AMOST) method for CO2 capture

Abstract

Layered double hydroxides (LDHs) have been intensively studied in recent years owing to their great potential in CO2 capture. However, the severe aggregation between platelets and low surface area restricted it from exhibiting very high CO2 adsorption capacity and CO2/N-2 selectivity. In this research, we for the first time synthesized Ni-Al-CO3 and Cu-Al-CO3 LDHs using aqueous miscible organic solvent treatment (AMOST) method. The as-synthesized materials were evaluated for CO2 adsorption at three different temperatures (50, 80, 120 degrees C) applicable to post-combustion CO2 capture. Characterized with XRD, N-2 adsorption-desorption, TEM, EDX, and TGA, we found the newly synthesized Ni-Al-CO3 LDH showed a nano-flower-like morphology comprising randomly oriented 2D nanoplatelets with both high surface area (249.45 m(2)/g) and pore volume (0.59 cc/g). Experimental results demonstrated that un-calcined Ni-Al-CO3 LDH is superior in terms of CO2 capture among the three LDHs, with a maximum CO2 adsorption capacity of 0.87 mmol/g and the ideal CO2/N-2 selectivity of 166 at 50 degrees C under 1200 mbar for typical flue gas CO2/N-2 composition (CO2:N-2 = 15:85, v/v). This is the first report of a delaminated Ni-Al-CO3 LDH showing better CO2 capture performance than the well-reported optimal Mg layered double hydroxide.