Novel M (Mg/Ni/Cu)-Al-CO3 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/N₂ 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 °C) applicable to post-combustion CO₂ capture. Characterized with XRD, N₂ 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 m²/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/N₂ selectivity of 166 at 50 °C under 1200 mbar for typical flue gas CO₂/N₂ composition (CO₂:N₂ = 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.

Keywords: CO(2) capture; CO(2)/N(2) selectivity; Layered double hydroxide; Ni-Al-CO(3).