Stepped enhancement of CO2 adsorption and separation in IL‐ZIF‐IL composites with shell‐interlayer‐core structure

Abstract

AbstractDevelopment of materials with excellent separation performance remains an ongoing challenge in separation science and technology. Herein, a novel strategy was proposed to gradually enhance gas separation performance in micro/nano‐materials, by constructing a shell‐interlayer‐core structure using ionic liquid (triethylenetetramine lactate, [TETA]L) and zeolitic imidazolate framework (ZIF‐8). Such structure includes outer [TETA]L shell, interlayer of ZIF‐8, and inner [TETA]L core, endowing the composite with more evident molecular sieving separation for CO2 mixtures than the reported materials. A high CO2 adsorption amount (1.53 mmol/g at 298 K and 1.0 bar) is maintained, while the uptakes for CH4 and N2 are very low. Corresponding ideal adsorbed solution theory selectivities are 260–1,990 and 1,688–5,572 for CO2/CH4 and CO2/N2 mixtures at the range of tested pressures. In addition, the separation performance can be controlled by varying the shell‐interlayer‐core structure with IL inside, outside or on both sides of ZIF‐8 and the thickness of outer shell.