In-situ amino-functionalization of zeolitic imidazolate frameworks for high-efficiency capture of low-concentration CO2 from flue gas

Abstract

The capture of low-concentration CO2 from flue gas is an on-going challenge. In this work, a novel series of amino-functionalized zeolitic imidazolate framework-8 materials (ZIF-DIA) was facilely synthesized via in-situ incorporating an large-size amino-functional imidazolium ligand during the synthesis process under atmospheric conditions, and its adsorption performance of CO2 from a simulated flue gas (15 vol% CO2) was investigated. With the introduction of amino-functional imidazolium ligand, the regular hexahedron structure of pure ZIF-8 is gradually converted into cluster-like morphology. The amino-functionalized ZIF materials exhibit high specific surface areas (712–941 m2·g−1), rapid CO2 adsorption rate (≤80 s), excellent CO2 adsorption capacities of up to 6.17 mmol·g−1 under wide temperature range (35–110 °C), overwhelming that of pure ZIF-8 (≤1.96 mmol·g−1) and other reported metal–organic frameworks (MOFs). DFT calculation verified that π-π stacking and hydrogen bonding between imidazole/aromatic rings on ligands and CO2 play crucial role in high CO2 uptake. Excellent recyclability in 10 runs under both low and high temperatures (55 °C, 110 °C) is exhibited, endowing this kind of materials with great potential for practical applications.