Aluminum-based metal organic frameworks for greenhouse gases CF4 and C2F6 capture with excellent capacity and selectivity

Abstract

The capture and recovery of perfluorinated greenhouse gases CF4 and C2F6 from industrial exaust can not only mitigate global warming but also produce value-added products. Adsorption technology based on porous materials is promising for such purpose, while adsorbents with high capacity and selectivity are still lacking due to the chemical inertness of CF4 and C2F6. Herein, three ultra-microporous Al-MOFs with multiple electropositive binding sites in 1D channel were synthesized and evaluated for CF4/C2F6 adsorption. Among the synthesized Al-MOFs, Al-Fum displayed the best adsorption performance due to its desirable pore environment. It has a record-breaking C2F6 adsorption capacity (3.30 mmol/g at 1 bar and 298 K) and C2F6/N2 (10/90, v/v) selectivity (299.6 at 1 bar). In addition, it also displays excellent CF4 adsorption performance, exceeding most of the reported adsorbents. Theoretical simulations demonstrate the high CF4/C2F6 affinity towards Al-Fum is resulted from the multiple interactions of F atoms with H atoms of fumarate linkers and corner hydroxyl groups in frameworks. Moreover, dynamic column breakthrough tests confirmed the excellent separation performance of CF4/N2 and C2F6/N2 on Al-Fum with outstanding regenerability. Due to the green and energy-efficient synthesis method and outstanding adsorption performance, Al-Fum is considered to be an ideal porous material for CF4/C2F6 capture under practical conditions.