A Microporous Bimetallic Aluminum-Copper-Carboxylate-Pyrazolate MOF for CO2 Capture

Herein, we present a novel bimetallic hetero-functional ultra-microporous MOF, labelled MIP-212(Al/Cu) (MIP stands for Materials from Institute of Porous Materials of Paris), designed based on Hard and Soft Acids and Bases (HSAB) principle. This MOF is constructed from Al3+ and Cu2+ ions together with the carboxylate-pyrazolate ligand (PyC), that endows the structure with two types of narrow tunnel-like pores decorated with either μ2-OH groups or Cu(II) open metal sites. While the structure shows a slight breathing behaviour depending on pore’s content, the confinement effect, in combination with open metal sites generated upon activation, leads to a remarkably high CO2 uptake capacity at ambient temperature and low pressure (ca. 2.30 mmol/g at 0.15 bar), comparable to benchmark MOFs, with a good CO2/N2 IAST estimated selectivity of ca. 30 at 1 bar. The calculated Qst (CO2) of -36.8 kJ·mol-1 suggests a relatively low energy demand for its regeneration process. Finally, dynamic breakthrough measurements conducted under binary gas mixture conditions of CO2:N2 (15:85) prompts MIP-212(Al/Cu) as a promising post-combustion CO2 capture adsorbent, when employed in a typical temperature swing adsorption (TSA) process, as predicted by process, techno-economics and environmental Key Performance Indicators