Amino-functional CPL-1 with abundant CO2-philic groups to enhance MMM-based CO2 separation

Abstract

Metal organic frameworks (MOFs) with appropriate pore size and sufficient CO2-philic groups are required to improve the mixed matrix membranes (MMMs)-based CO2 capture. Herein, NH2-CPL-1 is designed for capture by utilizing amino pyrazine instead of pyrazine in CPL-1. The introduced CO2-philic amino groups together with rich hydroxyl and carboxyl groups in CPL-1 could improve the selective adsorption of CO2, enhancing the solubility selectivity. At the meantime, after the introduction of amino-functional, the pore size of NH2-CPL-1 is decreased from 0.93 nm of CPL-1 to 0.85 nm, which is beneficial for the screening of CO2 over N2. As a result, the CO2 separation performances of MMMs could be promoted greatly under the action of NH2-CPL-1. MMM with NH2-CPL-1 of 10 wt.% exhibited the best CO2 separation performance, with CO2/N2 selectivity of 85 and CO2 permeability of 104 Barrer at 25 °C and 0.4 MPa. Compared with the CPL-1/Pebax-10 wt.% MMM, it was increased by 9.5 % and 13.3 %, respectively. This satisfactory CO2 separation performance surpasses those of most reported other MOFs based MMMs, which is attributed to the facilitated CO2 transport and pore size screening from the introduced amino groups. This is also confirmed by the improvement of diffusion selectivity and solution selectivity. The proposed NH2-CPL-1 shows great prospect as filler for enhanced MMMs-based CO2 capture.