Impregnation of 1-n-Butyl-3-methylimidazolium Dicyanide [BMIM][DCA] into ZIF-8 as a Versatile Sorbent for Efficient and Selective Separation of CO₂

Abstract

The efficient capture of carbon dioxide (CO 2 ) has industrial, economic, and environmental significance. Here, CO 2 capture performance in terms of CO 2 /CH 4 selectivity for the zeolitic imidazolate framework (ZIF-8) is enhanced by impregnation of 1-nbutyl-3-methylimidazolium dicyanide [BMIM][DCA]. The preparation of ionic liquids (ILs)/ZIF-8 composites, their comprehensive characterization, and the impact of IL impregnation are all investigated. The crystal structure and morphology of ZIF-8 remained intact even after the impregnation of ILs, according to X-ray diffraction and scanning electron microscopy studies. The infrared spectroscopy known as Fourier transform infrared spectroscopy determines the interaction between ILs and ZIF-8 in the composite. The isotherm fitting was also performed by dual site Langmuir models, which showed good agreement with the experimental results. The CO 2 /CH 4 selectivity results demonstrated that the ideal selectivity for the IL-impregnated ZIF-8 composite has five times higher selectivity than pristine ZIF-8 at 0.05 bar which is the highest reported selectivity. The normalized selectivity of this type of IL/ZIF-8 composite is also higher. This study suggested that the IL/MOF composite with a tunable structure have a strong potential for enhanced acid gas separation performance to meet the environmental challenges.

Composite of MIL-101(Cr) with a Pyrrolidinium-Based Ionic Liquid Providing High CO2 Selectivity

“…These increases in selectivities with the decreasing pressure are associated with the change in what drives the adsorption. The gas adsorption in the low-pressure region is governed by the interactions between the adsorbent and gas molecules, whereas at high pressures, it significantly depends on the available pore volume. , Hence, such a remarkable boost in the selectivity of the composite in the low-pressure region can be ascribed to the change in the adsorption mechanism from pore availability to surface affinity.…”

Integrating Molecular Simulations with Machine Learning Guides in the Design and Synthesis of [BMIM][BF4]/MOF Composites for CO2/N2 Separation

“…Metal–organic frameworks (MOFs), consisting of metal nodes and organic linkers, have been widely studied for gas separation thanks to their tunable pore sizes and chemical functionalities. − One of the major advancements in this field is the incorporation of ionic liquids (ILs) into MOFs via post-synthesis modification techniques , to improve the selectivity of MOFs by tuning the relative affinity of composites for a specific molecule, such as CO 2 . Experimental studies have examined a very limited number of IL/MOF composites to date for CO 2 /N 2 , − CO 2 /CH 4 , − ,− ,− and CH 4 /N 2 − ,,, separations and revealed their high gas separation potentials. There may be many other IL/MOF composites that can outperform the existing porous materials in terms of gas separation performance.…”

Effect of Surface Characteristics of Graphene Aerogels and Hydrophilicity of Ionic Liquids on the CO2/CH4 Separation Performance of Ionic Liquid/Reduced Graphene Aerogel Composites

“…The family of imidazolium-based ILs has been widely studied for gas separation applications, ,, whereas only a few studies reported the usage of pyrrolidinium-based ILs for the synthesis of highly selective composites. , The cations of both IL families consist of quaternary ammonium salts; while imidazolium has an aromatic property, the pyrrolidinium ring is nonaromatic. Pyrrolidinium-based ILs are generated to have higher electrochemical and thermal stabilities and lower toxicity compared to imidazolium-based counterparts .…”

“…4 Moreover, density functional theory calculations and grand canonical Monte Carlo simulations were used to investigate the impact of IL incorporation to 2D graphene layers, and the results showed that choosing 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF 4 ]) decreased the interlayer spacing between sheets and available pore size, resulting in CO 2 /CH 4 mixture selectivities as high as ∼1000. 30 The family of imidazolium-based ILs has been widely studied for gas separation applications, 4,19,31 whereas only a few studies reported the usage of pyrrolidinium-based ILs for the synthesis of highly selective composites. 32,33 The cations of both IL families consist of quaternary ammonium salts; while imidazolium has an aromatic property, the pyrrolidinium ring is nonaromatic.…”