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

The efficient capture of carbon dioxide (CO2) has industrial, economic, and environmental significance. Here, CO2 capture performance in terms of CO2/CH4 selectivity for the zeolitic imidazolate framework (ZIF-8) is enhanced by impregnation of 1-n-butyl-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 CO2/CH4 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.