Impregnation of 1-<i>n</i>-Butyl-3-methylimidazolium Dicyanide [BMIM][DCA] into ZIF-8 as a Versatile Sorbent for Efficient and Selective Separation of CO<sub>2</sub>
Shahid Hussain, Haifeng Dong, Yanqiang Zhang, Guoxiong Zhan, Shaojuan Zeng, Huifang Duan, Xiangping Zhang
Abstract
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.