Designed imidazolium-based ionic liquids to capture carbon dioxide from natural gas

Abstract

Natural gas is considered one of the most appealing fossil fuels in the world's energy supply nowadays, and it is primarily recognized as a clean energy source. However, the removal of pollutants from NG, particularly carbon dioxide (CO2), requires complex treatment strategies, significantly influencing its production. Consequently, the appealing properties of ionic liquids (ILs) make them interesting eco-friendly candidates for capturing CO2 from natural gas. In this work, a series of novel functionalized ILs (IL-Br, IL-BF4, and IL-PF6) were synthesized and characterized via a variety of analysis tools, including FT-IR, NMR, and thermal gravimetric analysis. Highly efficient capture of CO2 from natural gas was investigated at ambient temperature and was successfully achieved with the synthesized ILs. IL-PF6 recorded the highest capture CO2 capacity from the natural gas stream, which reached up to 94 % in only 5 min as a retention time. The experimental results revealed that each gram of IL-PF6, IL-BF4, and IL-Br could capture 2.02, 1.23, and 1.18 mmol of CO2, respectively. The used ILs were reused three times without any significant reduction in their capturing performance, which enhances their potential for eco-friendly and cost-saving issues. The CO2 capture efficiency of the used ILs was verified theoretically using the DFT method and Monte Carlo simulations (MCs). The quantum study matches with the experimental results, which confirmed the CO2 capture efficiency in the order of IL-PF6 > IL-BF4 > IL-Br.