Studies on the thermal stability and decomposition kinetics of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide via density functional theory and experimental methods

Imidazole ionic liquids have potential applications in gas capture processes such as carbon dioxide capture carried out under high-temperature conditions. Therefore, it is of great significance to explore the thermal stability and thermal decomposition of imidazole ionic liquids. In this work, the thermal stability and decomposition characteristics of an imidazole ionic liquid 1-ethyl-3-methylimidazolium bis(trifluor omethylsulfonyl)imide ([Emim][NTf2]) were investigated by thermogravimetric analysis combined with Fourier transform infrared spectroscopy experiments under nitrogen conditions. The structure of [Emim] [NTf2] was optimized by density function theory (B3LYP/M06-2X) with a 6-311++G(d,p) basis set. In the reaction kinetics section, model-free methods (Friedman, FWO, KAS) and a model-fitting method (Coats Redfern) were utilized for the evaluation of kinetic data for [Emim][NTf2] following ICTAC recommendations. The optimum mechanism model of [Emim][NTf2] under nitrogen conditions was determined from these different kinetic methods. Decomposed gaseous products of [Emim][NTf2], which were obtained from thermogravimetric experiments, were simultaneously analyzed by Fourier transform infrared spectroscopy. Finally, the possible decomposition mechanism and gaseous products of [Emim][NTf2] were also discussed. The whole work was meant to combine the experimental and theoretical results to provide a feasible research route for the thermal composition stability and mechanism of ionic liquid [Emim] [NTf2] and a significant reference for further investigations into the thermal decomposition characteristics of universal ILs. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

This study investigates the thermal stability and decomposition characteristics of an imidazole ionic liquid 1-ethyl-3-methylimidazolium bis(trifluor omethylsulfonyl)imide ([Emim][NTf2]). The research combines experimental and theoretical methods to provide insights into the thermal decomposition behavior of ionic liquids.