Thermal Stability and Decomposition Mechanism of 1-Ethyl-3-Methylimidazolium Halides

  • The thermochemical behavior of 1-ethyl-3-methylimidazolium [EMIm] halides (Cl, Br and I) has been investigated for their crystalline and liquid states in the temperature range from −90 °C to 600 °C using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The temperatures and enthalpies of phase transitions have been determined: Tfus = 86(1) °C, ΔHfus = 14.2(0.7) kJ mol−1 ([EMIm]Cl); Tfus = 67(1) °C, ΔHfus = 19.3(0.7) kJ mol−1 ([EMIm]Br); and Tfus = 74(1) °C, ΔHfus = 16.9(0.6) kJ mol−1 ([EMIm]I). The decomposition temperatures, determined by onset of DTG at 1 K min−1 are 233(5) °C ([EMIm]Cl), 246(5) °C ([EMIm]Br), and 249(5) °C ([EMIm]I). The maximum operation temperature (MOT) has been estimated based on dynamic TGA for an operation time of 24 h: 132 °C ([EMIm]Cl), 149 °C ([EMIm]Br), 139 °C ([EMIm]I) and 8000 h: 76 °C ([EMIm]Cl), 90 °C ([EMIm]Br), 77 °C ([EMIm]I). The decomposition products of the investigated ionic liquids (ILs) after heating experiments were identified by means of TGA complemented withThe thermochemical behavior of 1-ethyl-3-methylimidazolium [EMIm] halides (Cl, Br and I) has been investigated for their crystalline and liquid states in the temperature range from −90 °C to 600 °C using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The temperatures and enthalpies of phase transitions have been determined: Tfus = 86(1) °C, ΔHfus = 14.2(0.7) kJ mol−1 ([EMIm]Cl); Tfus = 67(1) °C, ΔHfus = 19.3(0.7) kJ mol−1 ([EMIm]Br); and Tfus = 74(1) °C, ΔHfus = 16.9(0.6) kJ mol−1 ([EMIm]I). The decomposition temperatures, determined by onset of DTG at 1 K min−1 are 233(5) °C ([EMIm]Cl), 246(5) °C ([EMIm]Br), and 249(5) °C ([EMIm]I). The maximum operation temperature (MOT) has been estimated based on dynamic TGA for an operation time of 24 h: 132 °C ([EMIm]Cl), 149 °C ([EMIm]Br), 139 °C ([EMIm]I) and 8000 h: 76 °C ([EMIm]Cl), 90 °C ([EMIm]Br), 77 °C ([EMIm]I). The decomposition products of the investigated ionic liquids (ILs) after heating experiments were identified by means of TGA complemented with mass spectrometry (MS), for establishment of the mechanism of thermal decomposition of the ILs. Complete degradation of [EMIm]X ionic liquids occurs under formation of characteristic molecule fragments CH3+, NH+, and X+, CH3X+, C2H5X+ (X = Cl, Br, I).show moreshow less

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Author: Anastasia EfimovaORCiD, Linda Pfützner, Peer SchmidtORCiD
URL:http://www.sciencedirect.com/science/article/pii/S0040603115000350
DOI:https://doi.org/10.1016/j.tca.2015.02.001
Title of the source (English):Thermochimica Acta
Document Type:Scientific journal article peer-reviewed
Language:English
Year of publication:2015
Tag:1-Ethyl-3-methylimidazolium halides ([EMIm] halides); Differential scanning calorimetry (DSC); Integral isoconversional method; Ionic liquids (ILs); Mass spectrometry (MS); Maximum operation temperature (MOT); Thermal decomposition mechanism; Thermogravimetric analysis (TGA)
Volume/Year:604
First Page:129
Last Page:136
Faculty/Chair:Fakultät 2 Umwelt und Naturwissenschaften / FG Anorganische Chemie
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