離子液體 ( Ionic Liquids, ILs )有綠色溶劑之稱，在工業上已證明可取代揮發性有機溶劑，並廣泛的應用於其他領域。離子液體具有極低的蒸氣壓，故被認為不具有易燃性，但最近有研究指出，離子液體是具有可燃性，在高溫時又會有熱分解的現象產生，與傳統有機溶劑特性有很大的差異。本研究主要是探討離子液體閃火點和熱分解間的關係，將以熱重量分析儀 ( thermogravimetric analysis, TGA )、差示掃描量熱儀 ( differential scanning calorimetry, DSC )、傅立葉轉換紅外線光譜儀 ( fourier transform infrared spectroscopy, FTIR )和閃火點測試儀來研究1-ethyl-3methylimidazolium ethyl sulfate [Emim][EtSO4]、1-hexyl-3-methylimidazolium chloride [C6mim][Cl]及1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [Bmim][NTf2] 這三種離子液體的易燃性。文獻中使用 Lyon’s method 來估計離子液體閃火點有相當大的誤差，容易高估離子液體的閃火點進而低估它的危害性，而這個方法僅限於估計有機化合物和聚合物，並不適用於離子液體。離子液體閃火點相較於傳統有機溶劑主要是熱分解而不是蒸發。了解離子液體易燃性的成因有助於火災、爆炸的風險評估與發展離子液體化學品處置、使用的本質安全設計。
Ionic liquid is known as green solvents. It has the potential in industry to replace volatile organic solvents, and widely used in many domains. Ionic liquids are often reported as nonflammable owing to its extreme low vapor pressure. Recently, ionic liquids have been verified to be combustible instead of nonflammable. The reason for ionic liquids to be combustible should be different from that of traditionally defined liquids. The flash point of ionic liquids in relation to their decomposition was investigated in this study by use of thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FTIR), and flash point analyzer. The ionic liquids 1-ethyl-3-methylimidazolium ethyl sulfate [Emim][EtSO4], 1-hexyl-3-methylimidazolium chloride [C6mim][Cl], 1-butyl-3methylimidazolium bis(trifluoromethylsulfonyl)imide [Bmim][NTf2] were selected as test samples in this study. In this study, Lyon’s method being used to estimate the flash point of ionic liquids was verified to be with substantial error and that will overestimate the flash point of ionic liquids, although it is applicable for organic compounds and polymers. The flammability of ionic liquids is primary attributed to the decomposition of ionic liquids rather than their vaporizing. Realizing the cause for the flammability of ionic liquids is helpful for the assessment of fire and explosion hazards and the development of inherently safer designs for chemical processes containing ionic liquids.
