Abstract The thermal stability and decomposition kinetics of a series of 1-alkyl-3-methylimidazolium chloride ionic liquids with different alkyl chain lengths (ethyl, propyl, butyl, hexyl, and decyl) were investigated with isothermal and non-isothermal thermogravimetric analysis. Isothermal experiments were conducted at 100, 125, 150, 175, 200, and 225 °C in nitrogen atmosphere. Non-isothermal experiments were conducted from 25−650 °C with heating rates of 5, 10, 15, and 20 ℃/min. Under both heating modes, the ionic liquids with the longer alkyl chains were found to display lower thermal stability. The activation energies E a determined from isothermal analysis ranged from 115-120 k J / m o l , except for the ionic liquid with the decyl chain, for which the value was higher (157 k J / m o l ). The E a determined by non-isothermal analysis were similar to the isothermal values for the ionic liquids with the ethyl and decyl chains, higher (144-154 k J / m o l ) for the ionic liquids with the propyl and butyl chains, and lower (98 k J / m o l ) for the ionic liquid with the hexyl chain. The pre-exponential factors ln ( A ) from isothermal analyses resulted in values in the range 25–29, which did not vary with reaction model. Non-isothermal analyses resulted in l n ( A ) values in the range 24–38, which were likewise not sensitive to reaction model. Among the models evaluated, the 3-dimensional reaction model was found to best represent both the isothermal and the non-isothermal data. No clear relationships were found between the alkyl chain length and the kinetic parameters.

中文翻译：

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等温和非等温条件下1-烷基-3-甲基咪唑氯化物离子液体的热分解动力学

摘要 采用等温和非等温热重分析研究了一系列不同烷基链长（乙基、丙基、丁基、己基和癸基）的1-烷基-3-甲基咪唑氯化物离子液体的热稳定性和分解动力学。等温实验在 100、125、150、175、200 和 225 °C 下在氮气气氛中进行。非等温实验在 25-650 °C 下进行，加热速率为 5、10、15 和 20 ℃/min。在两种加热模式下，发现具有较长烷基链的离子液体显示出较低的热稳定性。等温分析确定的活化能E a 范围为115-120 k J / mol ，除了具有癸基链的离子液体外，其值更高（157 k J / mol ）。非等温分析测得的E a 与具有乙基和癸基链的离子液体的等温值相似，具有丙基和丁基链的离子液体的等温值较高（144-154 k J / mol ），较低（ 98 k J / mol ) 为具有己基链的离子液体。来自等温分析的指数前因子 ln ( A ) 导致值在 25-29 范围内，该值不随反应模型而变化。非等温分析导致 ln ( A ) 值在 24-38 范围内，这同样对反应模型不敏感。在评估的模型中，发现 3 维反应模型最能代表等温和非等温数据。在烷基链长度和动力学参数之间没有发现明确的关系。