Piperazinium-Based Ionic Liquids with Lactate Anion for Extractive Desulfurization of Fuels

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• 作者：Xiaoxing Lu ; Lei Yue ; Minjie Hu ; Qi Cao ; Li Xu ; Yongsheng Guo ; Shenlin Hu ; Wenjun Fang
• 刊名：Energy & Fuels
• 出版年：2014
• 出版时间：March 20, 2014
• 年：2014
• 卷：28
• 期：3
• 页码：1774-1780
• 全文大小：331K
• 年卷期：v.28,no.3(March 20, 2014)
• ISSN：1520-5029

文摘

Three kinds of piperazinium-based room-temperature ionic liquids (RTILs), namely, N-methylpiperazinium lactate ([C₁pi][Lac]), N-ethylpiperazinium lactate ([C₂pi][Lac]), and N,N鈥?dimethylpiperazinium dilactate ([C₁C₁pi][Lac]₂), have been synthesized by the direct reaction of N-alkyl-substituted piperazines and lactate acid. Together with 1,1,3,3-tetramethylguanidinium lactate ([TMG][Lac]), they are employed as new extractants for removing aromatic sulfur compounds, thiophene (TS), benzothiophene (BT), dibenzothiophene (DBT), and 4-methyldibenzothiophene (4-MDBT), from various hydrocarbon fuels. The effects of the temperature, extraction time, and amount of ionic liquid (IL) on the sulfur removal are investigated systematically. The mutual solubility measurements show that the ILs are dissolved in n-heptane with the mass fraction less than 0.01 at 30 掳C. The solubility values of 93 gasoline in the ILs are observed with the following sequence: [C₁C₁pi][Lac]₂ (0.007 in mass fraction) < [C₁pi][Lac] (0.014 in mass fraction) < [TMG][Lac] (0.017 in mass fraction) < [C₂pi][Lac] (0.070 in mass fraction), and the sulfur distribution coefficient follows the order: [TMG][Lac] (1.08 in mass fraction) > [C₂pi][Lac] (0.98 in mass fraction) > [C₁pi][Lac] (0.78 in mass fraction) > [C₁C₁pi][Lac]₂ (0.53 in mass fraction) for 93 gasoline. Selectivity between TS and toluene is observed higher than 4 with the following sequence: [TMG][Lac] (13.19 in mass fraction) > [C₁pi][Lac] (10.59 in mass fraction) > [C₂pi][Lac] (7.12 in mass fraction) > [C₁C₁pi][Lac]₂ (4.94 in mass fraction), revealing that these ILs are more preferable to extract TS than toluene from hydrocarbon fuels. The used ILs can be recycled without a significant decrease of desulfurization activity after extraction 5 times. These fundamental results hopefully provide useful information for future commercialization and practical desulfurization.