AbstractBACKGROUNDAs a low‐rank coal, lignite (frequently referred to as ‘brown coal’) has a high latent moisture content and low energy density and thus has low value as a solid fuel, often being burned at power stations close to where it is mined. For this reason, an effective pretreatment is essential to the better utilization of low‐rank coal for energy and materials. Ionic liquids (ILs) are alternatives to conventional volatile organic solvents for pretreating coal due to their tailorable structures and physical properties, as well as their ability to partially dissolve/swell coal components. This study aimed to rationally design ionic liquids having a high hydrogen‐bond basicity, based on the acetate anion, paired with ether‐functionalized cations (especially the less‐expensive piperidinium) for lignite dissolution and treatment.RESULTSLignite treated by these functionalized ionic liquids at 105 °C led to the dissolution of 15.7–24.5 wt% lignite with a concomitant increase in coal aromaticity and rank, a reduction in coal decomposition residues, and the production of smaller and more uniform particles. The ether‐functionalized N‐(2‐ethoxyethyl)‐N‐methylpiperidinium acetate is a particularly attractive alternative to conventional imidazolium ILs due to its lower cost, high hydrogen‐bond basicity, and a strong capability for improving the coal aromaticity.CONCLUSIONOur results have demonstrated that pretreatment with functionalized ionic liquids can improve the coal aromaticity and rank, decrease coal decomposition residues, and yield smaller and more uniform particles, which enables a better utilization of low‐rank coal for fuel and materials. © 2021 Society of Chemical Industry (SCI).

中文翻译：

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用于褐煤溶解和处理的功能化离子液体

摘要背景作为一种低阶煤，褐煤（通常称为“褐煤”）具有较高的潜在水分含量和较低的能量密度，因此作为固体燃料的价值较低，通常在靠近开采地点的发电厂燃烧。因此，有效的预处理对于更好地利用低阶煤作为能源和材料至关重要。离子液体（IL）由于其可定制的结构和物理性质以及部分溶解/膨胀煤成分的能力，可以替代传统的挥发性有机溶剂来预处理煤。本研究旨在合理设计具有高氢键碱度的离子液体，基于乙酸根阴离子，与醚官能化阳离子（尤其是较便宜的哌啶鎓）配对，用于褐煤溶解和处理。结果在 105 °C 下用这些功能化离子液体处理褐煤导致 15.7–24.5 wt% 褐煤溶解，同时煤芳香度和等级增加，煤分解残留物减少，并产生更小、更均匀的颗粒。醚官能化氮-(2-乙氧基乙基)-氮醋酸甲基哌啶鎓盐由于其成本较低、氢键碱度高以及改善煤芳香度的能力强，是传统咪唑鎓离子液体的特别有吸引力的替代品。结论我们的研究结果表明，功能化离子液体预处理可以提高煤的芳香度和等级，减少煤的分解残留物，并产生更小、更均匀的颗粒，从而更好地利用低阶煤作为燃料和材料。© 2021 化学工业协会 (SCI)。