Abstract In light of current concerns about environmental impact, ionic liquids have been tested in a number of industrial applications, including gas purification, lubrication, and catalysis. In this work, cost-effective alkylammonium-based protic ionic liquids (PIL) were utilized as high-dosage gas hydrate inhibitors in order to achieve an inexpensive feedstock. Three structurally different PILs, ethylammonium formate ([EA][Of]), dimethylammonium formate ([DMA][Of]), and dimethylethylammonium formate ([DMEA][Of]), were studied to determine their inhibitory effect on methane gas hydrates. All of the studied PILs were initially tested for thermodynamic gas hydrate inhibition at 5 wt% and at 10 wt% to understand the effect of concentration by increasing the dosage. These PILs were produced by adding primary, secondary, and tertiary amines to formic acid, which is mildly acidic in nature and has biological significance. The PILs showed similar thermodynamic hydrate inhibition (THI) effects at the studied concentrations. The THI trend ([EA][Of] ≥ [DMA][Of] ≥ [DMEA][Of]) reflects the small effect of the structural variation of the cation, with the common formate anion providing the dominant inhibitory action due to presence of a carboxylic group. The pressure-temperature (P-T) equilibrium curve data of the investigated PILs were compared with the existing literature data for ILs including [TBMA][Of] at 10 wt% and 5 wt%. The comparison plots reveal that the THI effects of the studied PILs are better than or comparable to the other ILs, which is the matter of discussion over cost effective operation. Additionally, experimental kinetic hydrate inhibition (KHI) data were collected for 5 wt% PIL systems using polyethylene oxide (1 wt%) as an additive to demonstrate its synergistic effect.

中文翻译：

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用于抑制甲烷水合物的具有成本效益的基于甲酸烷基铵的质子离子液体

摘要 鉴于目前对环境影响的担忧，离子液体已在许多工业应用中进行了测试，包括气体净化、润滑和催化。在这项工作中，经济高效的基于烷基铵的质子离子液体 (PIL) 被用作高剂量气体水合物抑制剂，以实现廉价的原料。研究了三种结构不同的 PIL，甲酸乙铵 ([EA][Of])、甲酸二甲铵 ([DMA][Of]) 和甲酸二甲乙铵 ([DMEA][Of])，以确定它们对甲烷气体水合物的抑制作用. 最初对所有研究的 PIL 进行了 5 wt% 和 10 wt% 的热力学气体水合物抑制测试，以了解通过增加剂量来了解浓度的影响。这些 PIL 是通过添加初级、次级、和叔胺转化为甲酸，甲酸性质温和，具有生物学意义。在所研究的浓度下，PIL 显示出类似的热力学水合物抑制 (THI) 效果。THI 趋势 ([EA][Of] ≥ [DMA][Of] ≥ [DMEA][Of]) 反映了阳离子结构变化的小影响，由于存在，常见的甲酸阴离子提供了主要的抑制作用一个羧基。将所研究的 PIL 的压力-温度 (PT) 平衡曲线数据与包括 10 wt% 和 5 wt% 的 [TBMA][Of] 的 IL 的现有文献数据进行比较。比较图显示，所研究的 PIL 的 THI 效果优于或与其他 IL 相当，这是关于成本效益操作的讨论问题。此外，