In this work, the thermodynamic inhibition impact of four ammonium-based ionic liquids (AILs) on CO₂ rich mixed gas hydrate system (70–30 mol% CO₂ + CH₄) is experimentally studied, and the observed behaviour is modelled. The studied AILs are; tetramethylammonium hydroxide (TMAOH), tetraethylammonium hydroxide (TEAOH), tetrapropylammonium hydroxide (TPrAOH) and tetrabutylammonium hydroxide (TBAOH). Initially, the impact of 10 wt% AILs in an aqueous solution on the CO₂ enriched binary gas phase boundary is evaluated by measuring the dissociation temperature in the pressure range of 1.90–5.10 MPa. The thermodynamic inhibition influence of AILs is quantitatively analyzed by calculating the hydrate suppression temperatures for all studied systems. Further, the Clausius–Clapeyron equation is used to determine the molar hydrate enthalpy of dissociation (∆H_diss) for the studied systems. The results revealed that the inhibition influence of AILs is observed to be decreasing with the increasing alkyl chain length of AILs. Excluding TBAOH, all the other studied AILs act as thermodynamic inhibitors due to the relatively shorter alkyl chain. The ∆H_diss results of the binary mixed gas system in the presence and absence of AILs revealed that the presence of TMAOH, TEAOH and TPrAOH has negligible effect in hydrate cages formation. However, TBAOH exhibited a significant change in ∆H_diss which indicates the semi-clathratic nature of it. Among the considered AILs, TMAOH shown better thermodynamic impact attributed to its shortest alkyl chain length. Therefore it is further investigated for various concentrations (1, 5 and10 wt%). Moreover, the measured, mixed gas hydrate phase boundaries of various aqueous AILs solutions are also predicted via electrolyte model proposed by Dickens and Quinby-Hunt and are found to be in good agreement with the experimental data apart from TBAOH. Therefore, this study is relevant for the understanding of structural variations (alkyl chain elongation) of AILs on the hydrate phase stability of the high CO₂ content mixed gas system.

在这项工作中，实验研究了四种铵基离子液体（AIL）对富含CO _2的混合气体水合物系统（70–30 mol％CO ₂  + CH ₄）的热力学抑制作用，并对观察到的行为进行了建模。被研究的AIL是：氢氧化四甲铵（TMAOH），氢氧化四乙铵（TEAOH），氢氧化四丙铵（TPrAOH）和氢氧化四丁铵（TBAOH）。最初，水溶液中10 wt％的AIL对CO _2的影响通过测量在1.90-5.10 MPa压力范围内的离解温度，可以评估富集的二元气相边界。通过计算所有研究系统的水合物抑制温度，定量分析了AIL的热力学抑制影响。此外，克劳修斯–克拉珀龙方程用于确定所研究系统的离解摩尔水合物焓（∆ H _diss）。结果表明，随着AILs烷基链长度的增加，对AILs的抑制作用逐渐减小。除TBAOH外，所有其他已研究的AIL由于相对较短的烷基链而充当热力学抑制剂。该Δ ħ _DISS在存在和不存在AIL的情况下，二元混合气体系统的结果表明，TMAOH，TEAOH和TPrAOH的存在对水合物笼形成的影响可忽略不计。但是，TBAOH的∆ H _diss表现出显着变化这表明它具有半基督教的性质。在所考虑的AIL中，TMAOH由于其最短的烷基链长而表现出更好的热力学影响。因此，需要进一步研究各种浓度（1、5和10 wt％）。此外，还可以通过狄更斯和昆比-亨特提出的电解质模型来预测各种AIL水溶液的混合气体水合物相的边界，并发现它们与TBAOH的实验数据非常吻合。因此，这项研究对于了解AIL的结构变化（烷基链伸长）对高CO ₂含量混合气体系统的水合物相稳定性具有重要意义。