Solidified natural gas (SNG) is a perspective method for transportation and storing hydrocarbon gases under mild conditions. The aim of this work is to synthesize new compounds that are derivatives of several amino acids (leucine, methionine, phenylalanine, norleucine, aspartic acid, valine, glutamic acid, norvaline, proline, threonine, alanine, 6-aminohexanoic acid, cysteic acid) with nitrilotriacetic acid (NTA + AA) to improve the efficiency of methane transition from gas phase into hydrate form, compared to pure amino acids and sodium dodecyl sulfate (SDS). According to the results of high-pressure autoclave experiments, 7 NTA + AA samples out of 13 increase methane uptake and water to hydrate conversion better than SDS, which is a well-known effective promoter of hydrate formation, and 12 NTA + AA samples out of 13 have shorter induction times than SDS. In addition, visual observations showed that all the novel promoters synthesized from amino acids and nitrilotriacetic acid do not cause foaming throughout the process of methane hydrate dissociation, which improves the performance of this type of promoter in comparison with SDS. The efficiency of kinetic hydrate promoters at 0.05 wt% concentration by maximum mole consumption of methane decreased in the range of samples: NTA + Phenylalanine > NTA + Glutamic acid > NTA + Leucine > NTA + Norleucine > NTA + Aspartic acid > NTA + Alanine > NTA + Valine > NTA + Norvaline > SDS > NTA + Proline > NTA + Methionine > NTA + Threonine > NTA + Cysteic acid > NTA + 6-aminohexanoic acid. NTA + Phe (nitrilotriacetic acid + phenylalanine) was able to achieve 98.2 % water to hydrate conversion (0.164 mol gas/mole water) at 0.05 wt% concentration, and its induction time was independent of concentration and approximately equal to 30 min, which was about half that of SDS and pure phenylalanine. Thus NTA + Phe can be considered as one of the best promoters of methane gas hydrate formation, which can be used at low concentrations. Modification of amino acids with nitrilotriacetic acid was shown to significantly improve the efficiency of the compounds as kinetic promoters of hydrate formation, both in terms of induction time and methane uptake, compared to pure amino acids, which makes it possible to create more effective eco-friendly non-foaming promoters of methane hydrate formation used at low concentrations.

中文翻译：

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基于氨基酸的新型启动子，经次氮基三乙酸改性，可有效储存甲烷作为气体水合物而不起泡


凝固天然气 （SNG） 是一种在温和条件下运输和储存碳氢化合物气体的透视方法。这项工作的目的是合成作为几种氨基酸（亮氨酸、蛋氨酸、苯丙氨酸、去亮氨酸、天冬氨酸、缬氨酸、谷氨酸、正缬氨酸、脯氨酸、苏氨酸、丙氨酸、6-氨基己酸、半胱氨酸）与次氮基三乙酸 （NTA + AA） 衍生物的新化合物，以提高甲烷从气相转变为水合物形式的效率，与纯氨基酸和十二烷基硫酸钠 （SDS） 相比。根据高压釜实验的结果，13 个 NTA + AA 样品中有 7 个样品比 SDS 更好地增加甲烷吸收和水合物转化率，SDS 是众所周知的水合物形成的有效促进剂，12 个 NTA + AA 样品中的 13 个样品的诱导时间比 SDS 短。此外，目视观察表明，由氨基酸和次氮基三乙酸合成的所有新型启动子在整个甲烷水合物解离过程中不会产生泡沫，与 SDS 相比，这提高了该类型启动子的性能。在样品范围内，甲烷的最大摩尔消耗量导致浓度为 0.05 wt% 的动力学水合物促进剂的效率降低：NTA + 苯丙氨酸 > NTA + 谷氨酸 > NTA + 亮氨酸 > NTA + 去甲亮氨酸 > NTA + 天冬氨酸 > NTA + 丙氨酸 > NTA + 缬氨酸 > NTA + 正缬氨酸 > SDS > NTA + 脯氨酸 > NTA + 蛋氨酸 > NTA + 苏氨酸 > NTA + 半胱氨酸 > NTA + 6-氨基己酸。NTA + Phe（次氮基三乙酸 + 苯丙氨酸）能够在 0.05 wt% 浓度，其诱导时间与浓度无关，大约等于 30 分钟，大约是 SDS 和纯苯丙氨酸的一半。因此 NTA + Phe 可以被认为是甲烷气体水合物形成的最佳促进剂之一，可以在低浓度下使用。与纯氨基酸相比，用次氮基三乙酸对氨基酸进行修饰可以显著提高化合物作为水合物形成动力学促进剂的效率，无论是在诱导时间和甲烷吸收方面，这都可以创造出更有效的环保无泡促进剂，用于低浓度的甲烷水合物形成。