Abstract The carbon dioxide solubility in non-aqueous and aqueous mixtures of methyldiethanolamine (MDEA) with monoethylene glycol (MEG) was studied due to the relevance of these solvents for the combined acid gas removal and hydrate control in natural gas treatment. Vapour-liquid equilibrium (VLE) measurements were conducted at temperatures from 303 K to 393 K and pressures up to 600 kPa. In the aqueous solvents, the effect of water content in carbon dioxide solubility was investigated. The absorption capacity of the aqueous solvents decreased with increasing glycol content and decreasing water content, at constant amine concentration. A comparison of the studied systems with concentrated aqueous MDEA was also performed. The non-aqueous solvents were studied in the whole composition range, from pure MDEA to pure MEG. The solubility of carbon dioxide increased with increasing amine content only up to 30-50 wt% MDEA-MEG, upon which it decreased. Water content determination and Nuclear Magnetic Resonance (NMR) analysis were used for the chemical characterization of the systems and explanation of the results. It was found that in the presence of MDEA, a chemical reaction occurs between carbon dioxide and MEG. A theory based on MEG autoprotolysis is proposed which is further supported by supplementary VLE data obtained in blends of MDEA and triethylene glycol.

中文翻译：

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二氧化碳在甲基二乙醇胺与单乙二醇、单乙二醇 – 水、水和三乙二醇的混合物中的溶解度

摘要 由于甲基二乙醇胺 (MDEA) 与单乙二醇 (MEG) 的非水和水混合物中二氧化碳的溶解度，由于这些溶剂与天然气处理中酸性气体去除和水合物控制的相关性，因此研究了这些溶剂。气液平衡 (VLE) 测量在 303 K 至 393 K 的温度和高达 600 kPa 的压力下进行。在水性溶剂中，研究了水含量对二氧化碳溶解度的影响。在恒定的胺浓度下，水性溶剂的吸收能力随着乙二醇含量的增加和水含量的降低而降低。还对所研究的系统与浓 MDEA 水溶液进行了比较。在整个组成范围内研究了非水溶剂，从纯 MDEA 到纯 MEG。二氧化碳的溶解度随着胺含量的增加而增加，仅当 MDEA-MEG 达到 30-50 重量％时，它就会下降。含水量测定和核磁共振 (NMR) 分析用于系统的化学表征和结果的解释。发现在 MDEA 的存在下，二氧化碳和 MEG 之间会发生化学反应。提出了一种基于 MEG 自质子分解的理论，该理论得到了在 MDEA 和三甘醇混合物中获得的补充 VLE 数据的进一步支持。二氧化碳和 MEG 发生化学反应。提出了一种基于 MEG 自质子分解的理论，该理论得到了在 MDEA 和三甘醇混合物中获得的补充 VLE 数据的进一步支持。二氧化碳和 MEG 发生化学反应。提出了一种基于 MEG 自质子分解的理论，该理论得到了在 MDEA 和三甘醇混合物中获得的补充 VLE 数据的进一步支持。