Abstract:

The type and amount of promoters are essential for the kinetics of CO₂ hydrate separation. In order to clarify the effects of different concentrations of L-methionine, L-tryptophan, dodecyl trimethyl ammonium chloride (DTAC) and other accelerators on the formation kinetics and morphology of flue gas hydrates in cement plants, an intermittent reactor was used at 278.15K and an initial pressure of 3.60MPa. The method of high and low speed combined stirring was used to coordinate with tetra-n-butyl ammonium bromide (TBAB), and the induction time, gas uptake, t₉₀, CO₂ split fraction and separation factor were used as indicators. The results showed that L-methionine effectively improved the separation efficiency of CO₂ in flue gas, and the separation factor reached 19.86. L-Tryptophan had a prominent advantage in promoting the nucleation of flue gas hydrate. When the concentration of L-Tryptophan was 0.1%, the induction time decreased by 60.7% compared with pure TBAB solution, but the CO₂ loading was low. In the DTAC system, a large number of dispersed granular hydrates were formed in the liquid phase, which eliminated the suffocation effect, but reduced the separation efficiency. In addition, the induction time decreased to 20—30s after TBAB concentration increased, but increasing TBAB concentration had little effect on other indicators. In summary, 5%TBAB+0.2% L-methionine promotes excellent performance balance, and the captured CO₂ concentration reaches 80.21%. It has the advantages of less dosage, biodegradability and decomposition without foam generation. It is the best compound scheme and can provide theoretical reference for industrial application.

Key words: CO₂ separation and capture, hydrate, kinetics, tetra-n-butyl ammonium bromide (TBAB), amino acid, dodecyl trimethylammonium chloride (DTAC)

摘要：

促进剂对CO₂水合分离动力学影响较大。为了明确不同浓度的甲硫氨酸、色氨酸、十二烷基三甲基氯化铵（DTAC）等促进剂对水泥厂烟气水合物生成动力学和形态的影响，在温度278.15K、初始压力3.60MPa下使用间歇式反应釜，高、低转速组合搅拌的方法，分别与四丁基溴化铵（TBAB）复配，以诱导时间、载气量、t₉₀、CO₂回收率和分离因子为指标进行了实验研究。结果表明：甲硫氨酸有效提高了烟气中CO₂分离效率，分离因子达到19.86；色氨酸在促进烟气水合物成核方面优势突出，当浓度为0.1%（质量分数，下同）时诱导时间较纯TBAB溶液下降了60.7%，但CO₂载气量较低；DTAC体系下液相内部生成了大量分散的颗粒状水合物，消除了窒息效应，但降低了分离效率。另外， TBAB浓度升高后诱导时间骤降至20~30s，但对其他指标影响较小。综上，5%TBAB+0.2%甲硫氨酸促进性能平衡优良，捕集的CO₂浓度达到80.21%，且具有用量较少、可生物降解、分解无泡沫产生等优势，是最佳复配方案，可为工业化应用提供理论参考。

关键词: CO₂分离与捕集, 水合物, 动力学, 四丁基溴化铵, 氨基酸, 十二烷基三甲基氯化铵