Abstract: Monoethanolamine (MEA) aqueous solution has remarkable absorption capability for acid gas such as CO₂ and has a potential application prospect in the field of gas separation and purification. Absorption temperature, gas flow rate and MEA concentration were taken into account as influence factors on reaction rate by monitoring the variation of pH in MEA aqueous solution. A conception called specific activity describing the absorption performance of the solution was introduced. The descending rate of pH decreased, saturation time was extended and the pH of final saturation state increased with the increase of solution concentration. With increasing temperature, the descending rate of pH increased and saturation time was shortened, but both of them would maintain a relatively stable value when temperature was high enough. When gas flow rate of CO₂ increased, the pH of solution was gradually reducing at a faster rate, and finally, remained stable. The pH of saturated solution reached the lowest level at the flow rate of 70 ml·min^-1. The monitoring method was easy to operate and the result was highly accurate so that it could provide a reference for development of CO₂ absorption solutions.

Key words: CO₂, absorption, measurement, specific activity

摘要： 乙醇胺(MEA)溶液对CO₂等酸性气体具有良好的吸收效果,在气体分离与净化等领域有较好的应用前景。通过酸度计对MEA水溶液吸收CO₂过程中pH的变化进行实时监测,综合考虑了溶液浓度、原料气流量、温度对反应速率的影响,引入描述吸收性能的比催化活性概念。实验结果表明:随着溶液浓度增加,pH下降速率不断降低,饱和时间逐渐延长,饱和状态的pH不断提高;随着CO₂进气流量的增加,溶液pH下降速率逐渐提高并最终保持不变,溶液饱和时间逐渐缩短,饱和状态的pH随着流量的增加先降低后升高,在70 ml·min^-1进气流量下pH达到最低;随着溶液温度升高,pH下降速率先增加最终趋于稳定,饱和时间逐渐缩短最终趋于一致。该法操作简单,监测准确,并可以为CO₂吸收液的研发提供参考。

关键词: 二氧化碳, 吸收, 测量, 比催化活性