基于NaOH溶液CO_(2)膜吸收系统的膜结构及传质性能

Structure and mass transfer characteristics of membrane system for absorption of CO_(2) in NaOH solution

碳捕集与利用技术是实现减碳目标的有效方案。膜系统气体吸收技术能够实现CO_(2)以HCO_(3)^(-)、CO^(2-)_(3)形式存储在无机碱性吸收剂中,并还原成甲醇、乙醇等清洁燃料。本文采用膜单侧浸泡实验法和传质实验,分别考察了疏水性微孔滤膜聚四氟乙烯(PTFE)膜、聚偏氟乙烯(PVDF)膜、聚丙烯(PP)膜在NaOH碱性溶液中的结构和CO_(2)传质特性的变化。结果表明,PTFE膜和PP膜在NaOH碱性溶液中溶胀率上升,孔径减小,孔隙率下降,疏水性下降,传质系数下降;PVDF膜在NaOH溶液中会发生反应,结构被破坏,传质系数接近无膜吸收,但无法起到相界面的作用,不能直接用于以NaOH为吸收剂的膜吸收系统。

Carbon capture and utilization is an effective way to achieve the carbon reduction target.Gas absorption by alkaline solution on membrane can store CO_(2) in the form of HCO_(3)^(-) and CO^(2-)_(3),and the solution can be further used to convert the absorbed CO_(2) into clean fuels.The structure and mass transfer characteristics of PTFE,PVDF,PP membranes in the membrane absorption of CO_(2) by NaOH solution were investigated by single-sided membrane immersion and mass transfer experiments.The results showed that the swelling rates of PTFE and PP membranes in NaOH solution increased,and their pore size,porosity,hydrophobicity and mass transfer coefficient decreased.The mass transfer coefficient of PVDF membrane system was close to that of absorption without membrane,which could be attributed to the reaction between the membrane and NaOH solution,causing the structure damage and inability to function as the phase-interface.