PEGDME强化PVDF/PP复合膜的CO_2分离性能

Improving CO_2 separation performance of PEGDME-PVDF/PP composite membrane

膜分离技术具有投资小、设备简单等优点,目前广泛应用于CO2分离等方面,膜材料是膜分离技术的核心。研究表明,聚合物中醚氧基团的存在可有效提高膜对CO2的渗透速率和选择系数。聚乙二醇二甲醚(PEGDME)结构中含有丰富的醚氧基团,同时端基空间位阻提供了较高的CO2扩散系数。本文以液态PEGDME为添加剂,聚偏氟乙烯(PVDF)为共混膜材料,利用聚丙烯(PP)多孔膜为支撑,通过溶剂蒸发法制备出具有良好分离性能的PEGDME-PVDF/PP共混复合膜。结果显示,随着PEGDME含量的升高,复合膜对CO2的渗透速率和CO2/N2选择系数均呈上升趋势,当PEGDME共混含量达到50%时,CO2的渗透速率为42.9GPU,CO2/N2选择性为47.5;随着PVDF浓度的增加,CO2的渗透速率呈下降趋势,CO2/N2的选择系数则缓慢上升;适当降低溶剂蒸发温度,PVDF结晶度降低,有助于提高膜性能;当溶剂蒸发温度为30℃时,PEGDME-PVDF膜对CO2的渗透速率达到84.7GPU,CO2/N2的选择系数达到47.2。

Membrane technology is widely used in the field of CO2 separation due to its characteristics of low investment and simple equipment. The core of membrane technology is the material. According to research,the existence of ethylene oxide （EO） in polymer can effectively improve CO2 permeability and selectivity. Polyethylene glycol dimethyl ether （PEGDME）,a promising material for CO2 separation,is rich of EO units,and its methyl end groups provide higher CO2 diffusivity. The polyethylene glycol dimethyl ether （PEGDME） was proposed to blend with PVDF as a selective layer for CO2 in this study,and the PEGDME-PVDF blend selective layer was fabricated on a porous support layer of polypropylene （PP） by solvent evaporation method to manufacture PEGDME-PVDF/PP composite membranes for CO2 separation. With the increase of PEGDME content in the blend membrane,both CO2 permeability and CO2/N2 selectivity tend to rise. When the content of PEGDME reached 50wt%,CO2 permeability was 42.9GPU and CO2/N2 selectivity was 47.5. With the increase of PVDF concentration,CO2 permeability tended to decrease while CO2/N2 selectivity increased slowly. With the decrease of solvent evaporation temperature,PVDF crystallization decreased accordingly,and better membrane performance can be obtained. At solvent temperature of 30℃,the PEGDME-PVDF blend membrane performed excellently with CO2 permeation rate up to 84.7GPU,and the CO2/N2 selectivity was as high as 47.2.