表面改性ZSM-5分子筛填充PDMS/PEI复合膜的气体分离性能研究

通过对ZSM-5分子筛颗粒表面改性的方法,使之与聚二甲基硅氧烷(PDMS)形成更好的接触面结构,再将其涂覆在聚醚酰亚胺(PEI)基膜上,制备了表面改性ZSM-5分子筛填充的PDMS/PEI复合膜。将复合膜用于CO2/CH4体系与O2/N2体系的气体分离研究,实验结果表明:填充经过表面改性的ZSM-5分子筛的复合膜与填充未改性分子筛的复合膜相比,改性后分子筛在聚合物中的分散更加均匀,分子筛与聚合物基体之间的联结更加紧密,这都增强了分子筛的筛分作用;填充改性后分子筛的复合膜对气体的渗透能力略有增大,改性分子筛填充量(质量分数)为20%的复合膜对两种体系的分离效果最佳,CO2/CH4体系的分离系数提升23.8%,O2/N2体系提升28.6%。

PDMS/PEI composite membranes containing surface-modified ZSM-5 for gas separation

A surface graft/coating approach has been developed to modify the surface of ZSM-5 zeolite in an attempt to improve its interaction with a polydimethylsiloxane (PDMS) matrix. The surface-modified ZSM-5 was mixed with PMDS and then cast on a prepared polyetherimide (PEI) membrane. Permeability and gas pair selectivity of the composite membranes before and after modification were measured with different zeolite loadings and under different pressures. Enhanced CO2/CH4 and O2/N2selectivities were achieved by using PDMS/PEI composite membranes containing the modified ZSM-5 zeolite. SEM images and the experimental results both confirmed that the ZSM-5 particles were homogeneously dispersed in the PDMS matrix after surface-modification and a more compact interfacial contact could be formed between them which enhanced the molecular sieving effect. The selectivity of CO2/CH4 is increased by 23.8% after modification, from 4.2 to 5.2, and selectivity of O2/N2 is increased by 28.6%, from 2.1 to 2.7.