PDMS/PVDF复合膜的制备及其对C_3H_8/N_2体系的分离

Preparation of PDMS/PVDF composite membrane and its application in C_3H_8/N_2 separation

用相转化法制得PVDF底膜,并在此底膜上用表面涂敷法涂上PDMS分离层,对复合膜进行了表征,红外结果表明,PDMS预聚物发生了交联;扫描电镜(SEM)照片结果表明,PDMS在PVDF多孔膜表面形成均匀致密的分离层.利用PDMS/PVDF复合膜对C3H8/N2体系进行分离性能测试.考察了原料组成,原料压力和实验温度对PDMS/PVDF复合膜分离性能的影响.实验结果表明:随着原料压力升高,膜对C3H8/N2的分离因子降低,通量增大;随着实验温度降低,膜对C3H8/N2的分离因子升高,通量增大.在C3H8体积分数10%,原料压力0.6 MPa,实验温度15℃时,PDMS/PVDF复合膜对C3H8的通量为2 684.6×108m3/(m2.s.Pa),分离因子αC3H8/N2=35.6.

PVDF micro - porous membrane was prepared by the phase inversion process. The PDMS/PVDF composite membrane was made by coating polydimethylsiloxane （PDMS） on polyvinylidene fluoride （PVDF） support layer. The composite membrane was characterized by FTIR spectra and SEM. The FTIR spectra show that the PDMS pre- polymer crosslinked. The SEM images reveale that the composite membrane consists of a dense thin PDMS film layer and a microporous PVDF support layer. The PDMS layer is very smooth. Permeation performances of pure and mixed nitrogen and propane were investigated using the PDMS/PVDF composite membrane prepared. The experimental results show that the permeance of propane increases significantly with the decrease of temperature and increase of feed pressure. At the feed molar fraction 10 % C3H8 in the mixture, feed pressure 0.6 MPa and temperature 15℃, the permeance of C3H8 was 2 684.6 ×10^8m^3/（m2·s·Pa） and the separation factor αC3H8/N2 = 35.6.