十七氟癸基修饰的有机-无机杂化二氧化硅膜材料的制备及气体分离性能

以十七氟癸基三乙氧基硅烷(PFDTES)和1,2-双(三乙氧基硅基)乙烷(BTESE)为前驱体, 通过溶胶-凝胶法制备了十七氟癸基修饰的SiO2溶胶, 采用浸渍提拉法在γ-Al2O3/α-Al2O3多孔陶瓷支撑体上涂膜, 然后在N2气氛保护下烧结成完整无缺陷的有机-无机杂化SiO2膜. 利用扫描电子显微镜对膜材料的形貌进行观察, 通过动态光散射技术对溶胶粒径及分布进行测试, 利用视频光学接触角测量仪、 红外光谱仪和热分析仪表征了十七氟癸基修饰对有机-无机杂化SiO2膜疏水性的影响. 结果表明, 十七氟癸基已经成功修饰到SiO2膜材料中, 且随着PFDTES加入量的增大, 溶胶粒径和膜材料对水的接触角不断增大. 当n(PFDTES): n(BTESE)=0.25: 1时, 溶胶粒径分布较窄, 平均粒径为3.69 nm, 膜材料对水的接触角为(112.0±0.4)º. 在修饰后的有机-无机杂化SiO2膜中H2的输运遵循微孔扩散机理, 在300℃时, H2的渗透率达到5.99×10-7 mol·m-2·Pa-1·s-1, H2/CO和H2/CO2的理想分离系数分别达到9.54和5.20, 均高于Knudsen扩散的理想分离因子, 表明膜材料具有良好的分子筛分效应.

Preparation and Gas Separation of Organic-inorganic Hybrid Silica Membranes Modified by Perfluorodecyl Group

Hydrophobic organic-inorganic hybrid silica sols were prepared using 1,2-bis(triethoxysilyl)ethane(BTESE) and 1H,1H,2H,2H-perfluorodecyltriethoxysilane(PFDTES) as precursors under acidic condition, then the sols were deposited on γ-Al2O3/α-Al2O3 substrates by dip-coating under clean room condition. The cross-sectional morphology, particle size of the sols and hydrophobic property of the membranes were characterized by means of SEM, DLS, FTIR, water contact angle measurement and thermogravimetric analysis. The results show that the particle size of sols and the water contact angle of supported membranes increase with increasing the amount of PFDTES in the mixture. A narrow sol particle size distribution centered at 3.69 nm and a water contact angle of (112.0±0.4)º were obtained at a BTESE/PFDTES molar ratio of 0.25: 1. At 300℃, the membrane shows a high H2 permeance of 5.99×10-7 mol·m-2·Pa-1·s-1 and a H2/CO and H2/CO2 permselectivity of 9.54 and 5.20, respectively, which were higher than the corresponding Knudsen value(H2/CO=3.74, H2/CO2=4.69). The H2 transport in the modified silica membranes is subjected to a micropore diffusion mechanism.