以三氟丙基三甲氧基硅烷(TFPTMS)和正硅酸乙酯(TEOS)作为前驱体,通过溶胶-凝胶法制备三氟丙基修饰的SiO2膜材料,研究了三氟丙基修饰对膜材料孔结构和疏水性的作用、疏水膜材料的氢气渗透和分离性能以及水热稳定性能.结果表明三氟丙基修饰后的膜材料仍保持良好的微孔结构,孔径狭窄分布在0.45～0.7 nm之间.修饰后膜材料疏水性明显提高,当nTFPTMSTEOS=0.6时,对水的接触角达到(102.7°±0.1°).H2在修饰后膜材料的输运遵循微孔扩散机理,在300℃时,H2的单组份渗透率达到4.77×10-7 mol·m-2·s-1·Pa-1,H2/CO2的理想分离系数以及双组份分离系数分别达到6.99和6.93,均高于其Knudsen扩散分离因子.在200℃水蒸气物质的量含量为5％的环境中陈化220 h后,H2的单组份渗透率仅在前3h有轻微下降,然后基本保持不变,说明三氟丙基修饰的SiO2膜具有良好的水热稳定性.%Trifluoropropyl-modified silica membranes were prepared by sol-gel technique using tetraethyl orthosilicate (TEOS) and (trifluoropropyl)trimethoxysilane (TFPTMS) as precursors. The effect of trifluoropropyl modification on the hydrophobic pore structure, properties, hydrogen permeation and separation properties and long-term hydrothermal stability of the modified silica membranes were investigated in detail. The results show that the modified membranes retain a desirable microporous structure with a pore size distributed from 0.45 to 0.7 nm. The hydrophobic property of silica membranes has been considerably enhanced after modification, with a water contact angle of (102.7° ±0.1°) at a TFPTMS/TEOS molar ratio of 0.6. The hydrogen transport in the modified silica membranes complies with a micropore diffusion mechanism, with a single H2 permeance of 4.77× 10-7 mol·m-2·s-1·Pa-1, a H2/CO2 permselectivity of 6.99 and a H2/CO2 binary gas mixture separation factor of 6.93 at 300 ℃, higher than Knudsen permselectivity (4.69). Under a humid condition with a temperature of 200 ℃ and a water vapor molar ratio of 5%, the single H2 permeance slightly decrease in the first 3 hours and then almost remain constant for at least 220 hours, indicating that the modified membranes are more hydrothermally stable than pure SiO2 membranes.
展开▼
