摘要
以正硅酸乙酯(TEOS)和异丁基三乙氧基硅烷(iTES)为前体,通过溶胶-凝胶法在酸性条件下制备异丁基修饰的二氧化硅溶胶,并采用浸渍提拉法在γ-Al_2O_3/α-Al_2O_3支撑体上制备异丁基修饰的微孔二氧化硅膜材料.分别通过动态光散射技术、接触角测量、红外光谱、核磁共振以及N_2吸附等测试手段对溶胶的粒径分布、膜材料的疏水性能以及孔结构进行表征,并深入研究异丁基修饰膜材料的氢气渗透和分离性能.结果表明,当摩尔比n(iTES)/n(TEOS)=0.6时,溶胶的平均粒径约为5.1nm,膜材料的孔径狭窄分布在0.45~0.8nm,其对水的接触角达到(114.0±0.5)°.H2在膜材料中的渗透率随测试温度的升高而增大,300℃时达到9.07×10^(-7) mol/(m^2·s·Pa),H_2/CO_2和H_2/CO的理想分离系数分别为6.79和15.37,双组份混合气体分离系数分别为7.09和15.72,均高于对应的Knudsen扩散分离因子,H2在膜材料中的输运主要遵循活化扩散机理.在250℃水蒸气物质的量摩尔分数为5%的环境中陈化200h后,异丁基修饰的SiO_2膜具有良好的水热稳定性.
An isobutyl-modified silica sol was synthesized by the co-hydrolysis and condensation of tetraethyl orthosilicate（TEOS） and isobutyltriethoxysilane（iTES） under acidic condition and the sol was deposited on the γ-Al2O3/α-Al2O3 support by dip-coating in clean room（Grade 100）. The particle size distribution of silica sol, the hydrophobic properties and the pore size distribution of the silica membranes were characterized by means of dynamic light scattering（DLS）, water contact angle measurement, Fourier transform infrared spectroscopy（FT-IR）, solid state 29 Si magic-angle spinning nuclear magnetic resonance （29Si MAS NMR） and N2 adsorption-desorption. The hydrogen permeation and separation performance of modified silica membranes were also investigated in detail. The results show that the particle size of silica sol increases with increasing iTES/TEOS molar ratio, reaching 5.1 nm at an iTES/TEOS molar ratio of 0. 6. Isobutyl groups have been successfully incorporated into silica membranes, leading to＇an enhanced hydrophobic property with a water contact angle as high as （114. 0±0. 5）° for the modified membranes. The modified silica membranes possess a microporous structure with a pore size centered at 0. 45±0. 8 nm. The hydrogen permeance increases with increasing temperatures, indicating that the hydrogen transport in modified silica membranes complies predominantly with activated diffusion mechanism. At a temperature of 300 ℃, the modified membranes exhibit a significantly high H2 permeance of 9.07 × 10^-7 mol/（m2 · s ·Pa）, a H2/CO2 and H2/CO permseleetivity of 6. 79 and 15.37, a H2/CO2 and H2/CO binary gas mixture separation factor of 7. 09 and 15.72, respectively, both higher than that of Knudsen diffusion. Under a humid condition with a temperature of 250 ℃ and a water vapor molar ratio of 5% for at least 200 hours, the modified membranes possess an outstanding hydrothermal stability.
出处
《膜科学与技术》
CAS
CSCD
北大核心
2016年第4期46-53,共8页
Membrane Science and Technology
基金
国家自然科学基金(21171014)
北京市教委科技计划重点项目(KZ201410005006)
关键词
异丁基
有机-无机杂化微孔二氧化硅膜
孔结构
氢气分离
isobutyl groups
organic-inorganic hybrid microporous silica membranes
pore structure
hy- drogen separation
