溶胶-凝胶法甲基化改性SiO_2膜的气体渗透性和再生性研究

Gas permeance and regeneration of methyl-modified silica membranes by sol-gel method

以甲基三乙氧基硅烷替代部分正硅酸乙酯作为前驱物,用溶胶-凝胶法对亲水性SiO2膜进行改性,制备了甲基化改性SiO2膜.通过FTIR、SEM和气体渗透实验考察了甲基化改性对SiO2膜形貌、化学结构、气体渗透性及再生性的影响.结果表明,压差、温度对两种SiO2膜渗透分离性能的影响相似;甲基化改性使SiO2膜气体渗透速率显著增加,而H2/CO2选择性却没有明显下降;在水气环境中陈化后,虽然两种SiO2膜的H2/CO2选择性均未显著降低,但亲水性SiO2膜气体渗透速率下降明显,而甲基化改性SiO2膜则下降较小.再生可以部分恢复SiO2膜的渗透分离性能,与陈化前相比,再生使两种SiO2膜的渗透性能降低,H2/CO2选择性增大,甲基化改性大大减小了再生对膜渗透性能的劣化.

Methyl-modified silica membrane was prepared by acid catalysed co-hydrolysis and condensation reaction of tetraethylorthosilicate（TEOS） and methyltriethoxysilane（MTES）.The influences of methyl modification on the morphology,chemical structures,gas permeance and regeneration performance of methyl-modified silica membrane were investigated by FTIR,SEM and gas permeation experiments.It was found that the effects of pressure difference and temperature on gas permeance and H2/CO2 permselectivities in hydrophilic and methyl-modified silica membranes were similar.After methyl modification,the gas permselectivities in the SiO2 membrane had no obvious decrease in despite of the greatly increase of gas permeation rates.After aging in steam circumstances,the decrease of gas permeation rates in the hydrophilic silica membrane was far more than that in the methyl-modified silica membrane even though their H2/CO2 permselectivities both had no notable change.Regeneration could recover the permeation and separation performance of the two silica membranes to a different degree.Compared with before aging in steam,regeneration made the gas permeance of the two silica membranes decrease and the H2/CO2 permselectivities increase.Methyl modification greatly reduced the deterioration of the regeneration to the gas permeability in silica membrane.