多孔α-Al_2O_3载体上Silicalite-1膜的表面改性与选择性透醇分析

α-Al_2O_3 Supported Silicalite-1 Membranes: Surface Modification and Performance on Selective Permeation of Ethanol

分别使用十二烷基三甲氧基硅烷（DMS）和硬脂酸（STA）对α-Al2O3载体上二次生长合成的silicalite-1膜进行修饰,提高其表面疏水性.红外光谱和接触角测试结果表明,改性剂以化学键的形式结合于分子筛膜表面,膜表面由亲水变为疏水.表面改性的最佳预处理温度为150℃,改性剂的最佳质量分数为10％.进一步研究了膜表面润湿特性和热稳定性,其中DMS改性后的分子筛膜在空气中经250℃高温处理后仍保持疏水性不变.在乙醇/水分离应用中,高温脱除模板剂后缺陷的孔径分布在1～5nm,表面改性后乙醇分离因子较改性前提高5倍,最高可达21.6.

The silicalite-1 membrane on the α-Al2O3 substrate synthesized by the secondary growth method was modified to improve its surface hydrophobieity with dodecyltrimethoxysilane （DMS） and stearic acid （STA）. The FTIR spectroscopy and contact angle measurements revealed that modifying agents were presented at the silicalite-1 membrane surface by chemical bonding and the surface wetting property was varied from hydrophilic to hydrophobic. The optimum pretreatment temperature was 150 ℃, and the optimum mass fraction of the modifying agents was ca, 10%. Moreover, the relationship between wetting property and thermal stability was also investigated, the results showed that the modified membrane with DMS possessed good hydrophobieity below 250 ℃ in air. For the recovery of ethanol from its aqueous solution, although the defect size of the silicalite-1 membrane was ranged from 1 nm to 5 nm, the separation factor of the modified membrane was up to 21.6 which is five times higher that without surface modification.