多步组装合成介孔二氧化硅担载膜

采用浸渍法和表面改性多步组装合成技术在商业用多孔氧化铝管上制备介孔二氧化硅担载膜。所制备的介孔二氧化硅膜层的厚度平均为2μm,平均孔径为1.59nm。单一气体的渗透实验表明:气体通过介孔二氧化硅膜层符合Knudsen扩散模型,在298K和100kPa的恒定条件下,氦气和氮气的渗透量分别为15.6×10-6mol/(s·m2·Pa)和2.5×10-6mol/(s·m2·Pa)。渗透蒸发实验表明:经六甲基二硅氮烷表面改性的二氧化硅膜层在303K和313K下分别对含3%(质量分数,下同)和5%乙醇的水溶液进行乙醇组分的提浓,乙醇的分离系数和渗透通量分别为15.2～18.7和1.09～1.25kg/(m2·h)。

PREPARATION OF MESOPOROUS SILICA MEMBRANES BY MULTISTAGE ASSEMBLY SYNTHESIS

A multi-layer silica membrane supported on a commercially available porous alumina tube was prepared by a new method of dip-coating and surface modification multistage assembly synthesis. The separation layer of the silica membrane has an average thickness of 2 μm and a mean pore diameter of 1.59 nm. The single gas permeation for the silica membranes exhibits Knudsen-type permeation mechanism, and the permeating flows of helium and nitrogen gas are 15.6 × 10~(-6 ) mol/(s·m~2·Pa) and 2.5 × 10~(-6) mol/(s·m~2·Pa) at 100 kPa and 298 K, respectively. The pervaporation experiment shows that the mesoporous silica membrane modified by hexamethyldisilazane can effectively concentrate ethanol from 3% (mass fraction, the same below) to 5% ethanol-water binary feeds by pervaporation. The separation factors of ethanol and the total permeate fluxes at 303 K and 313 K are from 15.2 to 18.7 and from 1.09 to 1.25 kg/(m~2·h), respectively.