NaA 沸石膜的制备及在一氯甲烷脱水中的应用

Preparation of NaA Membrane and Application on Dehydration of Chloromethane

以氢氧化钠、铝酸钠和硅溶胶为原料,利用热浸渍提拉法预涂晶种,在孔径为2～3μm的亲水性α-Al2O3载体和孔径为800nm的疏水性炭载体上制备NaA沸石膜。借助于X射线衍射和扫描电子显微镜对合成的沸石膜进行了表征,采用单组分气体渗透法对NaA沸石膜的气体渗透性能进行了检测。结果表明:当H2渗透通量相近时,在亲水性α-Al2O3载体上制备的NaA沸石膜对H2/n-C4H10的分离因数为27.6,远远高于在疏水性炭载体上制备的NaA沸石膜的分离因数。NaA沸石膜在α-Al2O3载体上的生长速率为1.0μm/h,比在炭载体上生长速率快1倍,说明亲水性α-Al2O3载体更适合作为制备致密的强亲水性NaA沸石膜的载体。将在α-Al2O3载体上制备的NaA沸石膜用于一氯甲烷脱水实验,当进料水含量为0.252%(质量分数)时,水/一氯甲烷的分离因数为7.5×104。

Zeolite NaA membranes were synthesized on a hydrophilic α-Al2O3 support of 2-3 μm aperture and the hydrophobic car- bon support of 800 nm aperture with NaOH, NaAlO2 and colloidal silica as raw materials by a hot dip-coating pulling seeding method. The as-synthesized membranes were characterized by X-ray diffraction and scanning electron microscope. The gas permeation per- formance of NaA membranes was examined via the single component gas permeation experiments. The results indicate that when H2 flux of the membranes are similar, a H2/n-C4H10 separation factor of the membranes grown on α-Al2O3 support is 27.6, which is greater than that of the membranes grown on carbon support. The growth rate of NaA membrane on the α-Al2O3 support was 1.0 μm/h, which was twice greater than that on the carbon support. This indicated that the hydrophilic α-Al2O3 support was more suitable for the preparation of compact highly-hydrophilic NaA membranes rather than the hydrophobic carbon support. The dehydration of chloro- methane with the NaA membrane grown on the α-Al2O3 support was investigated. The separation factor of 7.5 × 10^4 was obtained at a water feed concentration of 0.252% （in mass）.