MFI纳米片沉积层气相转化制备超薄b轴取向沸石膜

利用乙二胺-水蒸汽进行气相转化(VPT)制备超薄、取向MFI沸石膜，通过将MFI纳米片沉积层转化为致密的沸石膜，实现了膜厚度的有效控制。扫描电子显微镜和X射线衍射表明，制备的沸石膜膜厚度约为280 nm，具有高度b轴取向的致密结构。丁烷异构体双组分分离测试结果表明，在333 K下，等物质的量的正丁烷/异丁烷混合物的正丁烷渗透速率和分离因子分别为1.5×10^-7 mol·m^-2·s^-1·Pa^-1和14.8。Na₂SiO₃作为低聚硅源在MFI沸石纳米片二次生长过程中能够提供硅源和碱度，通过在胺类蒸汽中实现MFI沸石纳米片间的融合生长，进一步提高了膜的取向度和致密性。

Vapor-phase transport of MFI nanosheets for the fabrication of ultrathin b-axis oriented zeolite membranes

Ultra-thin and b-axis oriented MFI zeolite membranes were fabricated by a vapor phase transport (VPT) method using ethylenediamine-water vapor. The membrane thickness was rationally controlled by converting a deposit layer of MFI nanosheets into a dense zeolite membrane. Scanning electron microscope and X-ray diffraction results revealed that the prepared membrane had a thickness of about 280 nm with a highly b-axis oriented dense structure. The binary gas separation test of butane isomers showed that a permeation rate of n-butane of 1.5×10^-7 mol·m^-2·s^-1·Pa^-1 at a separation factor of 14.8 could be achieved for an equimolar n-butane/iso-butane mixtures at 333 K. Na₂SiO₃, serving as a source of silica and alkalinity, played a crucial role in the secondary growth of MFI zeolite nanosheets. Na₂SiO₃ facilitated the fusion growth among the MFI zeolite nanosheets in the presence of amine vapor, which improved the orientation and compactness of the membranes.