Langmuir-Blodgett法制备b-轴取向MFI型分子筛膜

Fabrication of b-oriented MFI Film via Langmuir-Blodgett Technique

实验利用Langmuir-Blodgett(LB)技术大面积有序组装分子筛晶粒,进而制备连续致密且高度b-轴取向MFI型分子筛膜。首先,采用LB技术在表面性质不同的不锈钢载体和铂电极载体上实现了b-轴取向MFI分子筛晶粒的高度有序组装;其次,采用合成液预处理法对LB法制备的高度b-轴取向的MFI晶种层进行二次合成。XRD和SEM表征结果显示:采用合成液预处理法可以有效抑制分子筛晶粒在二次生长过程中生成孪晶,进而获得高度b-轴取向MFI分子筛膜;最后,电化学测试结果证实采用LB技术制备的b-轴取向MFI分子筛膜致密,无缺陷。

A compact and highly b-oriented MFI-type zeolite monolayer was fabricated by assembling anisotropic zeolite micro-crystals extending over the centimeter scale by Langmuir–Blodgett（LB） method. The LB monolayer was subsequently employed as a seed layer for the secondary growth of highly b-oriented and defect-free MFI zeolite films. Firstly, LB technique was used to assemble a highly b-oriented MFI type zeolite monolayer on stainless steel substrates and platinum electrodes at an optimum target pressure of 20 m N/m constantly. Secondly, the precursor pretreatment method for preparing highly b-oriented MFI films was proved to be achievable. The crystal intergrowth and orientation of the MFI films were characterized by scanning electron microscopy（SEM） and X-ray diffraction（XRD）. The experimental results confirmed that the precursor pretreatment method was an effective route to suppress the undesired a-oriented twin growth during the secondary growth step. Finally, the highly b-oriented MFI-type zeolite film modified platinum electrodes were further tested as the working electrodes in an aqueous solution including [Fe（CN）6]3？ with a diameter of 0.72 nm. Cyclic voltammetry experimental results demonstrated that the b-oriented MFI films fabricated by the Langmuir-Blodgett method were defect-free.