Langmuir-Blodgett法制备高度b-轴取向TS-1分子筛膜

Fabrication of Highly b-Oriented TS-1 Film via Langmuir-Blodgett Technique

采用水热合成法,通过调节合成液配比,合成出粒径均一且形貌规则的TS-1分子筛晶粒;选择粒径为1.2μm×0.9μm×0.4μm的棺状TS-1分子筛晶粒作为晶种,利用Langmuir–Blodgett(LB)技术,在不锈钢载体表面组装得到厘米尺度排列紧密且呈高度b-轴取向的TS-1分子筛晶种层;分别采用合成液加入碳酸铵法和合成液预晶化法,抑制二次生长过程中孪晶的生成,获得取向的TS-1分子筛膜。结果表明:采用合成液加入碳酸铵法,不能制备高度b-轴取向的TS-1分子筛膜;采用合成液预晶化法,在170℃生长6 h即可制备连续致密且高度b-轴取向的TS-1分子筛膜,其b-轴晶体优先取向值(CPO(0k0))高达0.884,且紫外漫反射光谱结果证实所得TS-1分子筛膜具有较高的骨架钛含量。因此,利用LB法可制备骨架钛含量高、连续致密且高度b-轴取向的TS-1分子筛膜。

TS-1 crystals with different sizes were synthesized via adjusting the molar composition of synthesis gels. The coffin shaped TS-1 crystals with a size of 1.2μm×0.9μm×0.4μm were selected as seeds. A compact and highly b-oriented TS-1 zeolite monolayer was then fabricated on stainless steel substrate by the Langmuir-Blodgett method. Finally, highly b-oriented TS-1 films were obtained after the secondary growth of the oriented seeds layer via inhibiting a-oriented twin crystals formation. The experimental results show that the addition of ammonium carbonate into the synthesis gel is not a suitable way for the preparation of TS-1 films. However, a precursor pretreatment method is more effective approach of preparing defect-free and highly b-oriented TS-1 film. The crystal preferred orientation CPO（0k0） value of TS-1 film prepared at 170 ℃ for 6 h is 0.884. Ultraviolet-visible spectra show that the TS-1 film has a great skeleton titanium content. It is indicated that the Langmuir-Blodgett method is an effective method for preparing compact and highly b-oriented TS-1 films with a great skeleton titanium content.