MFI沸石纳米片及b轴取向MFI沸石薄膜的制备

Preparation of MFI Zeolite Nanosheets and b-Oriented MFI Zeolite Film

我们通过自下而上(bottom-up)的方法制备了高宽深比、高结晶度的b轴方向上超薄的MFI沸石纳米片,为制备b轴取向MFI沸石薄膜提供了基础。采用滑动涂覆法(slip coating method)在玻璃片载体上制备了厚度约为100 nm的b轴取向MFI纳米片晶种层。采用无模板剂二次生长法,抑制晶种层面外孪晶生长,实现了晶种层的面内外延生长。在合成体系的nSiO_(2)∶nNa_(2)O∶nC_(2)H_(5)OH∶nH_(2)O=1∶0.03∶1.3∶0.89、晶化时间48 h、晶化温度180℃时,制备了厚度约为200 nm的连续致密的b轴取向MFI沸石膜,与基于四丙基氢氧化铵(TPAOH)的常规合成溶液水热二次生长制备的MFI沸石膜相比,厚度降低了90%,并且保持了晶种层的b轴取向性。

Herein,the bottom-up method was utilized for the synthesis of MFI nanosheet with a high aspect ratio and crystallinity by using homemade dC5(bis^(-1),5(tripropyl ammonium).b-Oriented MFI nanosheets seed layer was coated on glass supports by slip coating method with an average thickness of about 100 nm.The SDA(structuredirecting agent)free secondary growth of the MFI nanosheet layer was conducted to effectively seal the interlayer and nanoscale gap among the nanosheet layer.The SDA-free secondary growth effectively preserves the b-orientation of the MFI film while maintaining the minimal thickness.A continuous and dense b-oriented MFI zeolite film with a thickness of about 200 nm was prepared under nSiO_(2)∶nNa_(2)O∶nC_(2)H_(5)OH∶nH_(2)O=1∶0.03∶1.3∶0.89 with a crystallization time and temperature of 48 h and 180℃,respectively.A significant decrease was observed in the thickness(approximately 90%)of the synthesized film by the SDA-free secondary growth method as compared to MFI zeolite film prepared by the conventional secondary growth method containing tetrapropylammonium hydroxide(TPAOH)as SDA that fails to preserve the desired b-orientation of the film.