α-Al_2O_3载体上b-轴取向MFI分子筛膜的制备

b-Oriented MFI Membrane Prepared on α-Al_2O_3

在α-Al2O3支撑的PVA表面手工组装紧密排列的b-轴取向silicalite-1分子筛晶体层,煅烧除去高聚物层后可得到很好的晶种层。采用两步法二次合成工艺,在多孔氧化铝载体表面可直接合成完备的b-轴取向MFI型分子筛膜。n(TEOS)∶n(TPAOH)∶n(H2O)为1.0∶0.2∶200.0的合成液经150℃预加热处理可有效减少二次生长过程中α-轴孪晶的生成,保证制备的MFI膜为很好的b-轴取向。SEM及XRD检测表明所制备膜层的完备性及b-轴取向。另外采用多层取向晶种层经过一次晶化3 h即可制备完备的b-轴取向多层MFI型分子筛膜。实现了在大孔载体上直接合成b-轴取向的MFI膜,对提高膜的应用性能有重要意义。

Closely packed b-oriented siliealite-1 were manually assembled on α-Al2 O3 supported PVA film, which can acted as good seed layer after removal of the PVA layer by calcination. Perfect b-oriented MFI membrane was synthesized by second-time seeded growth procedure. When pre-heated the precursor solution which molar ratio was n （TEOS） ： n （ TPAOH ） ： n （ HE O） = 1. O： 0. 2： 200.0, the unwanted twin- growth could be effectively inhibited. SEM and XRD detections confirmed that a continuous and crackfree b-oriented MFI film was formed, and zeolite seeds had merged with each other very well. b-oriented multi-layer silicalite-1 crystals were also used as seed layer and continuous membrane was prepared after crystallization for 3 h. The preparation of b-oriented MFI films on maeroporous support could greatly im- prove separation and/or reaction performance.