Synthesis and characterization of (h 0 h)-oriented silicalite-1 films on α-Al2O3 substrates

✍ Scribed by Lin Lang; Xiufeng Liu; Baoquan Zhang

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 894 KB
• Volume: 254
• Category: Article
• ISSN: 0169-4332
• DOI: 10.1016/j.apsusc.2007.09.031

✦ Synopsis

A simple and well-designed synthesis procedure is proposed to fabricate silicalite-1 films on porous a-Al 2 O 3 substrates on purpose of preventing the aluminum leaching. The continuous and 2 mm thick seed layer of silicalite-1 crystals is fabricated by using a spin coater. The firsttime seeded growth is performed to synthesize a thin layer of intergrown ZSM-5 crystals on the silicalite-1 seed layer, where the use of low alkalinity and short synthesis time is to reduce the aluminum leaching. The intergrown layer of ZSM-5 crystals serves as a barrier to block the aluminum leaching from porous a-Al 2 O 3 substrates in the second-time seeded growth, leading to the formation of ca. 11 mm thick intergrown and oriented silicalite-1 films with an extremely high Si/Al ratio. According to SEM images and XRD measurements, the as-synthesized silicalite-1 film is dense, continuous, and (1 0 1)-oriented. The electron probe microanalysis (EPMA) of the resulting film demonstrates that there is no aluminum leaching in the second-time seeded growth. The leaking tests confirm that non-zeolitic pores in the silicalite-1 film are negligible.