Impacts of Binder-Zeolite Interactions on the Structure and Surface Properties of NaY鈥揝iO2 Extrudates

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• 作者：Nan-Yu Chen ; Ming-Chun Liu ; Shih-Chieh Yang ; Hwo-Shuen Sheu ; Jen-Ray Chang
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2015
• 出版时间：September 2, 2015
• 年：2015
• 卷：54
• 期：34
• 页码：8456-8468
• 全文大小：743K
• ISSN：1520-5045

文摘

NaY鈥揝iO₂ extrudate was prepared by blending NaY powder with silica gel, followed with kneading, extruding, and calcination. The impact of silica binder on the structure and surface properties of NaY鈥揝iO₂ extrudate was investigated. The nitrogen adsorption/desorption isotherm suggests the formation of cylindrical mesopores for NaY鈥揝iO₂. X-ray powder diffraction, transmission electron microscopy, and Fourier transform infrared suggest that in kneading, dealumination and cleavage of the intracrystalline Si鈥揙鈥揂l bond via acid hydrolysis occur. This acid hydrolysis causes shrinkage of the zeolite lattice along the zeolite channel due to dislodgement of Al³⁺ cations. The dealumination increases the silica/alumina ratio of NaY concomitantly with the removal of Na⁺, leading to an increase in the hydrophobicity of NaY, while reaction of the silica binder with NaY debris and/or aluminum residue forms new Br酶nsted acid sites. Moreover, backfilling the vacancies created in the dealumination by mobile Si(OH)₄ makes the zeolite more thermally stable, which lends the extrudate itself to industrial applications.