کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1526144 | 995367 | 2009 | 6 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Effect of the Si/Zr molar ratio on the synthesis of Zr-based mesoporous molecular sieves
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
مواد الکترونیکی، نوری و مغناطیسی
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Effect of the Si/Zr molar ratio on the synthesis of Zr-based mesoporous molecular sieves Effect of the Si/Zr molar ratio on the synthesis of Zr-based mesoporous molecular sieves](/preview/png/1526144.png)
چکیده انگلیسی
Highly ordered Zr-based mesoporous molecular sieves were synthesized via a surfactant-templated method and the effect of the Si/Zr molar ratio on the crystalline structure, textural properties and surface acidity were studied by XRD, FTIR, TEM and 29Si MAS-NMR techniques. FTIR spectra show that the intensity of the band around 890 cmâ1 which corresponds to the vibration of Si-O-Zr bond was increased with increasing of the zirconium content, therefore, this band may be used as an indicator of the degree of the zirconium incorporation into the Si-framework. When the zirconium content increased in the materials, the Q3/Q4 value obtained from 29Si MAS-NMR was linearly increased, whereas, the intensity the XRD peaks was gradually reduced; as a result, the pore wall thickness of the resultant materials was gradually increased, the surface area and the structural regularity were diminished. In order to obtain Zr-MCM-41 with highly ordered mesostructure and large surface area, proper Si/Zr molar ratio is a key factor, e.g., Si/Zr should be no less than 10. It was also found that the Brønsted acid sites which resulted from charge unbalance or local structure deformation due to the Zr4+ incorporation into the vicinity of the hydroxyls carrying silicon were created on the surface of the Zr-MCM-41 solids; strong Brønsted acidity could be formed on the solid with high zirconium content.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Materials Chemistry and Physics - Volume 114, Issue 1, 15 March 2009, Pages 139-144
Journal: Materials Chemistry and Physics - Volume 114, Issue 1, 15 March 2009, Pages 139-144
نویسندگان
P. Salas, J.A. Wang, H. Armendariz, C. Angeles-Chavez, L.F. Chen,