کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
77386 49165 2006 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Understanding the differences between microporous and mesoporous synthesis through the phase behavior of silica
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی کاتالیزور
پیش نمایش صفحه اول مقاله
Understanding the differences between microporous and mesoporous synthesis through the phase behavior of silica
چکیده انگلیسی

The link between M41S mesoporous silicates and all-silica zeolites during the initial stages of synthesis is analyzed with small-angle scattering and conductivity experiments. The phase behavior of silica in aqueous solutions is studied for a family of quaternary ammonium hydroxides, from tetramethylammonium to dodecyltrimethylammonium. All solutions exhibit a critical aggregation concentration at a 1:1 SiO2:[OH−]initial molar ratio with solutions containing short chain compounds forming optically transparent (clear) nanoparticle suspensions, and solutions of long chain compounds phase separating into a solid and a liquid phase. The solid phase is analyzed with X-ray diffraction and thermogravimetric analysis and is found to have a hexagonal structure similar to MCM-41. Mid-sized chain length compounds form solutions containing both the phase separated solid and nanoparticles. In addition to studying phase behavior, the role of attractive hydrophobic interactions is studied using water/ethanol solutions. In ethanolic solutions, the entire family of quarternary ammonium compounds are found to form stable nanoparticle suspensions.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Microporous and Mesoporous Materials - Volume 90, Issues 1–3, 20 March 2006, Pages 102–111
نویسندگان
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