کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1483607 | 1510539 | 2007 | 10 صفحه PDF | دانلود رایگان |

The development of the structure of silica/alumina gels was investigated by small angle X-ray scattering (SAXS) through all stages of the preparation process, that is gelation, aging, drying and calcination. Two series of gels were compared; the first was prepared from a single-source precursor, obtained by reaction of 3-oxoethyl-6-trimethoxysilyl-hexan-2-one (OTH-H) with Al(OsBu)3. The gels of the second series were prepared from the same precursors, but under conditions where hydrodeacylation of OTH-H occurs. It turned out that both series showed a similar structural development of the gels. Immediately after the start of the reaction small primary particles are formed, the size of which (r = 0.7 ± 0.1 nm) remains constant through the gelation and aging process. In some samples, Si(OEt)4 was added as an additional source for Si/O which was incorporated between the primary particles. Condensation proceeds by a slower aggregation of the primary particles, which initially form a rather open network. This network densifies during aging and drying.
Journal: Journal of Non-Crystalline Solids - Volume 353, Issues 16–17, 1 June 2007, Pages 1635–1644