1998 Fiscal Year Final Research Report Summary
Development of mesoporous materials by solid-liquid reactions within gel network
| Project/Area Number |
09555190
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Inorganic materials/Physical properties
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
NAKANISHI Kazuki Kyoto University, Graduate School of Engineering, Assoc.Professor, 工学研究科, 助教授 (00188989)
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| Co-Investigator(Kenkyū-buntansha) |
YANAGISAWA Kazumichi Kochi University, Faculty of Science, Associate Professor, 理学部, 助教授 (90145110)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Metal Alkoxide / Sol-Gel Transition / Phase Separation / Porous Structure / Mesopores / Chromatography / Aging Process |
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| Research Abstract |
The mesopore formation behavior in alkoxy-derived wet silica gels having co-continuous macropores has been investigated under varied conditions of aging. The starting gels were prepared via sol-gel route which include phase separation, and were aged under neutral to weakly basic conditions either by external addition or internal generation of ammonium hydroxide. The pH values of mother liquor of gels prepared in the presence of urea increased up to 10 by the thermal decomposition. Under non-hydrothemal conditions, the mesopore evolution depended only on pH values and temperatures during aging, and no substantial differences were recognized in the drying shrinkage and heat-evolution between the external and internal methods. In the additional hydrothermal aging performed with urea-containing gels, a significant acceleration of mesopore evolution rate was observed with an increase of aging temperature. At 200。C, the final size of mesopores reached 50nm with a marked decrease of their volume fraction. Above 200。C, the inner part of columnar gel skeletons eluted out and reprecipiated on their outer surface, thus resulted in the hollow columns with their walls consisting of granular building units less densely aggregated. The crystallization of the gel sample, however, was never observed possibly due to high purity of the gel samples. In contrast, the amorphous titania gels crystallized more easily under hydrothermal conditions.
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