期刊
ADVANCED POWDER TECHNOLOGY
卷 12, 期 3, 页码 331-342出版社
VSP BV
DOI: 10.1163/156855201750537884
关键词
silica gel; rehydroxylation; siloxane; surface hydroxyl group
The rehydroxylation reaction of siloxane bridges was studied for silica gel particles dehydrated by preheating. Adsorption isotherms of water vapor at 298 K were measured for the samples which were preheated at different temperatures. The amounts of total adsorption and irreversible adsorption were examined against the preheating temperature and vapor pressure. The number of the hydroxyl groups produced by the rehydroxylation of siloxane was measured by thermogravimetric analysis to determine the adsorption isotherms for chemisorption of water. For the surface preheated at 673 K, the siloxane bridges were fully rehydroxylated for about 3 h at a relative pressure of 0.3. The surface preheated at 873 K was gradually rehydroxylated with increasing pressure and the rehydroxylation was not complete even for 90 h at a relative pressure lower than 0.7. In the high-pressure region, the rehydroxylation was promoted by condensed water, The number of surface hydroxyls after rehydroxylation became greater than that on the original surface. The possibility of the generation of the geminal hydroxyls was suggested from the degree of rehydroxylation on the surface.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据