A Comparison of the Structure of a-SiO2 Prepared by Different Routes
Three different silica samples, Heraeus Suprasil I, silica prepared from colloidal silica gel and silica produced by hydrolysis were investigated using Magic Angle Spinning (MAS) 29Si and 1H NMR. Silica produced via the two low temperature routes contained a significant number of Si-OH linkages giving rise to Si03 (OH) and SiO2(OH)2 as well as Si04 tetrahedra. After heating to 950°C for the hydrolysis prepared sample and 1200°C for the sol-gel material most of the OH was removed and the silicon environment becomes similar to that in melt formed material.
KeywordsHydrolysis Zeolite Shrinkage Convolution Thermogravimetric Analysis
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