Preparation of titanium uniformly doped dried gel by sol-gel method

To fabricate well distributed dried gel precursor of titanium doped hollow glass microspheres (HGMs) by sol-gel method, titanium source and silicon source were pre-hydrolyzed separately and acetic acid was applied to control the hydrolysis of tetrabutyl titanate (TBOT). Effects of content of solvent, inhibitor and titanium on the stability and uniformity of sol and influences of aging and drying conditions and titanium concentration on the quality of gels were investigated. Besides, optimized conditions were obtained. Results show that acetic acid can control the hydrolysis of TBOT effectively and improve the stability of sol. With titanium source and silicon source pre-hydrolyzed separately, titanium doped sol precursors can be prepared under control. Stable and uniform sol can be obtained with mole ratio of anhydrous ethanol to alkoxides at 5, acetic acid to TBOT at 6 and atom ratio of Ti to Si (N (Ti)/N (Si)) from 2% to 20%. Sols with N (Ti)/ N (Si) less than 10% age at 100 ℃ for 24h and dry at 100 ℃ in open circumstance for 24 h convert to uniform gels. Sodium chloride separates from gels with N (Ti)/ N (Si) more than 10% during drying process, which reduces the uniformity of gels.