溶胶-凝胶法制备均相掺钛干凝胶

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

以溶胶-凝胶法制备掺钛干凝胶,采用冰乙酸控制钛酸四丁酯水解,结合钛源与硅源独立预水解技术制备前体掺钛溶胶和凝胶。考察了溶剂量、抑制剂量和掺钛量对溶胶稳定性和均匀性的影响,以及老化、干燥条件和掺钛量对凝胶均匀性的影响,并优化了工艺参数。结果表明,冰乙酸能够有效地控制钛源水解并改善溶胶均匀性,结合钛源和硅源独立预水解技术,能够可控地制备出掺钛溶胶。在乙醇与醇盐物质的量比为5、冰乙酸与钛酸四丁酯物质的量比为6、钛硅原子数比为2%~20%的条件下可以得到均匀、稳定的溶胶。钛硅原子数比低于10%的溶胶在100℃老化24h,100℃开放条件下干燥24h能够形成均匀的干凝胶。钛硅原子数比高于10%的凝胶在干燥过程中析出氯化钠,得不到均匀的凝胶。

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 influ- ences of aging and drying conditions and titanium concentration on the quality of gels were investigated. Besides, optimized condi- tions 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 24 h 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.