SiO2表面吸附层中钛酸丁酯的反应过程

研究了硅胶表面富含水吸附层中钛酸丁酯的反应过程.在不同条件的吸附相反应制备中,首先利用分光光度计测定了乙醇体相中Ti含量随反应进行的变化过程.结果表明由于吸附层中钛酸丁酯的快速水解,乙醇体相中的Ti含量在反应前60 min快速减少.钛酸丁酯与硅胶表面羟基、化学吸附层和物理吸附层中的水分子的反应活性均不相同,这导致了Ti含量曲线的不同变化.EDAX的分析结果表明温度对乙醇体相中钛酸丁酯的反应过程影响很小,但对吸附相反应有着较为复杂的影响,Ti含量和TiO2形貌都随着温度升高出现了两类变化.本文提出了温度对化学吸附和物理吸附的不同影响来解释样品中Ti含量和TiO2形貌的不同变化.

Reaction of Tetrabutyl Titanate in the Adsorption Layer on SiO2 Surface

Reaction of tetrabutyl titanate (Ti(OBu)_4) which happened in a water-rich adsorption layer on the silica surface was studied. The change of Ti content in the alcohol bulk during reaction process of Ti(OBu)_4 was measured by spectrophotometry. The results suggested that the sharp decrease of Ti content in the first 60 min of reaction time was due to quick hydrolysis of Ti(0Bu)4 in the adsorption layer. The different reaction activity of Ti(OBu)_4 with hydroxyl group and water molecule in two kinds of the adsorption layer caused various change in Ti content curves. The EDAX results indicated that increase of temperature influenced little on reaction of Ti(OBu)_4 in the alcohol bulk, whereas, the influence of temperature on the preparation process of adsorption phase synthesis was complicated. Both the changes of Ti content and morphology of TiO_2 had two kinds of features with temperature increasing. And these different changes were explained by various effects of temperature on chemical-adsorption and physical-adsorption.