摘要
采用钛酸丁酯和乙酰丙酮作用后的产物作为钛的前驱体 ,水热法一步合成出了Ti SBA 15分子筛 .通过X射线衍射、N2 气吸附脱附、紫外 -可见漫反射等表征手段 ,证明在Si Ti=5 0 ,2 5 ,2 0时 ,钛原子成功地取代了SBA 15中的硅原子而没有改变SBA 15高度有序的介孔二维六角结构 ,其中钛全部以四配位状态存在 ,而且高度分散 .当Si Ti=12 5时 ,钛的分散度降低 ,部分钛聚集生成二氧化钛 .与用两步法合成的Ti SBA 15比较 ,一步法合成的Ti SBA 15中钛分散度好 ,添加量高 ,对催化氧化环己烯有较高的催化活性 .对一步法和两步法合成Ti SBA
Titanium-substituted mesoporous molecular sieve SBA-15 have been first successfully synthesized by a new direct approach under conventional hydrothermal conditions. The products obtained by reacting titanium butoxide with acetylacetone were used as the titanium precursor. By means of X-ray diffraction, nitrogen adsorption, UV-Vis diffuse reflectance, a successful isomorphous substitution of titanium in the silica framework of SBA-15 samples with Si/Ti = 50, 25, 20 has been proved, the substitution of Ti for Si does not change the highly ordered two-dimensional hexagonal mesostructure of SBA-15. Titanium is totally tetrahedral and highly dispersed. Higher titanium loading leads to the formation of titanium dioxide. Comparing with two-step preparation method, it shows that under the direct synthesis method, or one-step preparation method, titanium and silicon precursor hydrolyze harmoniously. Ti-SBA-15 demonstrates relatively high catalytic ability on the oxidation of cyclohexene. The differences of structure and catalytic ability between Ti-SBA-15 synthesized by one-step method and two-step method are explained.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2003年第2期202-207,共6页
Acta Chimica Sinica
基金
国家杰出青年科学基金 (No.2 992 530 9)
国家教育部上海纳米科技中心 (0 1 52nm0 2 9)
国家 973重大基础研究 (G2 0 0 0 0 4 80 0 1 )资助项目
