含Ti介孔氧化铝分子筛的合成与表征

Synthesis and Characterization of Ti-Containing Mesoporous Alumina Molecular Sieves

采用烷氧基金属作铝源、钛源,Triton X-100作模板,于室温合成了具有MSU-2结构的含Ti介孔氧化铝分子筛,并用XRD、TEM、N2-吸附和UV-vis DRS对其结构和Ti物种的形态进行了表征.研究结果表明,Ti对氧化铝骨架有稳定作用,引入Ti后,样品的表面积和孔容增加.研究还表明,当wTi/WAl≤6％时,Ti以孤立的单核物种存在于氧化铝骨架.随Ti含量增加,Ti物种聚集为氧化物簇.与TiO2-Al2O3复合氧化物相比。该氧化物簇在介孔孔壁中更难长大,故当Ti含量较高时,Ti氧化物簇迁移至孔壁表面,造成孔道部分堵塞.但直至wTi/wAl=33％,未见明显的TiO2晶相出现,表明介孔氧化铝分子筛中Ti物种具有较高的分散度.

Ti-containing mesoporous alumina molecular sieves with a structure of MSU-2 have been synthesized using metal alkoxides as titanium and aluminum sources and Triton X-100 as templating surfactant, respectively. The structure of the products and the state of Ti species were characterized with XRD, TEM, N2-absorption and UV-vis DRS. It was found that the surface area and pore volume of sample increase when Ti were incorporated, suggesting an effect of Ti on stabilizing the alumina framework. It was also shown that Ti existed in the framework as an isolated mononulear species at Ti/A1<6% . As Ti content increased, polymerized Ti species and even TiO2 domainsive formed. But these domains grew so difficultly within mesoporous walls that they grafted to the surface of alumina walls at a high Ti content level, leading to some degree of pore blocking. However, up to Ti/Al= 33% , no well-defined bulk TiO2 were found,meaning that Ti species might be dispersed better in mesoporous alumina than in TiO2-Al2O3 complex.