TiO2在MCM-41内表面单层及双层分散的结构表征

首次以有机物钛酸丁酯为前驱体，合成了ＴiO2呈单层分散状态（Ｔi/Si=0．２０）或双层分散状态（Ｔi/Si=0．39)的介孔分子筛ＭＣＭ－４１（Si/Al=35），并以ＸＲＤ，ＦＴＩＲ，Ｎ２吸附－脱附，固体ＵＶ－vis漫反等表征手段对其结构特征的氧化钛分散状态进行了研究，结果表明：ＴiO2在介孔分子筛ＭＣＭ－４１孔道中分散，ＭＣＭ－４１骨架结构结晶度降低，但是附着二层ＴiO2后，仍能保持长程有序结构；ＴiO2与ＭＣＭ－４１骨架结构结果度降低低，但是附着二层ＴiO2后，仍能保持长程有序结构，ＴiO2与ＭＣＭ－４１孔道表面的ＳiO2比化学键连接，生成Ｓi-O-Ti键；无论是单层还是双层分散的ＴiO2在ＭＣＭ－４１内孔壁均匀分散，且由于ＴiO2粒子的减小使其对紫外光的吸收发生明显的蓝移现象。.

Preperation and Characterization of Monolayered or Two-layered Titania Modified Mesoporous Molecular Sieves MCM-41

Two kinds of titania modified the inner surface of mesoporous slilcate MCM-41 (MCM-TiO₂ and MCM-Ti-TiO₂) were synthesized by precursor tetrabutyltitanate and calcined MCM-41. The samples were characterized by XRD, FTIR, nitrogen adsorption/desorption at 77K and solid state diffuse reflectance UV-vis spectroscopy. XRD suggested that a long-range a long-range order kept in the hexagonal phase of titania modified MCM-41. Tetrabutyltitanate cocondensation with the pendant OH groups of MCM-41 via Si--O--Ti bonds and titania modified the inner walls of MCM-41. Titania on the inner walls of modified MCM-41 was estimated monolayer or two-layer according to the results of nitrogen adsorption/desorption isotherms. In UV-vis spectra, titania modified MCM-41 had significant blue shift compared to bulk TiO₂ which is attributed to the well known quantum size effect for semiconductor as the particle size decreases.