钛硅材料中钛的配位结构与催化活性关系

为探讨钛硅原子配位结构与催化氧化活性的关系，合成了多种不同结构的钛硅材料，采用氮气低温吸附-脱附、紫外-可见光谱（UV-Vis）、紫外-拉曼光谱（UV-Raman）和红外光谱等方法分析了钛硅材料的结构和Ti-Si配位状态，分别考察了在有机过氧化物、过氧化氢参与反应中的催化活性，并建立了初步关联。结果表明，TS-1分子筛中钛原子以四角四配位钛Ti(OSi)4]和锐钛矿型TiO2为主，Ti-MCM-41和Ti-SBA-15中钛物种以三角四配位钛Ti(OH)(OSi)3]为主，无定形TiO2-SiO2中五配位/六配位钛物种占优；钛原子催化活化过氧化氢和有机过氧化物的能力与其配位状态密切相关，四角四配位钛原子在有机过氧化物和过氧化氢参与的氧化反应中均具有较好的催化活性；三角四配位、五配位和六配位钛物种在有机过氧化物参与的反应中表现出优异的催化活性，但难以活化过氧化氢，这可能与分子筛的亲水特性有关。

Relationship Between Ti-Si Coordination and Catalytic Activity for Titanosilicates#br#

For titanosilicates, to better understand the relation between Ti Si coordination and catalytic activity, various titanosilicates were synthesized and their catalytic activities were investigated through epoxidation reactions with using H2O2 and organic peroxide as oxidants. Characterization results of UV Vis, UV Raman indicate that the coordination states of titanium in TS 1 are mainly as ［Ti(OSi)4］ and anatase TiO2. For Ti MCM 41 and Ti SBA 15, their main structure is Ti(OH)(OSi)3; however, amorphous TiO2 SiO2 is dominated in ［Ti(OSi)3OH)(H2O)］ and ［Ti(OSi)2(OH)2(H2O)2］. It was also found that the catalytic activity of Ti atoms in H2O2 and organic peroxide participated reactions is closely related with the Ti Si coordination. Both of H2O2 and organic peroxide could be activated by ［Ti(OSi)4］, however, only organic peroxide could be activated by ［Ti(OH)(OSi)3］, ［Ti(OSi)3OH)(H2O)］ and ［Ti(OSi)2(OH)2(H2O)2］. This may be attributed to the -OH in their structure which can be combined with water and prevent them from binding with substrates， and thus difficult to deliver oxygen atoms from H2O2.