【摘要】 以有机金属二氯二茂钛为钛源,六方介孔二氧化硅分子筛(HMS)为载体,采用嫁接法合成了含钛量(mol)分别为2.8%、3.8%和4.8%的Ti-HMS,HMS合成原料组成中H2O/EtOH(v/v)分别为0.5、1、2、5、9。合成材料用X射线粉末衍射(XRD)、N2吸附-脱附等温线、漫反射紫外可见光谱(UV-VIS)进行了表征,并考察了它们以叔丁基过氧化物(TBHP)为氧化剂在对叔丁基甲苯液相氧化中的催化性能。结果表明,表面钛嫁接后的HMS介孔结构有所损失,比表面积和孔体积减少。载体HMS合成原料中的H2O/EtOH(v/v)影响介孔织构和钛的配位环境。UV-VIS资料表明,H2O/EtOH(v/v)=0.5和9时不利于钛着床于分子筛骨架,H2O/EtOH(v/v)=1、2和5的HMS适合作为嫁接钛的载体。催化剂的活性主要受四配位Ti、介孔织构的影响。钛嫁接的HMS在氧化反应中表现出较好的催化活性,载钛量为4.8%Ti、H2O/EtOH(v/v)=1的Ti-HMS显示最好催化活性,对叔丁基甲苯转化率为21.8%。更多还原

【Abstract】 Using the organometallic precursor titanocene dichloride as titanium source and hexagonal mesoporous silica(HMS) prepared with different H2O/EtOH(v/v) = 0.5,1,2,5 and 9 as supports,the Ti-HMS catalysts with loading 2.8%,3.8% and 4.8 mol% titanium content were prepared by grafting method.The catalysts prepared were characterized by powder X-ray diffraction(XRD),nitrogen adsorption-desorption isotherms,and diffuse reflectance UV visible spectroscopy(UV-VIS).The catalytic performances of Ti-HMS prepared were tested by the oxidation reaction of 4-tert-butyltoluene in the liquid phase with tert-butylhydroperoxide(TBHP) as oxidant.The results show that grafting Ti onto the surface of HMS leads to damage to the mesostructure of HMS and decrease its surface area and its pore volume.The UV-VIS spectra show that the textural mesopores of HMS and the coordination environment of Ti(IV) are influenced by H2O/EtOH(v/v),and H2O/EtOH(v/v)=0.5 and 9 do not favor Ti atom being in four-coordinated state,while H2O/EtOH(v/v)=1,2 and 5 afford higher amount of isolated Ti(IV) framework sites.The catalytic activity of Ti-HMS depends on the amount of tetrahedral-coordinated Ti atoms and the textural mesopores of HMS.The grafted-Ti HMS samples exhibit high activities in the oxidation reactions,and Ti-HMS with loading 4.8% Ti and H2O/EtOH(v/v)=1 gives a maximum 4-tert-butyltoluene conversion of 21.8%.更多还原