Ti-SBA-15介孔分子筛的制备与表征

以水玻璃为硅源、TiCl3为钛源、表面活性剂P123为模板剂,采用水热合成法一步合成了Ti-SBA-15介孔分子筛,并借助XRD、低温N2吸附、TEM和UV-Vis等表征手段研究了母液酸度、n(Si)∶n(P123)、晶化温度和n(Si)∶n(Ti)等条件对Ti-SBA-15介孔分子筛结构特性的影响。实验结果表明,在适合的母液酸度、硅源含量和晶化温度下可获得高结晶度、高有序度、大比表面积和大孔体积的Ti-SBA-15介孔分子筛。晶化温度过高会导致分子筛孔径增大、孔壁厚度减小、结晶度和有序度下降,同时促进骨架外六配位钛物种的生成。在n(Si)∶n(Ti)>20时合成的Ti-SBA-15介孔分子筛上,钛物种主要以四配位状态存在于分子筛骨架中。

Synthesis and Characterization of Ti-SBA-15 Mesoporous Molecular Sieves

Ti-SBA-15 mesoporous molecular sieves were hydrothermally synthesized by one-step method,using sodium silicate as the Si source,titanium trichloride as the Ti source and surface active agent P123 as the template.The effects of HCl concentration,n(Si)∶n(P123),crystallization temperature and n(Si)∶n(Ti) on the structure properties of Ti-SBA-15 mesoporous molecular sieve samples were investigated by means of XRD,N2 adsorption,TEM and UV-Vis techniques.It is indicated that,appropriate synthesis mother liquor acidity,Si source concentration and crystallization temperature could improve the structural orderliness of Ti-SBA-15 mesoporous molecular sieves,and increase its specific surface area and pore volume.Exorbitant crystallization temperature would result in the increase in pore size,the decreases of wall thickness and crystallinity,and the formation of hexahedral-coordinated Ti species outside the framework.In the condition of n(Si)∶n(Ti) more than 20,the Ti atoms primarily existed in the form of tetrahedral-coordination in the framework of Ti-SBA-15 mesoporous molecular sieves.