关键词: Al-MCM-41, 骨架铝, 模板剂

Abstract: Mesoporous molecular sieves MCM-41 with different contents of incorporated structural aluminum were prepared by a modified hydrothermal method using simultaneously two templates. The characterization by using X-ray powder diffraction and nitrogen adsorption techniques revealed that all samples behaved a typical XRDdiffraction of MCM-41, an adsorption isotherm of type Ⅳ and a regular pore size distribution. Although the pore diameter and the uniformity of the pore size distribution were decreased to some extent with the increase of the content of aluminum. The last feature reflects that the Al-MCM-41 prepared by this method has a highly ordered structure of pore arrays. Solid state ²⁷Al MAS NMRinvestigation showed that Al atoms in these samples were incorporated tetrahedrally in the MCM-41 structure, without the existence of extra-framework aluminum. In this paper, the samples prepared by the traditional hydrothermal method were also investigated and compared with those prepared by the new method. The results showed that the purity and formation of cylindrical pore structure of MCM-41 was enhanced by the use of mixed template. The Al atoms could still be incorporated tetrahedrally in the MCM-41 structure even at high level of aluminum. Finally, a theoretical consideration on the simultaneous use of two templates in the synthesis was discussed.

Key words: Al-MCM-41, Tetrahedrally coordinated framework aluminum, Template