孔壁含有沸石次级结构单元的MCM-48的合成及催化研究

Mesoporous aluminosilicate MCM48 containing zeolite secondary building units in the pore wall, has been synthesized in alkaline media by a twostep procedure: the zeolite structure precursor was first synthesized by carefully controlling reaction conditions and then the presynthesized zeolite precursor was assembled using mixed templates of gemini surfactant \[C18H37N(CH3)2(CH2)3N(CH3)2 C18H37\]2+ and triethanolamine (TEA). Small angle XRD patterns of the asmade samples display strong diffraction peaks, indicating the highly ordered mesostructured MCM48 was formed. TEM images further show that the asmade sample has uniform cubic pore channel system with the pore diameter of about 2.5nm. FTIR technique was employed to characterize the pore wall of the MCM48 containing zeolite building units. IR spectra reveal an extra band at 520cm－1~600cm－1 assigned to fivemembered rings from zeolite structure, suggesting the presence of zeolite building units in the pore wall. N2 adsorption/desorption result shows the material has much higher specific surface area （1200m2/g）, compared with the reported data （1100m2/g） of MCM48. This may be ascribed to the presence of micropores produced by zeolite secondary building units in its pore wall. The hydrogenation dealkylation reaction of heavy aromatic hydrocarbons on the asmade MCM48 catalyst gives higher conversion than that on traditional MCM48. Thus, it is concluded that asmade MCM48 containing the secondary building units of zeolites is of potential application in the catalytic conversion of large molecules. The key factors in our synthesis of MCM48 are the controlled preparation of zeolite precursor and the selection of auxiliary template.