Abstract:
Mesoporous aluminosilicate MCM48 containing zeolite secondary building units in the pore wall, has been synthesized in alkaline media by a twostep procedure: the zeolite structure precursor was first synthesized by carefully controlling reaction conditions and then the presynthesized zeolite precursor was assembled using mixed templates of gemini surfactant \C18H37N(CH3)2(CH2)3N(CH3)2 C18H37\2+ and triethanolamine (TEA). Small angle XRD patterns of the asmade samples display strong diffraction peaks, indicating the highly ordered mesostructured MCM48 was formed. TEM images further show that the asmade sample has uniform cubic pore channel system with the pore diameter of about 2.5nm. FTIR technique was employed to characterize the pore wall of the MCM48 containing zeolite building units. IR spectra reveal an extra band at 520cm-1~600cm-1 assigned to fivemembered rings from zeolite structure, suggesting the presence of zeolite building units in the pore wall. N2 adsorption/desorption result shows the material has much higher specific surface area (1200m2/g), compared with the reported data (1100m2/g) of MCM48. 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 asmade MCM48 catalyst gives higher conversion than that on traditional MCM48. Thus, it is concluded that asmade MCM48 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 MCM48 are the controlled preparation of zeolite precursor and the selection of auxiliary template.