Frontiers of Chemical Science and Engineering
Synthesis, characterization and catalytic properties of mesoporous MCM-48 containing zeolite secondary building units
1.The CNPC Key Laboratory of Catalysis, China University of Petroleum, Beijing 102249, China; 2.The CNPC Key Laboratory of Catalysis, China University of Petroleum, Beijing 102249, China; Institute of Special Chemicals, Taiyuan University of Technology, Taiyuan 030024, China; 3.Institute of Special Chemicals, Taiyuan University of Technology, Taiyuan 030024, China; 4.Institute of Daqing Petro Chemical, Daqing 163714, China
Available online: 2007-03-05
Mesoporous aluminosilicate MCM-48 containing zeolite secondary building units in the pore wall has been synthesized in alkaline media with a two-step procedure. The aluminosilicate precursors comprising zeolite secondary building units were first synthesized by carefully controlling reaction conditions and then were assembled using cotemplates of gemini surfactant [CHN(CH)(CH)N(CH)CH] (18-3-18) and triethanolamine (TEA). X-ray Diffraction (XRD) patterns of the as-made samples indicated that highly ordered mesostructured MCM-48 was formed. Transmission Electron Microscopy (TEM) images further verified the formation of MCM-48 with uniform cubic pore channel system having the pore opening diameter of about 25 Å. Compared with the conventionally synthesized MCM-48, the as-synthesized MCM-48 sample showed an adsorption band at 520 600 cm in its FT-IR spectrum, which was assigned to five-membered ring vibration from zeolite structure. This suggested the presence of zeolite building units in the pore wall. N2 adsorption data showed that the material had a much higher specific surface area (1 200 m/g) than the conventional MCM-48(1 100 m/g). Finally, the catalytic performance of the as-made MCM-48 was evaluated by hydrogenation dealkylation reaction of heavy aromatic hydrocarbons. Catalytic results showed that the as-made MCM-48 catalyst exhibited higher conversion than the conventional MCM-48 catalyst. The as-made mesostructured MCM-48 may have a potential catalytic application in the conversion of bulky molecules.