Abstract: The effect of crystallization temperature on the structural transformations of mesoporous molecular sieve M41Smaterials was described for the cetyltrimethylammoniumsilicate system at a low surfactant/silica ratio and a low surfactant concentration.With increasing crystallization temperature to 135 ℃,the texture of originally formed hexagonal MCM-41 is changed.When crystallization temperature increases to 150℃, the thermal stability of M41Smaterials is decreased due to the transformation of mesoporous structure from hexagonal MCM-41 lattice to thermally unstable lamellar phase.Further increasing crystallization temperature to or above 165℃, the microporous ZSM-5 type zeolite instead of mesoporous M41Smaterials is formed in the same synthetic system, resulting from the structural transformation of M41Sto ZSM-5.

Key words: Mesoporous M41S materials, ZSMm-5 zeolite, Structural transformation