Effect of crystallization temperature on structural transformations of mesoporous molecular sieve M41S materials

The effect of crystallization temperature on the structural transformations of mesoporous molecular sieve M41S materials was described for the cetyltrimethylammoniumsilicate system at a low surfactant/silica ratio and a low surfactant concentration. With increasing crystallization temperature to 135 °C, the texture of originally formed hexagonal MCM-41 is changed. When crystallization temperature increases to 150 °C, the thermal stability of M41S materials 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 °C, the microporous ZSM-5 type zeolite instead of mesoporous M41S materials is formed in the same synthetic system, resulting from the structural transformation of M41S to ZSM-5.