Synthesis of MCM-22 zeolite by an ultrasonic-assisted aging procedure.

The synthesis of MCM-22 zeolite under hydrothermal crystallization conditions has been performed by an ultrasonic-assisted aging procedure. The ultrasonic-assisted aging of the initial aluminosilicate gel can shorten the crystallization time of MCM-22, decrease the amount of hexamethyleneimine (HMI) used, and broaden the range of SiO(2)/Al(2)O(3) ratios. By using the ultrasonic aging, pure phase of high-silica MCM-22 products with SiO(2)/Al(2)O(3)>100 can be obtained. When SiO(2)/Al(2)O(3) <or= 50, high crystalline MCM-22 zeolites with the reduced average crystal sizes can be made even with low HMI/SiO(2) ratio of 0.05 under static crystallization conditions. The acoustic cavitation of the ultrasonic is believed to be responsible for these positive results due to its cracking the crystal seeds and improving the solubility of silicate species.