The synthesis, characterization, and catalytic activity of omega and ZSM-4 zeolites

The zeolites omega and ZSM-4 were both synthesized in the [(CH3)4N]2ONa2OAl2O3SiO2H2O system at a temperature of 95 °C. Although the starting reagents and synthesis procedures are different, the omega and ZSM-4 zeolites, on the basis of X-ray diffraction, have similar aluminosilicate structures. In the omega synthesis, a faujasite → omega reconstructive transition was discovered. No such transition was found in the ZSM-4 synthesis. Adsorption measurements show that omega zeolite rapidly adsorbs cyclooctatetraene but not (C4F9)3N. Acid catalysts derived from omega exhibit high α values for cracking of n-hexane. Hydrogen and lanthanum forms of omega and cocrystallized omega and faujasite show an increase in catalytic cracking activity with an increase in faujasite content. Comparative studies between omega and ZSM-4 catalysts show a slightly higher catalytic cracking activity for omega zeolite.