Abstract: The pure ZSM-35 zeolite was synthesized in a static hydrothermal system at 220 ºC using cyclohexylamine as the template and silica sol as the Si source. When the initial gel contained a certain amount of K+, the mutual role of K+ and Na+ inhibited the formation of mordenite, and well crystallized product was formed with n(K+)/n(K++Na+) = 0.3. Optimum regions of the synthetic conditions of ZSM-35 zeolite obtained by X-ray diffraction were n(M2O)/n(Al2O3) = 3.2–3.4 and n(SiO2)/n(Al2O3) = 22. The building units in the precursor were identified as five-membered and six-membered silicate rings by UV-Raman spectroscopy. The intensity of the Raman band at 450 cm–1 increased in the beginning of crystallization, and the new bands at 421, 312, and 215 cm–1 appeared with consuming the amorphous gel, indicating that the ring species were turned out to be aggregate through the hydrothermal treatment, and finally formed ZSM-35 zeolite. The strong Raman band at 421 cm–1 should be assigned to the bending vibration of the five-membered silicate ring, and the Raman band at 312 cm–1 might cor-respond to the six-membered silicate ring of ZSM-35 zeolite framework.

Key words: ZSM-35 zeolite, static synthesis, cyclohexylamine, crystallization mechanism