Effects of SiO2/Al2O3 Ratio on Physicochemical Properties and Catalytic Performance of the Non-Templated ZSM-5 Zeolite

Abstract

The ZSM-5 zeolites of various SiO2/Al2O3ratios were synthesized without using any template agent. X-ray diffraction (XRD), transmission electron microscope (TEM), temperature- programmed desorption of ammonia (NH3-TPD) and Fourier transform infrared spectroscopy (FT-IR) techniques were employed to analyze the natures of the as-synthesized zeolite. The results show that the as-synthesized non-templated ZSM-5 zeolite is very pure. Meanwhile, Lewis acid sites and Bronsted acid sites are all presented in the as-synthesized non-templated HZSM-5 zeolite. The number of acid sites decreases almost linearly with the increasing of SiO2/Al2O3ratio of the zeolite. In addition, the reaction of propylene oligomerization was carried out over the as-synthesized non-templated HZSM-5 zeolite to evaluate the catalytic properties. The results show that the catalytic activity of propylene oligomerization decreases with the increasing of SiO2/Al2O3ratio.