SYNTHESIS AND PHYSICOCHEMICAL PROPERTIES OF ZEOLITES CONTAINING FRAMEWORK TITANIUM

Titanium-containing pure-silica ZSM-5 (TS-1), pure-silica ZSM-48 (Ti-ZSM-48) and zeolite beta (Ti-Al-beta) are synthesized and characterized by X-ray powder diffraction (XRD), elemental analysis, physical adsorption of nitrogen, Fourier transform infrared (FTIR), FT-Raman, and ultraviolet-visible (UV-VIS) spectroscopies. TS-1 is synthesized by five different methods. All materials are evaluated for their ability to oxidize 1-hexene and n-octane using aqueous hydrogen peroxide as the oxidant. The relationships between the physicochemical and catalytic properties of these titanium-containing zeolites are discussed. TS-1 samples synthesized at high pH are catalytically active and framework titanium is shown to be necessary for olefin epoxidation and alkane hydroxylation to occur. The existence of anatase in active TS-1 samples results in decreased hydrogen peroxide efficiencies in the epoxidation reaction. TS-1 produced at pH 7.4 and Ti-ZSM-48 each contain anatase and are not active. Ti-beta is found to contain framework titanium and be free of anatase. However, at the conditions used in this study these samples are not able to activate 1-hexene or n-octane.