SYNTHESIS AND CHARACTERIZATION OF TITANIUM CATALYST CONTAINING POLYSTYRENE COMPOSITES FOR EPOXIDATION OF 1-OCTENE

Abstract

The titanium catalyst containing polystyrene composites have been prepared by reacting titanium (iv) isopropoxide (TTIP) with octadecyllthrichlorosilane (OTS) under ambient atmosphere with absence and presence of water. The resulting catalysts were characterized by diffuse reflectance ultraviolet-visible (DR UV-Vis) spectroscopy, X-ray diffraction (XRD) spectroscopy, field emission scanning electron microscopy (FESEM) attached with energy dispersive X-ray (EDX) spectroscopy, Fourier transform infrared spectroscopy (FTIR) and ²⁹Si Magic Angle Spinning Nuclear Magnetic Resonances (²⁹Si MAS NMR). XRD patterns demonstrated that the as-synthesized titanium containing catalysts were in amorphous phase. Meanwhile, the optical analysis by DR UV-Vis spectroscopy showed that the intensity of tetrahedral titanium peak at wavelength of 360 nm was increased, suggesting that the presence of water during the reaction between TIPOT and OTS has facilitated the formation of Ti – O – Si linkages. The formation of Ti – O – Si linkages were also supported by NMR studies which demonstrated a peak shifting from lower to higher intensity in -40 ppm, which corresponds to the formation of Q². The as-prepared catalyst with the high content of titanium tetrahedral (0.5-SiO₂-TiO₂) was selected as catalyst in polymerization of styrene in the presence of aqueous hydrogen peroxide (H₂O₂). The polymerization of styrene using the 0.5-SiO₂-TiO₂ produced the polystyrene-TiO₂ composite. The catalytic performance of polystyrene TiO₂ composites have been evaluated in the epoxidation of 1-octene in the presence of aqueous hydrogen peroxide. However, it was observed that the presence of polystyrene in SiO₂-TiO₂ did not improve much the catalytic activity as 17.3 mmol of 1,2 epoxyoctane was obtained, a slight increase of 0.5% compared to unmodified TiO₂.