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کاتالیزور کاربردی a: عمومی 2012
جزئیات رویداد
همایش ، رویداد ، ژورنال
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  • styrene epoxidation over v-sba-15 with alkaline-earth metal ion promotion under photo-assisted conditions

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    • تاریخ ارائه: 1392/07/24
    • تاریخ انتشار در تی پی بین: 1392/07/24
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     the photo-assisted epoxidation of styrene over v/sba-15 modified by alkaline-earth metal ions was investigated with hydrogen peroxide at room temperature. the results indicated that the isolated vo4tetrahedron dispersed on the sio2 was the photo-assisted catalytic active site for the formation of styrene oxide, while v5+ polymer species in v/sba-15 with highly loaded v species caused deep oxidation of styrene oxide. among the catalysts modified by alkaline-earth metal ions, mg–v/sba-15 displayed the best catalytic performance. it was probably due to the fact that the metallic character of mg was weaker in alkaline-earth metals, so it was easier to disperse v5+ polymer species and the dispersion effect was especially obvious in the comparatively high loading weight of vanadium oxide. moreover, addition of alkaline-earth metals decreased the acidic sites of v/sba-15, inhibiting the ring-opening reaction on which the deep oxidation occurred. the structures of all catalysts were thoroughly investigated using different characterization techniques, including x-ray diffraction (xrd), transmission electron microscopy (tem), nh3-temperature programmed desorption (tpd), h2 temperature-programmed reduction (tpr) and x-ray photoelectron spectroscopy (xps), etc. a possible catalytic mechanism was proposed.

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