Vapor-phase dehydrogenation of ethylbenzene to styrene over a V2O5/TiO2–Al2O3 catalyst with CO2

Abstract

The activity of a V₂O₅/TiO₂–Al₂O₃ catalyst for oxidative dehydrogenation of ethylbenzene to styrene with various V₂O₅ loadings in the presence of CO₂ and N₂ was studied. Among the different loadings of V₂O₅, the 5 wt% V₂O₅/TiO₂–Al₂O₃ catalyst exhibited better activity. The incorporation of TiO₂ into the Al₂O₃ support greatly influenced the activity of the catalyst. The maximum conversion of ethylbenzene and styrene selectivity were observed to be 65% and 96%, respectively, at 550 °C and notable stability was observed up to 60 hours with CO₂. The conversion directly depends on the availability of active V⁵⁺ sites. The facile redox cycle between fully oxidized and reduced V species was effective for the reaction. The catalysts were characterized by X-ray diffraction, Raman spectroscopy, BET surface area and pore size distribution, scanning electron microscopy, and H₂–temperature programmed reduction. The results indicate that the surface area, interaction with the support, morphology of the catalyst and surface active sites had a significant influence on the activity.