Molecular oxygen-assisted oxidative dehydrogenation of ethylbenzene to styrene with nanocrystalline Ti1−xVxO2

Abstract

Oxidative dehydrogenation of ethylbenzene to styrene has been studied with vanadium-incorporated mesoporous nanocrystalline titania (Ti1−xVxO2) and molecular oxygen between 440 and 530 °C. Incorporation of V in TiO2 lattice framework has been achieved by simple solution combustion method. Incorporation of V in TiO2 lattice has been confirmed by X-ray diffraction, XPS and Raman spectra and other physicochemical analysis. High ethyl benzene conversion and stable styrene yield has been observed with 10% V-containing rutile phase titania at 500 °C. However, stable but relatively lower styrene yield has been observed with 2 and 5% V-containing catalysts between 440 and 500 °C. Highest selectivity is observed with lower vanadium content. Comparable activity has been observed under similar experimental conditions with four times higher air-flow than that of O2. In order to understand the structure activity relationship, spent catalysts were analyzed by all physico-chemical methods. Although there is a phase change from anatase to rutile Ti1−xVxO2 within 1 h of reaction, higher activity is primarily attributed to the ionic V5+ in Ti1−xVxO2 lattice, which prevents agglomeration to V2O5. It is to be underscored the reactivity is retained at the cost of textural properties and phase change from anatase to rutile, which is essential for the reaction.