| Dehydrogenation of hydrocarbons is one of the challenges in the petrochemical industry, since it is often confined by the thermodynamic equilibrium. Styrene, one of the monomers of synthetic polymers, is mainly produced by the dehydrogenation of ethylbenzene under high temperature. The process leads to the high operation cost and excessive energy consumption. However, reaction coupling by means of CO2 is one of the best substitutes of the commercial dehydrogenation technique, which has solved the above-mentioned problems faced in industry. The technique has been studied extensively in recent years.In recent work, by dopping a small amount of La2O3 or CeO2, 3%La2O317%Fe2O3/γ-Al2O3 and 3%La2O317%V2O-5/γ-Al2O3 series catalysts were prepared by means of a sol-gel technique. The catalyst was applied for weak oxidative dehydrogenation of ethylbenzene to styrene in the presence of CO2. Meanwhile, the effect of different catalysts on the conversion of ethylbenzene and CO2, as well as the selectivity of styrene was investigated. The factors that affected the activity of catalysts were probed, such as, preparation methods, contents of active species and reaction temperature. In addition, the cause of catalyst deactivation as well as the method of catalyst regeneration was studied. The function of CO2 and the mechanism of reaction coupling were discussed. The result indicated that, under the conditions of an atmospheric pressure,θ=600℃and GHSV=15 mmol/(gcat·h), 3%La2O317%V2O5/γ-Al2O3 catalyst exhibited in higher activity for dehydrogenation of ethylbenzene compared to other catalysts. The conversion of ethylbenzene and CO2 was 78.0% and 5.8%, respectively, and the selectivity of styrene was 98.2%. In addition, the structure of catalysts in bulk before and after reaction as well as the thermal weight loss of used catalyst was characterized by means of XRD, IR and TG-DTA techniques. The reason resulted in catalyst deactivation and the regeneration of catalyst was analyzed.
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