Catalytic activity of rare earth-promoted SO42-/SnO2 in the oxidative dehydrogenation of ethylbenzene

Rare earth-promoted (10%) sulfated SnO2 catalysts were prepared by differen t methods and have been characterized by employing XRD, SEM, Mercury porosi metry, BET surface-area analysis, TG-DTA, and IR spectroscopy. The strength of generated acid sites depends on the preparation method. A thermogravime tric analysis revealed that the removing the sulfate species from the catal yst surface took place at temperatures >1193 K. The adsorption of butylamin e and acetic acid was used to probe the acid-base properties of the catalys ts. The catalytic activity of these materials in the oxidative dehydrogenat ion of ethylbenzene was tested at different temperatures. It was found that rare earth-modified sulfated tin oxide catalysts are more active when comp ared to the corresponding mixed-oxide systems and sulfated tin oxide. The c ombined effect of rare earth oxide and the sulfate anion leads to a enhance d oxidation activity. The existence of strong acid sites generated as a res ult of a sulfate treatment is involved in the activation of ethylbenzene; t he addition of rare earth oxides brings about an enhancement of the reactio n between the adsorbed oxygen atoms and the adsorbed ethylbenzene.