Recycling of a spent iron based catalyst for the complete oxidation of toluene: effect of palladium

Abstract

Complete oxidation of volatile organic compound (toluene) was carried out to assess the property and activity of the palladium-spent iron based catalyst. The properties of the prepared catalysts were characterized by using the Brunauer–Emmett–Teller method and by conducting temperature-programmed reduction, X-ray diffraction, X-ray photoelectron spectroscopy and field emission transmission electron microscopy. The addition of palladium to the spent iron based catalyst pretreated with oxalic acid shifted the conversion curve for the total oxidation of toluene to lower temperature. An increase in the toluene conversion due to palladium was highly related to the easier lattice oxygen mobility of the catalysts. Instrumental analysis suggested the presence of a strong interaction between palladium and iron oxide species. Moreover, in the case of reducing the Pd/Fe catalyst with hydrogen, palladium accelerated the reducing iron oxides, subsequently decreasing the toluene conversion. As a result, the oxidation states of palladium and iron had an important effect on the catalytic activity.