Oxidation of SO2 to SO3 catalyzed by graphene oxide foams

Abstract

Porous graphene oxide foams were prepared by unidirectional freeze-drying technology and used to investigate the reaction between graphene oxide (GO) and SO₂. The structure and composition changes of the graphene oxide were monitored by X-ray photoelectron spectrometry (XPS), Raman, X-ray diffraction (XRD), Thermogravimetric analysis (TGA), and ultraviolet-visible spectroscopy (UV-vis), and the product of the reaction was analyzed by an EDTA titration. The results show that SO₂ was oxidized to SO₃ and the GO was reduced. GO not only acts as the oxidant in the reaction, but also as the catalyst to catalyze the reaction of SO₂ and O₂ to form SO₃. This catalytic action is more active in the aqueous GO suspensions than in the foams. The GO foams can adsorb SO₂ and convert it to SO₃ which then changes to SO₄²⁻ on contact with water. This offers a new effective method of converting noisome SO₂ gas to SO₃ at room temperature.