Reduction of sulphur dioxide using carbon monoxide over gold supported catalysts

One percent gold supported on three different metal oxides (TiO₂, ZnO and Al₂O₃) has been evaluated as a catalyst, to reduce sulphur dioxide with carbon monoxide at different reaction temperatures. During the reaction, no carbonyl sulphide was formed and the only sulphur-containing product that was detected was elemental sulphur which condensed as S₈ at the reactor exit. High-resolution transmission electron microscopy, X-ray photoemission spectroscopy and powder X-ray diffraction have been used to study the interaction between the metal and the support as well as the size of metal particles before and after the reaction. We found that gold nanoparticles supported on TiO₂ had the best performance among all the supported catalysts (86.4% conversion) at a reaction temperature of 300?°C, a feed ratio of CO:SO₂?=?2:1 and a gas hourly space velocity of 3600?mL?g_cat^?1?h^?1. Au/ZnO and AuAl₂O₃ were only slightly active for SO₂ reduction at a range of temperatures from 50 to 300?°C. After 144?h on stream, the conversion of SO₂ over Au/TiO₂ was still the same as it was initially. The high activity of the 1% Au/TiO₂ catalyst resulted from the size of the gold particles and the strong interaction between the metal and the titania.