SO_x tolerant Pt/TiO₂ catalysts for CO oxidation and the effect of TiO₂ supports on catalytic activity

We developed a new technique for mitigating catalyst deactivation caused by SO₂ in exhaust gases. A series of 0.1 wt %-Pt/TiO₂ catalysts with different surface, crystal, and pore structures were prepared and tested for CO oxidation activity in the presence of SO₂ and H₂O. The order of the CO oxidation activity under the influence of SO₂ was much different from that in the absence of SO₂. Catalysts with a high ratio of larger pores exhibited higher catalytic activity under the influence of SO₂ and H₂O in the temperature range of 250-300 °C, whereas other parameters, such as BET surface area and crystal structure of the TiO₂ support, had minor effects on the CO oxidation activity. The oxidation state of Pt differed significantly depending on the kind of TiO₂ support. Some catalysts were less active without H₂ reduction pretreatment due to the presence of oxidized Pt species.