Catalytic reduction of SO2 by CO over CeO2–TiO2 mixed oxides

Abstract The structure and catalytic desulfurization characteristics of CeO 2 –TiO 2 mixed oxides were investigated by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and catalytic activity tests. According to the results, a CeO 2 –TiO 2 solid solution is formed when the mole ratio of cerium to titanium n (Ce): n (Ti) is 5:5 or greater, and the most suitable n (Ce): n (Ti) is determined as 7:3, over which the conversion rate of SO 2 and the yield of sulfur at 500 °C reach 93% and 99%, respectively. According to the activity testing curve, Ce 0.7 Ti 0.3 O 2 ( n (Ce): n (Ti)=7:3) without any pretreatment can be gradually activated by reagent gas after about 10 min, and reaches a steady activation status 60 min later. The XPS results of Ce 0.7 Ti 0.3 O 2 after different time of SO 2 +CO reaction show that CeO 2 is the active component that offers the redox couple Ce 4+ /Ce 3+ and the labile oxygen vacancies, and TiO 2 only functions as a catalyst structure stabilizer during the catalytic reaction process. After 48 h of catalytic reaction at 500 °C, Ce 0.7 Ti 0.3 O 2 still maintains a stable structure without being vulcanized, demonstrating its good anti-sulfur poisoning performance.