SnO2-TiO2 solid solution catalyst for simultaneous reduction of SO2 and NO by COI . Catalytic performance of the catalyst

A novel highly active SnO2-TiO2 solid solution catalyst for the simultaneous reduction of SO2 and NO by CO to produce S and N-2 has been prepared by coprecipitation. Over the SnO2-TiO2 catalyst with a SnO2 content of 50 % (mole fraction), under the reaction conditions of 350 degreesC, 0.0525 % SO2, 0.052 % NO, 0.208 % CO and space velocity of 3 000 h (-1), the NO conversion is nearly 100 %, the SO2 conversion is 88 % and the selectivity for S and N-2 is both nearly 100 %. In the whole reaction process no COS, a high toxic gas, was formed. The catalyst also shows high activity for the reduction of SO2 alone by CO, at 350 degreesC, 0.105 % SO2, 0.208 % CO and 3 000 h the conversion of SO2 is 98 % and the selectivity for S is nearly 100 %. But for the NO reduction by CO, the catalyst activity is rather low, at 350 degreesC, 0.1025 % NO, 0.208 % CO and 3 000 h(-1), the conversion of NO is 50 %. Therefore, SO2 shows promotion effect on the reduction of NO by CO over SnO2-TiO2. For SO2 + CO, NO + CO or SO2 + NO + CO reactions the catalytic activity of pure SnO2 or TiO2 is very low, but the activity of SnO2-TiO2 is very high. This suggests that there is synergism between SnO2 and TiO2.