TiO2,CoS and SnO2 respectively by itself is inactive for the reduction of SO2 or/and NO by CO;however,we discovered that both TiO2- CoS （1:1 mass ratio） and TiO2- SnO2 （1:1 mass ratio） composite compounds are very active for such reactions,at 300－ 350℃ ,the conversion of SO2 to S,NO to N2 are over 90％ ,and the selectivity towards S or N2 are over 95％ .These mean that there are synergism effects between TiO2 and CoS,TiO2 and SnO2.It was confirmed by XRD characterization that TiO2 and CoO,TiO2 and SnO2 transform to rutile after calcinations at 500℃ ,however,individual TiO2（anatase） can only transform to rutile up to 900℃ .Therefore ,it is suggested that the synergism effects must be related to these composites comcound which exist as rutile structure.The study of the reaction mechanism and model of active phase are underway.
