The　mechanisms　of　sulfur　dioxide　poisoning　on　Mn/TiO2　and　Mn-Ce/TiO2　catalysts　are　studied　and　poisoning　resistance　effect　of　cerium　is　revealed.　Both　two　kinds　of　catalysts　were　deactivated　to　reduce　NOx　removal　in　the　presence　of　SO2,　however,　the　sulfur　resistance　performance　of　the　Ce　doping　catalysts　was　obviously　improved.　From　the　result　of　DRIFT　and　DFT,　SO2　can　first　adsorb　on　the　manganese-terminal　(Lewis　acid　sites)　to　form　sulfates,　which　inhibit　the　adsorption　of　NH3　in　the　SCR　reaction.　Deactivation　of　Bronsted　acid　sites　was　due　to　the　formation　of　bisulfite,　which　can　react　with　NH4+　form　NH4HSO4.　For　the　Mn-Ce/TiO2　catalysts,　SO2　preferentially　adsorbed　on　Ce　atom　as　sulfate　species,　alleviating　the　sulfation　of　the　main　active　sites　(Lewis　acid　sites　and　Broosted　acid　site　on　MnOx)　under　the　effect　of　SO2.　Furthermore,　cerium　sulfate　can　produce　new　Bronsted　acid　site　and　contribute　to　the　low-temperature　SCR　processes.　(C)　2016　Elsevier　B.V.　All　rights　reserved.