A　series　of　highly　dispersed　manganese-based　catalysts　coating　on　PPS　were　prepared　using　a　novel　in-situ　synthesis　method　to　enhance　selective　catalytic　reduction　of　NOx　with　NH3　(NH3-SCR)　performance.　The　changes　of　catalysts’　structure,　morphology,　and　valence　state　were　systematically　researched　to　explore　the　formation　mechanism　of　three-dimensional　(3D)　porous　structure.　The　best　ternary　Mn-based　catalytic　filter　(0.6　Mn-Ce-SnOx/PPS)　displayed　excellent　catalyst　performance,　achieving　100%　NO　conversion　at　120　°C　and　above　90%　conversion　in　a　wide　temperature　range　100　to　180　°C.　It　can　be　regarded　as　the　most　excellent　low-temperature　de-NOx　catalytic　filter　identified　so　far.　It　may　be　due　to　the　synergistic　effect　between　tin　and　cerium　ions,　as　well　as　the　3D　porous　structure,　the　weak　crystallization,　and　high　ratios　of　Mn4+/Mn3+,　Ce　3+/(Ce3+　+　Ce4+),　and　Oα/(Oα　+　Oβ).　©　2021