The　homogeneous　dispersed　material　with　enhanced　active　species　plays　a　dominant　role　in　the　catalytic　activity.　The　Mn-Al　oxides　are　facilely　synthesized　by　the　hydrolysis-driven　redox-precipitation　method.　The　OMS-2　active　phase　and　surface　properties　can　be　effectively　adjusted　by　Al/Mn　molar　ratio,　which　alters　the　acetone　conversion　and　CO2　selectivity　of　prepared　catalysts.　Among　them,　MnAl0.15　exhibits　the　best　catalytic　performance　(90%　of　acetone　converted　at　168　°C)　with　CO2　selectivity　higher　than　95%,　mainly　owing　to　its　abundant　Olatt　and　Mn3+with　weaker　Mn-O　bond.　Although　the　presence　of　H2O　results　in　the　slow　consumption　rate　of　acetic　acid　that　leads　to　the　slightly　reduction　of　acetone　conversion　and　CO2　yield,　the　MnAl0.15　still　exhibits　superior　catalytic　stability.　The　PTR-MS　and　in　situ　DRIFTS　demonstrate　that　the　acetone　can　firstly　be　oxidized　to　acetaldehyde　and　ethanol,　and　then　further　decomposed　to　acetic　acid　and　formic　acid　before　total　mineralization.　©　2023