The　mesoporous　alumina-supported　alkaline　earth　metal　5　M/MA　(MA　=　mesoporous　alumina,　M　=Mg,　Ca,　Sr,　and　Ba)　and　x　Mg/MA　(　x　=1,　3,　5,　and　7　wt%)　adsorbents　were　synthesized　via　evaporation-induced　self-assembly　(EISA)　and　impregnation　method.　The　adsorption　properties　of　CO　2　were　evaluated　by　thermal　gravimetric　analyzer　to　focus　on　exploring　the　dynamic　adsorption　process　of　the　prepared　adsorbents.　Loading　alkaline　earth　metals　mainly　enhanced　the　basic　sites　of　these　adsorbents,　and　the　alkaline　sites　played　an　extremely　critical　role　in　determining　the　amount　of　CO　2　adsorbed.　Of　all　the　adsorbents　prepared,　5Mg/MA　exhibited　the　highest　adsorption　uptake　(1.08　mmol/g),　a　2.16-fold　enhancement　compared　to　MA　(0.50　mmol/g).　In　-situ　DRIFTS　indicated　that　CO　2　primarily　existed　in　the　form　of　carbonate　species,　and　the　analysis　of　adsorption　kinetics　elucidated　that　the　adsorption　process　was　predominantly　chemisorbed,　with　external　diffusion　being　the　main　process　of　adsorption.　Simultaneously,　based　on　DFT　calculations,　it　has　been　found　that　Mg-loaded　MA　has　a　higher　affinity　for　CO　2　compared　to　MA,　which　providing　a　good　explanation　for　the　experimental　results.　Furthermore,　the　5　Mg/MA　adsorbent　not　only　exhibited　excellent　adsorption　capacity,　but　also　maintained　excellent　cyclic　stability　after　10　adsorption　and　desorption　cycle　runs,　making　it　a　highly　favorable　option　for　capturing　CO　2　.