Study of physisorbed carbon dioxide on zeolites modified by addition of oxides or acetate impregnation

•The strengths of the CO2 physisorbed species are related with the chemisorbed sites distribution.•The quantities of unidentate carbonates in NaX are improved with small magnesium amounts.•The “strong” physisorbed species are improved at the expense of the intermediate ones.•The carbon dioxide/zeolite interactions are modified with the mechanical mixtures.