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.

Fundamental study of carbon dioxide (CO2) physisorption and chemisorption is investigated with the NaX zeolite modified by addition of magnesium oxide (mechanical mixtures) or by impregnation of magnesium acetate (impregnated zeolites). Defined by their textural properties, these samples are characterized using the CO2 adsorption and desorption. Complementary results are obtained with infrared experiments. This study enabled to conclude that the addition of small amounts of magnesium oxide improved the interactions of physisorbed CO2 with the materials without noticeable increase of the chemisorption. The CO2 desorption energies are increased when small magnesium amounts are added. As shown with the deconvolution of the thermal desorption curves, all the “high” temperatures physisorbed species (300–400 K) are improved at the expense of the intermediate ones when the samples are modified.

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