In situ FTIR investigation of CO2 adsorption over MgO–Impregnated NaY zeolites

Abstract The CO2 capture represents a major technical challenge to fight against global warming. Adsorption is an interesting alternative for CO2 capture. The use of oxides to enhance the CO2 adsorption over zeolites is largely pointed out in the literature. This study, dedicated to MgO–impregnated NaY zeolite, is based on CO2 adsorption and desorption over this adsorbent at various MgO rates (2, 5, 10, and 15 %) via in situ FTIR spectroscopy. This later provides very useful information about the physisorbed and chemisorbed CO2 according to MgO impregnation rate. FTIR investigation, based on adsorption at 25 °C of low and high doses of CO2, then followed by desorption under vacuum at 25, 100, and 200 °C, indicates that CO2 is physically adsorbed on cationic sites and chemically in the form of carbonates. The major carbonate species formed are bicarbonate, unidentate, chelated and bridged bidentate carbonate as well as carboxylate species. The results show that the chelated bidentate carbonate, and carboxylate species are the most resistant to desorption, which is related to both basicity and accessible porosity. In addition, this investigation highlights the heterogeneity of zeolites due to the formation of various adsorption basic sites.