CO2 Adsorption Performance of Na/K-Impregnated MgO

Abstract

As a carbon dioxide solid sorbents, magnesium oxide has been widely studied due to its wide distribution and low price. But pure MgO under intermediate temperature (250–500 °C) showed a poor CO2 capture capacity. In our study, an effective method for improving the cyclic adsorption stability is to prepare the MgO-based sorbents promoted by sodium/potassium nitrate and citric acid through the mixing-impregnation method. The sorbents were determined by powder X-ray diffraction analyzer (XRD), thermogravimetric analyzer (TGA), and N2 adsorption and desorption were measured at 77 K. The morphology of the sorbents was investigated by scanning electron microscopy (SEM). The results showed that as-prepared composites promoted by sodium nitrate and citric acid exhibited a better adsorption capacity than those modified by potassium nitrate and citric acid, which was 3.9158 mmol/g during the cyclic CO2 adsorption reaction of calcination temperature of 450 °C and carbonation temperature of 350 °C. After 30 cycles of adsorption and desorption, the capture capacity of this sorbents was stable at 3.769 mmol/g. The SEM indicated that the pore morphology of these modified sorbents becomes abundant. Overall, the as-prepared Na/K impregnated MgO sorbent was promising for cyclic intermediate temperature CO2 capture.