Effect of the Composition and Synthesis Method on the Sorption Properties of NaNO3/MgO Sorbents with Respect to Carbon Dioxide

Abstract

In this work, sorbents based on magnesium oxide MgO modified with NaNO₃ taken in a concentration of 5–50 mol % have been synthesized and studied by various methods. It has been shown that the optimum synthesis method is impregnation of the MgO precursor. The optimum concentration of NaNO₃ as a modifier is 10 mol %; this concentration provides a sorption capacity of 6.5 mmol CO₂/g_sorb within 1 h of sorption at 320°C and a CO₂ content of 50 vol %. The sorption capacity achieved in 10 consecutive sorption–desorption cycles for 10 mol % NaNO₃ is 4.5–5.5 mmol CO₂/g_sorb within 30 min of sorption at 50 vol % CO₂ and temperatures of 300 and 350°C for the sorption and desorption stages, respectively. It has been found that an increase in the total sorption pressure to 10 atm makes it possible to decrease the sorption temperature to 220–260°C, and the achieved sorption capacity is 4.0 mmol CO₂/g_sorb at 25 vol % CO₂, which is almost 2 times higher than the sorption capacity value at 1 atm. It has been shown that treatment with steam and hydrogen does not lead to a significant change in the sorption properties and phase composition of MgO modified with NaNO₃.