CO2 capture by CaCO3-MgO and CeO2-MgO sorbents promoted by ternary alkali metal salts in a fixed bed reactor

Abstract

MgO-based sorbents present a high theoretical CO2 carrying capacity which make them promising materials for CO2 capture at intermediate temperatures (200–400 °C). In this work, the MgO, CaCO3-MgO and CeO2-MgO sorbents were successfully synthesized by sol–gel technique. To enhance the CO2 capture performance a eutectic ternary alkali metal salt mixture consisting of 15 % of NaNO3/KNO3/LiNO3 (18/30/52) was added to the sorbents. The sorbents were tested in a fixed bed reactor unit along ten carbonation-calcination cycles, at 280 °C (25 % or 100 % of CO2) and 400 °C (100 % air), respectively. To identify textural, mineralogical, and morphological properties, the fresh and spent sorbents were characterized by N2 adsorption, XRD and SEM techniques. The results show that the addition of Ca or Ce precursors enhance the stability of sorbents surface area along the carbonation-calcination cycles and improves the AMS dispersion, reducing their agglomeration and contributing to the enhancement of the MgO-based sorbents’ CO2 carrying capacity.