Fabrication of Strong Solid Base FeO–MgO for Warm CO2 Capture

Abstract

A strong solid base, FeO–MgO, is synthesized using magnesium acetate and ferrous acetate in order to meet the requirement of capturing CO2 in flue gas at a temperature higher than 423 K. After the two salts are ground and carbonized at 823 K, the ferric MgO composite with a surface area exceeding 160 m2 g−1 is obtained, where ferric oxide species are wrapped by magnesia particles. The influence of ferric salt on the structure and adsorption properties of the strong solid bases is investigated to determine the optimal amount, and the distribution of ferric additive is assessed with X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy (XPS). With a mass ratio of ferrous oxide of about 3%, the basic sorbent could capture 35 mg g−1 CO2 at 473 K and the ratio of strong base sites increases to 91%. Both the CO2 adsorption capacity and the ratio of strong basic sites are higher than those of the other MgO sorbents, which is beneficial for warm CO2 capture. Additionally, the function of strong basic sites in the ferric MgO sorbent is explored in the instantaneous adsorption of warm CO2. The capability in the cycled warm CO2 adsorption is found to be related to the desorption temperature of CO2. Different forms of CO2 injections are used in adsorption and the influence on the performance of the strong basic sorbent is also studied.