Fabrication of metal oxides-based adsorbents for SO2 capture with equimolar adsorption

Abstract

A series of novel porous metal oxides (MO, M = Mg, Ca, Ba, Mn and Zn) adsorbents were synthesized through simple thermal treatment of the corresponding metal sulfite for the remotion of sulfur dioxide (SO2). The obtained MO adsorbents were characterized by various techniques including scanning electron microscopy (SEM), thermal gravimetric analyzer (TGA), X-ray diffraction (XRD) and nitrogen adsorption studies. The results show that the SO2 adsorption capacity of manganese oxide (MnO) is much higher than that of other MO. And due to its highly dispersed and large specific surface area, especially its well-developed pore structure, equimolar adsorption of SO2 can be achieved for the first time among similar SO2 adsorbents. In addition, different sources of MnO were explored and it was found that the MnO obtained from the decomposition of MnSO3 had the highest SO2 adsorption capacity. Adsorption kinetic studies show that the reaction between MnO and SO2 conforms to the pseudo-second-order kinetic equation. Furthermore, it was found through seven-cycle experiments that the adsorption amount tended to stabilize in each of the following cycles, except for the first high temperature, which led to changes in the adsorbent and a decrease in cycling performance. This strategy has three advantages: one-step preparation at low temperatures, equimolar adsorption of SO2 as well as good reusability and selectivity.