This study presents the first results on comparing Na- and Ca-based absorbers for separating SO2 from flue gases in two-phase flows where the gas is modeled as a continuous phase and the absorber droplets are solved as a discrete phase. The reactions are solved as volumetric reactions where reactions are assumed to be in instantaneous equilibrium with finite rate. The results show that the Na-based absorbers have considerably higher SO2 removal efficiency compared to Ca-based absorbers. NaHCO3 is found to have the highest separation efficiency of around 96% while the lowest removal efficiency is for naturally abundant CaO. The physics behind the domination of Na-based over Ca-based absorbers is described in this work which shows that the lower activation energy and better dispersion of Na-based absorbers compared to Ca-based absorbers leads to high SO2 removal in Na-based absorbers. It is also found that the utilization of H2O2 increases the efficiency of SO2 removal for NaHCO3 to 99.8%, for CaO to 88%, and for CaCO3 to 98% due to the enhanced solubility in the presence of H2O2.