Simultaneous removal of SO2 and NO by self-activated NaHCO3

Abstract

Systematical experiments, mechanistic studies, and kinetic studies of SO2/NO removal with NaHCO3 were first carried out in this paper. The results showed that NaHCO3 was self-activated by an in-situ decomposition process that generated more active sites for SO2/NO removal. The efficiency of NO removal was sensitive to the oxygen concentration and the presence of SO2. The optimal SO2/NO removal efficiencies reached 100%/85% at 160 °C and with O2 concentrations over 5%. Additional mechanistic studies showed that the presence of NO facilitated the conversion of SO32-→SO42-. The intermediate NO2 generated by NO oxidation competed with SO2 for adsorption sites. Kinetic studies illustrated that the absorption of NO2 was the rate controlling step in the early NO removal process. The optimal parameters obtained were sulfur-to-sodium ratios of 2–3 and volume space velocities of 20,000–30,000 h−1. A potential application involving “Na2SO4 to NaHCO3” was proposed for Na2SO4 utilization and integrated SO2/NO2/CO2 removal.