Recent advances in simultaneous removal of SO2 and NOx from exhaust gases: Removal process, mechanism and kinetics

Abstract

• Oxidation, reduction, adsorption/absorption and microbial approaches are summarized. • Removal processes are divided into gas-gas, gas-liquid and gas-solid reactions. • Removal process, mechanism, and kinetics of pathways are systematically reviewed. • Effects of catalyzers and reaction conditions on removal efficiency are analyzed. • Challenges and potential breakthroughs in future de-SO 2 and de-NO x are discussed. SO 2 and NO x , major gaseous pollutants in exhaust gas, can exert adverse effects on human health and environmental disaster. Therefore, numerous desulfurization (de-SO 2 ) and denitrification (de-NO x ) technologies have been designed to reduce SO 2 and NO x emissions. Compared to traditional multi-step removal processes, simultaneous removal of SO 2 and NO x has been attracting significant attention recently. This paper timely reviewed available literature focused on simultaneous de-SO 2 and de-NO x methods, which are classified into four pathways as oxidation, reduction, adsorption/absorption and microbial purification. The removal process, basic mechanism and kinetics of each pathway are systematically reviewed in consideration of reactants, catalyzers, temperatures and atmosphere. Moreover, the main challenges and potential breakthroughs in developing novel simultaneous de-SO 2 and de-NO x methods are critically discussed to provide a roadmap for prospective research activities. Therefore, this review provides a deeper insight in understanding the mechanisms of de-SO 2 and de-NO x , and then helps to develop innovative simultaneous removal methods or improve the efficiency of available abatement methods.