Simultaneous catalytic reduction of SO2 and NO from flue gas using H2S as a reductant at low temperatures
Although harmful NO and SO2 in flue gas can be separately removed by the established technologies, such as selective catalytic reduction (SCR) or selective non-catalytic reduction(SNCR) and wet scrubbing process, integrated method for simultaneous desulfurization and denitrification is still in demand and attractive to improve energy efficiency and reduce investment and operation cost. Upon this, a novel sulfur-cycling integrated technology of simultaneous catalytic desulfurization and denitrification with H2S (H2S-SCDD) has been proposed and is considered to be a profitable solution to the flue gas treatment. However, the high operation temperature (over 600oC) was required in the H2S-SCDD process for the sulfur-cycling flue gas treatment as reported. To realize the H2S-SCDD process at low temperatures, different catalysts were prepared and tested, such as Al2O3-TiO2 (AT) loaded with transition metal oxides. The results show that, CeO2-loaded AT catalyst (Ce-AT) was the suitable catalyst to balance NO and SO2 removal by the H2S-SCDD process in the temperature range of 300−400℃. Increasing Ce loading on AT significantly increased the NO conversion but had a slightly negative effect on SO2 reduction. With 15% Ce loading on AT catalyst (Ce15-AT), the optimal temperature for the H2S-SCDD process was 240—280℃. While at 280℃, the SO2 and NO conversions were about 75% and 90%, respectively, implying the efficient and simultaneous reduction of NO and SO2. Upon this, the sulfur-cycling process is promising and attractive for flue gas treatment in industrial sectors.